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fix: simplify ScheduleInShard (#1610)

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Signed-off-by: Vladislav Oleshko <vlad@dragonflydb.io>
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Vladislav 2023-08-01 08:15:42 +03:00 • committed by GitHub
parent 977fc18e25
commit 3a4b3c97c8
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1 changed files with 21 additions and 37 deletions
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58
src/server/transaction.cc
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@ -1008,68 +1008,52 @@ bool Transaction::ScheduleUniqueShard(EngineShard* shard) {
// This function should not block since it's run via RunBriefInParallel.
pair<bool, bool> Transaction::ScheduleInShard(EngineShard* shard) {
DCHECK(!shard_data_.empty());
DCHECK(shard_data_[SidToId(shard->shard_id())].local_mask & ACTIVE);
// schedule_success, lock_granted.
pair<bool, bool> result{false, false};
if (shard->committed_txid() >= txid_) {
return result;
}
// If a more recent transaction already commited, we abort
if (shard->committed_txid() >= txid_)
return {false, false};
TxQueue* txq = shard->txq();
KeyLockArgs lock_args;
IntentLock::Mode mode = Mode();
bool spans_all = IsGlobal();
bool lock_granted = false;
ShardId sid = SidToId(shard->shard_id());
ShardId sid = SidToId(shard->shard_id());
auto& sd = shard_data_[sid];
if (!spans_all) {
bool shard_unlocked = shard->shard_lock()->Check(mode);
// Acquire intent locks
if (!IsGlobal()) {
lock_args = GetLockArgs(shard->shard_id());
// we need to acquire the lock unrelated to shard_unlocked since we register into Tx queue.
// All transactions in the queue must acquire the intent lock.
lock_granted = shard->db_slice().Acquire(mode, lock_args) && shard_unlocked;
// Key locks are acquired even if the shard is locked since intent locks are always acquired
bool shard_unlocked = shard->shard_lock()->Check(mode);
bool keys_unlocked = shard->db_slice().Acquire(mode, lock_args);
lock_granted = keys_unlocked && shard_unlocked;
sd.local_mask |= KEYLOCK_ACQUIRED;
DVLOG(3) << "Lock granted " << lock_granted << " for trans " << DebugId();
}
if (!txq->Empty()) {
// If the new transaction requires reordering of the pending queue (i.e. it comes before tail)
// and some other transaction already locked its keys we can not reorder 'trans' because
// that other transaction could have deduced that it can run OOO and eagerly execute. Hence, we
// fail this scheduling attempt for trans.
// However, when we schedule span-all transactions we can still reorder them. The reason is
// before we start scheduling them we lock the shards and disable OOO.
// We may record when they disable OOO via barrier_ts so if the queue contains transactions
// that were only scheduled afterwards we know they are not free so we can still
// reorder the queue. Currently, this optimization is disabled: barrier_ts < pq->HeadScore().
bool to_proceed = lock_granted || txq->TailScore() < txid_;
if (!to_proceed) {
if (sd.local_mask & KEYLOCK_ACQUIRED) { // rollback the lock.
shard->db_slice().Release(mode, lock_args);
sd.local_mask &= ~KEYLOCK_ACQUIRED;
}
return result; // false, false
// If the new transaction requires reordering of the pending queue (i.e. it comes before tail)
// and some other transaction already locked its keys we can not reorder 'trans' because
// that other transaction could have deduced that it can run OOO and eagerly execute. Hence, we
// fail this scheduling attempt for trans.
if (!txq->Empty() && txid_ < txq->TailScore() && !lock_granted) {
if (sd.local_mask & KEYLOCK_ACQUIRED) {
shard->db_slice().Release(mode, lock_args);
sd.local_mask &= ~KEYLOCK_ACQUIRED;
}
return {false, false};
}
result.second = lock_granted;
result.first = true;
TxQueue::Iterator it = txq->Insert(this);
DCHECK_EQ(TxQueue::kEnd, sd.pq_pos);
sd.pq_pos = it;
DVLOG(1) << "Insert into tx-queue, sid(" << sid << ") " << DebugId() << ", qlen " << txq->size();
return result;
return {true, lock_granted};
}
bool Transaction::CancelShardCb(EngineShard* shard) {