diff options
Diffstat (limited to 'absl/synchronization/mutex.cc')
| -rw-r--r-- | absl/synchronization/mutex.cc | 34 |
1 files changed, 9 insertions, 25 deletions
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc index ea0d96cf..8148fbde 100644 --- a/absl/synchronization/mutex.cc +++ b/absl/synchronization/mutex.cc @@ -960,8 +960,7 @@ static PerThreadSynch* Enqueue(PerThreadSynch* head, SynchWaitParams* waitp, } while (s->priority <= advance_to->priority); // termination guaranteed because s->priority > head->priority // and head is the end of a skip chain - } else if (waitp->how == kExclusive && - Condition::GuaranteedEqual(waitp->cond, nullptr)) { + } else if (waitp->how == kExclusive && waitp->cond == nullptr) { // An unlocker could be scanning the queue, but we know it will recheck // the queue front for writers that have no condition, which is what s // is, so an insert at front is safe. @@ -1542,15 +1541,11 @@ bool Mutex::AwaitCommon(const Condition& cond, KernelTimeout t) { SynchWaitParams waitp(how, &cond, t, nullptr /*no cvmu*/, Synch_GetPerThreadAnnotated(this), nullptr /*no cv_word*/); - int flags = kMuHasBlocked; - if (!Condition::GuaranteedEqual(&cond, nullptr)) { - flags |= kMuIsCond; - } this->UnlockSlow(&waitp); this->Block(waitp.thread); ABSL_TSAN_MUTEX_POST_UNLOCK(this, TsanFlags(how)); ABSL_TSAN_MUTEX_PRE_LOCK(this, TsanFlags(how)); - this->LockSlowLoop(&waitp, flags); + this->LockSlowLoop(&waitp, kMuHasBlocked | kMuIsCond); bool res = waitp.cond != nullptr || // => cond known true from LockSlowLoop EvalConditionAnnotated(&cond, this, true, false, how == kShared); ABSL_TSAN_MUTEX_POST_LOCK(this, TsanFlags(how), 0); @@ -1834,7 +1829,7 @@ bool Mutex::LockSlowWithDeadline(MuHow how, const Condition* cond, SynchWaitParams waitp(how, cond, t, nullptr /*no cvmu*/, Synch_GetPerThreadAnnotated(this), nullptr /*no cv_word*/); - if (!Condition::GuaranteedEqual(cond, nullptr)) { + if (cond != nullptr) { flags |= kMuIsCond; } if (unlock) { @@ -2024,7 +2019,6 @@ ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams* waitp) { // head of the list searched previously, or zero PerThreadSynch* old_h = nullptr; // a condition that's known to be false. - const Condition* known_false = nullptr; PerThreadSynch* wake_list = kPerThreadSynchNull; // list of threads to wake intptr_t wr_wait = 0; // set to kMuWrWait if we wake a reader and a // later writer could have acquired the lock @@ -2128,7 +2122,7 @@ ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams* waitp) { } } if (h->next->waitp->how == kExclusive && - Condition::GuaranteedEqual(h->next->waitp->cond, nullptr)) { + h->next->waitp->cond == nullptr) { // easy case: writer with no condition; no need to search pw = h; // wake w, the successor of h (=pw) w = h->next; @@ -2211,10 +2205,8 @@ ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams* waitp) { w_walk->wake = false; if (w_walk->waitp->cond == nullptr || // no condition => vacuously true OR - (w_walk->waitp->cond != known_false && - // this thread's condition is not known false, AND - // is in fact true - EvalConditionIgnored(this, w_walk->waitp->cond))) { + // this thread's condition is true + EvalConditionIgnored(this, w_walk->waitp->cond)) { if (w == nullptr) { w_walk->wake = true; // can wake this waiter w = w_walk; @@ -2228,8 +2220,6 @@ ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams* waitp) { } else { // writer with true condition wr_wait = kMuWrWait; } - } else { // can't wake; condition false - known_false = w_walk->waitp->cond; // remember last false condition } if (w_walk->wake) { // we're waking reader w_walk pw_walk = w_walk; // don't skip similar waiters @@ -2722,17 +2712,11 @@ Condition::Condition(const bool* cond) StoreCallback(dereference); } -bool Condition::Eval() const { - // eval_ == null for kTrue - return (this->eval_ == nullptr) || (*this->eval_)(this); -} +bool Condition::Eval() const { return (*this->eval_)(this); } bool Condition::GuaranteedEqual(const Condition* a, const Condition* b) { - // kTrue logic. - if (a == nullptr || a->eval_ == nullptr) { - return b == nullptr || b->eval_ == nullptr; - } else if (b == nullptr || b->eval_ == nullptr) { - return false; + if (a == nullptr || b == nullptr) { + return a == b; } // Check equality of the representative fields. return a->eval_ == b->eval_ && a->arg_ == b->arg_ && |