rocksdb/db/transaction_log_iterator_impl.cc

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#include "db/transaction_log_iterator_impl.h"
#include "db/write_batch_internal.h"
#include "db/filename.h"
namespace leveldb {
TransactionLogIteratorImpl::TransactionLogIteratorImpl(
const std::string& dbname,
const Options* options,
SequenceNumber& seq,
std::vector<LogFile>* files,
SequenceNumber const * const lastFlushedSequence) :
dbname_(dbname),
options_(options),
sequenceNumber_(seq),
files_(files),
started_(false),
isValid_(true),
currentFileIndex_(0),
lastFlushedSequence_(lastFlushedSequence) {
assert(files_ != nullptr);
assert(lastFlushedSequence_);
}
LogReporter
TransactionLogIteratorImpl::NewLogReporter(const uint64_t logNumber) {
LogReporter reporter;
reporter.env = options_->env;
reporter.info_log = options_->info_log.get();
reporter.log_number = logNumber;
return reporter;
}
Status TransactionLogIteratorImpl::OpenLogFile(
const LogFile& logFile,
unique_ptr<SequentialFile>* file) {
Env* env = options_->env;
if (logFile.type == kArchivedLogFile) {
std::string fname = ArchivedLogFileName(dbname_, logFile.logNumber);
return env->NewSequentialFile(fname, file);
} else {
std::string fname = LogFileName(dbname_, logFile.logNumber);
Status status = env->NewSequentialFile(fname, file);
if (!status.ok()) {
// If cannot open file in DB directory.
// Try the archive dir, as it could have moved in the meanwhile.
fname = ArchivedLogFileName(dbname_, logFile.logNumber);
status = env->NewSequentialFile(fname, file);
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 = currentSequence_;
result.writeBatchPtr = std::move(currentBatch_);
return result;
}
Status TransactionLogIteratorImpl::status() {
return currentStatus_;
}
bool TransactionLogIteratorImpl::Valid() {
return started_ && isValid_;
}
void TransactionLogIteratorImpl::Next() {
// First seek to the given seqNo. in the current file.
LogFile currentLogFile = files_->at(currentFileIndex_);
LogReporter reporter = NewLogReporter(currentLogFile.logNumber);
std::string scratch;
Slice record;
if (!started_) {
isValid_ = false;
if (sequenceNumber_ > *lastFlushedSequence_) {
currentStatus_ = Status::IOError("Looking for a sequence, "
"which is not flushed yet.");
return;
}
unique_ptr<SequentialFile> file;
Status status = OpenLogFile(currentLogFile, &file);
if (!status.ok()) {
currentStatus_ = status;
return;
}
assert(file);
unique_ptr<log::Reader> reader(
new log::Reader(std::move(file), &reporter, true, 0));
assert(reader);
while (reader->ReadRecord(&record, &scratch)) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
UpdateCurrentWriteBatch(record);
if (currentSequence_ >= sequenceNumber_) {
assert(currentSequence_ < *lastFlushedSequence_);
isValid_ = true;
currentLogReader_ = std::move(reader);
break;
}
}
if (!isValid_) {
// TODO read the entire first file. and did not find the seq number.
// Error out.
currentStatus_ =
Status::NotFound("Did not find the Seq no. in first file");
}
started_ = true;
} else {
LOOK_NEXT_FILE:
assert(currentLogReader_);
bool openNextFile = true;
if (currentSequence_ == *lastFlushedSequence_) {
// The last update has been read. and next is being called.
isValid_ = false;
currentStatus_ = Status::OK();
}
while (currentLogReader_->ReadRecord(&record, &scratch) &&
currentSequence_ < *lastFlushedSequence_) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
} else {
UpdateCurrentWriteBatch(record);
openNextFile = false;
break;
}
}
if (openNextFile) {
if (currentFileIndex_ < files_->size() - 1) {
++currentFileIndex_;
currentLogReader_.reset();
unique_ptr<SequentialFile> file;
Status status = OpenLogFile(files_->at(currentFileIndex_), &file);
if (!status.ok()) {
isValid_ = false;
currentStatus_ = status;
return;
}
currentLogReader_.reset(
new log::Reader(std::move(file), &reporter, true, 0));
goto LOOK_NEXT_FILE;
} else {
// LOOKED AT FILES. WE ARE DONE HERE.
isValid_ = false;
currentStatus_ = Status::IOError(" NO MORE DATA LEFT");
}
}
}
}
void TransactionLogIteratorImpl::UpdateCurrentWriteBatch(const Slice& record) {
WriteBatch* batch = new WriteBatch();
WriteBatchInternal::SetContents(batch, record);
currentSequence_ = WriteBatchInternal::Sequence(batch);
currentBatch_.reset(batch);
}
} // namespace leveldb