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rocksdb/db/version_set.cc
Igor Canadi 758fa8c359 Don't Finalize in CompactionPicker 
Summary:
Finalize re-sorts (read: mutates) the files_ in Version* and it is called by CompactionPicker during normal runtime. At the same time, this same Version* lives in the SuperVersion* and is accessed without the mutex in GetImpl() code path.

Mutating the files_ in one thread and reading the same files_ in another thread is a bad idea. It caused this issue: http://ci-builds.fb.com/job/rocksdb_crashtest/285/console

Long-term, we need to be more careful with method contracts and clearly document what state can be mutated when. Now that we are much faster because we don't lock in GetImpl(), we keep running into data races that were not a problem before when we were slower. db_stress has been very helpful in detecting those.

Short-term, I removed Finalize() from CompactionPicker.

Note: I believe this is an issue in current 2.7 version running in production.

Test Plan:
make check
Will also run db_stress to see if issue is gone

Reviewers: sdong, ljin, dhruba, haobo

Reviewed By: sdong

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16983
2014-03-18 13:59:59 -07:00

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// 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.
#define __STDC_FORMAT_MACROS
#include "db/version_set.h"
#include <inttypes.h>
#include <algorithm>
#include <climits>
#include <stdio.h>
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "db/memtable.h"
#include "db/merge_context.h"
#include "db/table_cache.h"
#include "db/compaction.h"
#include "rocksdb/env.h"
#include "rocksdb/merge_operator.h"
#include "table/table_reader.h"
#include "table/merger.h"
#include "table/two_level_iterator.h"
#include "table/format.h"
#include "table/meta_blocks.h"
#include "util/coding.h"
#include "util/logging.h"
#include "util/stop_watch.h"
namespace rocksdb {
static uint64_t TotalFileSize(const std::vector<FileMetaData*>& files) {
uint64_t sum = 0;
for (size_t i = 0; i < files.size() && files[i]; i++) {
sum += files[i]->file_size;
}
return sum;
}
Version::~Version() {
assert(refs_ == 0);
// Remove from linked list
prev_->next_ = next_;
next_->prev_ = prev_;
// Drop references to files
for (int level = 0; level < num_levels_; level++) {
for (size_t i = 0; i < files_[level].size(); i++) {
FileMetaData* f = files_[level][i];
assert(f->refs > 0);
f->refs--;
if (f->refs <= 0) {
if (f->table_reader_handle) {
vset_->table_cache_->ReleaseHandle(f->table_reader_handle);
f->table_reader_handle = nullptr;
}
vset_->obsolete_files_.push_back(f);
}
}
}
delete[] files_;
}
int FindFile(const InternalKeyComparator& icmp,
const std::vector<FileMetaData*>& files,
const Slice& key) {
uint32_t left = 0;
uint32_t right = files.size();
while (left < right) {
uint32_t mid = (left + right) / 2;
const FileMetaData* f = files[mid];
if (icmp.InternalKeyComparator::Compare(f->largest.Encode(), key) < 0) {
// Key at "mid.largest" is < "target". Therefore all
// files at or before "mid" are uninteresting.
left = mid + 1;
} else {
// Key at "mid.largest" is >= "target". Therefore all files
// after "mid" are uninteresting.
right = mid;
}
}
return right;
}
static bool AfterFile(const Comparator* ucmp,
const Slice* user_key, const FileMetaData* f) {
// nullptr user_key occurs before all keys and is therefore never after *f
return (user_key != nullptr &&
ucmp->Compare(*user_key, f->largest.user_key()) > 0);
}
static bool BeforeFile(const Comparator* ucmp,
const Slice* user_key, const FileMetaData* f) {
// nullptr user_key occurs after all keys and is therefore never before *f
return (user_key != nullptr &&
ucmp->Compare(*user_key, f->smallest.user_key()) < 0);
}
bool SomeFileOverlapsRange(
const InternalKeyComparator& icmp,
bool disjoint_sorted_files,
const std::vector<FileMetaData*>& files,
const Slice* smallest_user_key,
const Slice* largest_user_key) {
const Comparator* ucmp = icmp.user_comparator();
if (!disjoint_sorted_files) {
// Need to check against all files
for (size_t i = 0; i < files.size(); i++) {
const FileMetaData* f = files[i];
if (AfterFile(ucmp, smallest_user_key, f) ||
BeforeFile(ucmp, largest_user_key, f)) {
// No overlap
} else {
return true; // Overlap
}
}
return false;
}
// Binary search over file list
uint32_t index = 0;
if (smallest_user_key != nullptr) {
// Find the earliest possible internal key for smallest_user_key
InternalKey small(*smallest_user_key, kMaxSequenceNumber,kValueTypeForSeek);
index = FindFile(icmp, files, small.Encode());
}
if (index >= files.size()) {
// beginning of range is after all files, so no overlap.
return false;
}
return !BeforeFile(ucmp, largest_user_key, files[index]);
}
// An internal iterator. For a given version/level pair, yields
// information about the files in the level. For a given entry, key()
// is the largest key that occurs in the file, and value() is an
// 16-byte value containing the file number and file size, both
// encoded using EncodeFixed64.
class Version::LevelFileNumIterator : public Iterator {
public:
LevelFileNumIterator(const InternalKeyComparator& icmp,
const std::vector<FileMetaData*>* flist)
: icmp_(icmp),
flist_(flist),
index_(flist->size()) { // Marks as invalid
}
virtual bool Valid() const {
return index_ < flist_->size();
}
virtual void Seek(const Slice& target) {
index_ = FindFile(icmp_, *flist_, target);
}
virtual void SeekToFirst() { index_ = 0; }
virtual void SeekToLast() {
index_ = flist_->empty() ? 0 : flist_->size() - 1;
}
virtual void Next() {
assert(Valid());
index_++;
}
virtual void Prev() {
assert(Valid());
if (index_ == 0) {
index_ = flist_->size(); // Marks as invalid
} else {
index_--;
}
}
Slice key() const {
assert(Valid());
return (*flist_)[index_]->largest.Encode();
}
Slice value() const {
assert(Valid());
EncodeFixed64(value_buf_, (*flist_)[index_]->number);
EncodeFixed64(value_buf_+8, (*flist_)[index_]->file_size);
return Slice(value_buf_, sizeof(value_buf_));
}
virtual Status status() const { return Status::OK(); }
private:
const InternalKeyComparator icmp_;
const std::vector<FileMetaData*>* const flist_;
uint32_t index_;
// Backing store for value(). Holds the file number and size.
mutable char value_buf_[16];
};
static Iterator* GetFileIterator(void* arg, const ReadOptions& options,
const EnvOptions& soptions,
const InternalKeyComparator& icomparator,
const Slice& file_value, bool for_compaction) {
TableCache* cache = reinterpret_cast<TableCache*>(arg);
if (file_value.size() != 16) {
return NewErrorIterator(
Status::Corruption("FileReader invoked with unexpected value"));
} else {
ReadOptions options_copy;
if (options.prefix) {
// suppress prefix filtering since we have already checked the
// filters once at this point
options_copy = options;
options_copy.prefix = nullptr;
}
FileMetaData meta(DecodeFixed64(file_value.data()),
DecodeFixed64(file_value.data() + 8));
return cache->NewIterator(
options.prefix ? options_copy : options, soptions, icomparator, meta,
nullptr /* don't need reference to table*/, for_compaction);
}
}
bool Version::PrefixMayMatch(const ReadOptions& options,
const EnvOptions& soptions,
const Slice& internal_prefix,
Iterator* level_iter) const {
bool may_match = true;
level_iter->Seek(internal_prefix);
if (!level_iter->Valid()) {
// we're past end of level
may_match = false;
} else if (ExtractUserKey(level_iter->key()).starts_with(
ExtractUserKey(internal_prefix))) {
// TODO(tylerharter): do we need this case? Or are we guaranteed
// key() will always be the biggest value for this SST?
may_match = true;
} else {
may_match = vset_->table_cache_->PrefixMayMatch(
options, vset_->icmp_, DecodeFixed64(level_iter->value().data()),
DecodeFixed64(level_iter->value().data() + 8), internal_prefix,
nullptr);
}
return may_match;
}
Status Version::GetPropertiesOfAllTables(TablePropertiesCollection* props) {
auto table_cache = vset_->table_cache_;
auto options = vset_->options_;
for (int level = 0; level < num_levels_; level++) {
for (const auto& file_meta : files_[level]) {
auto fname = TableFileName(vset_->dbname_, file_meta->number);
// 1. If the table is already present in table cache, load table
// properties from there.
std::shared_ptr<const TableProperties> table_properties;
Status s = table_cache->GetTableProperties(
vset_->storage_options_, vset_->icmp_, *file_meta, &table_properties,
true /* no io */);
if (s.ok()) {
props->insert({fname, table_properties});
continue;
}
// We only ignore error type `Incomplete` since it's by design that we
// disallow table when it's not in table cache.
if (!s.IsIncomplete()) {
return s;
}
// 2. Table is not present in table cache, we'll read the table properties
// directly from the properties block in the file.
std::unique_ptr<RandomAccessFile> file;
s = vset_->env_->NewRandomAccessFile(fname, &file,
vset_->storage_options_);
if (!s.ok()) {
return s;
}
TableProperties* raw_table_properties;
// By setting the magic number to kInvalidTableMagicNumber, we can by
// pass the magic number check in the footer.
s = ReadTableProperties(
file.get(), file_meta->file_size,
Footer::kInvalidTableMagicNumber /* table's magic number */,
vset_->env_, options->info_log.get(), &raw_table_properties);
if (!s.ok()) {
return s;
}
RecordTick(options->statistics.get(),
NUMBER_DIRECT_LOAD_TABLE_PROPERTIES);
props->insert({fname, std::shared_ptr<const TableProperties>(
raw_table_properties)});
}
}
return Status::OK();
}
Iterator* Version::NewConcatenatingIterator(const ReadOptions& options,
const EnvOptions& soptions,
int level) const {
Iterator* level_iter = new LevelFileNumIterator(vset_->icmp_, &files_[level]);
if (options.prefix) {
InternalKey internal_prefix(*options.prefix, 0, kTypeValue);
if (!PrefixMayMatch(options, soptions,
internal_prefix.Encode(), level_iter)) {
delete level_iter;
// nothing in this level can match the prefix
return NewEmptyIterator();
}
}
return NewTwoLevelIterator(level_iter, &GetFileIterator, vset_->table_cache_,
options, soptions, vset_->icmp_);
}
void Version::AddIterators(const ReadOptions& options,
const EnvOptions& soptions,
std::vector<Iterator*>* iters) {
// Merge all level zero files together since they may overlap
for (const FileMetaData* file : files_[0]) {
iters->push_back(vset_->table_cache_->NewIterator(options, soptions,
vset_->icmp_, *file));
}
// For levels > 0, we can use a concatenating iterator that sequentially
// walks through the non-overlapping files in the level, opening them
// lazily.
for (int level = 1; level < num_levels_; level++) {
if (!files_[level].empty()) {
iters->push_back(NewConcatenatingIterator(options, soptions, level));
}
}
}
// Callback from TableCache::Get()
namespace {
enum SaverState {
kNotFound,
kFound,
kDeleted,
kCorrupt,
kMerge // saver contains the current merge result (the operands)
};
struct Saver {
SaverState state;
const Comparator* ucmp;
Slice user_key;
bool* value_found; // Is value set correctly? Used by KeyMayExist
std::string* value;
const MergeOperator* merge_operator;
// the merge operations encountered;
MergeContext* merge_context;
Logger* logger;
bool didIO; // did we do any disk io?
Statistics* statistics;
};
}
// Called from TableCache::Get and Table::Get when file/block in which
// key may exist are not there in TableCache/BlockCache respectively. In this
// case we can't guarantee that key does not exist and are not permitted to do
// IO to be certain.Set the status=kFound and value_found=false to let the
// caller know that key may exist but is not there in memory
static void MarkKeyMayExist(void* arg) {
Saver* s = reinterpret_cast<Saver*>(arg);
s->state = kFound;
if (s->value_found != nullptr) {
*(s->value_found) = false;
}
}
static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
const Slice& v, bool didIO) {
Saver* s = reinterpret_cast<Saver*>(arg);
MergeContext* merge_contex = s->merge_context;
std::string merge_result; // temporary area for merge results later
assert(s != nullptr && merge_contex != nullptr);
// TODO: didIO and Merge?
s->didIO = didIO;
if (s->ucmp->Compare(parsed_key.user_key, s->user_key) == 0) {
// Key matches. Process it
switch (parsed_key.type) {
case kTypeValue:
if (kNotFound == s->state) {
s->state = kFound;
s->value->assign(v.data(), v.size());
} else if (kMerge == s->state) {
assert(s->merge_operator != nullptr);
s->state = kFound;
if (!s->merge_operator->FullMerge(s->user_key, &v,
merge_contex->GetOperands(),
s->value, s->logger)) {
RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
s->state = kCorrupt;
}
} else {
assert(false);
}
return false;
case kTypeDeletion:
if (kNotFound == s->state) {
s->state = kDeleted;
} else if (kMerge == s->state) {
s->state = kFound;
if (!s->merge_operator->FullMerge(s->user_key, nullptr,
merge_contex->GetOperands(),
s->value, s->logger)) {
RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
s->state = kCorrupt;
}
} else {
assert(false);
}
return false;
case kTypeMerge:
assert(s->state == kNotFound || s->state == kMerge);
s->state = kMerge;
merge_contex->PushOperand(v);
while (merge_contex->GetNumOperands() >= 2) {
// Attempt to merge operands together via user associateive merge
if (s->merge_operator->PartialMerge(
s->user_key, merge_contex->GetOperand(0),
merge_contex->GetOperand(1), &merge_result, s->logger)) {
merge_contex->PushPartialMergeResult(merge_result);
} else {
// Associative merge returns false ==> stack the operands
break;
}
}
return true;
default:
assert(false);
break;
}
}
// s->state could be Corrupt, merge or notfound
return false;
}
static bool NewestFirst(FileMetaData* a, FileMetaData* b) {
return a->number > b->number;
}
static bool NewestFirstBySeqNo(FileMetaData* a, FileMetaData* b) {
if (a->smallest_seqno > b->smallest_seqno) {
assert(a->largest_seqno > b->largest_seqno);
return true;
}
assert(a->largest_seqno <= b->largest_seqno);
return false;
}
Version::Version(VersionSet* vset, uint64_t version_number)
: vset_(vset),
next_(this),
prev_(this),
refs_(0),
num_levels_(vset->num_levels_),
finalized_(false),
files_(new std::vector<FileMetaData*>[num_levels_]),
files_by_size_(num_levels_),
next_file_to_compact_by_size_(num_levels_),
file_to_compact_(nullptr),
file_to_compact_level_(-1),
compaction_score_(num_levels_),
compaction_level_(num_levels_),
version_number_(version_number) {}
void Version::Get(const ReadOptions& options,
const LookupKey& k,
std::string* value,
Status* status,
MergeContext* merge_context,
GetStats* stats,
const Options& db_options,
bool* value_found) {
assert(finalized_);
Slice ikey = k.internal_key();
Slice user_key = k.user_key();
const Comparator* ucmp = vset_->icmp_.user_comparator();
auto merge_operator = db_options.merge_operator.get();
auto logger = db_options.info_log;
assert(status->ok() || status->IsMergeInProgress());
Saver saver;
saver.state = status->ok()? kNotFound : kMerge;
saver.ucmp = ucmp;
saver.user_key = user_key;
saver.value_found = value_found;
saver.value = value;
saver.merge_operator = merge_operator;
saver.merge_context = merge_context;
saver.logger = logger.get();
saver.didIO = false;
saver.statistics = db_options.statistics.get();
stats->seek_file = nullptr;
stats->seek_file_level = -1;
FileMetaData* last_file_read = nullptr;
int last_file_read_level = -1;
// We can search level-by-level since entries never hop across
// levels. Therefore we are guaranteed that if we find data
// in an smaller level, later levels are irrelevant (unless we
// are MergeInProgress).
for (int level = 0; level < num_levels_; level++) {
size_t num_files = files_[level].size();
if (num_files == 0) continue;
// Get the list of files to search in this level
FileMetaData* const* files = &files_[level][0];
// Some files may overlap each other. We find
// all files that overlap user_key and process them in order from
// newest to oldest. In the context of merge-operator,
// this can occur at any level. Otherwise, it only occurs
// at Level-0 (since Put/Deletes are always compacted into a single entry).
uint32_t start_index;
if (level == 0) {
// On Level-0, we read through all files to check for overlap.
start_index = 0;
} else {
// On Level-n (n>=1), files are sorted.
// Binary search to find earliest index whose largest key >= ikey.
// We will also stop when the file no longer overlaps ikey
start_index = FindFile(vset_->icmp_, files_[level], ikey);
}
// Traverse each relevant file to find the desired key
#ifndef NDEBUG
FileMetaData* prev_file = nullptr;
#endif
for (uint32_t i = start_index; i < num_files; ++i) {
FileMetaData* f = files[i];
if (ucmp->Compare(user_key, f->smallest.user_key()) < 0 ||
ucmp->Compare(user_key, f->largest.user_key()) > 0) {
// Only process overlapping files.
if (level > 0) {
// If on Level-n (n>=1) then the files are sorted.
// So we can stop looking when we are past the ikey.
break;
}
// TODO: do we want to check file ranges for level0 files at all?
// For new SST format where Get() is fast, we might want to consider
// to avoid those two comparisons, if it can filter out too few files.
continue;
}
#ifndef NDEBUG
// Sanity check to make sure that the files are correctly sorted
if (prev_file) {
if (level != 0) {
int comp_sign = vset_->icmp_.Compare(prev_file->largest, f->smallest);
assert(comp_sign < 0);
} else {
// level == 0, the current file cannot be newer than the previous one.
if (vset_->options_->compaction_style == kCompactionStyleUniversal) {
assert(!NewestFirstBySeqNo(f, prev_file));
} else {
assert(!NewestFirst(f, prev_file));
}
}
}
prev_file = f;
#endif
bool tableIO = false;
*status =
vset_->table_cache_->Get(options, vset_->icmp_, *f, ikey, &saver,
SaveValue, &tableIO, MarkKeyMayExist);
// TODO: examine the behavior for corrupted key
if (!status->ok()) {
return;
}
if (last_file_read != nullptr && stats->seek_file == nullptr) {
// We have had more than one seek for this read. Charge the 1st file.
stats->seek_file = last_file_read;
stats->seek_file_level = last_file_read_level;
}
// If we did any IO as part of the read, then we remember it because
// it is a possible candidate for seek-based compaction. saver.didIO
// is true if the block had to be read in from storage and was not
// pre-exisiting in the block cache. Also, if this file was not pre-
// existing in the table cache and had to be freshly opened that needed
// the index blocks to be read-in, then tableIO is true. One thing
// to note is that the index blocks are not part of the block cache.
if (saver.didIO || tableIO) {
last_file_read = f;
last_file_read_level = level;
}
switch (saver.state) {
case kNotFound:
break; // Keep searching in other files
case kFound:
return;
case kDeleted:
*status = Status::NotFound(); // Use empty error message for speed
return;
case kCorrupt:
*status = Status::Corruption("corrupted key for ", user_key);
return;
case kMerge:
break;
}
}
}
if (kMerge == saver.state) {
// merge_operands are in saver and we hit the beginning of the key history
// do a final merge of nullptr and operands;
if (merge_operator->FullMerge(user_key, nullptr,
saver.merge_context->GetOperands(),
value, logger.get())) {
*status = Status::OK();
} else {
RecordTick(db_options.statistics.get(), NUMBER_MERGE_FAILURES);
*status = Status::Corruption("could not perform end-of-key merge for ",
user_key);
}
} else {
*status = Status::NotFound(); // Use an empty error message for speed
}
}
bool Version::UpdateStats(const GetStats& stats) {
FileMetaData* f = stats.seek_file;
if (f != nullptr) {
f->allowed_seeks--;
if (f->allowed_seeks <= 0 && file_to_compact_ == nullptr) {
file_to_compact_ = f;
file_to_compact_level_ = stats.seek_file_level;
return true;
}
}
return false;
}
void Version::Finalize(std::vector<uint64_t>& size_being_compacted) {
assert(!finalized_);
finalized_ = true;
// Pre-sort level0 for Get()
if (vset_->options_->compaction_style == kCompactionStyleUniversal) {
std::sort(files_[0].begin(), files_[0].end(), NewestFirstBySeqNo);
} else {
std::sort(files_[0].begin(), files_[0].end(), NewestFirst);
}
double max_score = 0;
int max_score_level = 0;
int num_levels_to_check =
(vset_->options_->compaction_style != kCompactionStyleUniversal)
? NumberLevels() - 1
: 1;
for (int level = 0; level < num_levels_to_check; level++) {
double score;
if (level == 0) {
// We treat level-0 specially by bounding the number of files
// instead of number of bytes for two reasons:
//
// (1) With larger write-buffer sizes, it is nice not to do too
// many level-0 compactions.
//
// (2) The files in level-0 are merged on every read and
// therefore we wish to avoid too many files when the individual
// file size is small (perhaps because of a small write-buffer
// setting, or very high compression ratios, or lots of
// overwrites/deletions).
int numfiles = 0;
for (unsigned int i = 0; i < files_[level].size(); i++) {
if (!files_[level][i]->being_compacted) {
numfiles++;
}
}
// If we are slowing down writes, then we better compact that first
if (numfiles >= vset_->options_->level0_stop_writes_trigger) {
score = 1000000;
// Log(options_->info_log, "XXX score l0 = 1000000000 max");
} else if (numfiles >= vset_->options_->level0_slowdown_writes_trigger) {
score = 10000;
// Log(options_->info_log, "XXX score l0 = 1000000 medium");
} else {
score = static_cast<double>(numfiles) /
vset_->options_->level0_file_num_compaction_trigger;
if (score >= 1) {
// Log(options_->info_log, "XXX score l0 = %d least", (int)score);
}
}
} else {
// Compute the ratio of current size to size limit.
const uint64_t level_bytes =
TotalFileSize(files_[level]) - size_being_compacted[level];
score = static_cast<double>(level_bytes) / vset_->MaxBytesForLevel(level);
if (score > 1) {
// Log(options_->info_log, "XXX score l%d = %d ", level, (int)score);
}
if (max_score < score) {
max_score = score;
max_score_level = level;
}
}
compaction_level_[level] = level;
compaction_score_[level] = score;
}
// update the max compaction score in levels 1 to n-1
max_compaction_score_ = max_score;
max_compaction_score_level_ = max_score_level;
// sort all the levels based on their score. Higher scores get listed
// first. Use bubble sort because the number of entries are small.
for (int i = 0; i < NumberLevels() - 2; i++) {
for (int j = i + 1; j < NumberLevels() - 1; j++) {
if (compaction_score_[i] < compaction_score_[j]) {
double score = compaction_score_[i];
int level = compaction_level_[i];
compaction_score_[i] = compaction_score_[j];
compaction_level_[i] = compaction_level_[j];
compaction_score_[j] = score;
compaction_level_[j] = level;
}
}
}
}
namespace {
// Compator that is used to sort files based on their size
// In normal mode: descending size
bool CompareSizeDescending(const Version::Fsize& first,
const Version::Fsize& second) {
return (first.file->file_size > second.file->file_size);
}
// A static compator used to sort files based on their seqno
// In universal style : descending seqno
bool CompareSeqnoDescending(const Version::Fsize& first,
const Version::Fsize& second) {
if (first.file->smallest_seqno > second.file->smallest_seqno) {
assert(first.file->largest_seqno > second.file->largest_seqno);
return true;
}
assert(first.file->largest_seqno <= second.file->largest_seqno);
return false;
}
} // anonymous namespace
void Version::UpdateFilesBySize() {
// No need to sort the highest level because it is never compacted.
int max_level =
(vset_->options_->compaction_style == kCompactionStyleUniversal)
? NumberLevels()
: NumberLevels() - 1;
for (int level = 0; level < max_level; level++) {
const std::vector<FileMetaData*>& files = files_[level];
std::vector<int>& files_by_size = files_by_size_[level];
assert(files_by_size.size() == 0);
// populate a temp vector for sorting based on size
std::vector<Fsize> temp(files.size());
for (unsigned int i = 0; i < files.size(); i++) {
temp[i].index = i;
temp[i].file = files[i];
}
// sort the top number_of_files_to_sort_ based on file size
if (vset_->options_->compaction_style == kCompactionStyleUniversal) {
int num = temp.size();
std::partial_sort(temp.begin(), temp.begin() + num, temp.end(),
CompareSeqnoDescending);
} else {
int num = Version::number_of_files_to_sort_;
if (num > (int)temp.size()) {
num = temp.size();
}
std::partial_sort(temp.begin(), temp.begin() + num, temp.end(),
CompareSizeDescending);
}
assert(temp.size() == files.size());
// initialize files_by_size_
for (unsigned int i = 0; i < temp.size(); i++) {
files_by_size.push_back(temp[i].index);
}
next_file_to_compact_by_size_[level] = 0;
assert(files_[level].size() == files_by_size_[level].size());
}
}
void Version::Ref() {
++refs_;
}
bool Version::Unref() {
assert(this != &vset_->dummy_versions_);
assert(refs_ >= 1);
--refs_;
if (refs_ == 0) {
delete this;
return true;
}
return false;
}
bool Version::NeedsCompaction() const {
if (file_to_compact_ != nullptr) {
return true;
}
// In universal compaction case, this check doesn't really
// check the compaction condition, but checks num of files threshold
// only. We are not going to miss any compaction opportunity
// but it's likely that more compactions are scheduled but
// ending up with nothing to do. We can improve it later.
// TODO(sdong): improve this function to be accurate for universal
// compactions.
int num_levels_to_check =
(vset_->options_->compaction_style != kCompactionStyleUniversal) ?
NumberLevels() - 1 : 1;
for (int i = 0; i < num_levels_to_check; i++) {
if (compaction_score_[i] >= 1) {
return true;
}
}
return false;
}
bool Version::OverlapInLevel(int level,
const Slice* smallest_user_key,
const Slice* largest_user_key) {
return SomeFileOverlapsRange(vset_->icmp_, (level > 0), files_[level],
smallest_user_key, largest_user_key);
}
int Version::PickLevelForMemTableOutput(
const Slice& smallest_user_key,
const Slice& largest_user_key) {
int level = 0;
if (!OverlapInLevel(0, &smallest_user_key, &largest_user_key)) {
// Push to next level if there is no overlap in next level,
// and the #bytes overlapping in the level after that are limited.
InternalKey start(smallest_user_key, kMaxSequenceNumber, kValueTypeForSeek);
InternalKey limit(largest_user_key, 0, static_cast<ValueType>(0));
std::vector<FileMetaData*> overlaps;
int max_mem_compact_level = vset_->options_->max_mem_compaction_level;
while (max_mem_compact_level > 0 && level < max_mem_compact_level) {
if (OverlapInLevel(level + 1, &smallest_user_key, &largest_user_key)) {
break;
}
if (level + 2 >= num_levels_) {
level++;
break;
}
GetOverlappingInputs(level + 2, &start, &limit, &overlaps);
const uint64_t sum = TotalFileSize(overlaps);
if (sum > vset_->compaction_picker_->MaxGrandParentOverlapBytes(level)) {
break;
}
level++;
}
}
return level;
}
// Store in "*inputs" all files in "level" that overlap [begin,end]
// If hint_index is specified, then it points to a file in the
// overlapping range.
// The file_index returns a pointer to any file in an overlapping range.
void Version::GetOverlappingInputs(
int level,
const InternalKey* begin,
const InternalKey* end,
std::vector<FileMetaData*>* inputs,
int hint_index,
int* file_index) {
inputs->clear();
Slice user_begin, user_end;
if (begin != nullptr) {
user_begin = begin->user_key();
}
if (end != nullptr) {
user_end = end->user_key();
}
if (file_index) {
*file_index = -1;
}
const Comparator* user_cmp = vset_->icmp_.user_comparator();
if (begin != nullptr && end != nullptr && level > 0) {
GetOverlappingInputsBinarySearch(level, user_begin, user_end, inputs,
hint_index, file_index);
return;
}
for (size_t i = 0; i < files_[level].size(); ) {
FileMetaData* f = files_[level][i++];
const Slice file_start = f->smallest.user_key();
const Slice file_limit = f->largest.user_key();
if (begin != nullptr && user_cmp->Compare(file_limit, user_begin) < 0) {
// "f" is completely before specified range; skip it
} else if (end != nullptr && user_cmp->Compare(file_start, user_end) > 0) {
// "f" is completely after specified range; skip it
} else {
inputs->push_back(f);
if (level == 0) {
// Level-0 files may overlap each other. So check if the newly
// added file has expanded the range. If so, restart search.
if (begin != nullptr && user_cmp->Compare(file_start, user_begin) < 0) {
user_begin = file_start;
inputs->clear();
i = 0;
} else if (end != nullptr
&& user_cmp->Compare(file_limit, user_end) > 0) {
user_end = file_limit;
inputs->clear();
i = 0;
}
} else if (file_index) {
*file_index = i-1;
}
}
}
}
// Store in "*inputs" all files in "level" that overlap [begin,end]
// Employ binary search to find at least one file that overlaps the
// specified range. From that file, iterate backwards and
// forwards to find all overlapping files.
void Version::GetOverlappingInputsBinarySearch(
int level,
const Slice& user_begin,
const Slice& user_end,
std::vector<FileMetaData*>* inputs,
int hint_index,
int* file_index) {
assert(level > 0);
int min = 0;
int mid = 0;
int max = files_[level].size() -1;
bool foundOverlap = false;
const Comparator* user_cmp = vset_->icmp_.user_comparator();
// if the caller already knows the index of a file that has overlap,
// then we can skip the binary search.
if (hint_index != -1) {
mid = hint_index;
foundOverlap = true;
}
while (!foundOverlap && min <= max) {
mid = (min + max)/2;
FileMetaData* f = files_[level][mid];
const Slice file_start = f->smallest.user_key();
const Slice file_limit = f->largest.user_key();
if (user_cmp->Compare(file_limit, user_begin) < 0) {
min = mid + 1;
} else if (user_cmp->Compare(user_end, file_start) < 0) {
max = mid - 1;
} else {
foundOverlap = true;
break;
}
}
// If there were no overlapping files, return immediately.
if (!foundOverlap) {
return;
}
// returns the index where an overlap is found
if (file_index) {
*file_index = mid;
}
ExtendOverlappingInputs(level, user_begin, user_end, inputs, mid);
}
// Store in "*inputs" all files in "level" that overlap [begin,end]
// The midIndex specifies the index of at least one file that
// overlaps the specified range. From that file, iterate backward
// and forward to find all overlapping files.
void Version::ExtendOverlappingInputs(
int level,
const Slice& user_begin,
const Slice& user_end,
std::vector<FileMetaData*>* inputs,
unsigned int midIndex) {
const Comparator* user_cmp = vset_->icmp_.user_comparator();
#ifndef NDEBUG
{
// assert that the file at midIndex overlaps with the range
assert(midIndex < files_[level].size());
FileMetaData* f = files_[level][midIndex];
const Slice fstart = f->smallest.user_key();
const Slice flimit = f->largest.user_key();
if (user_cmp->Compare(fstart, user_begin) >= 0) {
assert(user_cmp->Compare(fstart, user_end) <= 0);
} else {
assert(user_cmp->Compare(flimit, user_begin) >= 0);
}
}
#endif
int startIndex = midIndex + 1;
int endIndex = midIndex;
int count __attribute__((unused)) = 0;
// check backwards from 'mid' to lower indices
for (int i = midIndex; i >= 0 ; i--) {
FileMetaData* f = files_[level][i];
const Slice file_limit = f->largest.user_key();
if (user_cmp->Compare(file_limit, user_begin) >= 0) {
startIndex = i;
assert((count++, true));
} else {
break;
}
}
// check forward from 'mid+1' to higher indices
for (unsigned int i = midIndex+1; i < files_[level].size(); i++) {
FileMetaData* f = files_[level][i];
const Slice file_start = f->smallest.user_key();
if (user_cmp->Compare(file_start, user_end) <= 0) {
assert((count++, true));
endIndex = i;
} else {
break;
}
}
assert(count == endIndex - startIndex + 1);
// insert overlapping files into vector
for (int i = startIndex; i <= endIndex; i++) {
FileMetaData* f = files_[level][i];
inputs->push_back(f);
}
}
// Returns true iff the first or last file in inputs contains
// an overlapping user key to the file "just outside" of it (i.e.
// just after the last file, or just before the first file)
// REQUIRES: "*inputs" is a sorted list of non-overlapping files
bool Version::HasOverlappingUserKey(
const std::vector<FileMetaData*>* inputs,
int level) {
// If inputs empty, there is no overlap.
// If level == 0, it is assumed that all needed files were already included.
if (inputs->empty() || level == 0){
return false;
}
const Comparator* user_cmp = vset_->icmp_.user_comparator();
const std::vector<FileMetaData*>& files = files_[level];
const size_t kNumFiles = files.size();
// Check the last file in inputs against the file after it
size_t last_file = FindFile(vset_->icmp_, files,
inputs->back()->largest.Encode());
assert(0 <= last_file && last_file < kNumFiles); // File should exist!
if (last_file < kNumFiles-1) { // If not the last file
const Slice last_key_in_input = files[last_file]->largest.user_key();
const Slice first_key_after = files[last_file+1]->smallest.user_key();
if (user_cmp->Compare(last_key_in_input, first_key_after) == 0) {
// The last user key in input overlaps with the next file's first key
return true;
}
}
// Check the first file in inputs against the file just before it
size_t first_file = FindFile(vset_->icmp_, files,
inputs->front()->smallest.Encode());
assert(0 <= first_file && first_file <= last_file); // File should exist!
if (first_file > 0) { // If not first file
const Slice& first_key_in_input = files[first_file]->smallest.user_key();
const Slice& last_key_before = files[first_file-1]->largest.user_key();
if (user_cmp->Compare(first_key_in_input, last_key_before) == 0) {
// The first user key in input overlaps with the previous file's last key
return true;
}
}
return false;
}
int64_t Version::NumLevelBytes(int level) const {
assert(level >= 0);
assert(level < NumberLevels());
return TotalFileSize(files_[level]);
}
const char* Version::LevelSummary(LevelSummaryStorage* scratch) const {
int len = snprintf(scratch->buffer, sizeof(scratch->buffer), "files[");
for (int i = 0; i < NumberLevels(); i++) {
int sz = sizeof(scratch->buffer) - len;
int ret = snprintf(scratch->buffer + len, sz, "%d ", int(files_[i].size()));
if (ret < 0 || ret >= sz) break;
len += ret;
}
snprintf(scratch->buffer + len, sizeof(scratch->buffer) - len, "]");
return scratch->buffer;
}
const char* Version::LevelFileSummary(FileSummaryStorage* scratch,
int level) const {
int len = snprintf(scratch->buffer, sizeof(scratch->buffer), "files_size[");
for (const auto& f : files_[level]) {
int sz = sizeof(scratch->buffer) - len;
int ret = snprintf(scratch->buffer + len, sz,
"#%lu(seq=%lu,sz=%lu,%lu) ",
(unsigned long)f->number,
(unsigned long)f->smallest_seqno,
(unsigned long)f->file_size,
(unsigned long)f->being_compacted);
if (ret < 0 || ret >= sz)
break;
len += ret;
}
snprintf(scratch->buffer + len, sizeof(scratch->buffer) - len, "]");
return scratch->buffer;
}
int64_t Version::MaxNextLevelOverlappingBytes() {
uint64_t result = 0;
std::vector<FileMetaData*> overlaps;
for (int level = 1; level < NumberLevels() - 1; level++) {
for (const auto& f : files_[level]) {
GetOverlappingInputs(level + 1, &f->smallest, &f->largest, &overlaps);
const uint64_t sum = TotalFileSize(overlaps);
if (sum > result) {
result = sum;
}
}
}
return result;
}
void Version::AddLiveFiles(std::set<uint64_t>* live) {
for (int level = 0; level < NumberLevels(); level++) {
const std::vector<FileMetaData*>& files = files_[level];
for (const auto& file : files) {
live->insert(file->number);
}
}
}
std::string Version::DebugString(bool hex) const {
std::string r;
for (int level = 0; level < num_levels_; level++) {
// E.g.,
// --- level 1 ---
// 17:123['a' .. 'd']
// 20:43['e' .. 'g']
r.append("--- level ");
AppendNumberTo(&r, level);
r.append(" --- version# ");
AppendNumberTo(&r, version_number_);
r.append(" ---\n");
const std::vector<FileMetaData*>& files = files_[level];
for (size_t i = 0; i < files.size(); i++) {
r.push_back(' ');
AppendNumberTo(&r, files[i]->number);
r.push_back(':');
AppendNumberTo(&r, files[i]->file_size);
r.append("[");
r.append(files[i]->smallest.DebugString(hex));
r.append(" .. ");
r.append(files[i]->largest.DebugString(hex));
r.append("]\n");
}
}
return r;
}
// this is used to batch writes to the manifest file
struct VersionSet::ManifestWriter {
Status status;
bool done;
port::CondVar cv;
VersionEdit* edit;
explicit ManifestWriter(port::Mutex* mu, VersionEdit* e) :
done(false), cv(mu), edit(e) {}
};
// A helper class so we can efficiently apply a whole sequence
// of edits to a particular state without creating intermediate
// Versions that contain full copies of the intermediate state.
class VersionSet::Builder {
private:
// Helper to sort by v->files_[file_number].smallest
struct BySmallestKey {
const InternalKeyComparator* internal_comparator;
bool operator()(FileMetaData* f1, FileMetaData* f2) const {
int r = internal_comparator->Compare(f1->smallest, f2->smallest);
if (r != 0) {
return (r < 0);
} else {
// Break ties by file number
return (f1->number < f2->number);
}
}
};
typedef std::set<FileMetaData*, BySmallestKey> FileSet;
struct LevelState {
std::set<uint64_t> deleted_files;
FileSet* added_files;
};
VersionSet* vset_;
Version* base_;
LevelState* levels_;
public:
// Initialize a builder with the files from *base and other info from *vset
Builder(VersionSet* vset, Version* base) : vset_(vset), base_(base) {
base_->Ref();
levels_ = new LevelState[base->NumberLevels()];
BySmallestKey cmp;
cmp.internal_comparator = &vset_->icmp_;
for (int level = 0; level < base->NumberLevels(); level++) {
levels_[level].added_files = new FileSet(cmp);
}
}
~Builder() {
for (int level = 0; level < base_->NumberLevels(); level++) {
const FileSet* added = levels_[level].added_files;
std::vector<FileMetaData*> to_unref;
to_unref.reserve(added->size());
for (FileSet::const_iterator it = added->begin();
it != added->end(); ++it) {
to_unref.push_back(*it);
}
delete added;
for (uint32_t i = 0; i < to_unref.size(); i++) {
FileMetaData* f = to_unref[i];
f->refs--;
if (f->refs <= 0) {
if (f->table_reader_handle) {
vset_->table_cache_->ReleaseHandle(
f->table_reader_handle);
f->table_reader_handle = nullptr;
}
delete f;
}
}
}
delete[] levels_;
base_->Unref();
}
void CheckConsistency(Version* v) {
#ifndef NDEBUG
for (int level = 0; level < v->NumberLevels(); level++) {
// Make sure there is no overlap in levels > 0
if (level > 0) {
for (uint32_t i = 1; i < v->files_[level].size(); i++) {
const InternalKey& prev_end = v->files_[level][i-1]->largest;
const InternalKey& this_begin = v->files_[level][i]->smallest;
if (vset_->icmp_.Compare(prev_end, this_begin) >= 0) {
fprintf(stderr, "overlapping ranges in same level %s vs. %s\n",
prev_end.DebugString().c_str(),
this_begin.DebugString().c_str());
abort();
}
}
}
}
#endif
}
void CheckConsistencyForDeletes(VersionEdit* edit, unsigned int number,
int level) {
#ifndef NDEBUG
// a file to be deleted better exist in the previous version
bool found = false;
for (int l = 0; !found && l < base_->NumberLevels(); l++) {
const std::vector<FileMetaData*>& base_files = base_->files_[l];
for (unsigned int i = 0; i < base_files.size(); i++) {
FileMetaData* f = base_files[i];
if (f->number == number) {
found = true;
break;
}
}
}
// if the file did not exist in the previous version, then it
// is possibly moved from lower level to higher level in current
// version
for (int l = level+1; !found && l < base_->NumberLevels(); l++) {
const FileSet* added = levels_[l].added_files;
for (FileSet::const_iterator added_iter = added->begin();
added_iter != added->end(); ++added_iter) {
FileMetaData* f = *added_iter;
if (f->number == number) {
found = true;
break;
}
}
}
// maybe this file was added in a previous edit that was Applied
if (!found) {
const FileSet* added = levels_[level].added_files;
for (FileSet::const_iterator added_iter = added->begin();
added_iter != added->end(); ++added_iter) {
FileMetaData* f = *added_iter;
if (f->number == number) {
found = true;
break;
}
}
}
assert(found);
#endif
}
// Apply all of the edits in *edit to the current state.
void Apply(VersionEdit* edit) {
CheckConsistency(base_);
// Delete files
const VersionEdit::DeletedFileSet& del = edit->deleted_files_;
for (const auto& del_file : del) {
const auto level = del_file.first;
const auto number = del_file.second;
levels_[level].deleted_files.insert(number);
CheckConsistencyForDeletes(edit, number, level);
}
// Add new files
for (const auto& new_file : edit->new_files_) {
const int level = new_file.first;
FileMetaData* f = new FileMetaData(new_file.second);
f->refs = 1;
// We arrange to automatically compact this file after
// a certain number of seeks. Let's assume:
// (1) One seek costs 10ms
// (2) Writing or reading 1MB costs 10ms (100MB/s)
// (3) A compaction of 1MB does 25MB of IO:
// 1MB read from this level
// 10-12MB read from next level (boundaries may be misaligned)
// 10-12MB written to next level
// This implies that 25 seeks cost the same as the compaction
// of 1MB of data. I.e., one seek costs approximately the
// same as the compaction of 40KB of data. We are a little
// conservative and allow approximately one seek for every 16KB
// of data before triggering a compaction.
f->allowed_seeks = (f->file_size / 16384);
if (f->allowed_seeks < 100) f->allowed_seeks = 100;
levels_[level].deleted_files.erase(f->number);
levels_[level].added_files->insert(f);
}
}
// Save the current state in *v.
void SaveTo(Version* v) {
CheckConsistency(base_);
CheckConsistency(v);
BySmallestKey cmp;
cmp.internal_comparator = &vset_->icmp_;
for (int level = 0; level < base_->NumberLevels(); level++) {
// Merge the set of added files with the set of pre-existing files.
// Drop any deleted files. Store the result in *v.
const auto& base_files = base_->files_[level];
auto base_iter = base_files.begin();
auto base_end = base_files.end();
const auto& added_files = *levels_[level].added_files;
v->files_[level].reserve(base_files.size() + added_files.size());
for (const auto& added : added_files) {
// Add all smaller files listed in base_
for (auto bpos = std::upper_bound(base_iter, base_end, added, cmp);
base_iter != bpos;
++base_iter) {
MaybeAddFile(v, level, *base_iter);
}
MaybeAddFile(v, level, added);
}
// Add remaining base files
for (; base_iter != base_end; ++base_iter) {
MaybeAddFile(v, level, *base_iter);
}
}
CheckConsistency(v);
}
void LoadTableHandlers() {
for (int level = 0; level < vset_->NumberLevels(); level++) {
for (auto& file_meta : *(levels_[level].added_files)) {
assert (!file_meta->table_reader_handle);
bool table_io;
vset_->table_cache_->FindTable(vset_->storage_options_, vset_->icmp_,
file_meta->number, file_meta->file_size,
&file_meta->table_reader_handle,
&table_io, false);
}
}
}
void MaybeAddFile(Version* v, int level, FileMetaData* f) {
if (levels_[level].deleted_files.count(f->number) > 0) {
// File is deleted: do nothing
} else {
auto* files = &v->files_[level];
if (level > 0 && !files->empty()) {
// Must not overlap
assert(vset_->icmp_.Compare((*files)[files->size()-1]->largest,
f->smallest) < 0);
}
f->refs++;
files->push_back(f);
}
}
};
VersionSet::VersionSet(const std::string& dbname, const Options* options,
const EnvOptions& storage_options,
TableCache* table_cache,
const InternalKeyComparator* cmp)
: env_(options->env),
dbname_(dbname),
options_(options),
table_cache_(table_cache),
icmp_(*cmp),
next_file_number_(2),
manifest_file_number_(0), // Filled by Recover()
pending_manifest_file_number_(0),
last_sequence_(0),
log_number_(0),
prev_log_number_(0),
num_levels_(options_->num_levels),
dummy_versions_(this),
current_(nullptr),
need_slowdown_for_num_level0_files_(false),
current_version_number_(0),
manifest_file_size_(0),
storage_options_(storage_options),
storage_options_compactions_(storage_options_) {
if (options_->compaction_style == kCompactionStyleUniversal) {
compaction_picker_.reset(new UniversalCompactionPicker(options_, &icmp_));
} else {
compaction_picker_.reset(new LevelCompactionPicker(options_, &icmp_));
}
AppendVersion(new Version(this, current_version_number_++));
}
VersionSet::~VersionSet() {
current_->Unref();
assert(dummy_versions_.next_ == &dummy_versions_); // List must be empty
for (auto file : obsolete_files_) {
delete file;
}
obsolete_files_.clear();
}
void VersionSet::AppendVersion(Version* v) {
// Make "v" current
assert(v->refs_ == 0);
assert(v != current_);
if (current_ != nullptr) {
assert(current_->refs_ > 0);
current_->Unref();
}
current_ = v;
need_slowdown_for_num_level0_files_ =
(options_->level0_slowdown_writes_trigger >= 0 && current_ != nullptr &&
v->NumLevelFiles(0) >= options_->level0_slowdown_writes_trigger);
v->Ref();
// Append to linked list
v->prev_ = dummy_versions_.prev_;
v->next_ = &dummy_versions_;
v->prev_->next_ = v;
v->next_->prev_ = v;
}
Status VersionSet::LogAndApply(VersionEdit* edit, port::Mutex* mu,
Directory* db_directory,
bool new_descriptor_log) {
mu->AssertHeld();
// queue our request
ManifestWriter w(mu, edit);
manifest_writers_.push_back(&w);
while (!w.done && &w != manifest_writers_.front()) {
w.cv.Wait();
}
if (w.done) {
return w.status;
}
std::vector<VersionEdit*> batch_edits;
Version* v = new Version(this, current_version_number_++);
Builder builder(this, current_);
// process all requests in the queue
ManifestWriter* last_writer = &w;
assert(!manifest_writers_.empty());
assert(manifest_writers_.front() == &w);
uint64_t max_log_number_in_batch = 0;
for (const auto& writer : manifest_writers_) {
last_writer = writer;
LogAndApplyHelper(&builder, v, writer->edit, mu);
if (writer->edit->has_log_number_) {
// When batch commit of manifest writes, we could have multiple flush and
// compaction edits. A flush edit has a bigger log number than what
// VersionSet has while a compaction edit does not have a log number.
// In this case, we want to make sure the largest log number is updated
// to VersionSet
max_log_number_in_batch =
std::max(max_log_number_in_batch, writer->edit->log_number_);
}
batch_edits.push_back(writer->edit);
}
builder.SaveTo(v);
// Initialize new descriptor log file if necessary by creating
// a temporary file that contains a snapshot of the current version.
uint64_t new_manifest_file_size = 0;
Status s;
assert(pending_manifest_file_number_ == 0);
if (!descriptor_log_ ||
manifest_file_size_ > options_->max_manifest_file_size) {
pending_manifest_file_number_ = NewFileNumber();
batch_edits.back()->SetNextFile(next_file_number_);
new_descriptor_log = true;
} else {
pending_manifest_file_number_ = manifest_file_number_;
}
// Unlock during expensive operations. New writes cannot get here
// because &w is ensuring that all new writes get queued.
{
// calculate the amount of data being compacted at every level
std::vector<uint64_t> size_being_compacted(v->NumberLevels() - 1);
compaction_picker_->SizeBeingCompacted(size_being_compacted);
mu->Unlock();
if (options_->max_open_files == -1) {
// unlimited table cache. Pre-load table handle now.
// Need to do it out of the mutex.
builder.LoadTableHandlers();
}
// This is fine because everything inside of this block is serialized --
// only one thread can be here at the same time
if (new_descriptor_log) {
unique_ptr<WritableFile> descriptor_file;
s = env_->NewWritableFile(
DescriptorFileName(dbname_, pending_manifest_file_number_),
&descriptor_file, env_->OptimizeForManifestWrite(storage_options_));
if (s.ok()) {
descriptor_log_.reset(new log::Writer(std::move(descriptor_file)));
s = WriteSnapshot(descriptor_log_.get());
}
}
// The calls to Finalize and UpdateFilesBySize are cpu-heavy
// and is best called outside the mutex.
v->Finalize(size_being_compacted);
v->UpdateFilesBySize();
// Write new record to MANIFEST log
if (s.ok()) {
for (auto& e : batch_edits) {
std::string record;
e->EncodeTo(&record);
s = descriptor_log_->AddRecord(record);
if (!s.ok()) {
break;
}
}
if (s.ok()) {
if (options_->use_fsync) {
StopWatch sw(env_, options_->statistics.get(),
MANIFEST_FILE_SYNC_MICROS);
s = descriptor_log_->file()->Fsync();
} else {
StopWatch sw(env_, options_->statistics.get(),
MANIFEST_FILE_SYNC_MICROS);
s = descriptor_log_->file()->Sync();
}
}
if (!s.ok()) {
Log(options_->info_log, "MANIFEST write: %s\n", s.ToString().c_str());
bool all_records_in = true;
for (auto& e : batch_edits) {
std::string record;
e->EncodeTo(&record);
if (!ManifestContains(pending_manifest_file_number_, record)) {
all_records_in = false;
break;
}
}
if (all_records_in) {
Log(options_->info_log,
"MANIFEST contains log record despite error; advancing to new "
"version to prevent mismatch between in-memory and logged state"
" If paranoid is set, then the db is now in readonly mode.");
s = Status::OK();
}
}
}
// If we just created a new descriptor file, install it by writing a
// new CURRENT file that points to it.
if (s.ok() && new_descriptor_log) {
s = SetCurrentFile(env_, dbname_, pending_manifest_file_number_);
if (s.ok() && pending_manifest_file_number_ > manifest_file_number_) {
// delete old manifest file
Log(options_->info_log,
"Deleting manifest %" PRIu64 " current manifest %" PRIu64 "\n",
manifest_file_number_, pending_manifest_file_number_);
// we don't care about an error here, PurgeObsoleteFiles will take care
// of it later
env_->DeleteFile(DescriptorFileName(dbname_, manifest_file_number_));
}
if (!options_->disableDataSync && db_directory != nullptr) {
db_directory->Fsync();
}
}
if (s.ok()) {
// find offset in manifest file where this version is stored.
new_manifest_file_size = descriptor_log_->file()->GetFileSize();
}
LogFlush(options_->info_log);
mu->Lock();
}
// Install the new version
if (s.ok()) {
manifest_file_number_ = pending_manifest_file_number_;
manifest_file_size_ = new_manifest_file_size;
AppendVersion(v);
if (max_log_number_in_batch != 0) {
assert(log_number_ < max_log_number_in_batch);
log_number_ = max_log_number_in_batch;
}
prev_log_number_ = edit->prev_log_number_;
} else {
Log(options_->info_log, "Error in committing version %lu",
(unsigned long)v->GetVersionNumber());
delete v;
if (new_descriptor_log) {
descriptor_log_.reset();
env_->DeleteFile(
DescriptorFileName(dbname_, pending_manifest_file_number_));
}
}
pending_manifest_file_number_ = 0;
// wake up all the waiting writers
while (true) {
ManifestWriter* ready = manifest_writers_.front();
manifest_writers_.pop_front();
if (ready != &w) {
ready->status = s;
ready->done = true;
ready->cv.Signal();
}
if (ready == last_writer) break;
}
// Notify new head of write queue
if (!manifest_writers_.empty()) {
manifest_writers_.front()->cv.Signal();
}
return s;
}
void VersionSet::LogAndApplyHelper(Builder* builder, Version* v,
VersionEdit* edit, port::Mutex* mu) {
mu->AssertHeld();
if (edit->has_log_number_) {
assert(edit->log_number_ >= log_number_);
assert(edit->log_number_ < next_file_number_);
}
// If the edit does not have log number, it must be generated
// from a compaction
if (!edit->has_prev_log_number_) {
edit->SetPrevLogNumber(prev_log_number_);
}
edit->SetNextFile(next_file_number_);
edit->SetLastSequence(last_sequence_);
builder->Apply(edit);
}
Status VersionSet::Recover() {
struct LogReporter : public log::Reader::Reporter {
Status* status;
virtual void Corruption(size_t bytes, const Status& s) {
if (this->status->ok()) *this->status = s;
}
};
// Read "CURRENT" file, which contains a pointer to the current manifest file
std::string manifest_filename;
Status s = ReadFileToString(
env_, CurrentFileName(dbname_), &manifest_filename
);
if (!s.ok()) {
return s;
}
if (manifest_filename.empty() ||
manifest_filename.back() != '\n') {
return Status::Corruption("CURRENT file does not end with newline");
}
// remove the trailing '\n'
manifest_filename.resize(manifest_filename.size() - 1);
Log(options_->info_log, "Recovering from manifest file:%s\n",
manifest_filename.c_str());
manifest_filename = dbname_ + "/" + manifest_filename;
unique_ptr<SequentialFile> manifest_file;
s = env_->NewSequentialFile(
manifest_filename, &manifest_file, storage_options_
);
if (!s.ok()) {
return s;
}
uint64_t manifest_file_size;
s = env_->GetFileSize(manifest_filename, &manifest_file_size);
if (!s.ok()) {
return s;
}
bool have_version_number = false;
bool log_number_decrease = false;
bool have_log_number = false;
bool have_prev_log_number = false;
bool have_next_file = false;
bool have_last_sequence = false;
uint64_t next_file = 0;
uint64_t last_sequence = 0;
uint64_t log_number = 0;
uint64_t prev_log_number = 0;
Builder builder(this, current_);
{
LogReporter reporter;
reporter.status = &s;
log::Reader reader(std::move(manifest_file), &reporter, true /*checksum*/,
0 /*initial_offset*/);
Slice record;
std::string scratch;
while (reader.ReadRecord(&record, &scratch) && s.ok()) {
VersionEdit edit;
s = edit.DecodeFrom(record);
if (!s.ok()) {
break;
}
if (edit.max_level_ >= current_->NumberLevels()) {
s = Status::InvalidArgument(
"db has more levels than options.num_levels");
break;
}
if (edit.has_comparator_ &&
edit.comparator_ != icmp_.user_comparator()->Name()) {
s = Status::InvalidArgument(icmp_.user_comparator()->Name(),
"does not match existing comparator " +
edit.comparator_);
break;
}
builder.Apply(&edit);
if (edit.has_version_number_) {
have_version_number = true;
}
// Only a flush's edit or a new snapshot can write log number during
// LogAndApply. Since memtables are flushed and inserted into
// manifest_writers_ queue in order, the log number in MANIFEST file
// should be monotonically increasing.
if (edit.has_log_number_) {
if (have_log_number && log_number >= edit.log_number_) {
log_number_decrease = true;
} else {
log_number = edit.log_number_;
have_log_number = true;
}
}
if (edit.has_prev_log_number_) {
prev_log_number = edit.prev_log_number_;
have_prev_log_number = true;
}
if (edit.has_next_file_number_) {
next_file = edit.next_file_number_;
have_next_file = true;
}
if (edit.has_last_sequence_) {
last_sequence = edit.last_sequence_;
have_last_sequence = true;
}
}
if (s.ok() && log_number_decrease) {
// Since release 2.8, version number is added into MANIFEST file.
// Prior release 2.8, a bug in LogAndApply() can cause log_number
// to be smaller than the one from previous edit. To ensure backward
// compatibility, only fail for MANIFEST genearated by release 2.8
// and after.
if (have_version_number) {
s = Status::Corruption("log number decreases");
} else {
Log(options_->info_log, "decreasing of log_number is detected "
"in MANIFEST\n");
}
}
}
if (s.ok()) {
if (!have_next_file) {
s = Status::Corruption("no meta-nextfile entry in descriptor");
} else if (!have_log_number) {
s = Status::Corruption("no meta-lognumber entry in descriptor");
} else if (!have_last_sequence) {
s = Status::Corruption("no last-sequence-number entry in descriptor");
}
if (!have_prev_log_number) {
prev_log_number = 0;
}
MarkFileNumberUsed(prev_log_number);
MarkFileNumberUsed(log_number);
}
if (s.ok()) {
if (options_->max_open_files == -1) {
// unlimited table cache. Pre-load table handle now.
// Need to do it out of the mutex.
builder.LoadTableHandlers();
}
Version* v = new Version(this, current_version_number_++);
builder.SaveTo(v);
// Install recovered version
std::vector<uint64_t> size_being_compacted(v->NumberLevels() - 1);
compaction_picker_->SizeBeingCompacted(size_being_compacted);
v->Finalize(size_being_compacted);
manifest_file_size_ = manifest_file_size;
AppendVersion(v);
manifest_file_number_ = next_file;
next_file_number_ = next_file + 1;
last_sequence_ = last_sequence;
log_number_ = log_number;
prev_log_number_ = prev_log_number;
Log(options_->info_log, "Recovered from manifest file:%s succeeded,"
"manifest_file_number is %lu, next_file_number is %lu, "
"last_sequence is %lu, log_number is %lu,"
"prev_log_number is %lu\n",
manifest_filename.c_str(),
(unsigned long)manifest_file_number_,
(unsigned long)next_file_number_,
(unsigned long)last_sequence_,
(unsigned long)log_number_,
(unsigned long)prev_log_number_);
}
return s;
}
Status VersionSet::ReduceNumberOfLevels(const std::string& dbname,
const Options* options,
const EnvOptions& storage_options,
int new_levels) {
if (new_levels <= 1) {
return Status::InvalidArgument(
"Number of levels needs to be bigger than 1");
}
const InternalKeyComparator cmp(options->comparator);
TableCache tc(dbname, options, storage_options, 10);
VersionSet versions(dbname, options, storage_options, &tc, &cmp);
Status status;
status = versions.Recover();
if (!status.ok()) {
return status;
}
Version* current_version = versions.current();
int current_levels = current_version->NumberLevels();
if (current_levels <= new_levels) {
return Status::OK();
}
// Make sure there are file only on one level from
// (new_levels-1) to (current_levels-1)
int first_nonempty_level = -1;
int first_nonempty_level_filenum = 0;
for (int i = new_levels - 1; i < current_levels; i++) {
int file_num = current_version->NumLevelFiles(i);
if (file_num != 0) {
if (first_nonempty_level < 0) {
first_nonempty_level = i;
first_nonempty_level_filenum = file_num;
} else {
char msg[255];
snprintf(msg, sizeof(msg),
"Found at least two levels containing files: "
"[%d:%d],[%d:%d].\n",
first_nonempty_level, first_nonempty_level_filenum, i,
file_num);
return Status::InvalidArgument(msg);
}
}
}
std::vector<FileMetaData*>* old_files_list = current_version->files_;
// we need to allocate an array with the old number of levels size to
// avoid SIGSEGV in WriteSnapshot()
// however, all levels bigger or equal to new_levels will be empty
std::vector<FileMetaData*>* new_files_list =
new std::vector<FileMetaData*>[current_levels];
for (int i = 0; i < new_levels - 1; i++) {
new_files_list[i] = old_files_list[i];
}
if (first_nonempty_level > 0) {
new_files_list[new_levels - 1] = old_files_list[first_nonempty_level];
}
delete[] current_version->files_;
current_version->files_ = new_files_list;
current_version->num_levels_ = new_levels;
VersionEdit ve;
port::Mutex dummy_mutex;
MutexLock l(&dummy_mutex);
return versions.LogAndApply(&ve, &dummy_mutex, nullptr, true);
}
Status VersionSet::DumpManifest(Options& options, std::string& dscname,
bool verbose, bool hex) {
struct LogReporter : public log::Reader::Reporter {
Status* status;
virtual void Corruption(size_t bytes, const Status& s) {
if (this->status->ok()) *this->status = s;
}
};
// Open the specified manifest file.
unique_ptr<SequentialFile> file;
Status s = options.env->NewSequentialFile(dscname, &file, storage_options_);
if (!s.ok()) {
return s;
}
bool have_log_number = false;
bool have_prev_log_number = false;
bool have_next_file = false;
bool have_last_sequence = false;
uint64_t next_file = 0;
uint64_t last_sequence = 0;
uint64_t log_number = 0;
uint64_t prev_log_number = 0;
int count = 0;
VersionSet::Builder builder(this, current_);
{
LogReporter reporter;
reporter.status = &s;
log::Reader reader(std::move(file), &reporter, true/*checksum*/,
0/*initial_offset*/);
Slice record;
std::string scratch;
while (reader.ReadRecord(&record, &scratch) && s.ok()) {
VersionEdit edit;
s = edit.DecodeFrom(record);
if (s.ok()) {
if (edit.has_comparator_ &&
edit.comparator_ != icmp_.user_comparator()->Name()) {
s = Status::InvalidArgument(icmp_.user_comparator()->Name(),
"does not match existing comparator " +
edit.comparator_);
}
}
// Write out each individual edit
if (verbose) {
printf("*************************Edit[%d] = %s\n",
count, edit.DebugString(hex).c_str());
}
count++;
if (s.ok()) {
builder.Apply(&edit);
}
if (edit.has_log_number_) {
log_number = edit.log_number_;
have_log_number = true;
}
if (edit.has_prev_log_number_) {
prev_log_number = edit.prev_log_number_;
have_prev_log_number = true;
}
if (edit.has_next_file_number_) {
next_file = edit.next_file_number_;
have_next_file = true;
}
if (edit.has_last_sequence_) {
last_sequence = edit.last_sequence_;
have_last_sequence = true;
}
}
}
file.reset();
if (s.ok()) {
if (!have_next_file) {
s = Status::Corruption("no meta-nextfile entry in descriptor");
printf("no meta-nextfile entry in descriptor");
} else if (!have_log_number) {
s = Status::Corruption("no meta-lognumber entry in descriptor");
printf("no meta-lognumber entry in descriptor");
} else if (!have_last_sequence) {
printf("no last-sequence-number entry in descriptor");
s = Status::Corruption("no last-sequence-number entry in descriptor");
}
if (!have_prev_log_number) {
prev_log_number = 0;
}
MarkFileNumberUsed(prev_log_number);
MarkFileNumberUsed(log_number);
}
if (s.ok()) {
Version* v = new Version(this, 0);
builder.SaveTo(v);
// Install recovered version
std::vector<uint64_t> size_being_compacted(v->NumberLevels() - 1);
compaction_picker_->SizeBeingCompacted(size_being_compacted);
v->Finalize(size_being_compacted);
AppendVersion(v);
manifest_file_number_ = next_file;
next_file_number_ = next_file + 1;
last_sequence_ = last_sequence;
log_number_ = log_number;
prev_log_number_ = prev_log_number;
printf("manifest_file_number %lu next_file_number %lu last_sequence "
"%lu log_number %lu prev_log_number %lu\n",
(unsigned long)manifest_file_number_,
(unsigned long)next_file_number_,
(unsigned long)last_sequence,
(unsigned long)log_number,
(unsigned long)prev_log_number);
printf("%s \n", v->DebugString(hex).c_str());
}
return s;
}
void VersionSet::MarkFileNumberUsed(uint64_t number) {
if (next_file_number_ <= number) {
next_file_number_ = number + 1;
}
}
Status VersionSet::WriteSnapshot(log::Writer* log) {
// TODO: Break up into multiple records to reduce memory usage on recovery?
// Save metadata
VersionEdit edit;
edit.SetVersionNumber();
edit.SetComparatorName(icmp_.user_comparator()->Name());
// Save files
for (int level = 0; level < current_->NumberLevels(); level++) {
const auto& files = current_->files_[level];
for (size_t i = 0; i < files.size(); i++) {
const auto f = files[i];
edit.AddFile(level, f->number, f->file_size, f->smallest, f->largest,
f->smallest_seqno, f->largest_seqno);
}
}
edit.SetLogNumber(log_number_);
std::string record;
edit.EncodeTo(&record);
return log->AddRecord(record);
}
// Opens the mainfest file and reads all records
// till it finds the record we are looking for.
bool VersionSet::ManifestContains(uint64_t manifest_file_number,
const std::string& record) const {
std::string fname =
DescriptorFileName(dbname_, manifest_file_number);
Log(options_->info_log, "ManifestContains: checking %s\n", fname.c_str());
unique_ptr<SequentialFile> file;
Status s = env_->NewSequentialFile(fname, &file, storage_options_);
if (!s.ok()) {
Log(options_->info_log, "ManifestContains: %s\n", s.ToString().c_str());
Log(options_->info_log,
"ManifestContains: is unable to reopen the manifest file %s",
fname.c_str());
return false;
}
log::Reader reader(std::move(file), nullptr, true/*checksum*/, 0);
Slice r;
std::string scratch;
bool result = false;
while (reader.ReadRecord(&r, &scratch)) {
if (r == Slice(record)) {
result = true;
break;
}
}
Log(options_->info_log, "ManifestContains: result = %d\n", result ? 1 : 0);
return result;
}
uint64_t VersionSet::ApproximateOffsetOf(Version* v, const InternalKey& ikey) {
uint64_t result = 0;
for (int level = 0; level < v->NumberLevels(); level++) {
const std::vector<FileMetaData*>& files = v->files_[level];
for (size_t i = 0; i < files.size(); i++) {
if (icmp_.Compare(files[i]->largest, ikey) <= 0) {
// Entire file is before "ikey", so just add the file size
result += files[i]->file_size;
} else if (icmp_.Compare(files[i]->smallest, ikey) > 0) {
// Entire file is after "ikey", so ignore
if (level > 0) {
// Files other than level 0 are sorted by meta->smallest, so
// no further files in this level will contain data for
// "ikey".
break;
}
} else {
// "ikey" falls in the range for this table. Add the
// approximate offset of "ikey" within the table.
TableReader* table_reader_ptr;
Iterator* iter =
table_cache_->NewIterator(ReadOptions(), storage_options_, icmp_,
*(files[i]), &table_reader_ptr);
if (table_reader_ptr != nullptr) {
result += table_reader_ptr->ApproximateOffsetOf(ikey.Encode());
}
delete iter;
}
}
}
return result;
}
void VersionSet::AddLiveFiles(std::vector<uint64_t>* live_list) {
// pre-calculate space requirement
int64_t total_files = 0;
for (Version* v = dummy_versions_.next_;
v != &dummy_versions_;
v = v->next_) {
for (int level = 0; level < v->NumberLevels(); level++) {
total_files += v->files_[level].size();
}
}
// just one time extension to the right size
live_list->reserve(live_list->size() + total_files);
for (Version* v = dummy_versions_.next_;
v != &dummy_versions_;
v = v->next_) {
for (int level = 0; level < v->NumberLevels(); level++) {
for (const auto& f : v->files_[level]) {
live_list->push_back(f->number);
}
}
}
}
Compaction* VersionSet::PickCompaction(LogBuffer* log_buffer) {
return compaction_picker_->PickCompaction(current_, log_buffer);
}
Compaction* VersionSet::CompactRange(int input_level, int output_level,
const InternalKey* begin,
const InternalKey* end,
InternalKey** compaction_end) {
return compaction_picker_->CompactRange(current_, input_level, output_level,
begin, end, compaction_end);
}
Iterator* VersionSet::MakeInputIterator(Compaction* c) {
ReadOptions options;
options.verify_checksums = options_->verify_checksums_in_compaction;
options.fill_cache = false;
// Level-0 files have to be merged together. For other levels,
// we will make a concatenating iterator per level.
// TODO(opt): use concatenating iterator for level-0 if there is no overlap
const int space = (c->level() == 0 ? c->inputs(0)->size() + 1 : 2);
Iterator** list = new Iterator*[space];
int num = 0;
for (int which = 0; which < 2; which++) {
if (!c->inputs(which)->empty()) {
if (c->level() + which == 0) {
for (const auto& file : *c->inputs(which)) {
list[num++] = table_cache_->NewIterator(
options, storage_options_compactions_, icmp_, *file, nullptr,
true /* for compaction */);
}
} else {
// Create concatenating iterator for the files from this level
list[num++] = NewTwoLevelIterator(
new Version::LevelFileNumIterator(icmp_, c->inputs(which)),
&GetFileIterator, table_cache_, options, storage_options_, icmp_,
true /* for compaction */);
}
}
}
assert(num <= space);
Iterator* result = NewMergingIterator(env_, &icmp_, list, num);
delete[] list;
return result;
}
double VersionSet::MaxBytesForLevel(int level) {
return compaction_picker_->MaxBytesForLevel(level);
}
uint64_t VersionSet::MaxFileSizeForLevel(int level) {
return compaction_picker_->MaxFileSizeForLevel(level);
}
// verify that the files listed in this compaction are present
// in the current version
bool VersionSet::VerifyCompactionFileConsistency(Compaction* c) {
#ifndef NDEBUG
if (c->input_version() != current_) {
Log(options_->info_log, "VerifyCompactionFileConsistency version mismatch");
}
// verify files in level
int level = c->level();
for (int i = 0; i < c->num_input_files(0); i++) {
uint64_t number = c->input(0,i)->number;
// look for this file in the current version
bool found = false;
for (unsigned int j = 0; j < current_->files_[level].size(); j++) {
FileMetaData* f = current_->files_[level][j];
if (f->number == number) {
found = true;
break;
}
}
if (!found) {
return false; // input files non existant in current version
}
}
// verify level+1 files
level++;
for (int i = 0; i < c->num_input_files(1); i++) {
uint64_t number = c->input(1,i)->number;
// look for this file in the current version
bool found = false;
for (unsigned int j = 0; j < current_->files_[level].size(); j++) {
FileMetaData* f = current_->files_[level][j];
if (f->number == number) {
found = true;
break;
}
}
if (!found) {
return false; // input files non existant in current version
}
}
#endif
return true; // everything good
}
void VersionSet::ReleaseCompactionFiles(Compaction* c, Status status) {
compaction_picker_->ReleaseCompactionFiles(c, status);
}
Status VersionSet::GetMetadataForFile(uint64_t number, int* filelevel,
FileMetaData** meta) {
for (int level = 0; level < NumberLevels(); level++) {
const std::vector<FileMetaData*>& files = current_->files_[level];
for (size_t i = 0; i < files.size(); i++) {
if (files[i]->number == number) {
*meta = files[i];
*filelevel = level;
return Status::OK();
}
}
}
return Status::NotFound("File not present in any level");
}
void VersionSet::GetLiveFilesMetaData(std::vector<LiveFileMetaData>* metadata) {
for (int level = 0; level < NumberLevels(); level++) {
const std::vector<FileMetaData*>& files = current_->files_[level];
for (size_t i = 0; i < files.size(); i++) {
LiveFileMetaData filemetadata;
filemetadata.name = TableFileName("", files[i]->number);
filemetadata.level = level;
filemetadata.size = files[i]->file_size;
filemetadata.smallestkey = files[i]->smallest.user_key().ToString();
filemetadata.largestkey = files[i]->largest.user_key().ToString();
filemetadata.smallest_seqno = files[i]->smallest_seqno;
filemetadata.largest_seqno = files[i]->largest_seqno;
metadata->push_back(filemetadata);
}
}
}
void VersionSet::GetObsoleteFiles(std::vector<FileMetaData*>* files) {
files->insert(files->end(),
obsolete_files_.begin(),
obsolete_files_.end());
obsolete_files_.clear();
}
} // namespace rocksdb
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