Abseil Common Libraries (C++) (grcp 依赖)
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55 lines
1.7 KiB
55 lines
1.7 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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// 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/blocking_counter.h" |
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#include "absl/base/internal/raw_logging.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 BlockingCounter::DecrementCount() { |
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MutexLock l(&lock_); |
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count_--; |
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if (count_ < 0) { |
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ABSL_RAW_LOG( |
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FATAL, |
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"BlockingCounter::DecrementCount() called too many times. count=%d", |
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count_); |
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} |
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return count_ == 0; |
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} |
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void BlockingCounter::Wait() { |
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MutexLock l(&this->lock_); |
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ABSL_RAW_CHECK(count_ >= 0, "BlockingCounter underflow"); |
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// only one thread may call Wait(). To support more than one thread, |
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// implement a counter num_to_exit, like in the Barrier class. |
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ABSL_RAW_CHECK(num_waiting_ == 0, "multiple threads called Wait()"); |
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num_waiting_++; |
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this->lock_.Await(Condition(IsZero, &this->count_)); |
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// At this point, We know that all threads executing DecrementCount have |
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// released the lock, and so will not touch this object again. |
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// Therefore, the thread calling this method is free to delete the object |
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// after we return from this method. |
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} |
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} // namespace absl
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