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reuse scratch buffer in transaction_log_reader (#5702)

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Summary:
in order to avoid reallocations for a scratch std::string on every call to Next().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5702

Differential Revision: D16867803

fbshipit-source-id: 1391220a1b172b23336bbc71dc0c79ccf3b1c701
This commit is contained in:
jsteemann 2019-08-26 11:24:40 -07:00 committed by Facebook Github Bot
parent 2f41ecfe75
commit 62829ff751
2 changed files with 6 additions and 9 deletions
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12
db/transaction_log_impl.cc
View File

@ -78,19 +78,16 @@ Status TransactionLogIteratorImpl::status() { return current_status_; }
bool TransactionLogIteratorImpl::Valid() { return started_ && is_valid_; }
bool TransactionLogIteratorImpl::RestrictedRead(
Slice* record,
std::string* scratch) {
bool TransactionLogIteratorImpl::RestrictedRead(Slice* record) {
// Don't read if no more complete entries to read from logs
if (current_last_seq_ >= versions_->LastSequence()) {
return false;
}
return current_log_reader_->ReadRecord(record, scratch);
return current_log_reader_->ReadRecord(record, &scratch_);
}
void TransactionLogIteratorImpl::SeekToStartSequence(uint64_t start_file_index,
bool strict) {
std::string scratch;
Slice record;
started_ = false;
is_valid_ = false;
@ -104,7 +101,7 @@ void TransactionLogIteratorImpl::SeekToStartSequence(uint64_t start_file_index,
reporter_.Info(current_status_.ToString().c_str());
return;
}
while (RestrictedRead(&record, &scratch)) {
while (RestrictedRead(&record)) {
if (record.size() < WriteBatchInternal::kHeader) {
reporter_.Corruption(
record.size(), Status::Corruption("very small log record"));
@ -155,7 +152,6 @@ void TransactionLogIteratorImpl::Next() {
}
void TransactionLogIteratorImpl::NextImpl(bool internal) {
std::string scratch;
Slice record;
is_valid_ = false;
if (!internal && !started_) {
@ -167,7 +163,7 @@ void TransactionLogIteratorImpl::NextImpl(bool internal) {
if (current_log_reader_->IsEOF()) {
current_log_reader_->UnmarkEOF();
}
while (RestrictedRead(&record, &scratch)) {
while (RestrictedRead(&record)) {
if (record.size() < WriteBatchInternal::kHeader) {
reporter_.Corruption(
record.size(), Status::Corruption("very small log record"));

3
db/transaction_log_impl.h
View File

@ -86,6 +86,7 @@ class TransactionLogIteratorImpl : public TransactionLogIterator {
size_t current_file_index_;
std::unique_ptr<WriteBatch> current_batch_;
std::unique_ptr<log::Reader> current_log_reader_;
std::string scratch_;
Status OpenLogFile(const LogFile* log_file,
std::unique_ptr<SequentialFileReader>* file);
@ -107,7 +108,7 @@ class TransactionLogIteratorImpl : public TransactionLogIterator {
VersionSet const* const versions_;
const bool seq_per_batch_;
// Reads from transaction log only if the writebatch record has been written
bool RestrictedRead(Slice* record, std::string* scratch);
bool RestrictedRead(Slice* record);
// Seeks to startingSequenceNumber reading from startFileIndex in files_.
// If strict is set,then must get a batch starting with startingSequenceNumber
void SeekToStartSequence(uint64_t start_file_index = 0, bool strict = false);