bf29ee2a49
pthread_cond_signal does not need the mutex to be held to signal. This results in the thread waking up trying to grab the lock, failing, the signaling thread to wake up, release the lock, immediately get preempted for the signaled thread which can now proceed. Release the mutex before signaling to avoid the ping-pong scheduling issue, which shaves another 10us off of this Change-Id: Ie6bccca031ba6528f357eae8352b74626a6318c7
59 lines
1.4 KiB
C++
59 lines
1.4 KiB
C++
/*
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* Copyright (C) 2013 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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#ifndef ANDROID_HWUI_SIGNAL_H
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#define ANDROID_HWUI_SIGNAL_H
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#include <stdint.h>
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#include <sys/types.h>
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#include <utils/threads.h>
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namespace android {
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namespace uirenderer {
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class Signal {
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public:
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Signal(Condition::WakeUpType type = Condition::WAKE_UP_ALL) : mType(type), mSignaled(false) { }
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~Signal() { }
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void signal() {
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{
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Mutex::Autolock l(mLock);
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mSignaled = true;
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}
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mCondition.signal(mType);
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}
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void wait() {
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Mutex::Autolock l(mLock);
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while (!mSignaled) {
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mCondition.wait(mLock);
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}
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mSignaled = false;
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}
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private:
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Condition::WakeUpType mType;
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volatile bool mSignaled;
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mutable Mutex mLock;
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mutable Condition mCondition;
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};
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}; // namespace uirenderer
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}; // namespace android
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#endif // ANDROID_HWUI_SIGNAL_H
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