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Revert 6fbe4e981a: If disable wal is set, then batch commits are avoided

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Summary:
Revert "If disable wal is set, then batch commits are avoided" because
keeping the mutex while inserting into the skiplist means that readers
and writes are all serialized on the mutex.

Test Plan:

Reviewers:

CC:

Task ID: #

Blame Rev:
This commit is contained in:
Dhruba Borthakur 2013-07-24 10:01:13 -07:00
parent 52d7ecfc78
commit d7ba5bce37
1 changed files with 25 additions and 34 deletions
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59
db/db_impl.cc
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@ -2273,26 +2273,20 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
StopWatch sw(env_, options_.statistics, DB_WRITE);
MutexLock l(&mutex_);
// If WAL is disabled, we avoid any queueing.
if (!options.disableWAL) {
writers_.push_back(&w);
while (!w.done && &w != writers_.front()) {
w.cv.Wait();
}
if (w.done) {
return w.status;
}
writers_.push_back(&w);
while (!w.done && &w != writers_.front()) {
w.cv.Wait();
}
if (w.done) {
return w.status;
}
// May temporarily unlock and wait.
Status status = MakeRoomForWrite(my_batch == nullptr);
uint64_t last_sequence = versions_->LastSequence();
Writer* last_writer = &w;
if (status.ok() && my_batch != nullptr) { // nullptr batch is for compactions
WriteBatch* updates = options.disableWAL ? my_batch :
BuildBatchGroup(&last_writer);
WriteBatch* updates = BuildBatchGroup(&last_writer);
const SequenceNumber current_sequence = last_sequence + 1;
WriteBatchInternal::SetSequence(updates, current_sequence);
int my_batch_count = WriteBatchInternal::Count(updates);
@ -2307,12 +2301,12 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
// and protects against concurrent loggers and concurrent writes
// into mem_.
{
mutex_.Unlock();
if (options.disableWAL) {
// If WAL is disabled, then we do not drop the mutex. We keep the
// mutex to protect concurrent insertions into the memtable.
flush_on_destroy_ = true;
} else {
mutex_.Unlock();
}
if (!options.disableWAL) {
status = log_->AddRecord(WriteBatchInternal::Contents(updates));
if (status.ok() && options.sync) {
if (options_.use_fsync) {
@ -2337,29 +2331,25 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
versions_->SetLastSequence(last_sequence);
last_flushed_sequence_ = current_sequence;
}
if (!options.disableWAL) {
mutex_.Lock();
}
mutex_.Lock();
}
if (updates == &tmp_batch_) tmp_batch_.Clear();
}
if (!options.disableWAL) {
while (true) {
Writer* ready = writers_.front();
writers_.pop_front();
if (ready != &w) {
ready->status = status;
ready->done = true;
ready->cv.Signal();
}
if (ready == last_writer) break;
while (true) {
Writer* ready = writers_.front();
writers_.pop_front();
if (ready != &w) {
ready->status = status;
ready->done = true;
ready->cv.Signal();
}
if (ready == last_writer) break;
}
// Notify new head of write queue
if (!writers_.empty()) {
writers_.front()->cv.Signal();
}
// Notify new head of write queue
if (!writers_.empty()) {
writers_.front()->cv.Signal();
}
return status;
}
@ -2423,6 +2413,7 @@ WriteBatch* DBImpl::BuildBatchGroup(Writer** last_writer) {
// REQUIRES: this thread is currently at the front of the writer queue
Status DBImpl::MakeRoomForWrite(bool force) {
mutex_.AssertHeld();
assert(!writers_.empty());
bool allow_delay = !force;
bool allow_rate_limit_delay = !force;
uint64_t rate_limit_delay_millis = 0;