mirrors/dragonfly
1
0
Fork 0
mirror of https://github.com/dragonflydb/dragonfly.git synced 2025-05-11 10:25:47 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

fix(transaction): Replace with armed sync point (#2708)

Browse source 
1. Replaces run_barrier as a synchronization point with is_armed + an embedded blocking counter for awaiting running jobs
2. Replaces IsArmedInShard + GetLocalMask + is_armed.exchange chain with a single DisarmInShard() / DisarmInShardWhen

Signed-off-by: Vladislav Oleshko <vlad@dragonflydb.io>
This commit is contained in:
Vladislav 2024-03-14 17:40:32 +03:00 • committed by GitHub
parent 7e0536fd4c
commit 9c6e6a96b7
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
6 changed files with 103 additions and 128 deletions
Download patch file Download diff file Expand all files Collapse all files

54
src/server/engine_shard_set.cc
View file

@ -448,18 +448,24 @@ void EngineShard::PollExecution(const char* context, Transaction* trans) {
ShardId sid = shard_id();
stats_.poll_execution_total++;
// Check if the caller was handled by a previous poll.
if (trans && !trans->IsArmedInShard(sid))
// If any of the following flags are present, we are guaranteed to run in this function:
// 1. AWAKED_Q -> Blocking transactions are executed immediately after waking up, they don't
// occupy a place in txq and have highest priority
// 2. SUSPENDED_Q -> Suspended shards are run to clean up and finalize blocking keys
// 3. OUT_OF_ORDER -> Transactions without conflicting keys can run earlier than their position in
// txq is reached
uint16_t flags = Transaction::AWAKED_Q | Transaction::SUSPENDED_Q | Transaction::OUT_OF_ORDER;
auto [trans_mask, disarmed] =
trans ? trans->DisarmInShardWhen(sid, flags) : make_pair(uint16_t(0), false);
if (trans && trans_mask == 0) // If not armed, it means that this poll task expired
return;
auto local_mask = trans ? trans->GetLocalMask(sid) : 0; // safe only when trans is armed
// Blocked transactions are executed immediately after waking up
if (local_mask & Transaction::AWAKED_Q) {
if (trans_mask & Transaction::AWAKED_Q) {
CHECK(continuation_trans_ == nullptr || continuation_trans_ == trans)
<< continuation_trans_->DebugId() << " when polling " << trans->DebugId()
<< "cont_mask: " << continuation_trans_->GetLocalMask(sid) << " vs "
<< trans->GetLocalMask(sid);
<< "cont_mask: " << continuation_trans_->DEBUG_GetLocalMask(sid) << " vs "
<< trans->DEBUG_GetLocalMask(sid);
// Commands like BRPOPLPUSH don't conclude immediately
if (trans->RunInShard(this, false)) {
@ -481,10 +487,11 @@ void EngineShard::PollExecution(const char* context, Transaction* trans) {
// Check the currently running transaction, we have to handle it first until it concludes
if (continuation_trans_) {
if (trans == continuation_trans_)
bool is_self = continuation_trans_ == trans;
if (is_self)
trans = nullptr;
if (continuation_trans_->IsArmedInShard(sid)) {
if ((is_self && disarmed) || continuation_trans_->DisarmInShard(sid)) {
if (bool keep = run(continuation_trans_, false); !keep) {
// if this holds, we can remove this check altogether.
DCHECK(continuation_trans_ == nullptr);
@ -503,10 +510,12 @@ void EngineShard::PollExecution(const char* context, Transaction* trans) {
head = get<Transaction*>(txq_.Front());
VLOG(2) << "Considering head " << head->DebugId() << " isarmed: " << head->IsArmedInShard(sid);
VLOG(2) << "Considering head " << head->DebugId()
<< " isarmed: " << head->DEBUG_IsArmedInShard(sid);
// If the transaction isn't armed yet, it will be handled by a successive poll
if (!head->IsArmedInShard(sid))
bool should_run = (head == trans && disarmed) || head->DisarmInShard(sid);
if (!should_run)
break;
// Avoid processing the caller transaction below if we found it in the queue,
@ -525,23 +534,12 @@ void EngineShard::PollExecution(const char* context, Transaction* trans) {
continuation_trans_ = head;
}
// Either the poll had no caller or it was handled above
if (trans == nullptr)
return;
// If the pointer is valid, we didn't handle it above, so trans is still armed
DCHECK(trans->IsArmedInShard(sid));
// OOO means no transaction before us in the txq accesses our keys, so we can run earlier
bool is_ooo = local_mask & Transaction::OUT_OF_ORDER;
// Still suspended shards need to run just to finalize and unregister, so we can run anytime
bool is_suspended = local_mask & Transaction::SUSPENDED_Q;
DCHECK_EQ(local_mask & Transaction::AWAKED_Q, 0);
if (is_ooo || is_suspended) {
// If we disarmed, but didn't find ourselves in the loop, run now.
if (trans && disarmed) {
DCHECK(trans != head);
DCHECK(trans_mask & (Transaction::OUT_OF_ORDER | Transaction::SUSPENDED_Q));
bool is_ooo = trans_mask & Transaction::OUT_OF_ORDER;
bool keep = run(trans, is_ooo);
if (is_ooo && !keep) {
stats_.tx_ooo_total++;
@ -728,7 +726,7 @@ auto EngineShard::AnalyzeTxQueue() const -> TxQueueInfo {
max_db_id = trx->GetDbIndex();
}
bool is_armed = trx->IsArmedInShard(sid);
bool is_armed = trx->DEBUG_IsArmedInShard(sid);
DVLOG(1) << "Inspecting " << trx->DebugId() << " is_armed " << is_armed;
if (is_armed) {
info.tx_armed++;