rocksdb/db/version_builder.cc

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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.
#include "db/version_builder.h"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#include <algorithm>
#include <atomic>
#include <set>
#include <thread>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include "db/dbformat.h"
#include "db/internal_stats.h"
#include "db/table_cache.h"
#include "db/version_set.h"
#include "table/table_reader.h"
namespace rocksdb {
bool NewestFirstBySeqNo(FileMetaData* a, FileMetaData* b) {
if (a->smallest_seqno != b->smallest_seqno) {
return a->smallest_seqno > b->smallest_seqno;
}
if (a->largest_seqno != b->largest_seqno) {
return a->largest_seqno > b->largest_seqno;
}
// Break ties by file number
return a->fd.GetNumber() > b->fd.GetNumber();
}
namespace {
bool BySmallestKey(FileMetaData* a, FileMetaData* b,
const InternalKeyComparator* cmp) {
int r = cmp->Compare(a->smallest, b->smallest);
if (r != 0) {
return (r < 0);
}
// Break ties by file number
return (a->fd.GetNumber() < b->fd.GetNumber());
}
} // namespace
class VersionBuilder::Rep {
private:
// Helper to sort files_ in v
// kLevel0 -- NewestFirstBySeqNo
// kLevelNon0 -- BySmallestKey
struct FileComparator {
enum SortMethod { kLevel0 = 0, kLevelNon0 = 1, } sort_method;
const InternalKeyComparator* internal_comparator;
bool operator()(FileMetaData* f1, FileMetaData* f2) const {
switch (sort_method) {
case kLevel0:
return NewestFirstBySeqNo(f1, f2);
case kLevelNon0:
return BySmallestKey(f1, f2, internal_comparator);
}
assert(false);
return false;
}
};
struct LevelState {
std::unordered_set<uint64_t> deleted_files;
// Map from file number to file meta data.
std::unordered_map<uint64_t, FileMetaData*> added_files;
};
const EnvOptions& env_options_;
Logger* info_log_;
TableCache* table_cache_;
VersionStorageInfo* base_vstorage_;
LevelState* levels_;
FileComparator level_zero_cmp_;
FileComparator level_nonzero_cmp_;
public:
Rep(const EnvOptions& env_options, Logger* info_log, TableCache* table_cache,
VersionStorageInfo* base_vstorage)
: env_options_(env_options),
info_log_(info_log),
table_cache_(table_cache),
base_vstorage_(base_vstorage) {
levels_ = new LevelState[base_vstorage_->num_levels()];
level_zero_cmp_.sort_method = FileComparator::kLevel0;
level_nonzero_cmp_.sort_method = FileComparator::kLevelNon0;
level_nonzero_cmp_.internal_comparator =
base_vstorage_->InternalComparator();
}
~Rep() {
for (int level = 0; level < base_vstorage_->num_levels(); level++) {
const auto& added = levels_[level].added_files;
for (auto& pair : added) {
UnrefFile(pair.second);
}
}
delete[] levels_;
}
void UnrefFile(FileMetaData* f) {
f->refs--;
if (f->refs <= 0) {
if (f->table_reader_handle) {
assert(table_cache_ != nullptr);
table_cache_->ReleaseHandle(f->table_reader_handle);
f->table_reader_handle = nullptr;
}
delete f;
}
}
void CheckConsistency(VersionStorageInfo* vstorage) {
#ifndef NDEBUG
// make sure the files are sorted correctly
for (int level = 0; level < vstorage->num_levels(); level++) {
auto& level_files = vstorage->LevelFiles(level);
for (size_t i = 1; i < level_files.size(); i++) {
auto f1 = level_files[i - 1];
auto f2 = level_files[i];
if (level == 0) {
assert(level_zero_cmp_(f1, f2));
assert(f1->largest_seqno > f2->largest_seqno);
} else {
assert(level_nonzero_cmp_(f1, f2));
// Make sure there is no overlap in levels > 0
if (vstorage->InternalComparator()->Compare(f1->largest,
f2->smallest) >= 0) {
fprintf(stderr, "overlapping ranges in same level %s vs. %s\n",
(f1->largest).DebugString().c_str(),
(f2->smallest).DebugString().c_str());
abort();
}
}
}
}
#endif
}
void CheckConsistencyForDeletes(VersionEdit* edit, uint64_t 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_vstorage_->num_levels(); l++) {
const std::vector<FileMetaData*>& base_files =
base_vstorage_->LevelFiles(l);
for (unsigned int i = 0; i < base_files.size(); i++) {
FileMetaData* f = base_files[i];
if (f->fd.GetNumber() == 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_vstorage_->num_levels(); l++) {
auto& level_added = levels_[l].added_files;
auto got = level_added.find(number);
if (got != level_added.end()) {
found = true;
break;
}
}
// maybe this file was added in a previous edit that was Applied
if (!found) {
auto& level_added = levels_[level].added_files;
auto got = level_added.find(number);
if (got != level_added.end()) {
found = true;
}
}
if (!found) {
fprintf(stderr, "not found %" PRIu64 "\n", number);
}
assert(found);
#endif
}
// Apply all of the edits in *edit to the current state.
void Apply(VersionEdit* edit) {
CheckConsistency(base_vstorage_);
// Delete files
const VersionEdit::DeletedFileSet& del = edit->GetDeletedFiles();
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);
auto exising = levels_[level].added_files.find(number);
if (exising != levels_[level].added_files.end()) {
UnrefFile(exising->second);
levels_[level].added_files.erase(number);
}
}
// Add new files
for (const auto& new_file : edit->GetNewFiles()) {
const int level = new_file.first;
FileMetaData* f = new FileMetaData(new_file.second);
f->refs = 1;
assert(levels_[level].added_files.find(f->fd.GetNumber()) ==
levels_[level].added_files.end());
levels_[level].deleted_files.erase(f->fd.GetNumber());
levels_[level].added_files[f->fd.GetNumber()] = f;
}
}
// Save the current state in *v.
void SaveTo(VersionStorageInfo* vstorage) {
CheckConsistency(base_vstorage_);
CheckConsistency(vstorage);
for (int level = 0; level < base_vstorage_->num_levels(); level++) {
const auto& cmp = (level == 0) ? level_zero_cmp_ : level_nonzero_cmp_;
// 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_vstorage_->LevelFiles(level);
auto base_iter = base_files.begin();
auto base_end = base_files.end();
const auto& unordered_added_files = levels_[level].added_files;
vstorage->Reserve(level,
base_files.size() + unordered_added_files.size());
// Sort added files for the level.
std::vector<FileMetaData*> added_files;
added_files.reserve(unordered_added_files.size());
for (const auto& pair : unordered_added_files) {
added_files.push_back(pair.second);
}
std::sort(added_files.begin(), added_files.end(), cmp);
#ifndef NDEBUG
FileMetaData* prev_file = nullptr;
#endif
for (const auto& added : added_files) {
#ifndef NDEBUG
if (level > 0 && prev_file != nullptr) {
assert(base_vstorage_->InternalComparator()->Compare(
prev_file->smallest, added->smallest) <= 0);
}
prev_file = added;
#endif
// 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(vstorage, level, *base_iter);
}
MaybeAddFile(vstorage, level, added);
}
// Add remaining base files
for (; base_iter != base_end; ++base_iter) {
MaybeAddFile(vstorage, level, *base_iter);
}
}
CheckConsistency(vstorage);
}
void LoadTableHandlers(InternalStats* internal_stats, int max_threads) {
assert(table_cache_ != nullptr);
// <file metadata, level>
std::vector<std::pair<FileMetaData*, int>> files_meta;
for (int level = 0; level < base_vstorage_->num_levels(); level++) {
for (auto& file_meta_pair : levels_[level].added_files) {
auto* file_meta = file_meta_pair.second;
assert(!file_meta->table_reader_handle);
files_meta.emplace_back(file_meta, level);
}
}
std::atomic<size_t> next_file_meta_idx(0);
std::function<void()> load_handlers_func = [&]() {
while (true) {
size_t file_idx = next_file_meta_idx.fetch_add(1);
if (file_idx >= files_meta.size()) {
break;
}
auto* file_meta = files_meta[file_idx].first;
int level = files_meta[file_idx].second;
table_cache_->FindTable(env_options_,
*(base_vstorage_->InternalComparator()),
file_meta->fd, &file_meta->table_reader_handle,
false /*no_io */, true /* record_read_stats */,
internal_stats->GetFileReadHist(level));
if (file_meta->table_reader_handle != nullptr) {
// Load table_reader
file_meta->fd.table_reader = table_cache_->GetTableReaderFromHandle(
file_meta->table_reader_handle);
}
}
};
if (max_threads <= 1) {
load_handlers_func();
} else {
std::vector<std::thread> threads;
for (int i = 0; i < max_threads; i++) {
threads.emplace_back(load_handlers_func);
}
for (auto& t : threads) {
t.join();
}
}
}
void MaybeAddFile(VersionStorageInfo* vstorage, int level, FileMetaData* f) {
if (levels_[level].deleted_files.count(f->fd.GetNumber()) > 0) {
// File is deleted: do nothing
} else {
vstorage->AddFile(level, f, info_log_);
}
}
};
VersionBuilder::VersionBuilder(const EnvOptions& env_options,
TableCache* table_cache,
VersionStorageInfo* base_vstorage,
Logger* info_log)
: rep_(new Rep(env_options, info_log, table_cache, base_vstorage)) {}
VersionBuilder::~VersionBuilder() { delete rep_; }
void VersionBuilder::CheckConsistency(VersionStorageInfo* vstorage) {
rep_->CheckConsistency(vstorage);
}
void VersionBuilder::CheckConsistencyForDeletes(VersionEdit* edit,
uint64_t number, int level) {
rep_->CheckConsistencyForDeletes(edit, number, level);
}
void VersionBuilder::Apply(VersionEdit* edit) { rep_->Apply(edit); }
void VersionBuilder::SaveTo(VersionStorageInfo* vstorage) {
rep_->SaveTo(vstorage);
}
void VersionBuilder::LoadTableHandlers(InternalStats* internal_stats,
int max_threads) {
rep_->LoadTableHandlers(internal_stats, max_threads);
}
void VersionBuilder::MaybeAddFile(VersionStorageInfo* vstorage, int level,
FileMetaData* f) {
rep_->MaybeAddFile(vstorage, level, f);
}
} // namespace rocksdb