fc8dc48020
git-subtree-dir: third_party/abseil_cpp git-subtree-mainline:ffb2ae54begit-subtree-split:768eb2ca28
52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
// Copyright 2017 The Abseil Authors.
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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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// https://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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#include "absl/synchronization/barrier.h"
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#include "absl/base/internal/raw_logging.h"
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#include "absl/synchronization/mutex.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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// Return whether int *arg is zero.
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static bool IsZero(void *arg) {
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return 0 == *reinterpret_cast<int *>(arg);
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}
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bool Barrier::Block() {
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MutexLock l(&this->lock_);
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this->num_to_block_--;
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if (this->num_to_block_ < 0) {
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ABSL_RAW_LOG(
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FATAL,
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"Block() called too many times. num_to_block_=%d out of total=%d",
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this->num_to_block_, this->num_to_exit_);
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}
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this->lock_.Await(Condition(IsZero, &this->num_to_block_));
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// Determine which thread can safely delete this Barrier object
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this->num_to_exit_--;
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ABSL_RAW_CHECK(this->num_to_exit_ >= 0, "barrier underflow");
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// If num_to_exit_ == 0 then all other threads in the barrier have
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// exited the Wait() and have released the Mutex so this thread is
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// free to delete the barrier.
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return this->num_to_exit_ == 0;
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}
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ABSL_NAMESPACE_END
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} // namespace absl
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