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Remove global locks from FlushScheduler (#5372) 

Summary:
FlushScheduler's methods are instrumented with debug-time locks to check the scheduler state against a simple container definition. Since https://github.com/facebook/rocksdb/pull/2286 the scope of such locks are widened to the entire methods' body. The result is that the concurrency tested during testing (in debug mode) is stricter than the concurrency level manifested at runtime (in release mode).
The patch reverts this change to reduce the scope of such locks.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5372

Differential Revision: D15545831

Pulled By: maysamyabandeh

fbshipit-source-id: 01d69191afb1dd807d4bdc990fc74813ae7b5426
This commit is contained in:
Maysam Yabandeh 2019-06-10 16:46:04 -07:00 committed by Facebook Github Bot
parent 641cc8d541
commit b2584577fa
1 changed files with 15 additions and 13 deletions
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28
db/flush_scheduler.cc
View File

@ -13,9 +13,11 @@ namespace rocksdb {
void FlushScheduler::ScheduleFlush(ColumnFamilyData* cfd) {
#ifndef NDEBUG
std::lock_guard<std::mutex> lock(checking_mutex_);
assert(checking_set_.count(cfd) == 0);
checking_set_.insert(cfd);
{
std::lock_guard<std::mutex> lock(checking_mutex_);
assert(checking_set_.count(cfd) == 0);
checking_set_.insert(cfd);
}
#endif // NDEBUG
cfd->Ref();
// Suppress false positive clang analyzer warnings.
@ -32,9 +34,6 @@ void FlushScheduler::ScheduleFlush(ColumnFamilyData* cfd) {
}
ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
#ifndef NDEBUG
std::lock_guard<std::mutex> lock(checking_mutex_);
#endif // NDEBUG
while (true) {
if (head_.load(std::memory_order_relaxed) == nullptr) {
return nullptr;
@ -47,9 +46,12 @@ ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
delete node;
#ifndef NDEBUG
auto iter = checking_set_.find(cfd);
assert(iter != checking_set_.end());
checking_set_.erase(iter);
{
std::lock_guard<std::mutex> lock(checking_mutex_);
auto iter = checking_set_.find(cfd);
assert(iter != checking_set_.end());
checking_set_.erase(iter);
}
#endif // NDEBUG
if (!cfd->IsDropped()) {
@ -65,12 +67,12 @@ ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
}
bool FlushScheduler::Empty() {
#ifndef NDEBUG
std::lock_guard<std::mutex> lock(checking_mutex_);
#endif // NDEBUG
auto rv = head_.load(std::memory_order_relaxed) == nullptr;
#ifndef NDEBUG
assert(rv == checking_set_.empty());
std::lock_guard<std::mutex> lock(checking_mutex_);
// Empty is allowed to be called concurrnetly with ScheduleFlush. It would
// only miss the recent schedules.
assert((rv == checking_set_.empty()) || rv);
#endif // NDEBUG
return rv;
}