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Use ustricter consistency in thread local operations

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Summary:
ThreadSanitizer complains data race of super version and version's destructor with Get(). This patch will fix those warning.

The warning is likely from ColumnFamilyData::ReturnThreadLocalSuperVersion(). With relaxed consistency of CAS, reading the data of the super version can technically happen after swapping it in, enabling the background thread to clean it up.

Test Plan: make all check

Reviewers: rven, igor, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D32265
This commit is contained in:
sdong 2015-01-26 20:23:15 -08:00
parent 1b43ab58d9
commit 4c49fedaf1
1 changed files with 8 additions and 9 deletions
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17
util/thread_local.cc
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@ -36,7 +36,7 @@ void ThreadLocalPtr::StaticMeta::OnThreadExit(void* ptr) {
// Unref stored pointers of current thread from all instances
uint32_t id = 0;
for (auto& e : tls->entries) {
void* raw = e.ptr.load(std::memory_order_relaxed);
void* raw = e.ptr.load();
if (raw != nullptr) {
auto unref = inst->GetHandler(id);
if (unref != nullptr) {
@ -109,7 +109,7 @@ void* ThreadLocalPtr::StaticMeta::Get(uint32_t id) const {
if (UNLIKELY(id >= tls->entries.size())) {
return nullptr;
}
return tls->entries[id].ptr.load(std::memory_order_relaxed);
return tls->entries[id].ptr.load(std::memory_order_acquire);
}
void ThreadLocalPtr::StaticMeta::Reset(uint32_t id, void* ptr) {
@ -119,7 +119,7 @@ void ThreadLocalPtr::StaticMeta::Reset(uint32_t id, void* ptr) {
MutexLock l(&mutex_);
tls->entries.resize(id + 1);
}
tls->entries[id].ptr.store(ptr, std::memory_order_relaxed);
tls->entries[id].ptr.store(ptr, std::memory_order_release);
}
void* ThreadLocalPtr::StaticMeta::Swap(uint32_t id, void* ptr) {
@ -129,7 +129,7 @@ void* ThreadLocalPtr::StaticMeta::Swap(uint32_t id, void* ptr) {
MutexLock l(&mutex_);
tls->entries.resize(id + 1);
}
return tls->entries[id].ptr.exchange(ptr, std::memory_order_relaxed);
return tls->entries[id].ptr.exchange(ptr, std::memory_order_acquire);
}
bool ThreadLocalPtr::StaticMeta::CompareAndSwap(uint32_t id, void* ptr,
@ -140,8 +140,8 @@ bool ThreadLocalPtr::StaticMeta::CompareAndSwap(uint32_t id, void* ptr,
MutexLock l(&mutex_);
tls->entries.resize(id + 1);
}
return tls->entries[id].ptr.compare_exchange_strong(expected, ptr,
std::memory_order_relaxed, std::memory_order_relaxed);
return tls->entries[id].ptr.compare_exchange_strong(
expected, ptr, std::memory_order_release, std::memory_order_relaxed);
}
void ThreadLocalPtr::StaticMeta::Scrape(uint32_t id, autovector<void*>* ptrs,
@ -150,7 +150,7 @@ void ThreadLocalPtr::StaticMeta::Scrape(uint32_t id, autovector<void*>* ptrs,
for (ThreadData* t = head_.next; t != &head_; t = t->next) {
if (id < t->entries.size()) {
void* ptr =
t->entries[id].ptr.exchange(replacement, std::memory_order_relaxed);
t->entries[id].ptr.exchange(replacement, std::memory_order_acquire);
if (ptr != nullptr) {
ptrs->push_back(ptr);
}
@ -198,8 +198,7 @@ void ThreadLocalPtr::StaticMeta::ReclaimId(uint32_t id) {
auto unref = GetHandler(id);
for (ThreadData* t = head_.next; t != &head_; t = t->next) {
if (id < t->entries.size()) {
void* ptr =
t->entries[id].ptr.exchange(nullptr, std::memory_order_relaxed);
void* ptr = t->entries[id].ptr.exchange(nullptr);
if (ptr != nullptr && unref != nullptr) {
unref(ptr);
}