64 lines
1.5 KiB
C++
64 lines
1.5 KiB
C++
// Copyright 2014 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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#include "emugl/common/message_channel.h"
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namespace emugl {
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MessageChannelBase::MessageChannelBase(size_t capacity) :
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mPos(0U),
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mCount(0U),
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mCapacity(capacity),
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mLock(),
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mCanRead(),
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mCanWrite() {}
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MessageChannelBase::~MessageChannelBase() {}
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size_t MessageChannelBase::beforeWrite() {
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mLock.lock();
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while (mCount >= mCapacity) {
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mCanWrite.wait(&mLock);
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}
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size_t result = mPos + mCount;
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if (result >= mCapacity) {
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result -= mCapacity;
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}
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return result;
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}
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void MessageChannelBase::afterWrite() {
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mCount++;
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mCanRead.signal();
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mLock.unlock();
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}
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size_t MessageChannelBase::beforeRead() {
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mLock.lock();
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while (mCount == 0) {
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mCanRead.wait(&mLock);
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}
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return mPos;
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}
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void MessageChannelBase::afterRead() {
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if (++mPos == mCapacity) {
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mPos = 0U;
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}
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mCount--;
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mCanWrite.signal();
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mLock.unlock();
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}
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} // namespace emugl
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