diff options
| -rw-r--r-- | absl/synchronization/mutex.cc | 25 | ||||
| -rw-r--r-- | absl/synchronization/mutex.h | 8 |
2 files changed, 12 insertions, 21 deletions
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc index 353a8280..9a25570c 100644 --- a/absl/synchronization/mutex.cc +++ b/absl/synchronization/mutex.cc @@ -966,8 +966,7 @@ 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. @@ -1627,15 +1626,11 @@ 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); @@ -1917,7 +1912,7 @@ 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) { @@ -2211,7 +2206,7 @@ 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; @@ -2815,17 +2810,11 @@ 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 == nullptr && b == nullptr; } // Check equality of the representative fields. return a->eval_ == b->eval_ && a->arg_ == b->arg_ && diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h index 645c26d9..f2bafa97 100644 --- a/absl/synchronization/mutex.h +++ b/absl/synchronization/mutex.h @@ -807,10 +807,10 @@ class Condition { #endif // Function with which to evaluate callbacks and/or arguments. - bool (*eval_)(const Condition*) = nullptr; + bool (*const eval_)(const Condition*); // Either an argument for a function call or an object for a method call. - void* arg_ = nullptr; + void* const arg_; // Various functions eval_ can point to: static bool CallVoidPtrFunction(const Condition*); @@ -833,8 +833,10 @@ class Condition { std::memcpy(callback, callback_, sizeof(*callback)); } + static bool AlwaysTrue(const Condition*) { return true; } + // Used only to create kTrue. - constexpr Condition() = default; + constexpr Condition() : eval_(AlwaysTrue), arg_(nullptr) {} }; // ----------------------------------------------------------------------------- |