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