rocksdb/db/db_impl.cc
Siying Dong 073cbfc8f0 Enable background flush thread by default and fix issues related to it
Summary:
Enable background flush thread in this patch and fix unit tests with:
(1) After background flush, schedule a background compaction if condition satisfied;
(2) Fix a bug that if universal compaction is enabled and number of levels are set to be 0, compaction will not be automatically triggered
(3) Fix unit tests to wait for compaction to finish instead of flush, before checking the compaction results.

Test Plan: pass all unit tests

Reviewers: haobo, xjin, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13461
2013-10-16 13:32:53 -07:00

3342 lines
113 KiB
C++

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/db_impl.h"
#include <algorithm>
#include <climits>
#include <cstdio>
#include <set>
#include <string>
#include <stdint.h>
#include <stdexcept>
#include <vector>
#include <unordered_set>
#include "db/builder.h"
#include "db/db_iter.h"
#include "db/dbformat.h"
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "db/memtable.h"
#include "db/memtablelist.h"
#include "db/merge_helper.h"
#include "db/prefix_filter_iterator.h"
#include "db/table_cache.h"
#include "db/version_set.h"
#include "db/write_batch_internal.h"
#include "db/transaction_log_impl.h"
#include "rocksdb/compaction_filter.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/table_builder.h"
#include "port/port.h"
#include "table/block.h"
#include "table/merger.h"
#include "table/table.h"
#include "table/two_level_iterator.h"
#include "util/auto_roll_logger.h"
#include "util/build_version.h"
#include "util/coding.h"
#include "util/logging.h"
#include "util/mutexlock.h"
#include "util/stop_watch.h"
namespace rocksdb {
void dumpLeveldbBuildVersion(Logger * log);
// Information kept for every waiting writer
struct DBImpl::Writer {
Status status;
WriteBatch* batch;
bool sync;
bool disableWAL;
bool done;
port::CondVar cv;
explicit Writer(port::Mutex* mu) : cv(mu) { }
};
struct DBImpl::CompactionState {
Compaction* const compaction;
// If there were two snapshots with seq numbers s1 and
// s2 and s1 < s2, and if we find two instances of a key k1 then lies
// entirely within s1 and s2, then the earlier version of k1 can be safely
// deleted because that version is not visible in any snapshot.
std::vector<SequenceNumber> existing_snapshots;
// Files produced by compaction
struct Output {
uint64_t number;
uint64_t file_size;
InternalKey smallest, largest;
SequenceNumber smallest_seqno, largest_seqno;
};
std::vector<Output> outputs;
std::list<uint64_t> allocated_file_numbers;
// State kept for output being generated
unique_ptr<WritableFile> outfile;
unique_ptr<TableBuilder> builder;
uint64_t total_bytes;
Output* current_output() { return &outputs[outputs.size()-1]; }
explicit CompactionState(Compaction* c)
: compaction(c),
total_bytes(0) {
}
};
struct DBImpl::DeletionState {
// the list of all live files that cannot be deleted
std::vector<uint64_t> live;
// a list of all siles that exists in the db directory
std::vector<std::string> allfiles;
// the current filenumber, lognumber and prevlognumber
// that corresponds to the set of files in 'live'.
uint64_t filenumber, lognumber, prevlognumber;
// the list of all files to be evicted from the table cache
std::vector<uint64_t> files_to_evict;
};
// Fix user-supplied options to be reasonable
template <class T, class V>
static void ClipToRange(T* ptr, V minvalue, V maxvalue) {
if (static_cast<V>(*ptr) > maxvalue) *ptr = maxvalue;
if (static_cast<V>(*ptr) < minvalue) *ptr = minvalue;
}
Options SanitizeOptions(const std::string& dbname,
const InternalKeyComparator* icmp,
const InternalFilterPolicy* ipolicy,
const Options& src) {
Options result = src;
result.comparator = icmp;
result.filter_policy = (src.filter_policy != nullptr) ? ipolicy : nullptr;
ClipToRange(&result.max_open_files, 20, 1000000);
ClipToRange(&result.write_buffer_size, ((size_t)64)<<10,
((size_t)64)<<30);
ClipToRange(&result.block_size, 1<<10, 4<<20);
// if user sets arena_block_size, we trust user to use this value. Otherwise,
// calculate a proper value from writer_buffer_size;
if (result.arena_block_size <= 0) {
result.arena_block_size = result.write_buffer_size / 10;
}
result.min_write_buffer_number_to_merge = std::min(
result.min_write_buffer_number_to_merge, result.max_write_buffer_number-1);
if (result.info_log == nullptr) {
Status s = CreateLoggerFromOptions(dbname, result.db_log_dir, src.env,
result, &result.info_log);
if (!s.ok()) {
// No place suitable for logging
result.info_log = nullptr;
}
}
if (result.block_cache == nullptr && !result.no_block_cache) {
result.block_cache = NewLRUCache(8 << 20);
}
result.compression_per_level = src.compression_per_level;
if (result.block_size_deviation < 0 || result.block_size_deviation > 100) {
result.block_size_deviation = 0;
}
if (result.max_mem_compaction_level >= result.num_levels) {
result.max_mem_compaction_level = result.num_levels - 1;
}
if (result.soft_rate_limit > result.hard_rate_limit) {
result.soft_rate_limit = result.hard_rate_limit;
}
if (result.compaction_filter &&
result.compaction_filter_factory->CreateCompactionFilter().get()) {
Log(result.info_log, "Both filter and factory specified. Using filter");
}
if (result.prefix_extractor) {
// If a prefix extractor has been supplied and a PrefixHashRepFactory is
// being used, make sure that the latter uses the former as its transform
// function.
auto factory = dynamic_cast<PrefixHashRepFactory*>(
result.memtable_factory.get());
if (factory &&
factory->GetTransform() != result.prefix_extractor) {
Log(result.info_log, "A prefix hash representation factory was supplied "
"whose prefix extractor does not match options.prefix_extractor. "
"Falling back to skip list representation factory");
result.memtable_factory = std::make_shared<SkipListFactory>();
} else if (factory) {
Log(result.info_log, "Prefix hash memtable rep is in use.");
}
}
if (result.wal_dir.empty()) {
// Use dbname as default
result.wal_dir = dbname;
}
return result;
}
DBImpl::DBImpl(const Options& options, const std::string& dbname)
: env_(options.env),
dbname_(dbname),
internal_comparator_(options.comparator),
options_(SanitizeOptions(
dbname, &internal_comparator_, &internal_filter_policy_, options)),
internal_filter_policy_(options.filter_policy),
owns_info_log_(options_.info_log != options.info_log),
db_lock_(nullptr),
mutex_(options.use_adaptive_mutex),
shutting_down_(nullptr),
bg_cv_(&mutex_),
mem_rep_factory_(options_.memtable_factory),
mem_(new MemTable(internal_comparator_, mem_rep_factory_,
NumberLevels(), options_)),
logfile_number_(0),
tmp_batch_(),
bg_compaction_scheduled_(0),
bg_flush_scheduled_(0),
bg_logstats_scheduled_(false),
manual_compaction_(nullptr),
logger_(nullptr),
disable_delete_obsolete_files_(false),
delete_obsolete_files_last_run_(0),
purge_wal_files_last_run_(0),
last_stats_dump_time_microsec_(0),
stall_level0_slowdown_(0),
stall_memtable_compaction_(0),
stall_level0_num_files_(0),
stall_level0_slowdown_count_(0),
stall_memtable_compaction_count_(0),
stall_level0_num_files_count_(0),
started_at_(options.env->NowMicros()),
flush_on_destroy_(false),
stats_(options.num_levels),
delayed_writes_(0),
last_flushed_sequence_(0),
storage_options_(options),
bg_work_gate_closed_(false),
refitting_level_(false) {
mem_->Ref();
env_->GetAbsolutePath(dbname, &db_absolute_path_);
stall_leveln_slowdown_.resize(options.num_levels);
stall_leveln_slowdown_count_.resize(options.num_levels);
for (int i = 0; i < options.num_levels; ++i) {
stall_leveln_slowdown_[i] = 0;
stall_leveln_slowdown_count_[i] = 0;
}
// Reserve ten files or so for other uses and give the rest to TableCache.
const int table_cache_size = options_.max_open_files - 10;
table_cache_.reset(new TableCache(dbname_, &options_,
storage_options_, table_cache_size));
versions_.reset(new VersionSet(dbname_, &options_, storage_options_,
table_cache_.get(), &internal_comparator_));
dumpLeveldbBuildVersion(options_.info_log.get());
options_.Dump(options_.info_log.get());
char name[100];
Status st = env_->GetHostName(name, 100L);
if (st.ok()) {
host_name_ = name;
} else {
Log(options_.info_log, "Can't get hostname, use localhost as host name.");
host_name_ = "localhost";
}
last_log_ts = 0;
}
DBImpl::~DBImpl() {
// Wait for background work to finish
if (flush_on_destroy_ && mem_->GetFirstSequenceNumber() != 0) {
FlushMemTable(FlushOptions());
}
mutex_.Lock();
shutting_down_.Release_Store(this); // Any non-nullptr value is ok
while (bg_compaction_scheduled_ ||
bg_flush_scheduled_ ||
bg_logstats_scheduled_) {
bg_cv_.Wait();
}
mutex_.Unlock();
if (db_lock_ != nullptr) {
env_->UnlockFile(db_lock_);
}
if (mem_ != nullptr) mem_->Unref();
imm_.UnrefAll();
}
// Do not flush and close database elegantly. Simulate a crash.
void DBImpl::TEST_Destroy_DBImpl() {
// ensure that no new memtable flushes can occur
flush_on_destroy_ = false;
// wait till all background compactions are done.
mutex_.Lock();
while (bg_compaction_scheduled_ ||
bg_flush_scheduled_ ||
bg_logstats_scheduled_) {
bg_cv_.Wait();
}
// Prevent new compactions from occuring.
bg_work_gate_closed_ = true;
const int LargeNumber = 10000000;
bg_compaction_scheduled_ += LargeNumber;
mutex_.Unlock();
// force release the lock file.
if (db_lock_ != nullptr) {
env_->UnlockFile(db_lock_);
}
log_.reset();
versions_.reset();
table_cache_.reset();
}
uint64_t DBImpl::TEST_Current_Manifest_FileNo() {
return versions_->ManifestFileNumber();
}
Status DBImpl::NewDB() {
VersionEdit new_db(NumberLevels());
new_db.SetComparatorName(user_comparator()->Name());
new_db.SetLogNumber(0);
new_db.SetNextFile(2);
new_db.SetLastSequence(0);
const std::string manifest = DescriptorFileName(dbname_, 1);
unique_ptr<WritableFile> file;
Status s = env_->NewWritableFile(manifest, &file, storage_options_);
if (!s.ok()) {
return s;
}
file->SetPreallocationBlockSize(options_.manifest_preallocation_size);
{
log::Writer log(std::move(file));
std::string record;
new_db.EncodeTo(&record);
s = log.AddRecord(record);
}
if (s.ok()) {
// Make "CURRENT" file that points to the new manifest file.
s = SetCurrentFile(env_, dbname_, 1);
} else {
env_->DeleteFile(manifest);
}
return s;
}
void DBImpl::MaybeIgnoreError(Status* s) const {
if (s->ok() || options_.paranoid_checks) {
// No change needed
} else {
Log(options_.info_log, "Ignoring error %s", s->ToString().c_str());
*s = Status::OK();
}
}
const Status DBImpl::CreateArchivalDirectory() {
if (options_.WAL_ttl_seconds > 0) {
std::string archivalPath = ArchivalDirectory(options_.wal_dir);
return env_->CreateDirIfMissing(archivalPath);
}
return Status::OK();
}
void DBImpl::PrintStatistics() {
auto dbstats = options_.statistics;
if (dbstats) {
Log(options_.info_log,
"STATISTCS:\n %s",
dbstats->ToString().c_str());
}
}
void DBImpl::MaybeDumpStats() {
if (options_.stats_dump_period_sec == 0) return;
const uint64_t now_micros = env_->NowMicros();
if (last_stats_dump_time_microsec_ +
options_.stats_dump_period_sec * 1000000
<= now_micros) {
// Multiple threads could race in here simultaneously.
// However, the last one will update last_stats_dump_time_microsec_
// atomically. We could see more than one dump during one dump
// period in rare cases.
last_stats_dump_time_microsec_ = now_micros;
std::string stats;
GetProperty("rocksdb.stats", &stats);
Log(options_.info_log, "%s", stats.c_str());
PrintStatistics();
}
}
// Returns the list of live files in 'live' and the list
// of all files in the filesystem in 'allfiles'.
void DBImpl::FindObsoleteFiles(DeletionState& deletion_state) {
mutex_.AssertHeld();
// if deletion is disabled, do nothing
if (disable_delete_obsolete_files_) {
return;
}
// This method is costly when the number of files is large.
// Do not allow it to trigger more often than once in
// delete_obsolete_files_period_micros.
if (options_.delete_obsolete_files_period_micros != 0) {
const uint64_t now_micros = env_->NowMicros();
if (delete_obsolete_files_last_run_ +
options_.delete_obsolete_files_period_micros > now_micros) {
return;
}
delete_obsolete_files_last_run_ = now_micros;
}
// Make a list of all of the live files; set is slow, should not
// be used.
deletion_state.live.assign(pending_outputs_.begin(),
pending_outputs_.end());
versions_->AddLiveFiles(&deletion_state.live);
// set of all files in the directory
env_->GetChildren(dbname_, &deletion_state.allfiles); // Ignore errors
//Add log files in wal_dir
if (options_.wal_dir != dbname_) {
std::vector<std::string> log_files;
env_->GetChildren(options_.wal_dir, &log_files); // Ignore errors
deletion_state.allfiles.insert(
deletion_state.allfiles.end(),
log_files.begin(),
log_files.end()
);
}
// store the current filenum, lognum, etc
deletion_state.filenumber = versions_->ManifestFileNumber();
deletion_state.lognumber = versions_->LogNumber();
deletion_state.prevlognumber = versions_->PrevLogNumber();
}
Status DBImpl::DeleteLogFile(uint64_t number) {
Status s;
auto filename = LogFileName(options_.wal_dir, number);
if (options_.WAL_ttl_seconds > 0) {
s = env_->RenameFile(filename,
ArchivedLogFileName(options_.wal_dir, number));
if (!s.ok()) {
Log(options_.info_log, "RenameFile logfile #%lu FAILED", number);
}
} else {
s = env_->DeleteFile(filename);
if(!s.ok()) {
Log(options_.info_log, "Delete logfile #%lu FAILED", number);
}
}
return s;
}
// Diffs the files listed in filenames and those that do not
// belong to live files are posibly removed. If the removed file
// is a sst file, then it returns the file number in files_to_evict.
// It is not necessary to hold the mutex when invoking this method.
void DBImpl::PurgeObsoleteFiles(DeletionState& state) {
uint64_t number;
FileType type;
std::vector<std::string> old_log_files;
// Now, convert live list to an unordered set, WITHOUT mutex held;
// set is slow.
std::unordered_set<uint64_t> live_set(state.live.begin(),
state.live.end());
for (size_t i = 0; i < state.allfiles.size(); i++) {
if (ParseFileName(state.allfiles[i], &number, &type)) {
bool keep = true;
switch (type) {
case kLogFile:
keep = ((number >= state.lognumber) ||
(number == state.prevlognumber));
break;
case kDescriptorFile:
// Keep my manifest file, and any newer incarnations'
// (in case there is a race that allows other incarnations)
keep = (number >= state.filenumber);
break;
case kTableFile:
keep = (live_set.find(number) != live_set.end());
break;
case kTempFile:
// Any temp files that are currently being written to must
// be recorded in pending_outputs_, which is inserted into "live"
keep = (live_set.find(number) != live_set.end());
break;
case kInfoLogFile:
keep = true;
if (number != 0) {
old_log_files.push_back(state.allfiles[i]);
}
break;
case kCurrentFile:
case kDBLockFile:
case kMetaDatabase:
keep = true;
break;
}
if (!keep) {
if (type == kTableFile) {
// record the files to be evicted from the cache
state.files_to_evict.push_back(number);
}
Log(options_.info_log, "Delete type=%d #%lu", int(type), number);
if (type == kLogFile) {
DeleteLogFile(number);
} else {
Status st = env_->DeleteFile(dbname_ + "/" + state.allfiles[i]);
if (!st.ok()) {
Log(options_.info_log, "Delete type=%d #%lld FAILED\n",
int(type),
static_cast<unsigned long long>(number));
}
}
}
}
}
// Delete old info log files.
size_t old_log_file_count = old_log_files.size();
// NOTE: Currently we only support log purge when options_.db_log_dir is
// located in `dbname` directory.
if (old_log_file_count >= options_.keep_log_file_num &&
options_.db_log_dir.empty()) {
std::sort(old_log_files.begin(), old_log_files.end());
size_t end = old_log_file_count - options_.keep_log_file_num;
for (unsigned int i = 0; i <= end; i++) {
std::string& to_delete = old_log_files.at(i);
// Log(options_.info_log, "Delete type=%d %s\n",
// int(kInfoLogFile), to_delete.c_str());
env_->DeleteFile(dbname_ + "/" + to_delete);
}
}
PurgeObsoleteWALFiles();
}
void DBImpl::EvictObsoleteFiles(DeletionState& state) {
for (unsigned int i = 0; i < state.files_to_evict.size(); i++) {
table_cache_->Evict(state.files_to_evict[i]);
}
}
void DBImpl::DeleteObsoleteFiles() {
mutex_.AssertHeld();
DeletionState deletion_state;
FindObsoleteFiles(deletion_state);
PurgeObsoleteFiles(deletion_state);
EvictObsoleteFiles(deletion_state);
}
void DBImpl::PurgeObsoleteWALFiles() {
int64_t current_time;
Status s = env_->GetCurrentTime(&current_time);
uint64_t now_seconds = static_cast<uint64_t>(current_time);
assert(s.ok());
if (options_.WAL_ttl_seconds != ULONG_MAX && options_.WAL_ttl_seconds > 0) {
if (purge_wal_files_last_run_ + options_.WAL_ttl_seconds > now_seconds) {
return;
}
std::vector<std::string> wal_files;
std::string archival_dir = ArchivalDirectory(options_.wal_dir);
env_->GetChildren(archival_dir, &wal_files);
for (const auto& f : wal_files) {
uint64_t file_m_time;
const std::string file_path = archival_dir + "/" + f;
const Status s = env_->GetFileModificationTime(file_path, &file_m_time);
if (s.ok() && (now_seconds - file_m_time > options_.WAL_ttl_seconds)) {
Status status = env_->DeleteFile(file_path);
if (!status.ok()) {
Log(options_.info_log,
"Failed Deleting a WAL file Error : i%s",
status.ToString().c_str());
}
} // Ignore errors.
}
}
purge_wal_files_last_run_ = now_seconds;
}
// If externalTable is set, then apply recovered transactions
// to that table. This is used for readonly mode.
Status DBImpl::Recover(VersionEdit* edit, MemTable* external_table,
bool error_if_log_file_exist) {
mutex_.AssertHeld();
assert(db_lock_ == nullptr);
if (!external_table) {
// We call CreateDirIfMissing() as the directory may already exist (if we
// are reopening a DB), when this happens we don't want creating the
// directory to cause an error. However, we need to check if creating the
// directory fails or else we may get an obscure message about the lock
// file not existing. One real-world example of this occurring is if
// env->CreateDirIfMissing() doesn't create intermediate directories, e.g.
// when dbname_ is "dir/db" but when "dir" doesn't exist.
Status s = env_->CreateDirIfMissing(dbname_);
if (!s.ok()) {
return s;
}
s = env_->LockFile(LockFileName(dbname_), &db_lock_);
if (!s.ok()) {
return s;
}
if (!env_->FileExists(CurrentFileName(dbname_))) {
if (options_.create_if_missing) {
// TODO: add merge_operator name check
s = NewDB();
if (!s.ok()) {
return s;
}
} else {
return Status::InvalidArgument(
dbname_, "does not exist (create_if_missing is false)");
}
} else {
if (options_.error_if_exists) {
return Status::InvalidArgument(
dbname_, "exists (error_if_exists is true)");
}
}
}
Status s = versions_->Recover();
if (s.ok()) {
SequenceNumber max_sequence(0);
// Recover from all newer log files than the ones named in the
// descriptor (new log files may have been added by the previous
// incarnation without registering them in the descriptor).
//
// Note that PrevLogNumber() is no longer used, but we pay
// attention to it in case we are recovering a database
// produced by an older version of rocksdb.
const uint64_t min_log = versions_->LogNumber();
const uint64_t prev_log = versions_->PrevLogNumber();
std::vector<std::string> filenames;
s = env_->GetChildren(options_.wal_dir, &filenames);
if (!s.ok()) {
return s;
}
uint64_t number;
FileType type;
std::vector<uint64_t> logs;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type)
&& type == kLogFile
&& ((number >= min_log) || (number == prev_log))) {
logs.push_back(number);
}
}
if (logs.size() > 0 && error_if_log_file_exist) {
return Status::Corruption(""
"The db was opened in readonly mode with error_if_log_file_exist"
"flag but a log file already exists");
}
// Recover in the order in which the logs were generated
std::sort(logs.begin(), logs.end());
for (size_t i = 0; i < logs.size(); i++) {
s = RecoverLogFile(logs[i], edit, &max_sequence, external_table);
// The previous incarnation may not have written any MANIFEST
// records after allocating this log number. So we manually
// update the file number allocation counter in VersionSet.
versions_->MarkFileNumberUsed(logs[i]);
}
if (s.ok()) {
if (versions_->LastSequence() < max_sequence) {
versions_->SetLastSequence(max_sequence);
last_flushed_sequence_ = max_sequence;
} else {
last_flushed_sequence_ = versions_->LastSequence();
}
SetTickerCount(options_.statistics, SEQUENCE_NUMBER,
versions_->LastSequence());
}
}
return s;
}
Status DBImpl::RecoverLogFile(uint64_t log_number,
VersionEdit* edit,
SequenceNumber* max_sequence,
MemTable* external_table) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
Logger* info_log;
const char* fname;
Status* status; // nullptr if options_.paranoid_checks==false or
// options_.skip_log_error_on_recovery==true
virtual void Corruption(size_t bytes, const Status& s) {
Log(info_log, "%s%s: dropping %d bytes; %s",
(this->status == nullptr ? "(ignoring error) " : ""),
fname, static_cast<int>(bytes), s.ToString().c_str());
if (this->status != nullptr && this->status->ok()) *this->status = s;
}
};
mutex_.AssertHeld();
// Open the log file
std::string fname = LogFileName(options_.wal_dir, log_number);
unique_ptr<SequentialFile> file;
Status status = env_->NewSequentialFile(fname, &file, storage_options_);
if (!status.ok()) {
MaybeIgnoreError(&status);
return status;
}
// Create the log reader.
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log.get();
reporter.fname = fname.c_str();
reporter.status = (options_.paranoid_checks &&
!options_.skip_log_error_on_recovery ? &status : nullptr);
// We intentially make log::Reader do checksumming even if
// paranoid_checks==false so that corruptions cause entire commits
// to be skipped instead of propagating bad information (like overly
// large sequence numbers).
log::Reader reader(std::move(file), &reporter, true/*checksum*/,
0/*initial_offset*/);
Log(options_.info_log, "Recovering log #%llu",
(unsigned long long) log_number);
// Read all the records and add to a memtable
std::string scratch;
Slice record;
WriteBatch batch;
MemTable* mem = nullptr;
if (external_table) {
mem = external_table;
}
while (reader.ReadRecord(&record, &scratch) && status.ok()) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
WriteBatchInternal::SetContents(&batch, record);
if (mem == nullptr) {
mem = new MemTable(internal_comparator_, mem_rep_factory_,
NumberLevels(), options_);
mem->Ref();
}
status = WriteBatchInternal::InsertInto(&batch, mem, &options_);
MaybeIgnoreError(&status);
if (!status.ok()) {
break;
}
const SequenceNumber last_seq =
WriteBatchInternal::Sequence(&batch) +
WriteBatchInternal::Count(&batch) - 1;
if (last_seq > *max_sequence) {
*max_sequence = last_seq;
}
if (!external_table &&
mem->ApproximateMemoryUsage() > options_.write_buffer_size) {
status = WriteLevel0TableForRecovery(mem, edit);
if (!status.ok()) {
// Reflect errors immediately so that conditions like full
// file-systems cause the DB::Open() to fail.
break;
}
mem->Unref();
mem = nullptr;
}
}
if (status.ok() && mem != nullptr && !external_table) {
status = WriteLevel0TableForRecovery(mem, edit);
// Reflect errors immediately so that conditions like full
// file-systems cause the DB::Open() to fail.
}
if (mem != nullptr && !external_table) mem->Unref();
return status;
}
Status DBImpl::WriteLevel0TableForRecovery(MemTable* mem, VersionEdit* edit) {
mutex_.AssertHeld();
const uint64_t start_micros = env_->NowMicros();
FileMetaData meta;
meta.number = versions_->NewFileNumber();
pending_outputs_.insert(meta.number);
Iterator* iter = mem->NewIterator();
const SequenceNumber newest_snapshot = snapshots_.GetNewest();
const SequenceNumber earliest_seqno_in_memtable =
mem->GetFirstSequenceNumber();
Log(options_.info_log, "Level-0 table #%llu: started",
(unsigned long long) meta.number);
Status s;
{
mutex_.Unlock();
s = BuildTable(dbname_, env_, options_, storage_options_,
table_cache_.get(), iter, &meta,
user_comparator(), newest_snapshot,
earliest_seqno_in_memtable);
mutex_.Lock();
}
Log(options_.info_log, "Level-0 table #%llu: %lld bytes %s",
(unsigned long long) meta.number,
(unsigned long long) meta.file_size,
s.ToString().c_str());
delete iter;
pending_outputs_.erase(meta.number);
// Note that if file_size is zero, the file has been deleted and
// should not be added to the manifest.
int level = 0;
if (s.ok() && meta.file_size > 0) {
edit->AddFile(level, meta.number, meta.file_size,
meta.smallest, meta.largest,
meta.smallest_seqno, meta.largest_seqno);
}
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros;
stats.bytes_written = meta.file_size;
stats.files_out_levelnp1 = 1;
stats_[level].Add(stats);
return s;
}
Status DBImpl::WriteLevel0Table(std::vector<MemTable*> &mems, VersionEdit* edit,
uint64_t* filenumber) {
mutex_.AssertHeld();
const uint64_t start_micros = env_->NowMicros();
FileMetaData meta;
meta.number = versions_->NewFileNumber();
*filenumber = meta.number;
pending_outputs_.insert(meta.number);
std::vector<Iterator*> list;
for (MemTable* m : mems) {
list.push_back(m->NewIterator());
}
Iterator* iter = NewMergingIterator(&internal_comparator_, &list[0],
list.size());
const SequenceNumber newest_snapshot = snapshots_.GetNewest();
const SequenceNumber earliest_seqno_in_memtable =
mems[0]->GetFirstSequenceNumber();
Log(options_.info_log, "Level-0 flush table #%llu: started",
(unsigned long long) meta.number);
Version* base = versions_->current();
base->Ref(); // it is likely that we do not need this reference
Status s;
{
mutex_.Unlock();
s = BuildTable(dbname_, env_, options_, storage_options_,
table_cache_.get(), iter, &meta,
user_comparator(), newest_snapshot,
earliest_seqno_in_memtable);
mutex_.Lock();
}
base->Unref();
Log(options_.info_log, "Level-0 flush table #%llu: %lld bytes %s",
(unsigned long long) meta.number,
(unsigned long long) meta.file_size,
s.ToString().c_str());
delete iter;
// re-acquire the most current version
base = versions_->current();
// There could be multiple threads writing to its own level-0 file.
// The pending_outputs cannot be cleared here, otherwise this newly
// created file might not be considered as a live-file by another
// compaction thread that is concurrently deleting obselete files.
// The pending_outputs can be cleared only after the new version is
// committed so that other threads can recognize this file as a
// valid one.
// pending_outputs_.erase(meta.number);
// Note that if file_size is zero, the file has been deleted and
// should not be added to the manifest.
int level = 0;
if (s.ok() && meta.file_size > 0) {
const Slice min_user_key = meta.smallest.user_key();
const Slice max_user_key = meta.largest.user_key();
// if we have more than 1 background thread, then we cannot
// insert files directly into higher levels because some other
// threads could be concurrently producing compacted files for
// that key range.
if (base != nullptr && options_.max_background_compactions <= 1 &&
options_.compaction_style == kCompactionStyleLevel) {
level = base->PickLevelForMemTableOutput(min_user_key, max_user_key);
}
edit->AddFile(level, meta.number, meta.file_size,
meta.smallest, meta.largest,
meta.smallest_seqno, meta.largest_seqno);
}
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros;
stats.bytes_written = meta.file_size;
stats_[level].Add(stats);
return s;
}
Status DBImpl::FlushMemTableToOutputFile(bool* madeProgress) {
mutex_.AssertHeld();
assert(imm_.size() != 0);
if (!imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log, "FlushMemTableToOutputFile already in progress");
Status s = Status::IOError("FlushMemTableToOutputFile already in progress");
return s;
}
// Save the contents of the earliest memtable as a new Table
uint64_t file_number;
std::vector<MemTable*> mems;
imm_.PickMemtablesToFlush(&mems);
if (mems.empty()) {
Log(options_.info_log, "Nothing in memstore to flush");
Status s = Status::IOError("Nothing in memstore to flush");
return s;
}
// record the logfile_number_ before we release the mutex
MemTable* m = mems[0];
VersionEdit* edit = m->GetEdits();
edit->SetPrevLogNumber(0);
edit->SetLogNumber(m->GetNextLogNumber()); // Earlier logs no longer needed
auto to_delete = m->GetLogNumber();
// This will release and re-acquire the mutex.
Status s = WriteLevel0Table(mems, edit, &file_number);
if (s.ok() && shutting_down_.Acquire_Load()) {
s = Status::IOError(
"Database shutdown started during memtable compaction"
);
}
// Replace immutable memtable with the generated Table
s = imm_.InstallMemtableFlushResults(
mems, versions_.get(), s, &mutex_, options_.info_log.get(),
file_number, pending_outputs_);
if (s.ok()) {
if (madeProgress) {
*madeProgress = 1;
}
MaybeScheduleLogDBDeployStats();
// TODO: if log deletion failed for any reason, we probably
// should store the file number in the shared state, and retry
// However, for now, PurgeObsoleteFiles will take care of that
// anyways.
if (options_.purge_log_after_memtable_flush &&
!disable_delete_obsolete_files_ &&
to_delete > 0) {
mutex_.Unlock();
DeleteLogFile(to_delete);
mutex_.Lock();
}
}
return s;
}
void DBImpl::CompactRange(const Slice* begin, const Slice* end,
bool reduce_level, int target_level) {
int max_level_with_files = 1;
{
MutexLock l(&mutex_);
Version* base = versions_->current();
for (int level = 1; level < NumberLevels(); level++) {
if (base->OverlapInLevel(level, begin, end)) {
max_level_with_files = level;
}
}
}
TEST_FlushMemTable(); // TODO(sanjay): Skip if memtable does not overlap
for (int level = 0; level < max_level_with_files; level++) {
TEST_CompactRange(level, begin, end);
}
if (reduce_level) {
ReFitLevel(max_level_with_files, target_level);
}
}
// return the same level if it cannot be moved
int DBImpl::FindMinimumEmptyLevelFitting(int level) {
mutex_.AssertHeld();
int minimum_level = level;
for (int i = level - 1; i > 0; --i) {
// stop if level i is not empty
if (versions_->NumLevelFiles(i) > 0) break;
// stop if level i is too small (cannot fit the level files)
if (versions_->MaxBytesForLevel(i) < versions_->NumLevelBytes(level)) break;
minimum_level = i;
}
return minimum_level;
}
void DBImpl::ReFitLevel(int level, int target_level) {
assert(level < NumberLevels());
MutexLock l(&mutex_);
// only allow one thread refitting
if (refitting_level_) {
Log(options_.info_log, "ReFitLevel: another thread is refitting");
return;
}
refitting_level_ = true;
// wait for all background threads to stop
bg_work_gate_closed_ = true;
while (bg_compaction_scheduled_ > 0 || bg_flush_scheduled_) {
Log(options_.info_log,
"RefitLevel: waiting for background threads to stop: %d %d",
bg_compaction_scheduled_, bg_flush_scheduled_);
bg_cv_.Wait();
}
// move to a smaller level
int to_level = target_level;
if (target_level < 0) {
to_level = FindMinimumEmptyLevelFitting(level);
}
assert(to_level <= level);
if (to_level < level) {
Log(options_.info_log, "Before refitting:\n%s",
versions_->current()->DebugString().data());
VersionEdit edit(NumberLevels());
for (const auto& f : versions_->current()->files_[level]) {
edit.DeleteFile(level, f->number);
edit.AddFile(to_level, f->number, f->file_size, f->smallest, f->largest,
f->smallest_seqno, f->largest_seqno);
}
Log(options_.info_log, "Apply version edit:\n%s",
edit.DebugString().data());
auto status = versions_->LogAndApply(&edit, &mutex_);
Log(options_.info_log, "LogAndApply: %s\n", status.ToString().data());
if (status.ok()) {
Log(options_.info_log, "After refitting:\n%s",
versions_->current()->DebugString().data());
}
}
refitting_level_ = false;
bg_work_gate_closed_ = false;
}
int DBImpl::NumberLevels() {
return options_.num_levels;
}
int DBImpl::MaxMemCompactionLevel() {
return options_.max_mem_compaction_level;
}
int DBImpl::Level0StopWriteTrigger() {
return options_.level0_stop_writes_trigger;
}
Status DBImpl::Flush(const FlushOptions& options) {
Status status = FlushMemTable(options);
return status;
}
SequenceNumber DBImpl::GetLatestSequenceNumber() {
return versions_->LastSequence();
}
Status DBImpl::GetUpdatesSince(SequenceNumber seq,
unique_ptr<TransactionLogIterator>* iter) {
RecordTick(options_.statistics, GET_UPDATES_SINCE_CALLS);
if (seq > last_flushed_sequence_) {
return Status::IOError("Requested sequence not yet written in the db");
}
// Get all sorted Wal Files.
// Do binary search and open files and find the seq number.
std::unique_ptr<VectorLogPtr> wal_files(new VectorLogPtr);
Status s = GetSortedWalFiles(*wal_files);
if (!s.ok()) {
return s;
}
s = RetainProbableWalFiles(*wal_files, seq);
if (!s.ok()) {
return s;
}
iter->reset(
new TransactionLogIteratorImpl(options_.wal_dir,
&options_,
storage_options_,
seq,
std::move(wal_files),
&last_flushed_sequence_));
return (*iter)->status();
}
Status DBImpl::RetainProbableWalFiles(VectorLogPtr& all_logs,
const SequenceNumber target) {
long start = 0; // signed to avoid overflow when target is < first file.
long end = static_cast<long>(all_logs.size()) - 1;
// Binary Search. avoid opening all files.
while (end >= start) {
long mid = start + (end - start) / 2; // Avoid overflow.
SequenceNumber current_seq_num = all_logs.at(mid)->StartSequence();
if (current_seq_num == target) {
end = mid;
break;
} else if (current_seq_num < target) {
start = mid + 1;
} else {
end = mid - 1;
}
}
size_t start_index = std::max(0l, end); // end could be -ve.
// The last wal file is always included
all_logs.erase(all_logs.begin(), all_logs.begin() + start_index);
return Status::OK();
}
bool DBImpl::CheckWalFileExistsAndEmpty(const WalFileType type,
const uint64_t number) {
const std::string fname = (type == kAliveLogFile) ?
LogFileName(options_.wal_dir, number) :
ArchivedLogFileName(options_.wal_dir, number);
uint64_t file_size;
Status s = env_->GetFileSize(fname, &file_size);
return (s.ok() && (file_size == 0));
}
Status DBImpl::ReadFirstRecord(const WalFileType type, const uint64_t number,
WriteBatch* const result) {
if (type == kAliveLogFile) {
std::string fname = LogFileName(options_.wal_dir, number);
Status status = ReadFirstLine(fname, result);
if (!status.ok()) {
// check if the file got moved to archive.
std::string archived_file =
ArchivedLogFileName(options_.wal_dir, number);
Status s = ReadFirstLine(archived_file, result);
if (!s.ok()) {
return Status::IOError("Log File has been deleted: " + archived_file);
}
}
return Status::OK();
} else if (type == kArchivedLogFile) {
std::string fname = ArchivedLogFileName(options_.wal_dir, number);
Status status = ReadFirstLine(fname, result);
return status;
}
return Status::NotSupported("File Type Not Known: " + type);
}
Status DBImpl::ReadFirstLine(const std::string& fname,
WriteBatch* const batch) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
Logger* info_log;
const char* fname;
Status* status; // nullptr if options_.paranoid_checks==false
virtual void Corruption(size_t bytes, const Status& s) {
Log(info_log, "%s%s: dropping %d bytes; %s",
(this->status == nullptr ? "(ignoring error) " : ""),
fname, static_cast<int>(bytes), s.ToString().c_str());
if (this->status != nullptr && this->status->ok()) *this->status = s;
}
};
unique_ptr<SequentialFile> file;
Status status = env_->NewSequentialFile(fname, &file, storage_options_);
if (!status.ok()) {
return status;
}
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log.get();
reporter.fname = fname.c_str();
reporter.status = (options_.paranoid_checks ? &status : nullptr);
log::Reader reader(std::move(file), &reporter, true/*checksum*/,
0/*initial_offset*/);
std::string scratch;
Slice record;
if (reader.ReadRecord(&record, &scratch) && status.ok()) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
return Status::IOError("Corruption noted");
// TODO read record's till the first no corrupt entry?
}
WriteBatchInternal::SetContents(batch, record);
return Status::OK();
}
return Status::IOError("Error reading from file " + fname);
}
struct CompareLogByPointer {
bool operator() (const unique_ptr<LogFile>& a,
const unique_ptr<LogFile>& b) {
LogFileImpl* a_impl = dynamic_cast<LogFileImpl*>(a.get());
LogFileImpl* b_impl = dynamic_cast<LogFileImpl*>(b.get());
return *a_impl < *b_impl;
}
};
Status DBImpl::AppendSortedWalsOfType(const std::string& path,
VectorLogPtr& log_files, WalFileType log_type) {
std::vector<std::string> all_files;
const Status status = env_->GetChildren(path, &all_files);
if (!status.ok()) {
return status;
}
log_files.reserve(log_files.size() + all_files.size());
VectorLogPtr::iterator pos_start;
if (!log_files.empty()) {
pos_start = log_files.end() - 1;
} else {
pos_start = log_files.begin();
}
for (const auto& f : all_files) {
uint64_t number;
FileType type;
if (ParseFileName(f, &number, &type) && type == kLogFile){
WriteBatch batch;
Status s = ReadFirstRecord(log_type, number, &batch);
if (!s.ok()) {
if (CheckWalFileExistsAndEmpty(log_type, number)) {
continue;
}
return s;
}
uint64_t size_bytes;
s = env_->GetFileSize(LogFileName(path, number), &size_bytes);
if (!s.ok()) {
return s;
}
log_files.push_back(std::move(unique_ptr<LogFile>(new LogFileImpl(
number, log_type, WriteBatchInternal::Sequence(&batch), size_bytes))));
}
}
CompareLogByPointer compare_log_files;
std::sort(pos_start, log_files.end(), compare_log_files);
return status;
}
void DBImpl::TEST_CompactRange(int level, const Slice* begin,const Slice* end) {
assert(level >= 0);
InternalKey begin_storage, end_storage;
ManualCompaction manual;
manual.level = level;
manual.done = false;
manual.in_progress = false;
// For universal compaction, we enforce every manual compaction to compact
// all files.
if (begin == nullptr ||
options_.compaction_style == kCompactionStyleUniversal) {
manual.begin = nullptr;
} else {
begin_storage = InternalKey(*begin, kMaxSequenceNumber, kValueTypeForSeek);
manual.begin = &begin_storage;
}
if (end == nullptr ||
options_.compaction_style == kCompactionStyleUniversal) {
manual.end = nullptr;
} else {
end_storage = InternalKey(*end, 0, static_cast<ValueType>(0));
manual.end = &end_storage;
}
MutexLock l(&mutex_);
// When a manual compaction arrives, temporarily throttle down
// the number of background compaction threads to 1. This is
// needed to ensure that this manual compaction can compact
// any range of keys/files. We artificialy increase
// bg_compaction_scheduled_ by a large number, this causes
// the system to have a single background thread. Now,
// this manual compaction can progress without stomping
// on any other concurrent compactions.
const int LargeNumber = 10000000;
const int newvalue = options_.max_background_compactions-1;
bg_compaction_scheduled_ += LargeNumber;
while (bg_compaction_scheduled_ > LargeNumber) {
Log(options_.info_log, "Manual compaction request waiting for background threads to fall below 1");
bg_cv_.Wait();
}
Log(options_.info_log, "Manual compaction starting");
while (!manual.done) {
while (manual_compaction_ != nullptr) {
bg_cv_.Wait();
}
manual_compaction_ = &manual;
if (bg_compaction_scheduled_ == LargeNumber) {
bg_compaction_scheduled_ = newvalue;
}
MaybeScheduleFlushOrCompaction();
while (manual_compaction_ == &manual) {
bg_cv_.Wait();
}
}
assert(!manual.in_progress);
// wait till there are no background threads scheduled
bg_compaction_scheduled_ += LargeNumber;
while (bg_compaction_scheduled_ > LargeNumber + newvalue) {
Log(options_.info_log, "Manual compaction resetting background threads");
bg_cv_.Wait();
}
bg_compaction_scheduled_ = 0;
}
Status DBImpl::FlushMemTable(const FlushOptions& options) {
// nullptr batch means just wait for earlier writes to be done
Status s = Write(WriteOptions(), nullptr);
if (s.ok() && options.wait) {
// Wait until the compaction completes
s = WaitForFlushMemTable();
}
return s;
}
Status DBImpl::WaitForFlushMemTable() {
Status s;
// Wait until the compaction completes
MutexLock l(&mutex_);
while (imm_.size() > 0 && bg_error_.ok()) {
bg_cv_.Wait();
}
if (imm_.size() != 0) {
s = bg_error_;
}
return s;
}
Status DBImpl::TEST_FlushMemTable() {
return FlushMemTable(FlushOptions());
}
Status DBImpl::TEST_WaitForFlushMemTable() {
return WaitForFlushMemTable();
}
Status DBImpl::TEST_WaitForCompact() {
// Wait until the compaction completes
// TODO: a bug here. This function actually does not necessarily
// wait for compact. It actually waits for scheduled compaction
// OR flush to finish.
MutexLock l(&mutex_);
while ((bg_compaction_scheduled_ || bg_flush_scheduled_) &&
bg_error_.ok()) {
bg_cv_.Wait();
}
return bg_error_;
}
void DBImpl::MaybeScheduleFlushOrCompaction() {
mutex_.AssertHeld();
if (bg_work_gate_closed_) {
// gate closed for backgrond work
} else if (shutting_down_.Acquire_Load()) {
// DB is being deleted; no more background compactions
} else {
bool is_flush_pending =
imm_.IsFlushPending(options_.min_write_buffer_number_to_merge);
if (is_flush_pending &&
(bg_flush_scheduled_ < options_.max_background_flushes)) {
// memtable flush needed
bg_flush_scheduled_++;
env_->Schedule(&DBImpl::BGWorkFlush, this, Env::Priority::HIGH);
}
if ((manual_compaction_ ||
versions_->NeedsCompaction() ||
(is_flush_pending && (options_.max_background_flushes <= 0))) &&
bg_compaction_scheduled_ < options_.max_background_compactions) {
// compaction needed, or memtable flush needed but HIGH pool not enabled.
bg_compaction_scheduled_++;
env_->Schedule(&DBImpl::BGWorkCompaction, this, Env::Priority::LOW);
}
}
}
void DBImpl::BGWorkFlush(void* db) {
reinterpret_cast<DBImpl*>(db)->BackgroundCallFlush();
}
void DBImpl::BGWorkCompaction(void* db) {
reinterpret_cast<DBImpl*>(db)->BackgroundCallCompaction();
}
Status DBImpl::BackgroundFlush(bool* madeProgress) {
Status stat;
while (stat.ok() &&
imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log,
"BackgroundCallFlush doing FlushMemTableToOutputFile, flush slots available %d",
options_.max_background_flushes - bg_flush_scheduled_);
stat = FlushMemTableToOutputFile(madeProgress);
}
return stat;
}
void DBImpl::BackgroundCallFlush() {
bool madeProgress = false;
assert(bg_flush_scheduled_);
MutexLock l(&mutex_);
if (!shutting_down_.Acquire_Load()) {
Status s = BackgroundFlush(&madeProgress);
if (!s.ok()) {
// Wait a little bit before retrying background compaction in
// case this is an environmental problem and we do not want to
// chew up resources for failed compactions for the duration of
// the problem.
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
Log(options_.info_log, "Waiting after background flush error: %s",
s.ToString().c_str());
mutex_.Unlock();
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
}
bg_flush_scheduled_--;
if (madeProgress) {
MaybeScheduleFlushOrCompaction();
}
bg_cv_.SignalAll();
}
void DBImpl::TEST_PurgeObsoleteteWAL() {
PurgeObsoleteWALFiles();
}
void DBImpl::BackgroundCallCompaction() {
bool madeProgress = false;
DeletionState deletion_state;
MaybeDumpStats();
MutexLock l(&mutex_);
// Log(options_.info_log, "XXX BG Thread %llx process new work item", pthread_self());
assert(bg_compaction_scheduled_);
if (!shutting_down_.Acquire_Load()) {
Status s = BackgroundCompaction(&madeProgress, deletion_state);
if (!s.ok()) {
// Wait a little bit before retrying background compaction in
// case this is an environmental problem and we do not want to
// chew up resources for failed compactions for the duration of
// the problem.
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
Log(options_.info_log, "Waiting after background compaction error: %s",
s.ToString().c_str());
mutex_.Unlock();
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
}
// delete unnecessary files if any, this is done outside the mutex
if (!deletion_state.live.empty()) {
mutex_.Unlock();
PurgeObsoleteFiles(deletion_state);
EvictObsoleteFiles(deletion_state);
mutex_.Lock();
}
bg_compaction_scheduled_--;
MaybeScheduleLogDBDeployStats();
// Previous compaction may have produced too many files in a level,
// So reschedule another compaction if we made progress in the
// last compaction.
if (madeProgress) {
MaybeScheduleFlushOrCompaction();
}
bg_cv_.SignalAll();
}
Status DBImpl::BackgroundCompaction(bool* madeProgress,
DeletionState& deletion_state) {
*madeProgress = false;
mutex_.AssertHeld();
// TODO: remove memtable flush from formal compaction
while (imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log,
"BackgroundCompaction doing FlushMemTableToOutputFile, compaction slots "
"available %d",
options_.max_background_compactions - bg_compaction_scheduled_);
Status stat = FlushMemTableToOutputFile(madeProgress);
if (!stat.ok()) {
return stat;
}
}
unique_ptr<Compaction> c;
bool is_manual = (manual_compaction_ != nullptr) &&
(manual_compaction_->in_progress == false);
InternalKey manual_end;
if (is_manual) {
ManualCompaction* m = manual_compaction_;
assert(!m->in_progress);
m->in_progress = true; // another thread cannot pick up the same work
c.reset(versions_->CompactRange(m->level, m->begin, m->end));
if (c) {
manual_end = c->input(0, c->num_input_files(0) - 1)->largest;
} else {
m->done = true;
}
Log(options_.info_log,
"Manual compaction at level-%d from %s .. %s; will stop at %s\n",
m->level,
(m->begin ? m->begin->DebugString().c_str() : "(begin)"),
(m->end ? m->end->DebugString().c_str() : "(end)"),
(m->done ? "(end)" : manual_end.DebugString().c_str()));
} else if (!options_.disable_auto_compactions) {
c.reset(versions_->PickCompaction());
}
Status status;
if (!c) {
// Nothing to do
Log(options_.info_log, "Compaction nothing to do");
} else if (!is_manual && c->IsTrivialMove()) {
// Move file to next level
assert(c->num_input_files(0) == 1);
FileMetaData* f = c->input(0, 0);
c->edit()->DeleteFile(c->level(), f->number);
c->edit()->AddFile(c->level() + 1, f->number, f->file_size,
f->smallest, f->largest,
f->smallest_seqno, f->largest_seqno);
status = versions_->LogAndApply(c->edit(), &mutex_);
VersionSet::LevelSummaryStorage tmp;
Log(options_.info_log, "Moved #%lld to level-%d %lld bytes %s: %s\n",
static_cast<unsigned long long>(f->number),
c->level() + 1,
static_cast<unsigned long long>(f->file_size),
status.ToString().c_str(),
versions_->LevelSummary(&tmp));
versions_->ReleaseCompactionFiles(c.get(), status);
*madeProgress = true;
} else {
MaybeScheduleFlushOrCompaction(); // do more compaction work in parallel.
CompactionState* compact = new CompactionState(c.get());
status = DoCompactionWork(compact);
CleanupCompaction(compact);
versions_->ReleaseCompactionFiles(c.get(), status);
c->ReleaseInputs();
FindObsoleteFiles(deletion_state);
*madeProgress = true;
}
c.reset();
if (status.ok()) {
// Done
} else if (shutting_down_.Acquire_Load()) {
// Ignore compaction errors found during shutting down
} else {
Log(options_.info_log,
"Compaction error: %s", status.ToString().c_str());
if (options_.paranoid_checks && bg_error_.ok()) {
bg_error_ = status;
}
}
if (is_manual) {
ManualCompaction* m = manual_compaction_;
if (!status.ok()) {
m->done = true;
}
// For universal compaction:
// Because universal compaction always happens at level 0, so one
// compaction will pick up all overlapped files. No files will be
// filtered out due to size limit and left for a successive compaction.
// So we can safely conclude the current compaction.
//
// Also note that, if we don't stop here, then the current compaction
// writes a new file back to level 0, which will be used in successive
// compaction. Hence the manual compaction will never finish.
if (options_.compaction_style == kCompactionStyleUniversal) {
m->done = true;
}
if (!m->done) {
// We only compacted part of the requested range. Update *m
// to the range that is left to be compacted.
m->tmp_storage = manual_end;
m->begin = &m->tmp_storage;
}
m->in_progress = false; // not being processed anymore
manual_compaction_ = nullptr;
}
return status;
}
void DBImpl::CleanupCompaction(CompactionState* compact) {
mutex_.AssertHeld();
if (compact->builder != nullptr) {
// May happen if we get a shutdown call in the middle of compaction
compact->builder->Abandon();
compact->builder.reset();
} else {
assert(compact->outfile == nullptr);
}
for (size_t i = 0; i < compact->outputs.size(); i++) {
const CompactionState::Output& out = compact->outputs[i];
pending_outputs_.erase(out.number);
}
delete compact;
}
// Allocate the file numbers for the output file. We allocate as
// many output file numbers as there are files in level+1.
// Insert them into pending_outputs so that they do not get deleted.
void DBImpl::AllocateCompactionOutputFileNumbers(CompactionState* compact) {
mutex_.AssertHeld();
assert(compact != nullptr);
assert(compact->builder == nullptr);
int filesNeeded = compact->compaction->num_input_files(1);
for (int i = 0; i < filesNeeded; i++) {
uint64_t file_number = versions_->NewFileNumber();
pending_outputs_.insert(file_number);
compact->allocated_file_numbers.push_back(file_number);
}
}
// Frees up unused file number.
void DBImpl::ReleaseCompactionUnusedFileNumbers(CompactionState* compact) {
mutex_.AssertHeld();
for (const auto file_number : compact->allocated_file_numbers) {
pending_outputs_.erase(file_number);
// Log(options_.info_log, "XXX releasing unused file num %d", file_number);
}
}
Status DBImpl::OpenCompactionOutputFile(CompactionState* compact) {
assert(compact != nullptr);
assert(compact->builder == nullptr);
uint64_t file_number;
// If we have not yet exhausted the pre-allocated file numbers,
// then use the one from the front. Otherwise, we have to acquire
// the heavyweight lock and allocate a new file number.
if (!compact->allocated_file_numbers.empty()) {
file_number = compact->allocated_file_numbers.front();
compact->allocated_file_numbers.pop_front();
} else {
mutex_.Lock();
file_number = versions_->NewFileNumber();
pending_outputs_.insert(file_number);
mutex_.Unlock();
}
CompactionState::Output out;
out.number = file_number;
out.smallest.Clear();
out.largest.Clear();
out.smallest_seqno = out.largest_seqno = 0;
compact->outputs.push_back(out);
// Make the output file
std::string fname = TableFileName(dbname_, file_number);
Status s = env_->NewWritableFile(fname, &compact->outfile, storage_options_);
if (s.ok()) {
// Over-estimate slightly so we don't end up just barely crossing
// the threshold.
compact->outfile->SetPreallocationBlockSize(
1.1 * versions_->MaxFileSizeForLevel(compact->compaction->output_level()));
compact->builder.reset(new TableBuilder(options_, compact->outfile.get(),
compact->compaction->output_level()));
}
return s;
}
Status DBImpl::FinishCompactionOutputFile(CompactionState* compact,
Iterator* input) {
assert(compact != nullptr);
assert(compact->outfile);
assert(compact->builder != nullptr);
const uint64_t output_number = compact->current_output()->number;
assert(output_number != 0);
// Check for iterator errors
Status s = input->status();
const uint64_t current_entries = compact->builder->NumEntries();
if (s.ok()) {
s = compact->builder->Finish();
} else {
compact->builder->Abandon();
}
const uint64_t current_bytes = compact->builder->FileSize();
compact->current_output()->file_size = current_bytes;
compact->total_bytes += current_bytes;
compact->builder.reset();
// Finish and check for file errors
if (s.ok() && !options_.disableDataSync) {
if (options_.use_fsync) {
StopWatch sw(env_, options_.statistics, COMPACTION_OUTFILE_SYNC_MICROS);
s = compact->outfile->Fsync();
} else {
StopWatch sw(env_, options_.statistics, COMPACTION_OUTFILE_SYNC_MICROS);
s = compact->outfile->Sync();
}
}
if (s.ok()) {
s = compact->outfile->Close();
}
compact->outfile.reset();
if (s.ok() && current_entries > 0) {
// Verify that the table is usable
Iterator* iter = table_cache_->NewIterator(ReadOptions(),
storage_options_,
output_number,
current_bytes);
s = iter->status();
delete iter;
if (s.ok()) {
Log(options_.info_log,
"Generated table #%llu: %lld keys, %lld bytes",
(unsigned long long) output_number,
(unsigned long long) current_entries,
(unsigned long long) current_bytes);
}
}
return s;
}
Status DBImpl::InstallCompactionResults(CompactionState* compact) {
mutex_.AssertHeld();
// paranoia: verify that the files that we started with
// still exist in the current version and in the same original level.
// This ensures that a concurrent compaction did not erroneously
// pick the same files to compact.
if (!versions_->VerifyCompactionFileConsistency(compact->compaction)) {
Log(options_.info_log, "Compaction %d@%d + %d@%d files aborted",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1);
return Status::IOError("Compaction input files inconsistent");
}
Log(options_.info_log, "Compacted %d@%d + %d@%d files => %lld bytes",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1,
static_cast<long long>(compact->total_bytes));
// Add compaction outputs
compact->compaction->AddInputDeletions(compact->compaction->edit());
const int level = compact->compaction->level();
for (size_t i = 0; i < compact->outputs.size(); i++) {
const CompactionState::Output& out = compact->outputs[i];
compact->compaction->edit()->AddFile(
(options_.compaction_style == kCompactionStyleUniversal) ?
level : level + 1,
out.number, out.file_size, out.smallest, out.largest,
out.smallest_seqno, out.largest_seqno);
}
return versions_->LogAndApply(compact->compaction->edit(), &mutex_);
}
//
// Given a sequence number, return the sequence number of the
// earliest snapshot that this sequence number is visible in.
// The snapshots themselves are arranged in ascending order of
// sequence numbers.
// Employ a sequential search because the total number of
// snapshots are typically small.
inline SequenceNumber DBImpl::findEarliestVisibleSnapshot(
SequenceNumber in, std::vector<SequenceNumber>& snapshots,
SequenceNumber* prev_snapshot) {
SequenceNumber prev __attribute__((unused)) = 0;
for (const auto cur : snapshots) {
assert(prev <= cur);
if (cur >= in) {
*prev_snapshot = prev;
return cur;
}
prev = cur; // assignment
assert(prev);
}
Log(options_.info_log,
"Looking for seqid %ld but maxseqid is %ld", in,
snapshots[snapshots.size()-1]);
assert(0);
return 0;
}
Status DBImpl::DoCompactionWork(CompactionState* compact) {
int64_t imm_micros = 0; // Micros spent doing imm_ compactions
Log(options_.info_log,
"Compacting %d@%d + %d@%d files, score %.2f slots available %d",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1,
compact->compaction->score(),
options_.max_background_compactions - bg_compaction_scheduled_);
char scratch[256];
compact->compaction->Summary(scratch, sizeof(scratch));
Log(options_.info_log, "Compaction start summary: %s\n", scratch);
assert(versions_->NumLevelFiles(compact->compaction->level()) > 0);
assert(compact->builder == nullptr);
assert(!compact->outfile);
SequenceNumber visible_at_tip = 0;
SequenceNumber earliest_snapshot;
SequenceNumber latest_snapshot = 0;
snapshots_.getAll(compact->existing_snapshots);
if (compact->existing_snapshots.size() == 0) {
// optimize for fast path if there are no snapshots
visible_at_tip = versions_->LastSequence();
earliest_snapshot = visible_at_tip;
} else {
latest_snapshot = compact->existing_snapshots.back();
// Add the current seqno as the 'latest' virtual
// snapshot to the end of this list.
compact->existing_snapshots.push_back(versions_->LastSequence());
earliest_snapshot = compact->existing_snapshots[0];
}
// Is this compaction producing files at the bottommost level?
bool bottommost_level = compact->compaction->BottomMostLevel();
// Allocate the output file numbers before we release the lock
AllocateCompactionOutputFileNumbers(compact);
// Release mutex while we're actually doing the compaction work
mutex_.Unlock();
const uint64_t start_micros = env_->NowMicros();
unique_ptr<Iterator> input(versions_->MakeInputIterator(compact->compaction));
input->SeekToFirst();
Status status;
ParsedInternalKey ikey;
std::string current_user_key;
bool has_current_user_key = false;
SequenceNumber last_sequence_for_key __attribute__((unused)) =
kMaxSequenceNumber;
SequenceNumber visible_in_snapshot = kMaxSequenceNumber;
std::string compaction_filter_value;
std::vector<char> delete_key; // for compaction filter
MergeHelper merge(user_comparator(), options_.merge_operator.get(),
options_.info_log.get(),
false /* internal key corruption is expected */);
auto compaction_filter = options_.compaction_filter;
std::unique_ptr<CompactionFilter> compaction_filter_from_factory = nullptr;
if (!compaction_filter) {
compaction_filter_from_factory = std::move(
options_.compaction_filter_factory->CreateCompactionFilter());
compaction_filter = compaction_filter_from_factory.get();
}
for (; input->Valid() && !shutting_down_.Acquire_Load(); ) {
// Prioritize immutable compaction work
// TODO: remove memtable flush from normal compaction work
if (imm_.imm_flush_needed.NoBarrier_Load() != nullptr) {
const uint64_t imm_start = env_->NowMicros();
mutex_.Lock();
if (imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
FlushMemTableToOutputFile();
bg_cv_.SignalAll(); // Wakeup MakeRoomForWrite() if necessary
}
mutex_.Unlock();
imm_micros += (env_->NowMicros() - imm_start);
}
Slice key = input->key();
Slice value = input->value();
if (compact->compaction->ShouldStopBefore(key) &&
compact->builder != nullptr) {
status = FinishCompactionOutputFile(compact, input.get());
if (!status.ok()) {
break;
}
}
// Handle key/value, add to state, etc.
bool drop = false;
bool current_entry_is_merging = false;
if (!ParseInternalKey(key, &ikey)) {
// Do not hide error keys
// TODO: error key stays in db forever? Figure out the intention/rationale
// v10 error v8 : we cannot hide v8 even though it's pretty obvious.
current_user_key.clear();
has_current_user_key = false;
last_sequence_for_key = kMaxSequenceNumber;
visible_in_snapshot = kMaxSequenceNumber;
} else {
if (!has_current_user_key ||
user_comparator()->Compare(ikey.user_key,
Slice(current_user_key)) != 0) {
// First occurrence of this user key
current_user_key.assign(ikey.user_key.data(), ikey.user_key.size());
has_current_user_key = true;
last_sequence_for_key = kMaxSequenceNumber;
visible_in_snapshot = kMaxSequenceNumber;
// apply the compaction filter to the first occurrence of the user key
if (compaction_filter &&
ikey.type == kTypeValue &&
(visible_at_tip || ikey.sequence > latest_snapshot)) {
// If the user has specified a compaction filter and the sequence
// number is greater than any external snapshot, then invoke the
// filter.
// If the return value of the compaction filter is true, replace
// the entry with a delete marker.
bool value_changed = false;
compaction_filter_value.clear();
bool to_delete =
compaction_filter->Filter(compact->compaction->level(),
ikey.user_key, value,
&compaction_filter_value,
&value_changed);
if (to_delete) {
// make a copy of the original key
delete_key.assign(key.data(), key.data() + key.size());
// convert it to a delete
UpdateInternalKey(&delete_key[0], delete_key.size(),
ikey.sequence, kTypeDeletion);
// anchor the key again
key = Slice(&delete_key[0], delete_key.size());
// needed because ikey is backed by key
ParseInternalKey(key, &ikey);
// no value associated with delete
value.clear();
RecordTick(options_.statistics, COMPACTION_KEY_DROP_USER);
} else if (value_changed) {
value = compaction_filter_value;
}
}
}
// If there are no snapshots, then this kv affect visibility at tip.
// Otherwise, search though all existing snapshots to find
// the earlist snapshot that is affected by this kv.
SequenceNumber prev_snapshot = 0; // 0 means no previous snapshot
SequenceNumber visible = visible_at_tip ?
visible_at_tip :
findEarliestVisibleSnapshot(ikey.sequence,
compact->existing_snapshots,
&prev_snapshot);
if (visible_in_snapshot == visible) {
// If the earliest snapshot is which this key is visible in
// is the same as the visibily of a previous instance of the
// same key, then this kv is not visible in any snapshot.
// Hidden by an newer entry for same user key
// TODO: why not > ?
assert(last_sequence_for_key >= ikey.sequence);
drop = true; // (A)
RecordTick(options_.statistics, COMPACTION_KEY_DROP_NEWER_ENTRY);
} else if (ikey.type == kTypeDeletion &&
ikey.sequence <= earliest_snapshot &&
compact->compaction->IsBaseLevelForKey(ikey.user_key)) {
// For this user key:
// (1) there is no data in higher levels
// (2) data in lower levels will have larger sequence numbers
// (3) data in layers that are being compacted here and have
// smaller sequence numbers will be dropped in the next
// few iterations of this loop (by rule (A) above).
// Therefore this deletion marker is obsolete and can be dropped.
drop = true;
RecordTick(options_.statistics, COMPACTION_KEY_DROP_OBSOLETE);
} else if (ikey.type == kTypeMerge) {
// We know the merge type entry is not hidden, otherwise we would
// have hit (A)
// We encapsulate the merge related state machine in a different
// object to minimize change to the existing flow. Turn out this
// logic could also be nicely re-used for memtable flush purge
// optimization in BuildTable.
merge.MergeUntil(input.get(), prev_snapshot, bottommost_level,
options_.statistics);
current_entry_is_merging = true;
if (merge.IsSuccess()) {
// Successfully found Put/Delete/(end-of-key-range) while merging
// Get the merge result
key = merge.key();
ParseInternalKey(key, &ikey);
value = merge.value();
} else {
// Did not find a Put/Delete/(end-of-key-range) while merging
// We now have some stack of merge operands to write out.
// NOTE: key,value, and ikey are now referring to old entries.
// These will be correctly set below.
assert(!merge.keys().empty());
assert(merge.keys().size() == merge.values().size());
// Hack to make sure last_sequence_for_key is correct
ParseInternalKey(merge.keys().front(), &ikey);
}
}
last_sequence_for_key = ikey.sequence;
visible_in_snapshot = visible;
}
#if 0
Log(options_.info_log,
" Compact: %s, seq %d, type: %d %d, drop: %d, is_base: %d, "
"%d smallest_snapshot: %d level: %d bottommost %d",
ikey.user_key.ToString().c_str(),
(int)ikey.sequence, ikey.type, kTypeValue, drop,
compact->compaction->IsBaseLevelForKey(ikey.user_key),
(int)last_sequence_for_key, (int)earliest_snapshot,
compact->compaction->level(), bottommost_level);
#endif
if (!drop) {
// We may write a single key (e.g.: for Put/Delete or successful merge).
// Or we may instead have to write a sequence/list of keys.
// We have to write a sequence iff we have an unsuccessful merge
bool has_merge_list = current_entry_is_merging && !merge.IsSuccess();
const std::deque<std::string>* keys = nullptr;
const std::deque<std::string>* values = nullptr;
std::deque<std::string>::const_reverse_iterator key_iter;
std::deque<std::string>::const_reverse_iterator value_iter;
if (has_merge_list) {
keys = &merge.keys();
values = &merge.values();
key_iter = keys->rbegin(); // The back (*rbegin()) is the first key
value_iter = values->rbegin();
key = Slice(*key_iter);
value = Slice(*value_iter);
}
// If we have a list of keys to write, traverse the list.
// If we have a single key to write, simply write that key.
while (true) {
// Invariant: key,value,ikey will always be the next entry to write
char* kptr = (char*)key.data();
std::string kstr;
// Zeroing out the sequence number leads to better compression.
// If this is the bottommost level (no files in lower levels)
// and the earliest snapshot is larger than this seqno
// then we can squash the seqno to zero.
if (options_.compaction_style == kCompactionStyleLevel &&
bottommost_level && ikey.sequence < earliest_snapshot &&
ikey.type != kTypeMerge) {
assert(ikey.type != kTypeDeletion);
// make a copy because updating in place would cause problems
// with the priority queue that is managing the input key iterator
kstr.assign(key.data(), key.size());
kptr = (char *)kstr.c_str();
UpdateInternalKey(kptr, key.size(), (uint64_t)0, ikey.type);
}
Slice newkey(kptr, key.size());
assert((key.clear(), 1)); // we do not need 'key' anymore
// Open output file if necessary
if (compact->builder == nullptr) {
status = OpenCompactionOutputFile(compact);
if (!status.ok()) {
break;
}
}
SequenceNumber seqno = GetInternalKeySeqno(newkey);
if (compact->builder->NumEntries() == 0) {
compact->current_output()->smallest.DecodeFrom(newkey);
compact->current_output()->smallest_seqno = seqno;
} else {
compact->current_output()->smallest_seqno =
std::min(compact->current_output()->smallest_seqno, seqno);
}
compact->current_output()->largest.DecodeFrom(newkey);
compact->builder->Add(newkey, value);
compact->current_output()->largest_seqno =
std::max(compact->current_output()->largest_seqno, seqno);
// Close output file if it is big enough
if (compact->builder->FileSize() >=
compact->compaction->MaxOutputFileSize()) {
status = FinishCompactionOutputFile(compact, input.get());
if (!status.ok()) {
break;
}
}
// If we have a list of entries, move to next element
// If we only had one entry, then break the loop.
if (has_merge_list) {
++key_iter;
++value_iter;
// If at end of list
if (key_iter == keys->rend() || value_iter == values->rend()) {
// Sanity Check: if one ends, then both end
assert(key_iter == keys->rend() && value_iter == values->rend());
break;
}
// Otherwise not at end of list. Update key, value, and ikey.
key = Slice(*key_iter);
value = Slice(*value_iter);
ParseInternalKey(key, &ikey);
} else{
// Only had one item to begin with (Put/Delete)
break;
}
}
}
// MergeUntil has moved input to the next entry
if (!current_entry_is_merging) {
input->Next();
}
}
if (status.ok() && shutting_down_.Acquire_Load()) {
status = Status::IOError("Database shutdown started during compaction");
}
if (status.ok() && compact->builder != nullptr) {
status = FinishCompactionOutputFile(compact, input.get());
}
if (status.ok()) {
status = input->status();
}
input.reset();
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros - imm_micros;
if (options_.statistics) {
options_.statistics->measureTime(COMPACTION_TIME, stats.micros);
}
stats.files_in_leveln = compact->compaction->num_input_files(0);
stats.files_in_levelnp1 = compact->compaction->num_input_files(1);
int num_output_files = compact->outputs.size();
if (compact->builder != nullptr) {
// An error occured so ignore the last output.
assert(num_output_files > 0);
--num_output_files;
}
stats.files_out_levelnp1 = num_output_files;
for (int i = 0; i < compact->compaction->num_input_files(0); i++)
stats.bytes_readn += compact->compaction->input(0, i)->file_size;
for (int i = 0; i < compact->compaction->num_input_files(1); i++)
stats.bytes_readnp1 += compact->compaction->input(1, i)->file_size;
for (int i = 0; i < num_output_files; i++) {
stats.bytes_written += compact->outputs[i].file_size;
}
mutex_.Lock();
stats_[compact->compaction->output_level()].Add(stats);
// if there were any unused file number (mostly in case of
// compaction error), free up the entry from pending_putputs
ReleaseCompactionUnusedFileNumbers(compact);
if (status.ok()) {
status = InstallCompactionResults(compact);
}
VersionSet::LevelSummaryStorage tmp;
Log(options_.info_log,
"compacted to: %s, %.1f MB/sec, level %d, files in(%d, %d) out(%d) "
"MB in(%.1f, %.1f) out(%.1f), read-write-amplify(%.1f) "
"write-amplify(%.1f) %s\n",
versions_->LevelSummary(&tmp),
(stats.bytes_readn + stats.bytes_readnp1 + stats.bytes_written) /
(double) stats.micros,
compact->compaction->output_level(),
stats.files_in_leveln, stats.files_in_levelnp1, stats.files_out_levelnp1,
stats.bytes_readn / 1048576.0,
stats.bytes_readnp1 / 1048576.0,
stats.bytes_written / 1048576.0,
(stats.bytes_written + stats.bytes_readnp1 + stats.bytes_readn) /
(double) stats.bytes_readn,
stats.bytes_written / (double) stats.bytes_readn,
status.ToString().c_str());
return status;
}
namespace {
struct IterState {
port::Mutex* mu;
Version* version;
std::vector<MemTable*> mem; // includes both mem_ and imm_
};
static void CleanupIteratorState(void* arg1, void* arg2) {
IterState* state = reinterpret_cast<IterState*>(arg1);
state->mu->Lock();
for (unsigned int i = 0; i < state->mem.size(); i++) {
state->mem[i]->Unref();
}
state->version->Unref();
state->mu->Unlock();
delete state;
}
} // namespace
Iterator* DBImpl::NewInternalIterator(const ReadOptions& options,
SequenceNumber* latest_snapshot) {
IterState* cleanup = new IterState;
mutex_.Lock();
*latest_snapshot = versions_->LastSequence();
// Collect together all needed child iterators for mem
std::vector<Iterator*> list;
mem_->Ref();
list.push_back(mem_->NewIterator(options.prefix));
cleanup->mem.push_back(mem_);
// Collect together all needed child iterators for imm_
std::vector<MemTable*> immutables;
imm_.GetMemTables(&immutables);
for (unsigned int i = 0; i < immutables.size(); i++) {
MemTable* m = immutables[i];
m->Ref();
list.push_back(m->NewIterator(options.prefix));
cleanup->mem.push_back(m);
}
// Collect iterators for files in L0 - Ln
versions_->current()->AddIterators(options, storage_options_, &list);
Iterator* internal_iter =
NewMergingIterator(&internal_comparator_, &list[0], list.size());
versions_->current()->Ref();
cleanup->mu = &mutex_;
cleanup->version = versions_->current();
internal_iter->RegisterCleanup(CleanupIteratorState, cleanup, nullptr);
mutex_.Unlock();
return internal_iter;
}
Iterator* DBImpl::TEST_NewInternalIterator() {
SequenceNumber ignored;
return NewInternalIterator(ReadOptions(), &ignored);
}
int64_t DBImpl::TEST_MaxNextLevelOverlappingBytes() {
MutexLock l(&mutex_);
return versions_->MaxNextLevelOverlappingBytes();
}
Status DBImpl::Get(const ReadOptions& options,
const Slice& key,
std::string* value) {
return GetImpl(options, key, value);
}
Status DBImpl::GetImpl(const ReadOptions& options,
const Slice& key,
std::string* value,
bool* value_found) {
Status s;
StopWatch sw(env_, options_.statistics, DB_GET);
SequenceNumber snapshot;
mutex_.Lock();
if (options.snapshot != nullptr) {
snapshot = reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_;
} else {
snapshot = versions_->LastSequence();
}
MemTable* mem = mem_;
MemTableList imm = imm_;
Version* current = versions_->current();
mem->Ref();
imm.RefAll();
current->Ref();
// Unlock while reading from files and memtables
mutex_.Unlock();
bool have_stat_update = false;
Version::GetStats stats;
// Prepare to store a list of merge operations if merge occurs.
std::deque<std::string> merge_operands;
// First look in the memtable, then in the immutable memtable (if any).
// s is both in/out. When in, s could either be OK or MergeInProgress.
// merge_operands will contain the sequence of merges in the latter case.
LookupKey lkey(key, snapshot);
if (mem->Get(lkey, value, &s, &merge_operands, options_)) {
// Done
} else if (imm.Get(lkey, value, &s, &merge_operands, options_)) {
// Done
} else {
current->Get(options, lkey, value, &s, &merge_operands, &stats,
options_, value_found);
have_stat_update = true;
}
mutex_.Lock();
if (!options_.disable_seek_compaction &&
have_stat_update && current->UpdateStats(stats)) {
MaybeScheduleFlushOrCompaction();
}
mem->Unref();
imm.UnrefAll();
current->Unref();
mutex_.Unlock();
// Note, tickers are atomic now - no lock protection needed any more.
RecordTick(options_.statistics, NUMBER_KEYS_READ);
RecordTick(options_.statistics, BYTES_READ, value->size());
return s;
}
std::vector<Status> DBImpl::MultiGet(const ReadOptions& options,
const std::vector<Slice>& keys,
std::vector<std::string>* values) {
StopWatch sw(env_, options_.statistics, DB_MULTIGET);
SequenceNumber snapshot;
mutex_.Lock();
if (options.snapshot != nullptr) {
snapshot = reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_;
} else {
snapshot = versions_->LastSequence();
}
MemTable* mem = mem_;
MemTableList imm = imm_;
Version* current = versions_->current();
mem->Ref();
imm.RefAll();
current->Ref();
// Unlock while reading from files and memtables
mutex_.Unlock();
bool have_stat_update = false;
Version::GetStats stats;
// Prepare to store a list of merge operations if merge occurs.
std::deque<std::string> merge_operands;
// Note: this always resizes the values array
int numKeys = keys.size();
std::vector<Status> statList(numKeys);
values->resize(numKeys);
// Keep track of bytes that we read for statistics-recording later
uint64_t bytesRead = 0;
// For each of the given keys, apply the entire "get" process as follows:
// First look in the memtable, then in the immutable memtable (if any).
// s is both in/out. When in, s could either be OK or MergeInProgress.
// merge_operands will contain the sequence of merges in the latter case.
for (int i=0; i<numKeys; ++i) {
merge_operands.clear();
Status& s = statList[i];
std::string* value = &(*values)[i];
LookupKey lkey(keys[i], snapshot);
if (mem->Get(lkey, value, &s, &merge_operands, options_)) {
// Done
} else if (imm.Get(lkey, value, &s, &merge_operands, options_)) {
// Done
} else {
current->Get(options, lkey, value, &s, &merge_operands, &stats, options_);
have_stat_update = true;
}
if (s.ok()) {
bytesRead += value->size();
}
}
// Post processing (decrement reference counts and record statistics)
mutex_.Lock();
if (!options_.disable_seek_compaction &&
have_stat_update && current->UpdateStats(stats)) {
MaybeScheduleFlushOrCompaction();
}
mem->Unref();
imm.UnrefAll();
current->Unref();
mutex_.Unlock();
RecordTick(options_.statistics, NUMBER_MULTIGET_CALLS);
RecordTick(options_.statistics, NUMBER_MULTIGET_KEYS_READ, numKeys);
RecordTick(options_.statistics, NUMBER_MULTIGET_BYTES_READ, bytesRead);
return statList;
}
bool DBImpl::KeyMayExist(const ReadOptions& options,
const Slice& key,
std::string* value,
bool* value_found) {
if (value_found != nullptr) {
*value_found = true; // falsify later if key-may-exist but can't fetch value
}
ReadOptions roptions = options;
roptions.read_tier = kBlockCacheTier; // read from block cache only
return GetImpl(roptions, key, value, value_found).ok();
}
Iterator* DBImpl::NewIterator(const ReadOptions& options) {
SequenceNumber latest_snapshot;
Iterator* iter = NewInternalIterator(options, &latest_snapshot);
iter = NewDBIterator(
&dbname_, env_, options_, user_comparator(), iter,
(options.snapshot != nullptr
? reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_
: latest_snapshot));
if (options.prefix) {
// use extra wrapper to exclude any keys from the results which
// don't begin with the prefix
iter = new PrefixFilterIterator(iter, *options.prefix,
options_.prefix_extractor);
}
return iter;
}
const Snapshot* DBImpl::GetSnapshot() {
MutexLock l(&mutex_);
return snapshots_.New(versions_->LastSequence());
}
void DBImpl::ReleaseSnapshot(const Snapshot* s) {
MutexLock l(&mutex_);
snapshots_.Delete(reinterpret_cast<const SnapshotImpl*>(s));
}
// Convenience methods
Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
return DB::Put(o, key, val);
}
Status DBImpl::Merge(const WriteOptions& o, const Slice& key,
const Slice& val) {
if (!options_.merge_operator) {
return Status::NotSupported("Provide a merge_operator when opening DB");
} else {
return DB::Merge(o, key, val);
}
}
Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
return DB::Delete(options, key);
}
Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
Writer w(&mutex_);
w.batch = my_batch;
w.sync = options.sync;
w.disableWAL = options.disableWAL;
w.done = false;
StopWatch sw(env_, options_.statistics, DB_WRITE);
MutexLock l(&mutex_);
writers_.push_back(&w);
while (!w.done && &w != writers_.front()) {
w.cv.Wait();
}
if (w.done) {
return w.status;
}
// May temporarily unlock and wait.
Status status = MakeRoomForWrite(my_batch == nullptr);
uint64_t last_sequence = versions_->LastSequence();
Writer* last_writer = &w;
if (status.ok() && my_batch != nullptr) { // nullptr batch is for compactions
// TODO: BuildBatchGroup physically concatenate/copy all write batches into
// a new one. Mem copy is done with the lock held. Ideally, we only need
// the lock to obtain the last_writer and the references to all batches.
// Creation (copy) of the merged batch could have been done outside of the
// lock protected region.
WriteBatch* updates = BuildBatchGroup(&last_writer);
// Add to log and apply to memtable. We can release the lock
// during this phase since &w is currently responsible for logging
// and protects against concurrent loggers and concurrent writes
// into mem_.
{
mutex_.Unlock();
const SequenceNumber current_sequence = last_sequence + 1;
WriteBatchInternal::SetSequence(updates, current_sequence);
int my_batch_count = WriteBatchInternal::Count(updates);
last_sequence += my_batch_count;
// Record statistics
RecordTick(options_.statistics, NUMBER_KEYS_WRITTEN, my_batch_count);
RecordTick(options_.statistics,
BYTES_WRITTEN,
WriteBatchInternal::ByteSize(updates));
if (options.disableWAL) {
flush_on_destroy_ = true;
}
if (!options.disableWAL) {
status = log_->AddRecord(WriteBatchInternal::Contents(updates));
if (status.ok() && options.sync) {
if (options_.use_fsync) {
StopWatch(env_, options_.statistics, WAL_FILE_SYNC_MICROS);
status = log_->file()->Fsync();
} else {
StopWatch(env_, options_.statistics, WAL_FILE_SYNC_MICROS);
status = log_->file()->Sync();
}
}
}
if (status.ok()) {
status = WriteBatchInternal::InsertInto(updates, mem_, &options_, this,
options_.filter_deletes);
if (!status.ok()) {
// Panic for in-memory corruptions
// Note that existing logic was not sound. Any partial failure writing
// into the memtable would result in a state that some write ops might
// have succeeded in memtable but Status reports error for all writes.
throw std::runtime_error("In memory WriteBatch corruption!");
}
SetTickerCount(options_.statistics, SEQUENCE_NUMBER, last_sequence);
}
mutex_.Lock();
if (status.ok()) {
versions_->SetLastSequence(last_sequence);
last_flushed_sequence_ = current_sequence;
}
}
if (updates == &tmp_batch_) tmp_batch_.Clear();
}
while (true) {
Writer* ready = writers_.front();
writers_.pop_front();
if (ready != &w) {
ready->status = status;
ready->done = true;
ready->cv.Signal();
}
if (ready == last_writer) break;
}
// Notify new head of write queue
if (!writers_.empty()) {
writers_.front()->cv.Signal();
}
return status;
}
// REQUIRES: Writer list must be non-empty
// REQUIRES: First writer must have a non-nullptr batch
WriteBatch* DBImpl::BuildBatchGroup(Writer** last_writer) {
assert(!writers_.empty());
Writer* first = writers_.front();
WriteBatch* result = first->batch;
assert(result != nullptr);
size_t size = WriteBatchInternal::ByteSize(first->batch);
// Allow the group to grow up to a maximum size, but if the
// original write is small, limit the growth so we do not slow
// down the small write too much.
size_t max_size = 1 << 20;
if (size <= (128<<10)) {
max_size = size + (128<<10);
}
*last_writer = first;
std::deque<Writer*>::iterator iter = writers_.begin();
++iter; // Advance past "first"
for (; iter != writers_.end(); ++iter) {
Writer* w = *iter;
if (w->sync && !first->sync) {
// Do not include a sync write into a batch handled by a non-sync write.
break;
}
if (!w->disableWAL && first->disableWAL) {
// Do not include a write that needs WAL into a batch that has
// WAL disabled.
break;
}
if (w->batch != nullptr) {
size += WriteBatchInternal::ByteSize(w->batch);
if (size > max_size) {
// Do not make batch too big
break;
}
// Append to *reuslt
if (result == first->batch) {
// Switch to temporary batch instead of disturbing caller's batch
result = &tmp_batch_;
assert(WriteBatchInternal::Count(result) == 0);
WriteBatchInternal::Append(result, first->batch);
}
WriteBatchInternal::Append(result, w->batch);
}
*last_writer = w;
}
return result;
}
// This function computes the amount of time in microseconds by which a write
// should be delayed based on the number of level-0 files according to the
// following formula:
// if n < bottom, return 0;
// if n >= top, return 1000;
// otherwise, let r = (n - bottom) /
// (top - bottom)
// and return r^2 * 1000.
// The goal of this formula is to gradually increase the rate at which writes
// are slowed. We also tried linear delay (r * 1000), but it seemed to do
// slightly worse. There is no other particular reason for choosing quadratic.
uint64_t DBImpl::SlowdownAmount(int n, int top, int bottom) {
uint64_t delay;
if (n >= top) {
delay = 1000;
}
else if (n < bottom) {
delay = 0;
}
else {
// If we are here, we know that:
// level0_start_slowdown <= n < level0_slowdown
// since the previous two conditions are false.
float how_much =
(float) (n - bottom) /
(top - bottom);
delay = how_much * how_much * 1000;
}
assert(delay <= 1000);
return delay;
}
// REQUIRES: mutex_ is held
// REQUIRES: this thread is currently at the front of the writer queue
Status DBImpl::MakeRoomForWrite(bool force) {
mutex_.AssertHeld();
assert(!writers_.empty());
bool allow_delay = !force;
bool allow_hard_rate_limit_delay = !force;
bool allow_soft_rate_limit_delay = !force;
uint64_t rate_limit_delay_millis = 0;
Status s;
double score;
while (true) {
if (!bg_error_.ok()) {
// Yield previous error
s = bg_error_;
break;
} else if (
allow_delay &&
versions_->NumLevelFiles(0) >=
options_.level0_slowdown_writes_trigger) {
// We are getting close to hitting a hard limit on the number of
// L0 files. Rather than delaying a single write by several
// seconds when we hit the hard limit, start delaying each
// individual write by 0-1ms to reduce latency variance. Also,
// this delay hands over some CPU to the compaction thread in
// case it is sharing the same core as the writer.
mutex_.Unlock();
uint64_t delayed;
{
StopWatch sw(env_, options_.statistics, STALL_L0_SLOWDOWN_COUNT);
env_->SleepForMicroseconds(
SlowdownAmount(versions_->NumLevelFiles(0),
options_.level0_slowdown_writes_trigger,
options_.level0_stop_writes_trigger)
);
delayed = sw.ElapsedMicros();
}
RecordTick(options_.statistics, STALL_L0_SLOWDOWN_MICROS, delayed);
stall_level0_slowdown_ += delayed;
stall_level0_slowdown_count_++;
allow_delay = false; // Do not delay a single write more than once
//Log(options_.info_log,
// "delaying write %llu usecs for level0_slowdown_writes_trigger\n",
// (long long unsigned int)delayed);
mutex_.Lock();
delayed_writes_++;
} else if (!force &&
(mem_->ApproximateMemoryUsage() <= options_.write_buffer_size)) {
// There is room in current memtable
if (allow_delay) {
DelayLoggingAndReset();
}
break;
} else if (imm_.size() == options_.max_write_buffer_number - 1) {
// We have filled up the current memtable, but the previous
// ones are still being compacted, so we wait.
DelayLoggingAndReset();
Log(options_.info_log, "wait for memtable compaction...\n");
uint64_t stall;
{
StopWatch sw(env_, options_.statistics,
STALL_MEMTABLE_COMPACTION_COUNT);
bg_cv_.Wait();
stall = sw.ElapsedMicros();
}
RecordTick(options_.statistics, STALL_MEMTABLE_COMPACTION_MICROS, stall);
stall_memtable_compaction_ += stall;
stall_memtable_compaction_count_++;
} else if (versions_->NumLevelFiles(0) >=
options_.level0_stop_writes_trigger) {
// There are too many level-0 files.
DelayLoggingAndReset();
Log(options_.info_log, "wait for fewer level0 files...\n");
uint64_t stall;
{
StopWatch sw(env_, options_.statistics, STALL_L0_NUM_FILES_COUNT);
bg_cv_.Wait();
stall = sw.ElapsedMicros();
}
RecordTick(options_.statistics, STALL_L0_NUM_FILES_MICROS, stall);
stall_level0_num_files_ += stall;
stall_level0_num_files_count_++;
} else if (
allow_hard_rate_limit_delay &&
options_.hard_rate_limit > 1.0 &&
(score = versions_->MaxCompactionScore()) > options_.hard_rate_limit) {
// Delay a write when the compaction score for any level is too large.
int max_level = versions_->MaxCompactionScoreLevel();
mutex_.Unlock();
uint64_t delayed;
{
StopWatch sw(env_, options_.statistics, HARD_RATE_LIMIT_DELAY_COUNT);
env_->SleepForMicroseconds(1000);
delayed = sw.ElapsedMicros();
}
stall_leveln_slowdown_[max_level] += delayed;
stall_leveln_slowdown_count_[max_level]++;
// Make sure the following value doesn't round to zero.
uint64_t rate_limit = std::max((delayed / 1000), (uint64_t) 1);
rate_limit_delay_millis += rate_limit;
RecordTick(options_.statistics, RATE_LIMIT_DELAY_MILLIS, rate_limit);
if (options_.rate_limit_delay_max_milliseconds > 0 &&
rate_limit_delay_millis >=
(unsigned)options_.rate_limit_delay_max_milliseconds) {
allow_hard_rate_limit_delay = false;
}
// Log(options_.info_log,
// "delaying write %llu usecs for rate limits with max score %.2f\n",
// (long long unsigned int)delayed, score);
mutex_.Lock();
} else if (
allow_soft_rate_limit_delay &&
options_.soft_rate_limit > 0.0 &&
(score = versions_->MaxCompactionScore()) > options_.soft_rate_limit) {
// Delay a write when the compaction score for any level is too large.
// TODO: add statistics
mutex_.Unlock();
{
StopWatch sw(env_, options_.statistics, SOFT_RATE_LIMIT_DELAY_COUNT);
env_->SleepForMicroseconds(SlowdownAmount(
score,
options_.soft_rate_limit,
options_.hard_rate_limit)
);
rate_limit_delay_millis += sw.ElapsedMicros();
}
allow_soft_rate_limit_delay = false;
mutex_.Lock();
} else {
// Attempt to switch to a new memtable and trigger compaction of old
DelayLoggingAndReset();
assert(versions_->PrevLogNumber() == 0);
uint64_t new_log_number = versions_->NewFileNumber();
unique_ptr<WritableFile> lfile;
EnvOptions soptions(storage_options_);
soptions.use_mmap_writes = false;
s = env_->NewWritableFile(
LogFileName(options_.wal_dir, new_log_number),
&lfile,
soptions
);
if (!s.ok()) {
// Avoid chewing through file number space in a tight loop.
versions_->ReuseFileNumber(new_log_number);
break;
}
// Our final size should be less than write_buffer_size
// (compression, etc) but err on the side of caution.
lfile->SetPreallocationBlockSize(1.1 * options_.write_buffer_size);
logfile_number_ = new_log_number;
log_.reset(new log::Writer(std::move(lfile)));
mem_->SetNextLogNumber(logfile_number_);
imm_.Add(mem_);
if (force) {
imm_.FlushRequested();
}
mem_ = new MemTable(internal_comparator_, mem_rep_factory_,
NumberLevels(), options_);
mem_->Ref();
mem_->SetLogNumber(logfile_number_);
force = false; // Do not force another compaction if have room
MaybeScheduleFlushOrCompaction();
}
}
return s;
}
bool DBImpl::GetProperty(const Slice& property, std::string* value) {
value->clear();
MutexLock l(&mutex_);
Slice in = property;
Slice prefix("rocksdb.");
if (!in.starts_with(prefix)) return false;
in.remove_prefix(prefix.size());
if (in.starts_with("num-files-at-level")) {
in.remove_prefix(strlen("num-files-at-level"));
uint64_t level;
bool ok = ConsumeDecimalNumber(&in, &level) && in.empty();
if (!ok || (int)level >= NumberLevels()) {
return false;
} else {
char buf[100];
snprintf(buf, sizeof(buf), "%d",
versions_->NumLevelFiles(static_cast<int>(level)));
*value = buf;
return true;
}
} else if (in == "levelstats") {
char buf[1000];
snprintf(buf, sizeof(buf),
"Level Files Size(MB)\n"
"--------------------\n");
value->append(buf);
for (int level = 0; level < NumberLevels(); level++) {
snprintf(buf, sizeof(buf),
"%3d %8d %8.0f\n",
level,
versions_->NumLevelFiles(level),
versions_->NumLevelBytes(level) / 1048576.0);
value->append(buf);
}
return true;
} else if (in == "stats") {
char buf[1000];
uint64_t total_bytes_written = 0;
uint64_t total_bytes_read = 0;
uint64_t micros_up = env_->NowMicros() - started_at_;
// Add "+1" to make sure seconds_up is > 0 and avoid NaN later
double seconds_up = (micros_up + 1) / 1000000.0;
uint64_t total_slowdown = 0;
uint64_t total_slowdown_count = 0;
uint64_t interval_bytes_written = 0;
uint64_t interval_bytes_read = 0;
uint64_t interval_bytes_new = 0;
double interval_seconds_up = 0;
// Pardon the long line but I think it is easier to read this way.
snprintf(buf, sizeof(buf),
" Compactions\n"
"Level Files Size(MB) Score Time(sec) Read(MB) Write(MB) Rn(MB) Rnp1(MB) Wnew(MB) RW-Amplify Read(MB/s) Write(MB/s) Rn Rnp1 Wnp1 NewW Count Ln-stall Stall-cnt\n"
"--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\n"
);
value->append(buf);
for (int level = 0; level < NumberLevels(); level++) {
int files = versions_->NumLevelFiles(level);
if (stats_[level].micros > 0 || files > 0) {
int64_t bytes_read = stats_[level].bytes_readn +
stats_[level].bytes_readnp1;
int64_t bytes_new = stats_[level].bytes_written -
stats_[level].bytes_readnp1;
double amplify = (stats_[level].bytes_readn == 0)
? 0.0
: (stats_[level].bytes_written +
stats_[level].bytes_readnp1 +
stats_[level].bytes_readn) /
(double) stats_[level].bytes_readn;
total_bytes_read += bytes_read;
total_bytes_written += stats_[level].bytes_written;
snprintf(
buf, sizeof(buf),
"%3d %8d %8.0f %5.1f %9.0f %9.0f %9.0f %9.0f %9.0f %9.0f %10.1f %9.1f %11.1f %8d %8d %8d %8d %8d %9.1f %9lu\n",
level,
files,
versions_->NumLevelBytes(level) / 1048576.0,
versions_->NumLevelBytes(level) /
versions_->MaxBytesForLevel(level),
stats_[level].micros / 1e6,
bytes_read / 1048576.0,
stats_[level].bytes_written / 1048576.0,
stats_[level].bytes_readn / 1048576.0,
stats_[level].bytes_readnp1 / 1048576.0,
bytes_new / 1048576.0,
amplify,
// +1 to avoid division by 0
(bytes_read / 1048576.0) / ((stats_[level].micros+1) / 1000000.0),
(stats_[level].bytes_written / 1048576.0) /
((stats_[level].micros+1) / 1000000.0),
stats_[level].files_in_leveln,
stats_[level].files_in_levelnp1,
stats_[level].files_out_levelnp1,
stats_[level].files_out_levelnp1 - stats_[level].files_in_levelnp1,
stats_[level].count,
stall_leveln_slowdown_[level] / 1000000.0,
(unsigned long) stall_leveln_slowdown_count_[level]);
total_slowdown += stall_leveln_slowdown_[level];
total_slowdown_count += stall_leveln_slowdown_count_[level];
value->append(buf);
}
}
interval_bytes_new = stats_[0].bytes_written - last_stats_.bytes_new_;
interval_bytes_read = total_bytes_read - last_stats_.bytes_read_;
interval_bytes_written = total_bytes_written - last_stats_.bytes_written_;
interval_seconds_up = seconds_up - last_stats_.seconds_up_;
snprintf(buf, sizeof(buf), "Uptime(secs): %.1f total, %.1f interval\n",
seconds_up, interval_seconds_up);
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO cumulative (GB): "
"%.2f new, %.2f read, %.2f write, %.2f read+write\n",
stats_[0].bytes_written / (1048576.0 * 1024),
total_bytes_read / (1048576.0 * 1024),
total_bytes_written / (1048576.0 * 1024),
(total_bytes_read + total_bytes_written) / (1048576.0 * 1024));
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO cumulative (MB/sec): "
"%.1f new, %.1f read, %.1f write, %.1f read+write\n",
stats_[0].bytes_written / 1048576.0 / seconds_up,
total_bytes_read / 1048576.0 / seconds_up,
total_bytes_written / 1048576.0 / seconds_up,
(total_bytes_read + total_bytes_written) / 1048576.0 / seconds_up);
value->append(buf);
// +1 to avoid divide by 0 and NaN
snprintf(buf, sizeof(buf),
"Amplification cumulative: %.1f write, %.1f compaction\n",
(double) total_bytes_written / (stats_[0].bytes_written+1),
(double) (total_bytes_written + total_bytes_read)
/ (stats_[0].bytes_written+1));
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO interval (MB): "
"%.2f new, %.2f read, %.2f write, %.2f read+write\n",
interval_bytes_new / 1048576.0,
interval_bytes_read/ 1048576.0,
interval_bytes_written / 1048576.0,
(interval_bytes_read + interval_bytes_written) / 1048576.0);
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO interval (MB/sec): "
"%.1f new, %.1f read, %.1f write, %.1f read+write\n",
interval_bytes_new / 1048576.0 / interval_seconds_up,
interval_bytes_read / 1048576.0 / interval_seconds_up,
interval_bytes_written / 1048576.0 / interval_seconds_up,
(interval_bytes_read + interval_bytes_written)
/ 1048576.0 / interval_seconds_up);
value->append(buf);
// +1 to avoid divide by 0 and NaN
snprintf(buf, sizeof(buf),
"Amplification interval: %.1f write, %.1f compaction\n",
(double) interval_bytes_written / (interval_bytes_new+1),
(double) (interval_bytes_written + interval_bytes_read) /
(interval_bytes_new+1));
value->append(buf);
snprintf(buf, sizeof(buf),
"Stalls(secs): %.3f level0_slowdown, %.3f level0_numfiles, "
"%.3f memtable_compaction, %.3f leveln_slowdown\n",
stall_level0_slowdown_ / 1000000.0,
stall_level0_num_files_ / 1000000.0,
stall_memtable_compaction_ / 1000000.0,
total_slowdown / 1000000.0);
value->append(buf);
snprintf(buf, sizeof(buf),
"Stalls(count): %lu level0_slowdown, %lu level0_numfiles, "
"%lu memtable_compaction, %lu leveln_slowdown\n",
(unsigned long) stall_level0_slowdown_count_,
(unsigned long) stall_level0_num_files_count_,
(unsigned long) stall_memtable_compaction_count_,
(unsigned long) total_slowdown_count);
value->append(buf);
last_stats_.bytes_read_ = total_bytes_read;
last_stats_.bytes_written_ = total_bytes_written;
last_stats_.bytes_new_ = stats_[0].bytes_written;
last_stats_.seconds_up_ = seconds_up;
return true;
} else if (in == "sstables") {
*value = versions_->current()->DebugString();
return true;
} else if (in == "num-immutable-mem-table") {
*value = std::to_string(imm_.size());
return true;
}
return false;
}
void DBImpl::GetApproximateSizes(
const Range* range, int n,
uint64_t* sizes) {
// TODO(opt): better implementation
Version* v;
{
MutexLock l(&mutex_);
versions_->current()->Ref();
v = versions_->current();
}
for (int i = 0; i < n; i++) {
// Convert user_key into a corresponding internal key.
InternalKey k1(range[i].start, kMaxSequenceNumber, kValueTypeForSeek);
InternalKey k2(range[i].limit, kMaxSequenceNumber, kValueTypeForSeek);
uint64_t start = versions_->ApproximateOffsetOf(v, k1);
uint64_t limit = versions_->ApproximateOffsetOf(v, k2);
sizes[i] = (limit >= start ? limit - start : 0);
}
{
MutexLock l(&mutex_);
v->Unref();
}
}
inline void DBImpl::DelayLoggingAndReset() {
if (delayed_writes_ > 0) {
Log(options_.info_log, "delayed %d write...\n", delayed_writes_ );
delayed_writes_ = 0;
}
}
Status DBImpl::DeleteFile(std::string name) {
uint64_t number;
FileType type;
if (!ParseFileName(name, &number, &type) ||
(type != kTableFile)) {
Log(options_.info_log, "DeleteFile #%lld FAILED. Invalid file name\n",
static_cast<unsigned long long>(number));
return Status::InvalidArgument("Invalid file name");
}
int level;
FileMetaData metadata;
int maxlevel = NumberLevels();
VersionEdit edit(maxlevel);
DeletionState deletion_state;
Status status;
{
MutexLock l(&mutex_);
status = versions_->GetMetadataForFile(number, &level, &metadata);
if (!status.ok()) {
Log(options_.info_log, "DeleteFile #%lld FAILED. File not found\n",
static_cast<unsigned long long>(number));
return Status::InvalidArgument("File not found");
}
assert((level > 0) && (level < maxlevel));
// If the file is being compacted no need to delete.
if (metadata.being_compacted) {
Log(options_.info_log,
"DeleteFile #%lld Skipped. File about to be compacted\n",
static_cast<unsigned long long>(number));
return Status::OK();
}
// Only the files in the last level can be deleted externally.
// This is to make sure that any deletion tombstones are not
// lost. Check that the level passed is the last level.
for (int i = level + 1; i < maxlevel; i++) {
if (versions_->NumLevelFiles(i) != 0) {
Log(options_.info_log,
"DeleteFile #%lld FAILED. File not in last level\n",
static_cast<unsigned long long>(number));
return Status::InvalidArgument("File not in last level");
}
}
edit.DeleteFile(level, number);
status = versions_->LogAndApply(&edit, &mutex_);
if (status.ok()) {
FindObsoleteFiles(deletion_state);
}
} // lock released here
if (status.ok()) {
// remove files outside the db-lock
PurgeObsoleteFiles(deletion_state);
EvictObsoleteFiles(deletion_state);
}
return status;
}
void DBImpl::GetLiveFilesMetaData(std::vector<LiveFileMetaData> *metadata) {
MutexLock l(&mutex_);
return versions_->GetLiveFilesMetaData(metadata);
}
// Default implementations of convenience methods that subclasses of DB
// can call if they wish
Status DB::Put(const WriteOptions& opt, const Slice& key, const Slice& value) {
WriteBatch batch;
batch.Put(key, value);
return Write(opt, &batch);
}
Status DB::Delete(const WriteOptions& opt, const Slice& key) {
WriteBatch batch;
batch.Delete(key);
return Write(opt, &batch);
}
Status DB::Merge(const WriteOptions& opt, const Slice& key,
const Slice& value) {
WriteBatch batch;
batch.Merge(key, value);
return Write(opt, &batch);
}
DB::~DB() { }
Status DB::Open(const Options& options, const std::string& dbname, DB** dbptr) {
*dbptr = nullptr;
EnvOptions soptions;
if (options.block_cache != nullptr && options.no_block_cache) {
return Status::InvalidArgument(
"no_block_cache is true while block_cache is not nullptr");
}
DBImpl* impl = new DBImpl(options, dbname);
Status s = impl->env_->CreateDirIfMissing(impl->options_.wal_dir);
if (!s.ok()) {
delete impl;
return s;
}
s = impl->CreateArchivalDirectory();
if (!s.ok()) {
delete impl;
return s;
}
impl->mutex_.Lock();
VersionEdit edit(impl->NumberLevels());
s = impl->Recover(&edit); // Handles create_if_missing, error_if_exists
if (s.ok()) {
uint64_t new_log_number = impl->versions_->NewFileNumber();
unique_ptr<WritableFile> lfile;
soptions.use_mmap_writes = false;
s = options.env->NewWritableFile(
LogFileName(impl->options_.wal_dir, new_log_number),
&lfile,
soptions
);
if (s.ok()) {
lfile->SetPreallocationBlockSize(1.1 * options.write_buffer_size);
edit.SetLogNumber(new_log_number);
impl->logfile_number_ = new_log_number;
impl->log_.reset(new log::Writer(std::move(lfile)));
s = impl->versions_->LogAndApply(&edit, &impl->mutex_);
}
if (s.ok()) {
impl->mem_->SetLogNumber(impl->logfile_number_);
impl->DeleteObsoleteFiles();
impl->MaybeScheduleFlushOrCompaction();
impl->MaybeScheduleLogDBDeployStats();
}
}
impl->mutex_.Unlock();
if (options.compaction_style == kCompactionStyleUniversal) {
int num_files;
for (int i = 1; i < impl->NumberLevels(); i++) {
num_files = impl->versions_->NumLevelFiles(i);
if (num_files > 0) {
s = Status::InvalidArgument("Not all files are at level 0. Cannot "
"open with universal compaction style.");
break;
}
}
}
if (s.ok()) {
*dbptr = impl;
} else {
delete impl;
}
return s;
}
Snapshot::~Snapshot() {
}
Status DestroyDB(const std::string& dbname, const Options& options) {
const InternalKeyComparator comparator(options.comparator);
const InternalFilterPolicy filter_policy(options.filter_policy);
const Options& soptions(SanitizeOptions(
dbname, &comparator, &filter_policy, options));
Env* env = soptions.env;
std::vector<std::string> filenames;
std::vector<std::string> archiveFiles;
std::string archivedir = ArchivalDirectory(dbname);
// Ignore error in case directory does not exist
env->GetChildren(dbname, &filenames);
if (dbname != soptions.wal_dir) {
std::vector<std::string> logfilenames;
env->GetChildren(soptions.wal_dir, &logfilenames);
filenames.insert(filenames.end(), logfilenames.begin(), logfilenames.end());
archivedir = ArchivalDirectory(soptions.wal_dir);
}
if (filenames.empty()) {
return Status::OK();
}
FileLock* lock;
const std::string lockname = LockFileName(dbname);
Status result = env->LockFile(lockname, &lock);
if (result.ok()) {
uint64_t number;
FileType type;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type) &&
type != kDBLockFile) { // Lock file will be deleted at end
Status del;
if (type == kMetaDatabase) {
del = DestroyDB(dbname + "/" + filenames[i], options);
} else if (type == kLogFile) {
del = env->DeleteFile(soptions.wal_dir + "/" + filenames[i]);
} else {
del = env->DeleteFile(dbname + "/" + filenames[i]);
}
if (result.ok() && !del.ok()) {
result = del;
}
}
}
env->GetChildren(archivedir, &archiveFiles);
// Delete archival files.
for (size_t i = 0; i < archiveFiles.size(); ++i) {
if (ParseFileName(archiveFiles[i], &number, &type) &&
type == kLogFile) {
Status del = env->DeleteFile(archivedir + "/" + archiveFiles[i]);
if (result.ok() && !del.ok()) {
result = del;
}
}
}
// ignore case where no archival directory is present.
env->DeleteDir(archivedir);
env->UnlockFile(lock); // Ignore error since state is already gone
env->DeleteFile(lockname);
env->DeleteDir(dbname); // Ignore error in case dir contains other files
env->DeleteDir(soptions.wal_dir);
}
return result;
}
//
// A global method that can dump out the build version
void dumpLeveldbBuildVersion(Logger * log) {
Log(log, "Git sha %s", rocksdb_build_git_sha);
Log(log, "Compile time %s %s",
rocksdb_build_compile_time, rocksdb_build_compile_date);
}
} // namespace rocksdb