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rippled/Subtrees/hyperleveldb/db/version_set.cc

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// 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_set.h"
#include <algorithm>
#include <stdio.h>
#include "dbformat.h"
#include "filename.h"
#include "log_reader.h"
#include "log_writer.h"
#include "memtable.h"
#include "table_cache.h"
#include "../hyperleveldb/env.h"
#include "../hyperleveldb/table_builder.h"
#include "../table/merger.h"
#include "../table/two_level_iterator.h"
#include "../util/coding.h"
#include "../util/logging.h"
namespace hyperleveldb {
static double MaxBytesForLevel(int level) {
assert(level < leveldb::config::kNumLevels);
static const double bytes[] = {10 * 1048576.0,
100 * 1048576.0,
100 * 1048576.0,
1000 * 1048576.0,
10000 * 1048576.0,
100000 * 1048576.0,
1000000 * 1048576.0};
return bytes[level];
}
static uint64_t MaxFileSizeForLevel(int level) {
assert(level < leveldb::config::kNumLevels);
static const uint64_t bytes[] = {8 * 1048576,
8 * 1048576,
8 * 1048576,
8 * 1048576,
8 * 1048576,
8 * 1048576,
8 * 1048576};
return bytes[level];
}
static uint64_t MaxCompactionBytesForLevel(int level) {
assert(level < leveldb::config::kNumLevels);
static const uint64_t bytes[] = {128 * 1048576,
128 * 1048576,
128 * 1048576,
256 * 1048576,
256 * 1048576,
256 * 1048576,
256 * 1048576};
return bytes[level];
}
static int64_t TotalFileSize(const std::vector<FileMetaData*>& files) {
int64_t sum = 0;
for (size_t i = 0; i < files.size(); i++) {
sum += files[i]->file_size;
}
return sum;
}
namespace {
std::string IntSetToString(const std::set<uint64_t>& s) {
std::string result = "{";
for (std::set<uint64_t>::const_iterator it = s.begin();
it != s.end();
++it) {
result += (result.size() > 1) ? "," : "";
result += NumberToString(*it);
}
result += "}";
return result;
}
} // namespace
Version::~Version() {
assert(refs_ == 0);
// Remove from linked list
prev_->next_ = next_;
next_->prev_ = prev_;
// Drop references to files
for (int level = 0; level < config::kNumLevels; 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) {
delete f;
}
}
}
}
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) {
// NULL user_key occurs before all keys and is therefore never after *f
return (user_key != NULL &&
ucmp->Compare(*user_key, f->largest.user_key()) > 0);
}
static bool BeforeFile(const Comparator* ucmp,
const Slice* user_key, const FileMetaData* f) {
// NULL user_key occurs after all keys and is therefore never before *f
return (user_key != NULL &&
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 != NULL) {
// 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 Slice& file_value) {
TableCache* cache = reinterpret_cast<TableCache*>(arg);
if (file_value.size() != 16) {
return NewErrorIterator(
Status::Corruption("FileReader invoked with unexpected value"));
} else {
return cache->NewIterator(options,
DecodeFixed64(file_value.data()),
DecodeFixed64(file_value.data() + 8));
}
}
Iterator* Version::NewConcatenatingIterator(const ReadOptions& options,
int level) const {
return NewTwoLevelIterator(
new LevelFileNumIterator(vset_->icmp_, &files_[level]),
&GetFileIterator, vset_->table_cache_, options);
}
void Version::AddIterators(const ReadOptions& options,
std::vector<Iterator*>* iters) {
// Merge all level zero files together since they may overlap
for (size_t i = 0; i < files_[0].size(); i++) {
iters->push_back(
vset_->table_cache_->NewIterator(
options, files_[0][i]->number, files_[0][i]->file_size));
}
// 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 < config::kNumLevels; level++) {
if (!files_[level].empty()) {
iters->push_back(NewConcatenatingIterator(options, level));
}
}
}
// Callback from TableCache::Get()
namespace {
enum SaverState {
kNotFound,
kFound,
kDeleted,
kCorrupt,
};
struct Saver {
SaverState state;
const Comparator* ucmp;
Slice user_key;
std::string* value;
};
}
static void SaveValue(void* arg, const Slice& ikey, const Slice& v) {
Saver* s = reinterpret_cast<Saver*>(arg);
ParsedInternalKey parsed_key;
if (!ParseInternalKey(ikey, &parsed_key)) {
s->state = kCorrupt;
} else {
if (s->ucmp->Compare(parsed_key.user_key, s->user_key) == 0) {
s->state = (parsed_key.type == kTypeValue) ? kFound : kDeleted;
if (s->state == kFound) {
s->value->assign(v.data(), v.size());
}
}
}
}
static bool NewestFirst(FileMetaData* a, FileMetaData* b) {
return a->number > b->number;
}
Status Version::Get(const ReadOptions& options,
const LookupKey& k,
std::string* value,
GetStats* stats) {
Slice ikey = k.internal_key();
Slice user_key = k.user_key();
const Comparator* ucmp = vset_->icmp_.user_comparator();
Status s;
stats->seek_file = NULL;
stats->seek_file_level = -1;
FileMetaData* last_file_read = NULL;
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.
std::vector<FileMetaData*> tmp;
FileMetaData* tmp2;
for (int level = 0; level < config::kNumLevels; 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];
if (level == 0) {
// Level-0 files may overlap each other. Find all files that
// overlap user_key and process them in order from newest to oldest.
tmp.reserve(num_files);
for (uint32_t i = 0; 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) {
tmp.push_back(f);
}
}
if (tmp.empty()) continue;
std::sort(tmp.begin(), tmp.end(), NewestFirst);
files = &tmp[0];
num_files = tmp.size();
} else {
// Binary search to find earliest index whose largest key >= ikey.
uint32_t index = FindFile(vset_->icmp_, files_[level], ikey);
if (index >= num_files) {
files = NULL;
num_files = 0;
} else {
tmp2 = files[index];
if (ucmp->Compare(user_key, tmp2->smallest.user_key()) < 0) {
// All of "tmp2" is past any data for user_key
files = NULL;
num_files = 0;
} else {
files = &tmp2;
num_files = 1;
}
}
}
for (uint32_t i = 0; i < num_files; ++i) {
if (last_file_read != NULL && stats->seek_file == NULL) {
// 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;
}
FileMetaData* f = files[i];
last_file_read = f;
last_file_read_level = level;
Saver saver;
saver.state = kNotFound;
saver.ucmp = ucmp;
saver.user_key = user_key;
saver.value = value;
s = vset_->table_cache_->Get(options, f->number, f->file_size,
ikey, &saver, SaveValue);
if (!s.ok()) {
return s;
}
switch (saver.state) {
case kNotFound:
break; // Keep searching in other files
case kFound:
return s;
case kDeleted:
s = Status::NotFound(Slice()); // Use empty error message for speed
return s;
case kCorrupt:
s = Status::Corruption("corrupted key for ", user_key);
return s;
}
}
}
return Status::NotFound(Slice()); // Use an empty error message for speed
}
void Version::Ref() {
++refs_;
}
void Version::Unref() {
assert(this != &vset_->dummy_versions_);
assert(refs_ >= 1);
--refs_;
if (refs_ == 0) {
delete this;
}
}
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;
while (level < config::kMaxMemCompactLevel) {
if (OverlapInLevel(level + 1, &smallest_user_key, &largest_user_key)) {
break;
}
GetOverlappingInputs(level + 2, &start, &limit, &overlaps);
const int64_t sum = TotalFileSize(overlaps);
level++;
}
}
return level;
}
// Store in "*inputs" all files in "level" that overlap [begin,end]
void Version::GetOverlappingInputs(
int level,
const InternalKey* begin,
const InternalKey* end,
std::vector<FileMetaData*>* inputs) {
inputs->clear();
Slice user_begin, user_end;
if (begin != NULL) {
user_begin = begin->user_key();
}
if (end != NULL) {
user_end = end->user_key();
}
const Comparator* user_cmp = vset_->icmp_.user_comparator();
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 != NULL && user_cmp->Compare(file_limit, user_begin) < 0) {
// "f" is completely before specified range; skip it
} else if (end != NULL && 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 != NULL && user_cmp->Compare(file_start, user_begin) < 0) {
user_begin = file_start;
inputs->clear();
i = 0;
} else if (end != NULL && user_cmp->Compare(file_limit, user_end) > 0) {
user_end = file_limit;
inputs->clear();
i = 0;
}
}
}
}
}
std::string Version::DebugString() const {
std::string r;
for (int level = 0; level < config::kNumLevels; level++) {
// E.g.,
// --- level 1 ---
// 17:123['a' .. 'd']
// 20:43['e' .. 'g']
r.append("--- level ");
AppendNumberTo(&r, level);
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());
r.append(" .. ");
r.append(files[i]->largest.DebugString());
r.append("]\n");
}
}
return r;
}
// 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_[config::kNumLevels];
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();
BySmallestKey cmp;
cmp.internal_comparator = &vset_->icmp_;
for (int level = 0; level < config::kNumLevels; level++) {
levels_[level].added_files = new FileSet(cmp);
}
}
~Builder() {
for (int level = 0; level < config::kNumLevels; 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) {
delete f;
}
}
}
base_->Unref();
}
// Apply all of the edits in *edit to the current state.
void Apply(VersionEdit* edit) {
// Update compaction pointers
for (size_t i = 0; i < edit->compact_pointers_.size(); i++) {
const int level = edit->compact_pointers_[i].first;
vset_->compact_pointer_[level] =
edit->compact_pointers_[i].second.Encode().ToString();
}
// Delete files
const VersionEdit::DeletedFileSet& del = edit->deleted_files_;
for (VersionEdit::DeletedFileSet::const_iterator iter = del.begin();
iter != del.end();
++iter) {
const int level = iter->first;
const uint64_t number = iter->second;
levels_[level].deleted_files.insert(number);
}
// Add new files
for (size_t i = 0; i < edit->new_files_.size(); i++) {
const int level = edit->new_files_[i].first;
FileMetaData* f = new FileMetaData(edit->new_files_[i].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) {
BySmallestKey cmp;
cmp.internal_comparator = &vset_->icmp_;
for (int level = 0; level < config::kNumLevels; level++) {
// Merge the set of added files with the set of pre-existing files.
// Drop any deleted files. Store the result in *v.
const std::vector<FileMetaData*>& base_files = base_->files_[level];
std::vector<FileMetaData*>::const_iterator base_iter = base_files.begin();
std::vector<FileMetaData*>::const_iterator base_end = base_files.end();
const FileSet* added = levels_[level].added_files;
v->files_[level].reserve(base_files.size() + added->size());
for (FileSet::const_iterator added_iter = added->begin();
added_iter != added->end();
++added_iter) {
// Add all smaller files listed in base_
for (std::vector<FileMetaData*>::const_iterator bpos
= std::upper_bound(base_iter, base_end, *added_iter, cmp);
base_iter != bpos;
++base_iter) {
MaybeAddFile(v, level, *base_iter);
}
MaybeAddFile(v, level, *added_iter);
}
// Add remaining base files
for (; base_iter != base_end; ++base_iter) {
MaybeAddFile(v, level, *base_iter);
}
#ifndef NDEBUG
// 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 MaybeAddFile(Version* v, int level, FileMetaData* f) {
if (levels_[level].deleted_files.count(f->number) > 0) {
// File is deleted: do nothing
} else {
std::vector<FileMetaData*>* 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,
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()
last_sequence_(0),
log_number_(0),
prev_log_number_(0),
descriptor_file_(NULL),
descriptor_log_(NULL),
dummy_versions_(this),
current_(NULL) {
AppendVersion(new Version(this));
}
VersionSet::~VersionSet() {
current_->Unref();
assert(dummy_versions_.next_ == &dummy_versions_); // List must be empty
delete descriptor_log_;
delete descriptor_file_;
}
void VersionSet::AppendVersion(Version* v) {
// Make "v" current
assert(v->refs_ == 0);
assert(v != current_);
if (current_ != NULL) {
current_->Unref();
}
current_ = v;
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, port::CondVar* cv, bool* wt) {
while (*wt) {
cv->Wait();
}
*wt = true;
if (edit->has_log_number_) {
assert(edit->log_number_ >= log_number_);
assert(edit->log_number_ < next_file_number_);
} else {
edit->SetLogNumber(log_number_);
}
if (!edit->has_prev_log_number_) {
edit->SetPrevLogNumber(prev_log_number_);
}
edit->SetNextFile(next_file_number_);
edit->SetLastSequence(last_sequence_);
Version* v = new Version(this);
{
Builder builder(this, current_);
builder.Apply(edit);
builder.SaveTo(v);
}
Finalize(v);
// Initialize new descriptor log file if necessary by creating
// a temporary file that contains a snapshot of the current version.
std::string new_manifest_file;
Status s;
if (descriptor_log_ == NULL) {
// No reason to unlock *mu here since we only hit this path in the
// first call to LogAndApply (when opening the database).
assert(descriptor_file_ == NULL);
new_manifest_file = DescriptorFileName(dbname_, manifest_file_number_);
edit->SetNextFile(next_file_number_);
s = env_->NewWritableFile(new_manifest_file, &descriptor_file_);
if (s.ok()) {
descriptor_log_ = new log::Writer(descriptor_file_);
s = WriteSnapshot(descriptor_log_);
}
}
// Unlock during expensive MANIFEST log write
{
mu->Unlock();
// Write new record to MANIFEST log
if (s.ok()) {
std::string record;
edit->EncodeTo(&record);
s = descriptor_log_->AddRecord(record);
if (s.ok()) {
// XXX Unlock during expensive MANIFEST log write
s = descriptor_file_->Sync();
}
if (!s.ok()) {
Log(options_->info_log, "MANIFEST write: %s\n", s.ToString().c_str());
if (ManifestContains(record)) {
Log(options_->info_log,
"MANIFEST contains log record despite error; advancing to new "
"version to prevent mismatch between in-memory and logged state");
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_manifest_file.empty()) {
s = SetCurrentFile(env_, dbname_, manifest_file_number_);
// No need to double-check MANIFEST in case of error since it
// will be discarded below.
}
mu->Lock();
}
// Install the new version
if (s.ok()) {
AppendVersion(v);
log_number_ = edit->log_number_;
prev_log_number_ = edit->prev_log_number_;
} else {
delete v;
if (!new_manifest_file.empty()) {
delete descriptor_log_;
delete descriptor_file_;
descriptor_log_ = NULL;
descriptor_file_ = NULL;
env_->DeleteFile(new_manifest_file);
}
}
*wt = false;
cv->Signal();
return s;
}
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 current;
Status s = ReadFileToString(env_, CurrentFileName(dbname_), &current);
if (!s.ok()) {
return s;
}
if (current.empty() || current[current.size()-1] != '\n') {
return Status::Corruption("CURRENT file does not end with newline");
}
current.resize(current.size() - 1);
std::string dscname = dbname_ + "/" + current;
SequentialFile* file;
s = env_->NewSequentialFile(dscname, &file);
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;
Builder builder(this, current_);
{
LogReporter reporter;
reporter.status = &s;
log::Reader reader(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(
edit.comparator_ + " does not match existing comparator ",
icmp_.user_comparator()->Name());
}
}
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;
}
}
}
delete file;
file = NULL;
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()) {
Version* v = new Version(this);
builder.SaveTo(v);
// Install recovered version
Finalize(v);
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;
}
return s;
}
void VersionSet::MarkFileNumberUsed(uint64_t number) {
if (next_file_number_ <= number) {
next_file_number_ = number + 1;
}
}
void VersionSet::Finalize(Version* v) {
// Compute the ratio of disk usage to its limit
for (int level = 0; level + 1 < config::kNumLevels; ++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).
score = v->files_[level].size() /
static_cast<double>(config::kL0_CompactionTrigger);
} else {
// Compute the ratio of current size to size limit.
const uint64_t level_bytes = TotalFileSize(v->files_[level]);
score = static_cast<double>(level_bytes) / MaxBytesForLevel(level);
}
v->compaction_scores_[level] = score;
}
}
Status VersionSet::WriteSnapshot(log::Writer* log) {
// TODO: Break up into multiple records to reduce memory usage on recovery?
// Save metadata
VersionEdit edit;
edit.SetComparatorName(icmp_.user_comparator()->Name());
// Save compaction pointers
for (int level = 0; level < config::kNumLevels; level++) {
if (!compact_pointer_[level].empty()) {
InternalKey key;
key.DecodeFrom(compact_pointer_[level]);
edit.SetCompactPointer(level, key);
}
}
// Save files
for (int level = 0; level < config::kNumLevels; level++) {
const std::vector<FileMetaData*>& files = current_->files_[level];
for (size_t i = 0; i < files.size(); i++) {
const FileMetaData* f = files[i];
edit.AddFile(level, f->number, f->file_size, f->smallest, f->largest);
}
}
std::string record;
edit.EncodeTo(&record);
return log->AddRecord(record);
}
int VersionSet::NumLevelFiles(int level) const {
assert(level >= 0);
assert(level < config::kNumLevels);
return current_->files_[level].size();
}
const char* VersionSet::LevelSummary(LevelSummaryStorage* scratch) const {
// Update code if kNumLevels changes
assert(config::kNumLevels == 7);
snprintf(scratch->buffer, sizeof(scratch->buffer),
"files[ %d %d %d %d %d %d %d ]",
int(current_->files_[0].size()),
int(current_->files_[1].size()),
int(current_->files_[2].size()),
int(current_->files_[3].size()),
int(current_->files_[4].size()),
int(current_->files_[5].size()),
int(current_->files_[6].size()));
return scratch->buffer;
}
// Return true iff the manifest contains the specified record.
bool VersionSet::ManifestContains(const std::string& record) const {
std::string fname = DescriptorFileName(dbname_, manifest_file_number_);
Log(options_->info_log, "ManifestContains: checking %s\n", fname.c_str());
SequentialFile* file = NULL;
Status s = env_->NewSequentialFile(fname, &file);
if (!s.ok()) {
Log(options_->info_log, "ManifestContains: %s\n", s.ToString().c_str());
return false;
}
log::Reader reader(file, NULL, true/*checksum*/, 0);
Slice r;
std::string scratch;
bool result = false;
while (reader.ReadRecord(&r, &scratch)) {
if (r == Slice(record)) {
result = true;
break;
}
}
delete file;
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 < config::kNumLevels; 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.
Table* tableptr;
Iterator* iter = table_cache_->NewIterator(
ReadOptions(), files[i]->number, files[i]->file_size, &tableptr);
if (tableptr != NULL) {
result += tableptr->ApproximateOffsetOf(ikey.Encode());
}
delete iter;
}
}
}
return result;
}
void VersionSet::AddLiveFiles(std::set<uint64_t>* live) {
for (Version* v = dummy_versions_.next_;
v != &dummy_versions_;
v = v->next_) {
for (int level = 0; level < config::kNumLevels; level++) {
const std::vector<FileMetaData*>& files = v->files_[level];
for (size_t i = 0; i < files.size(); i++) {
live->insert(files[i]->number);
}
}
}
}
int64_t VersionSet::NumLevelBytes(int level) const {
assert(level >= 0);
assert(level < config::kNumLevels);
return TotalFileSize(current_->files_[level]);
}
int64_t VersionSet::MaxNextLevelOverlappingBytes() {
int64_t result = 0;
std::vector<FileMetaData*> overlaps;
for (int level = 1; level < config::kNumLevels - 1; level++) {
for (size_t i = 0; i < current_->files_[level].size(); i++) {
const FileMetaData* f = current_->files_[level][i];
current_->GetOverlappingInputs(level+1, &f->smallest, &f->largest,
&overlaps);
const int64_t sum = TotalFileSize(overlaps);
if (sum > result) {
result = sum;
}
}
}
return result;
}
// Stores the minimal range that covers all entries in inputs in
// *smallest, *largest.
// REQUIRES: inputs is not empty
void VersionSet::GetRange(const std::vector<FileMetaData*>& inputs,
InternalKey* smallest,
InternalKey* largest) {
assert(!inputs.empty());
smallest->Clear();
largest->Clear();
for (size_t i = 0; i < inputs.size(); i++) {
FileMetaData* f = inputs[i];
if (i == 0) {
*smallest = f->smallest;
*largest = f->largest;
} else {
if (icmp_.Compare(f->smallest, *smallest) < 0) {
*smallest = f->smallest;
}
if (icmp_.Compare(f->largest, *largest) > 0) {
*largest = f->largest;
}
}
}
}
// Stores the minimal range that covers all entries in inputs1 and inputs2
// in *smallest, *largest.
// REQUIRES: inputs is not empty
void VersionSet::GetRange2(const std::vector<FileMetaData*>& inputs1,
const std::vector<FileMetaData*>& inputs2,
InternalKey* smallest,
InternalKey* largest) {
std::vector<FileMetaData*> all = inputs1;
all.insert(all.end(), inputs2.begin(), inputs2.end());
GetRange(all, smallest, largest);
}
Iterator* VersionSet::MakeInputIterator(Compaction* c) {
ReadOptions options;
options.verify_checksums = options_->paranoid_checks;
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) {
const std::vector<FileMetaData*>& files = c->inputs_[which];
for (size_t i = 0; i < files.size(); i++) {
list[num++] = table_cache_->NewIterator(
options, files[i]->number, files[i]->file_size);
}
} else {
// Create concatenating iterator for the files from this level
list[num++] = NewTwoLevelIterator(
new Version::LevelFileNumIterator(icmp_, &c->inputs_[which]),
&GetFileIterator, table_cache_, options);
}
}
}
assert(num <= space);
Iterator* result = NewMergingIterator(&icmp_, list, num);
delete[] list;
return result;
}
struct CompactionBoundary {
size_t start;
size_t limit;
CompactionBoundary() : start(0), limit(0) {}
CompactionBoundary(size_t s, size_t l) : start(s), limit(l) {}
};
struct CmpByRange {
CmpByRange(const Comparator* cmp) : cmp_(cmp) {}
bool operator () (const FileMetaData* lhs, const FileMetaData* rhs) {
int smallest = cmp_->Compare(lhs->smallest.user_key(), rhs->smallest.user_key());
if (smallest == 0) {
return cmp_->Compare(lhs->largest.user_key(), rhs->largest.user_key()) < 0;
}
return smallest < 0;
}
private:
const Comparator* cmp_;
};
// Stores the compaction boundaries between level and level + 1
void VersionSet::GetCompactionBoundaries(int level,
std::vector<FileMetaData*>* LA,
std::vector<FileMetaData*>* LB,
std::vector<uint64_t>* LA_sizes,
std::vector<uint64_t>* LB_sizes,
std::vector<CompactionBoundary>* boundaries)
{
const Comparator* user_cmp = icmp_.user_comparator();
*LA = current_->files_[level + 0];
*LB = current_->files_[level + 1];
*LA_sizes = std::vector<uint64_t>(LA->size() + 1, 0);
*LB_sizes = std::vector<uint64_t>(LB->size() + 1, 0);
std::sort(LA->begin(), LA->end(), CmpByRange(user_cmp));
std::sort(LB->begin(), LB->end(), CmpByRange(user_cmp));
boundaries->resize(LA->size());
// compute sizes
for (size_t i = 0; i < LA->size(); ++i) {
(*LA_sizes)[i + 1] = (*LA_sizes)[i] + (*LA)[i]->file_size;
}
for (size_t i = 0; i < LB->size(); ++i) {
(*LB_sizes)[i + 1] = (*LB_sizes)[i] + (*LB)[i]->file_size;
}
// compute boundaries
size_t start = 0;
size_t limit = 0;
// figure out which range of LB each LA covers
for (size_t i = 0; i < LA->size(); ++i) {
// find smallest start s.t. LB[start] overlaps LA[i]
while (start < LB->size() &&
user_cmp->Compare((*LB)[start]->largest.user_key(),
(*LA)[i]->smallest.user_key()) < 0) {
++start;
}
limit = std::max(start, limit);
// find smallest limit >= start s.t. LB[limit] does not overlap LA[i]
while (limit < LB->size() &&
user_cmp->Compare((*LB)[limit]->smallest.user_key(),
(*LA)[i]->largest.user_key()) <= 0) {
++limit;
}
(*boundaries)[i].start = start;
(*boundaries)[i].limit = limit;
}
}
int VersionSet::PickCompactionLevel(bool* locked) {
// Find an unlocked level has score >= 1 where level + 1 has score < 1.
int level = config::kNumLevels;
for (int i = 0; i + 1 < config::kNumLevels; ++i) {
if (locked[i] || locked[i + 1]) {
continue;
}
if (current_->compaction_scores_[i + 0] >= 1.0 &&
current_->compaction_scores_[i + 1] < 1.0) {
level = i;
break;
}
}
return level;
}
static bool OldestFirst(FileMetaData* a, FileMetaData* b) {
return a->number < b->number;
}
Compaction* VersionSet::PickCompaction(int level) {
assert(0 <= level && level < config::kNumLevels);
bool trivial = false;
if (current_->files_[level].empty()) {
return NULL;
}
Compaction* c = new Compaction(level);
c->input_version_ = current_;
c->input_version_->Ref();
if (level > 0) {
std::vector<FileMetaData*> LA;
std::vector<FileMetaData*> LB;
std::vector<uint64_t> LA_sizes;
std::vector<uint64_t> LB_sizes;
std::vector<CompactionBoundary> boundaries;
GetCompactionBoundaries(level, &LA, &LB, &LA_sizes, &LB_sizes, &boundaries);
// find the best set of files: maximize the ratio of sizeof(LA)/sizeof(LB)
// while keeping sizeof(LA)+sizeof(LB) < some threshold. If there's a tie
// for ratio, minimize size.
size_t best_idx_start = 0;
size_t best_idx_limit = 0;
uint64_t best_size = 0;
double best_ratio = -1;
for (size_t i = 0; i < boundaries.size(); ++i) {
for (size_t j = i; j < boundaries.size(); ++j) {
uint64_t sz_a = LA_sizes[j + 1] - LA_sizes[i];
uint64_t sz_b = LB_sizes[boundaries[j].limit] - LB_sizes[boundaries[i].start];
if (boundaries[j].start == boundaries[j].limit) {
trivial = true;
break;
}
if (sz_a + sz_b >= MaxCompactionBytesForLevel(level)) {
break;
}
assert(sz_b > 0); // true because we exclude trivial moves
double ratio = double(sz_a) / double(sz_b);
if (ratio > best_ratio ||
(ratio == best_ratio && sz_a + sz_b < best_size)) {
best_ratio = ratio;
best_size = sz_a + sz_b;
best_idx_start = i;
best_idx_limit = j + 1;
}
}
}
// Trivial moves have a near-0 cost, so do them first.
if (trivial) {
for (size_t i = 0; i < LA.size(); ++i) {
if (boundaries[i].start == boundaries[i].limit) {
c->inputs_[0].push_back(LA[i]);
}
}
trivial = level != 0;
c->SetRatio(1.0);
// If the best we could do would be wasteful and the best level has more
// data in it than the next level would have, move it all
} else if (level < 4 && best_ratio >= 0.0 &&
LA_sizes.back() * best_ratio >= LB_sizes.back()) {
for (size_t i = 0 ; i < LA.size(); ++i) {
c->inputs_[0].push_back(LA[i]);
}
c->SetRatio(double(LA_sizes.back()) / double(LB_sizes.back()));
// otherwise go with the best ratio
} else if (best_ratio >= 0.0) {
for (size_t i = best_idx_start; i < best_idx_limit; ++i) {
assert(i >= 0 && i < LA.size());
c->inputs_[0].push_back(LA[i]);
}
for (size_t i = boundaries[best_idx_start].start;
i < boundaries[best_idx_limit - 1].limit; ++i) {
assert(i >= 0 && i < LB.size());
c->inputs_[1].push_back(LB[i]);
}
c->SetRatio(best_ratio);
// otherwise just pick the file with least overlap
} else {
assert(level >= 0);
assert(level+1 < config::kNumLevels);
// Pick the file that overlaps with the fewest files in the next level
size_t largest = boundaries.size();
size_t smallest = boundaries.size();
for (size_t i = 0; i < boundaries.size(); ++i) {
if (smallest == boundaries.size() ||
boundaries[smallest].limit - boundaries[smallest].start >
boundaries[i].limit - boundaries[i].start) {
smallest = i;
}
}
assert(smallest < boundaries.size());
c->inputs_[0].push_back(LA[smallest]);
for (size_t i = boundaries[smallest].start; i < boundaries[smallest].limit; ++i) {
c->inputs_[1].push_back(LB[i]);
}
}
} else {
std::vector<FileMetaData*> tmp(current_->files_[0]);
std::sort(tmp.begin(), tmp.end(), OldestFirst);
for (size_t i = 0; i < tmp.size() && c->inputs_[0].size() < 32; ++i) {
c->inputs_[0].push_back(tmp[i]);
}
}
assert(!c->inputs_[0].empty());
if (!trivial) {
SetupOtherInputs(c);
}
return c;
}
void VersionSet::SetupOtherInputs(Compaction* c) {
const int level = c->level();
InternalKey smallest, largest;
GetRange(c->inputs_[0], &smallest, &largest);
current_->GetOverlappingInputs(level+1, &smallest, &largest, &c->inputs_[1]);
// Update the place where we will do the next compaction for this level.
// We update this immediately instead of waiting for the VersionEdit
// to be applied so that if the compaction fails, we will try a different
// key range next time.
compact_pointer_[level] = largest.Encode().ToString();
c->edit_.SetCompactPointer(level, largest);
}
Compaction* VersionSet::CompactRange(
int level,
const InternalKey* begin,
const InternalKey* end) {
std::vector<FileMetaData*> inputs;
current_->GetOverlappingInputs(level, begin, end, &inputs);
if (inputs.empty()) {
return NULL;
}
// Avoid compacting too much in one shot in case the range is large.
// But we cannot do this for level-0 since level-0 files can overlap
// and we must not pick one file and drop another older file if the
// two files overlap.
if (level > 0) {
const uint64_t limit = MaxFileSizeForLevel(level);
uint64_t total = 0;
for (size_t i = 0; i < inputs.size(); i++) {
uint64_t s = inputs[i]->file_size;
total += s;
if (total >= limit) {
inputs.resize(i + 1);
break;
}
}
}
Compaction* c = new Compaction(level);
c->input_version_ = current_;
c->input_version_->Ref();
c->inputs_[0] = inputs;
SetupOtherInputs(c);
return c;
}
Compaction::Compaction(int level)
: level_(level),
max_output_file_size_(MaxFileSizeForLevel(level)),
input_version_(NULL),
ratio_(0) {
for (int i = 0; i < config::kNumLevels; i++) {
level_ptrs_[i] = 0;
}
}
Compaction::~Compaction() {
if (input_version_ != NULL) {
input_version_->Unref();
}
}
bool Compaction::IsTrivialMove() const {
return num_input_files(1) == 0;
}
void Compaction::AddInputDeletions(VersionEdit* edit) {
for (int which = 0; which < 2; which++) {
for (size_t i = 0; i < inputs_[which].size(); i++) {
edit->DeleteFile(level_ + which, inputs_[which][i]->number);
}
}
}
bool Compaction::IsBaseLevelForKey(const Slice& user_key) {
// Maybe use binary search to find right entry instead of linear search?
const Comparator* user_cmp = input_version_->vset_->icmp_.user_comparator();
for (int lvl = level_ + 2; lvl < config::kNumLevels; lvl++) {
const std::vector<FileMetaData*>& files = input_version_->files_[lvl];
for (; level_ptrs_[lvl] < files.size(); ) {
FileMetaData* f = files[level_ptrs_[lvl]];
if (user_cmp->Compare(user_key, f->largest.user_key()) <= 0) {
// We've advanced far enough
if (user_cmp->Compare(user_key, f->smallest.user_key()) >= 0) {
// Key falls in this file's range, so definitely not base level
return false;
}
break;
}
level_ptrs_[lvl]++;
}
}
return true;
}
void Compaction::ReleaseInputs() {
if (input_version_ != NULL) {
input_version_->Unref();
input_version_ = NULL;
}
}
} // namespace hyperleveldb
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