1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "include/ThrottledSource.h" 18 19 #include <media/stagefright/foundation/ADebug.h> 20 #include <media/stagefright/foundation/ALooper.h> 21 22 namespace android { 23 24 ThrottledSource::ThrottledSource( 25 const sp<DataSource> &source, 26 int32_t bandwidthLimitBytesPerSecond) 27 : mSource(source), 28 mBandwidthLimitBytesPerSecond(bandwidthLimitBytesPerSecond), 29 mStartTimeUs(-1), 30 mTotalTransferred(0) { 31 CHECK(mBandwidthLimitBytesPerSecond > 0); 32 } 33 34 ssize_t ThrottledSource::readAt(off64_t offset, void *data, size_t size) { 35 Mutex::Autolock autoLock(mLock); 36 37 ssize_t n = mSource->readAt(offset, data, size); 38 39 if (n <= 0) { 40 return n; 41 } 42 43 mTotalTransferred += n; 44 45 int64_t nowUs = ALooper::GetNowUs(); 46 47 if (mStartTimeUs < 0) { 48 mStartTimeUs = nowUs; 49 } 50 51 // How long would it have taken to transfer everything we ever 52 // transferred given the limited bandwidth. 53 int64_t durationUs = 54 mTotalTransferred * 1000000ll / mBandwidthLimitBytesPerSecond; 55 56 int64_t whenUs = mStartTimeUs + durationUs; 57 58 if (whenUs > nowUs) { 59 usleep(whenUs - nowUs); 60 } 61 return n; 62 } 63 64 65 } // namespace android 66 67
