| // Copyright 2014 The Android Open Source Project |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "android/base/synchronization/MessageChannel.h" |
| |
| namespace android { |
| namespace base { |
| |
| MessageChannelBase::MessageChannelBase(size_t capacity) : |
| mPos(0U), |
| mCount(0U), |
| mCapacity(capacity), |
| mLock(), |
| mCanRead(), |
| mCanWrite() {} |
| |
| MessageChannelBase::~MessageChannelBase() {} |
| |
| size_t MessageChannelBase::beforeWrite() { |
| mLock.lock(); |
| while (mCount >= mCapacity) { |
| mCanWrite.wait(&mLock); |
| } |
| size_t result = mPos + mCount; |
| if (result >= mCapacity) { |
| result -= mCapacity; |
| } |
| return result; |
| } |
| |
| void MessageChannelBase::afterWrite() { |
| mCount++; |
| mCanRead.signal(); |
| mLock.unlock(); |
| } |
| |
| size_t MessageChannelBase::beforeRead() { |
| mLock.lock(); |
| while (mCount == 0) { |
| mCanRead.wait(&mLock); |
| } |
| return mPos; |
| } |
| |
| void MessageChannelBase::afterRead() { |
| if (++mPos == mCapacity) { |
| mPos = 0U; |
| } |
| mCount--; |
| mCanWrite.signal(); |
| mLock.unlock(); |
| } |
| |
| } // namespace base |
| } // namespace android |