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/*
* 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
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