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GetSnapshot() and ReleaseSnapshot() to move new and free out of DB mutex

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Summary: We currently issue malloc and free inside DB mutex in GetSnapshot() and ReleaseSnapshot(). Move them out.

Test Plan:
Go through all tests
make valgrind_check

Reviewers: yhchiang, rven, IslamAbdelRahman, anthony, igor

Reviewed By: igor

Subscribers: maykov, hermanlee4, MarkCallaghan, yoshinorim, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D39753
This commit is contained in:
sdong 2015-06-08 16:57:44 -07:00
parent 643bbbf081
commit d8c8f08c12
2 changed files with 15 additions and 7 deletions
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16
db/db_impl.cc
View File

@ -3212,16 +3212,24 @@ Status DBImpl::NewIterators(
const Snapshot* DBImpl::GetSnapshot() {
int64_t unix_time = 0;
env_->GetCurrentTime(&unix_time); // Ignore error
SnapshotImpl* s = new SnapshotImpl;
InstrumentedMutexLock l(&mutex_);
// returns null if the underlying memtable does not support snapshot.
if (!is_snapshot_supported_) return nullptr;
return snapshots_.New(versions_->LastSequence(), unix_time);
if (!is_snapshot_supported_) {
delete s;
return nullptr;
}
return snapshots_.New(s, versions_->LastSequence(), unix_time);
}
void DBImpl::ReleaseSnapshot(const Snapshot* s) {
InstrumentedMutexLock l(&mutex_);
snapshots_.Delete(reinterpret_cast<const SnapshotImpl*>(s));
const SnapshotImpl* casted_s = reinterpret_cast<const SnapshotImpl*>(s);
{
InstrumentedMutexLock l(&mutex_);
snapshots_.Delete(casted_s);
}
delete casted_s;
}
// Convenience methods

6
db/snapshot.h
View File

@ -49,8 +49,8 @@ class SnapshotList {
SnapshotImpl* oldest() const { assert(!empty()); return list_.next_; }
SnapshotImpl* newest() const { assert(!empty()); return list_.prev_; }
const SnapshotImpl* New(SequenceNumber seq, uint64_t unix_time) {
SnapshotImpl* s = new SnapshotImpl;
const SnapshotImpl* New(SnapshotImpl* s, SequenceNumber seq,
uint64_t unix_time) {
s->number_ = seq;
s->unix_time_ = unix_time;
s->list_ = this;
@ -62,12 +62,12 @@ class SnapshotList {
return s;
}
// Do not responsible to free the object.
void Delete(const SnapshotImpl* s) {
assert(s->list_ == this);
s->prev_->next_ = s->next_;
s->next_->prev_ = s->prev_;
count_--;
delete s;
}
// retrieve all snapshot numbers. They are sorted in ascending order.