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Fix stale AgentGroup TLS access after bthread migration #3522

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Fix stale AgentGroup TLS access after bthread migration #3522

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42 changes: 25 additions & 17 deletions src/bvar/detail/agent_group.h
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Original file line number Diff line number Diff line change
Expand Up @@ -113,10 +113,12 @@ class AgentGroup {
// We need this function to be as fast as possible.
inline static Agent* get_tls_agent(AgentId id) {
if (__builtin_expect(id >= 0, 1)) {
if (_s_tls_blocks) {
std::vector<ThreadBlock*>* tls_blocks =
BAIDU_GET_VOLATILE_THREAD_LOCAL(_s_tls_blocks);
if (tls_blocks) {
const size_t block_id = (size_t)id / ELEMENTS_PER_BLOCK;
if (block_id < _s_tls_blocks->size()) {
ThreadBlock* const tb = (*_s_tls_blocks)[block_id];
if (block_id < tls_blocks->size()) {
ThreadBlock* const tb = (*tls_blocks)[block_id];
if (tb) {
return tb->at(id - block_id * ELEMENTS_PER_BLOCK);
}
Expand All @@ -132,41 +134,46 @@ class AgentGroup {
CHECK(false) << "Invalid id=" << id;
return nullptr;
}
if (_s_tls_blocks == nullptr) {
_s_tls_blocks = new (std::nothrow) std::vector<ThreadBlock *>;
if (__builtin_expect(_s_tls_blocks == nullptr, 0)) {
std::vector<ThreadBlock*>* tls_blocks =
BAIDU_GET_VOLATILE_THREAD_LOCAL(_s_tls_blocks);
if (tls_blocks == nullptr) {
tls_blocks = new (std::nothrow) std::vector<ThreadBlock *>;
if (__builtin_expect(tls_blocks == nullptr, 0)) {
LOG(FATAL) << "Fail to create vector, " << berror();
return nullptr;
}
BAIDU_SET_VOLATILE_THREAD_LOCAL(_s_tls_blocks, tls_blocks);
butil::thread_atexit(_destroy_tls_blocks);
}
const size_t block_id = (size_t)id / ELEMENTS_PER_BLOCK;
if (block_id >= _s_tls_blocks->size()) {
if (block_id >= tls_blocks->size()) {
// The 32ul avoid pointless small resizes.
_s_tls_blocks->resize(std::max(block_id + 1, 32ul));
tls_blocks->resize(std::max(block_id + 1, 32ul));
}
ThreadBlock* tb = (*_s_tls_blocks)[block_id];
ThreadBlock* tb = (*tls_blocks)[block_id];
if (tb == nullptr) {
ThreadBlock *new_block = new (std::nothrow) ThreadBlock;
if (__builtin_expect(new_block == nullptr, 0)) {
return nullptr;
}
tb = new_block;
(*_s_tls_blocks)[block_id] = new_block;
(*tls_blocks)[block_id] = new_block;
}
return tb->at(id - block_id * ELEMENTS_PER_BLOCK);
}

private:
static void _destroy_tls_blocks() {
if (!_s_tls_blocks) {
std::vector<ThreadBlock*>* tls_blocks =
BAIDU_GET_VOLATILE_THREAD_LOCAL(_s_tls_blocks);
if (!tls_blocks) {
return;
}
for (size_t i = 0; i < _s_tls_blocks->size(); ++i) {
delete (*_s_tls_blocks)[i];
for (size_t i = 0; i < tls_blocks->size(); ++i) {
delete (*tls_blocks)[i];
}
delete _s_tls_blocks;
_s_tls_blocks = nullptr;
delete tls_blocks;
BAIDU_SET_VOLATILE_THREAD_LOCAL(_s_tls_blocks, nullptr);
}

inline static std::deque<AgentId> &_get_free_ids() {
Expand All @@ -180,7 +187,8 @@ class AgentGroup {
static pthread_mutex_t _s_mutex;
static AgentId _s_agent_kinds;
static std::deque<AgentId> *_s_free_ids;
static __thread std::vector<ThreadBlock *> *_s_tls_blocks;
STATIC_MEMBER_BAIDU_VOLATILE_THREAD_LOCAL(
std::vector<ThreadBlock*>*, _s_tls_blocks);
};

template <typename Agent>
Expand All @@ -193,7 +201,7 @@ template <typename Agent>
AgentId AgentGroup<Agent>::_s_agent_kinds = 0;

template <typename Agent>
__thread std::vector<typename AgentGroup<Agent>::ThreadBlock *>
BAIDU_THREAD_LOCAL std::vector<typename AgentGroup<Agent>::ThreadBlock *>
*AgentGroup<Agent>::_s_tls_blocks = nullptr;

} // namespace detail
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