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rocksdb/db/version_set.cc
Yueh-Hsuan Chiang cda4006e87 Enhance partial merge to support multiple arguments 
Summary:
* PartialMerge api now takes a list of operands instead of two operands.
* Add min_pertial_merge_operands to Options, indicating the minimum
  number of operands to trigger partial merge.
* This diff is based on Schalk's previous diff (D14601), but it also
  includes necessary changes such as updating the pure C api for
  partial merge.

Test Plan:
* make check all
* develop tests for cases where partial merge takes more than two
  operands.

TODOs (from Schalk):
* Add test with min_partial_merge_operands > 2.
* Perform benchmarks to measure the performance improvements (can probably
  use results of task #2837810.)
* Add description of problem to doc/index.html.
* Change wiki pages to reflect the interface changes.

Reviewers: haobo, igor, vamsi

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D16815
2014-03-24 17:57:13 -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);
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_),
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) {
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.get();
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;
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)) {
*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::ComputeCompactionScore(
std::vector<uint64_t>& size_being_compacted) {
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);
}
}
// TODO(icanadi) do it in the loop above, which already sorts the files
// Pre-sort level0 for Get()
if (v->vset_->options_->compaction_style == kCompactionStyleUniversal) {
std::sort(v->files_[0].begin(), v->files_[0].end(), NewestFirstBySeqNo);
} else {
std::sort(v->files_[0].begin(), v->files_[0].end(), NewestFirst);
}
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 ComputeCompactionScore and UpdateFilesBySize are cpu-heavy
// and is best called outside the mutex.
v->ComputeCompactionScore(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->ComputeCompactionScore(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->ComputeCompactionScore(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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