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Commit ddc43521 authored by Andreas Huber's avatar Andreas Huber
Browse files

Changes to the prefetcher to allow for bursts of data to be transferred,... 

Changes to the prefetcher to allow for bursts of data to be transferred, hopefully allowing the radio to go to low-power mode while idle.

Change-Id: I03dbdac3cd250340059ea43b341129b30acce4e2
related-to-bug: 2736779
parent 139a5d5b

media/libstagefright/Prefetcher.cpp

+50 −12
Original line number Diff line number Diff line
@@ -58,13 +58,14 @@ private: 
    status_t mFinalStatus;

    int64_t mSeekTimeUs;

    int64_t mCacheDurationUs;

    size_t mCacheSizeBytes;

    bool mPrefetcherStopped;

    bool mCurrentlyPrefetching;



    List<MediaBuffer *> mCachedBuffers;



    // Returns true iff source is currently caching.

    bool getCacheDurationUs(int64_t *durationUs);

    bool getCacheDurationUs(int64_t *durationUs, size_t *totalSize = NULL);



    void updateCacheDuration_l();

    void clearCache_l();
@@ -125,21 +126,31 @@ int Prefetcher::ThreadWrapper(void *me) { 
    return 0;

}



// Cache about 10secs for each source.

static int64_t kMaxCacheDurationUs = 10000000ll;

// Cache at most 1 min for each source.

static int64_t kMaxCacheDurationUs = 60 * 1000000ll;



// At the same time cache at most 5MB per source.

static size_t kMaxCacheSizeBytes = 5 * 1024 * 1024;



// If the amount of cached data drops below this,

// fill the cache up to the max duration again.

static int64_t kLowWaterDurationUs = 5000000ll;



void Prefetcher::threadFunc() {

    bool fillingCache = false;



    for (;;) {

        sp<PrefetchedSource> minSource;

        int64_t minCacheDurationUs = -1;



        {

            Mutex::Autolock autoLock(mLock);

            if (mDone) {

                break;

            }

            mCondition.waitRelative(mLock, 10000000ll);

            mCondition.waitRelative(

                    mLock, fillingCache ? 10000000ll : 1000000000ll);



            int64_t minCacheDurationUs = -1;

            ssize_t minIndex = -1;

            for (size_t i = 0; i < mSources.size(); ++i) {

                sp<PrefetchedSource> source = mSources[i].promote();
@@ -149,11 +160,18 @@ void Prefetcher::threadFunc() { 
                }



                int64_t cacheDurationUs;

                if (!source->getCacheDurationUs(&cacheDurationUs)) {

                size_t cacheSizeBytes;

                if (!source->getCacheDurationUs(&cacheDurationUs, &cacheSizeBytes)) {

                    continue;

                }



                if (cacheDurationUs >= kMaxCacheDurationUs) {

                if (cacheSizeBytes > kMaxCacheSizeBytes) {

                    LOGI("max cache size reached");

                    continue;

                }



                if (mSources.size() > 1 && cacheDurationUs >= kMaxCacheDurationUs) {

                    LOGI("max duration reached, size = %d bytes", cacheSizeBytes);

                    continue;

                }
@@ -165,15 +183,27 @@ void Prefetcher::threadFunc() { 
            }



            if (minIndex < 0) {

                if (fillingCache) {

                    LOGV("[%p] done filling the cache, above high water mark.",

                         this);

                    fillingCache = false;

                }

                continue;

            }

        }



        if (!fillingCache && minCacheDurationUs < kLowWaterDurationUs) {

            LOGI("[%p] cache below low water mark, filling cache.", this);

            fillingCache = true;

        }



        if (fillingCache) {

            // Make sure not to hold the lock while calling into the source.

            // The lock guards the list of sources, not the individual sources

            // themselves.

            minSource->cacheMore();

        }

    }



    Mutex::Autolock autoLock(mLock);

    for (size_t i = 0; i < mSources.size(); ++i) {
@@ -250,6 +280,7 @@ PrefetchedSource::PrefetchedSource( 
      mReachedEOS(false),

      mSeekTimeUs(0),

      mCacheDurationUs(0),

      mCacheSizeBytes(0),

      mPrefetcherStopped(false),

      mCurrentlyPrefetching(false) {

}
@@ -323,6 +354,7 @@ status_t PrefetchedSource::read( 
    *out = *mCachedBuffers.begin();

    mCachedBuffers.erase(mCachedBuffers.begin());

    updateCacheDuration_l();

    mCacheSizeBytes -= (*out)->size();



    return OK;

}
@@ -331,10 +363,14 @@ sp<MetaData> PrefetchedSource::getFormat() { 
    return mSource->getFormat();

}



bool PrefetchedSource::getCacheDurationUs(int64_t *durationUs) {

bool PrefetchedSource::getCacheDurationUs(

        int64_t *durationUs, size_t *totalSize) {

    Mutex::Autolock autoLock(mLock);



    *durationUs = mCacheDurationUs;

    if (totalSize != NULL) {

        *totalSize = mCacheSizeBytes;

    }



    if (!mStarted || mReachedEOS) {

        return false;
@@ -397,6 +433,7 @@ void PrefetchedSource::cacheMore() { 


    mCachedBuffers.push_back(copy);

    updateCacheDuration_l();

    mCacheSizeBytes += copy->size();



    mCurrentlyPrefetching = false;

    mCondition.signal();
@@ -425,6 +462,7 @@ void PrefetchedSource::clearCache_l() { 
    }



    updateCacheDuration_l();

    mCacheSizeBytes = 0;

}



void PrefetchedSource::onPrefetcherStopped() {