| /* |
| * Copyright (C) 2010 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 "include/ThrottledSource.h" |
| |
| #include <media/stagefright/foundation/ADebug.h> |
| #include <media/stagefright/foundation/ALooper.h> |
| |
| namespace android { |
| |
| ThrottledSource::ThrottledSource( |
| const sp<DataSource> &source, |
| int32_t bandwidthLimitBytesPerSecond) |
| : mSource(source), |
| mBandwidthLimitBytesPerSecond(bandwidthLimitBytesPerSecond), |
| mStartTimeUs(-1), |
| mTotalTransferred(0) { |
| CHECK(mBandwidthLimitBytesPerSecond > 0); |
| } |
| |
| ssize_t ThrottledSource::readAt(off64_t offset, void *data, size_t size) { |
| Mutex::Autolock autoLock(mLock); |
| |
| ssize_t n = mSource->readAt(offset, data, size); |
| |
| if (n <= 0) { |
| return n; |
| } |
| |
| mTotalTransferred += n; |
| |
| int64_t nowUs = ALooper::GetNowUs(); |
| |
| if (mStartTimeUs < 0) { |
| mStartTimeUs = nowUs; |
| } |
| |
| // How long would it have taken to transfer everything we ever |
| // transferred given the limited bandwidth. |
| int64_t durationUs = |
| mTotalTransferred * 1000000ll / mBandwidthLimitBytesPerSecond; |
| |
| int64_t whenUs = mStartTimeUs + durationUs; |
| |
| if (whenUs > nowUs) { |
| usleep(whenUs - nowUs); |
| } |
| return n; |
| } |
| |
| |
| } // namespace android |
| |