115 lines
3.4 KiB
C++
115 lines
3.4 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "barrier.h"
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#include <android-base/logging.h>
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#include "base/aborting.h"
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#include "base/mutex.h"
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#include "base/time_utils.h"
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#include "thread.h"
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namespace art {
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Barrier::Barrier(int count, bool verify_count_on_shutdown)
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: count_(count),
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lock_(new Mutex("GC barrier lock", kThreadSuspendCountLock)),
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condition_(new ConditionVariable("GC barrier condition", *lock_)),
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verify_count_on_shutdown_(verify_count_on_shutdown) {
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}
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template void Barrier::Increment<Barrier::kAllowHoldingLocks>(Thread* self, int delta);
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template void Barrier::Increment<Barrier::kDisallowHoldingLocks>(Thread* self, int delta);
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void Barrier::Pass(Thread* self) {
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MutexLock mu(self, *GetLock());
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SetCountLocked(self, count_ - 1);
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}
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void Barrier::Wait(Thread* self) {
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Increment(self, -1);
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}
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void Barrier::Init(Thread* self, int count) {
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MutexLock mu(self, *GetLock());
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SetCountLocked(self, count);
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}
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template <Barrier::LockHandling locks>
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void Barrier::Increment(Thread* self, int delta) {
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MutexLock mu(self, *GetLock());
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SetCountLocked(self, count_ + delta);
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// Increment the count. If it becomes zero after the increment
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// then all the threads have already passed the barrier. If
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// it is non-zero then there is still one or more threads
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// that have not yet called the Pass function. When the
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// Pass function is called by the last thread, the count will
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// be decremented to zero and a Broadcast will be made on the
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// condition variable, thus waking this up.
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while (count_ != 0) {
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if (locks == kAllowHoldingLocks) {
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condition_->WaitHoldingLocks(self);
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} else {
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condition_->Wait(self);
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}
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}
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}
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bool Barrier::Increment(Thread* self, int delta, uint32_t timeout_ms) {
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MutexLock mu(self, *GetLock());
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SetCountLocked(self, count_ + delta);
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bool timed_out = false;
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if (count_ != 0) {
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uint32_t timeout_ns = 0;
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uint64_t abs_timeout = NanoTime() + MsToNs(timeout_ms);
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for (;;) {
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timed_out = condition_->TimedWait(self, timeout_ms, timeout_ns);
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if (timed_out || count_ == 0) return timed_out;
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// Compute time remaining on timeout.
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uint64_t now = NanoTime();
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int64_t time_left = abs_timeout - now;
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if (time_left <= 0) return true;
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timeout_ns = time_left % (1000*1000);
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timeout_ms = time_left / (1000*1000);
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}
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}
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return timed_out;
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}
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int Barrier::GetCount(Thread* self) {
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MutexLock mu(self, *GetLock());
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return count_;
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}
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void Barrier::SetCountLocked(Thread* self, int count) {
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count_ = count;
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if (count == 0) {
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condition_->Broadcast(self);
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}
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}
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Barrier::~Barrier() {
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if (count_ != 0) {
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// Only check when not aborting and if we verify the count on shutdown.
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LOG((gAborting == 0 && verify_count_on_shutdown_) ? FATAL : WARNING)
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<< "Attempted to destroy barrier with non zero count " << count_;
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}
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}
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} // namespace art
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