Abseil Common Libraries (C++) (grcp 依赖)
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50 lines
1.5 KiB
50 lines
1.5 KiB
// 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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// 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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#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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// 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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} // namespace absl
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