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rocksdb/db/transaction_log_impl.cc

262 lines
8.6 KiB

// 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.
//
#include "db/transaction_log_impl.h"
#include "db/write_batch_internal.h"
namespace rocksdb {
TransactionLogIteratorImpl::TransactionLogIteratorImpl(
const std::string& dir,
const Options* options,
const EnvOptions& soptions,
const SequenceNumber seq,
std::unique_ptr<VectorLogPtr> files,
DBImpl const * const dbimpl) :
dir_(dir),
options_(options),
soptions_(soptions),
startingSequenceNumber_(seq),
files_(std::move(files)),
started_(false),
isValid_(false),
currentFileIndex_(0),
currentBatchSeq_(0),
currentLastSeq_(0),
dbimpl_(dbimpl) {
assert(files_ != nullptr);
assert(dbimpl_ != nullptr);
reporter_.env = options_->env;
reporter_.info_log = options_->info_log.get();
SeekToStartSequence(); // Seek till starting sequence
}
Status TransactionLogIteratorImpl::OpenLogFile(
const LogFile* logFile,
unique_ptr<SequentialFile>* file) {
Env* env = options_->env;
if (logFile->Type() == kArchivedLogFile) {
std::string fname = ArchivedLogFileName(dir_, logFile->LogNumber());
return env->NewSequentialFile(fname, file, soptions_);
} else {
std::string fname = LogFileName(dir_, logFile->LogNumber());
Status status = env->NewSequentialFile(fname, file, soptions_);
if (!status.ok()) {
// If cannot open file in DB directory.
// Try the archive dir, as it could have moved in the meanwhile.
fname = ArchivedLogFileName(dir_, logFile->LogNumber());
status = env->NewSequentialFile(fname, file, soptions_);
if (!status.ok()) {
return Status::IOError("Requested file not present in the dir");
}
}
return status;
}
}
BatchResult TransactionLogIteratorImpl::GetBatch() {
assert(isValid_); // cannot call in a non valid state.
BatchResult result;
result.sequence = currentBatchSeq_;
result.writeBatchPtr = std::move(currentBatch_);
return result;
}
Status TransactionLogIteratorImpl::status() {
return currentStatus_;
}
bool TransactionLogIteratorImpl::Valid() {
return started_ && isValid_;
}
bool TransactionLogIteratorImpl::RestrictedRead(
Slice* record,
std::string* scratch) {
// Don't read if no more complete entries to read from logs
if (currentLastSeq_ >= dbimpl_->GetLatestSequenceNumber()) {
return false;
}
return currentLogReader_->ReadRecord(record, scratch);
}
void TransactionLogIteratorImpl::SeekToStartSequence(
uint64_t startFileIndex,
bool strict) {
std::string scratch;
Slice record;
started_ = false;
isValid_ = false;
if (files_->size() <= startFileIndex) {
return;
}
Status s = OpenLogReader(files_->at(startFileIndex).get());
if (!s.ok()) {
currentStatus_ = s;
return;
}
while (RestrictedRead(&record, &scratch)) {
if (record.size() < 12) {
reporter_.Corruption(
record.size(), Status::Corruption("very small log record"));
continue;
}
UpdateCurrentWriteBatch(record);
if (currentLastSeq_ >= startingSequenceNumber_) {
if (strict && currentBatchSeq_ != startingSequenceNumber_) {
currentStatus_ = Status::Corruption("Gap in sequence number. Could not "
"seek to required sequence number");
reporter_.Info(currentStatus_.ToString().c_str());
return;
} else if (strict) {
reporter_.Info("Could seek required sequence number. Iterator will "
"continue.");
}
isValid_ = true;
started_ = true; // set started_ as we could seek till starting sequence
return;
} else {
isValid_ = false;
}
}
// Could not find start sequence in first file. Normally this must be the
// only file. Otherwise log the error and let the iterator return next entry
// If strict is set, we want to seek exactly till the start sequence and it
// should have been present in the file we scanned above
if (strict) {
currentStatus_ = Status::Corruption("Gap in sequence number. Could not "
"seek to required sequence number");
reporter_.Info(currentStatus_.ToString().c_str());
} else if (files_->size() != 1) {
currentStatus_ = Status::Corruption("Start sequence was not found, "
"skipping to the next available");
reporter_.Info(currentStatus_.ToString().c_str());
// Let NextImpl find the next available entry. started_ remains false
// because we don't want to check for gaps while moving to start sequence
NextImpl(true);
}
}
void TransactionLogIteratorImpl::Next() {
return NextImpl(false);
}
void TransactionLogIteratorImpl::NextImpl(bool internal) {
std::string scratch;
Slice record;
isValid_ = false;
if (!internal && !started_) {
// Runs every time until we can seek to the start sequence
return SeekToStartSequence();
}
while(true) {
assert(currentLogReader_);
if (currentLogReader_->IsEOF()) {
currentLogReader_->UnmarkEOF();
}
while (RestrictedRead(&record, &scratch)) {
if (record.size() < 12) {
reporter_.Corruption(
record.size(), Status::Corruption("very small log record"));
continue;
} else {
// started_ should be true if called by application
assert(internal || started_);
// started_ should be false if called internally
assert(!internal || !started_);
UpdateCurrentWriteBatch(record);
if (internal && !started_) {
started_ = true;
}
return;
}
}
// Open the next file
if (currentFileIndex_ < files_->size() - 1) {
++currentFileIndex_;
Status status =OpenLogReader(files_->at(currentFileIndex_).get());
if (!status.ok()) {
isValid_ = false;
currentStatus_ = status;
return;
}
} else {
isValid_ = false;
if (currentLastSeq_ == dbimpl_->GetLatestSequenceNumber()) {
currentStatus_ = Status::OK();
} else {
currentStatus_ = Status::IOError("NO MORE DATA LEFT");
}
return;
}
}
}
bool TransactionLogIteratorImpl::IsBatchExpected(
const WriteBatch* batch,
const SequenceNumber expectedSeq) {
assert(batch);
SequenceNumber batchSeq = WriteBatchInternal::Sequence(batch);
if (batchSeq != expectedSeq) {
char buf[200];
snprintf(buf, sizeof(buf),
"Discontinuity in log records. Got seq=%llu, Expected seq=%llu, "
"Last flushed seq=%llu.Log iterator will reseek the correct "
"batch.",
batchSeq, expectedSeq, dbimpl_->GetLatestSequenceNumber());
reporter_.Info(buf);
return false;
}
return true;
}
void TransactionLogIteratorImpl::UpdateCurrentWriteBatch(const Slice& record) {
std::unique_ptr<WriteBatch> batch(new WriteBatch());
WriteBatchInternal::SetContents(batch.get(), record);
SequenceNumber expectedSeq = currentLastSeq_ + 1;
// If the iterator has started, then confirm that we get continuous batches
if (started_ && !IsBatchExpected(batch.get(), expectedSeq)) {
// Seek to the batch having expected sequence number
if (expectedSeq < files_->at(currentFileIndex_)->StartSequence()) {
// Expected batch must lie in the previous log file
// Avoid underflow.
if (currentFileIndex_ != 0) {
currentFileIndex_--;
}
}
startingSequenceNumber_ = expectedSeq;
// currentStatus_ will be set to Ok if reseek succeeds
currentStatus_ = Status::NotFound("Gap in sequence numbers");
return SeekToStartSequence(currentFileIndex_, true);
}
currentBatchSeq_ = WriteBatchInternal::Sequence(batch.get());
currentLastSeq_ = currentBatchSeq_ +
WriteBatchInternal::Count(batch.get()) - 1;
// currentBatchSeq_ can only change here
assert(currentLastSeq_ <= dbimpl_->GetLatestSequenceNumber());
currentBatch_ = move(batch);
isValid_ = true;
currentStatus_ = Status::OK();
}
Status TransactionLogIteratorImpl::OpenLogReader(const LogFile* logFile) {
unique_ptr<SequentialFile> file;
Status status = OpenLogFile(logFile, &file);
if (!status.ok()) {
return status;
}
assert(file);
currentLogReader_.reset(
new log::Reader(std::move(file), &reporter_, true, 0)
);
return Status::OK();
}
} // namespace rocksdb