Initial check-in of new caching/prefetching data source implementation.

Change-Id: I97a6e3f03c69c9b1219f1f06bd109c0102f2c504

1 files changed, 458 insertions, 0 deletions

diff --git a/media/libstagefright/NuCachedSource2.cpp b/media/libstagefright/NuCachedSource2.cpp
new file mode 100644
index 0000000..63ba000
--- /dev/null
+++ b/media/libstagefright/NuCachedSource2.cpp
@@ -0,0 +1,458 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "NuCachedSource2"
+#include <utils/Log.h>
+
+#include "include/NuCachedSource2.h"
+
+#include <media/stagefright/foundation/ADebug.h>
+#include <media/stagefright/foundation/AMessage.h>
+#include <media/stagefright/MediaErrors.h>
+
+namespace android {
+
+struct PageCache {
+    PageCache(size_t pageSize);
+    ~PageCache();
+
+    struct Page {
+        void *mData;
+        size_t mSize;
+    };
+
+    Page *acquirePage();
+    void releasePage(Page *page);
+
+    void appendPage(Page *page);
+    size_t releaseFromStart(size_t maxBytes);
+
+    size_t totalSize() const {
+        return mTotalSize;
+    }
+
+    void copy(size_t from, void *data, size_t size);
+
+private:
+    size_t mPageSize;
+    size_t mTotalSize;
+
+    List<Page *> mActivePages;
+    List<Page *> mFreePages;
+
+    void freePages(List<Page *> *list);
+
+    DISALLOW_EVIL_CONSTRUCTORS(PageCache);
+};
+
+PageCache::PageCache(size_t pageSize)
+    : mPageSize(pageSize),
+      mTotalSize(0) {
+}
+
+PageCache::~PageCache() {
+    freePages(&mActivePages);
+    freePages(&mFreePages);
+}
+
+void PageCache::freePages(List<Page *> *list) {
+    List<Page *>::iterator it = list->begin();
+    while (it != list->end()) {
+        Page *page = *it;
+
+        free(page->mData);
+        delete page;
+        page = NULL;
+
+        ++it;
+    }
+}
+
+PageCache::Page *PageCache::acquirePage() {
+    if (!mFreePages.empty()) {
+        List<Page *>::iterator it = mFreePages.begin();
+        Page *page = *it;
+        mFreePages.erase(it);
+
+        return page;
+    }
+
+    Page *page = new Page;
+    page->mData = malloc(mPageSize);
+    page->mSize = 0;
+
+    return page;
+}
+
+void PageCache::releasePage(Page *page) {
+    page->mSize = 0;
+    mFreePages.push_back(page);
+}
+
+void PageCache::appendPage(Page *page) {
+    mTotalSize += page->mSize;
+    mActivePages.push_back(page);
+}
+
+size_t PageCache::releaseFromStart(size_t maxBytes) {
+    size_t bytesReleased = 0;
+
+    while (maxBytes > 0 && !mActivePages.empty()) {
+        List<Page *>::iterator it = mActivePages.begin();
+
+        Page *page = *it;
+
+        if (maxBytes < page->mSize) {
+            break;
+        }
+
+        mActivePages.erase(it);
+
+        maxBytes -= page->mSize;
+        bytesReleased += page->mSize;
+
+        releasePage(page);
+    }
+
+    mTotalSize -= bytesReleased;
+    return bytesReleased;
+}
+
+void PageCache::copy(size_t from, void *data, size_t size) {
+    LOG(VERBOSE) << "copy from " << from << " size " << size;
+
+    CHECK_LE(from + size, mTotalSize);
+
+    size_t offset = 0;
+    List<Page *>::iterator it = mActivePages.begin();
+    while (from >= offset + (*it)->mSize) {
+        offset += (*it)->mSize;
+        ++it;
+    }
+
+    size_t delta = from - offset;
+    size_t avail = (*it)->mSize - delta;
+
+    if (avail >= size) {
+        memcpy(data, (const uint8_t *)(*it)->mData + delta, size);
+        return;
+    }
+
+    memcpy(data, (const uint8_t *)(*it)->mData + delta, avail);
+    ++it;
+    data = (uint8_t *)data + avail;
+    size -= avail;
+
+    while (size > 0) {
+        size_t copy = (*it)->mSize;
+        if (copy > size) {
+            copy = size;
+        }
+        memcpy(data, (*it)->mData, copy);
+        data = (uint8_t *)data + copy;
+        size -= copy;
+        ++it;
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+NuCachedSource2::NuCachedSource2(const sp<DataSource> &source)
+    : mSource(source),
+      mReflector(new AHandlerReflector<NuCachedSource2>(this)),
+      mLooper(new ALooper),
+      mCache(new PageCache(kPageSize)),
+      mCacheOffset(0),
+      mFinalStatus(OK),
+      mLastAccessPos(0),
+      mFetching(true) {
+    mLooper->registerHandler(mReflector);
+    mLooper->start();
+
+    Mutex::Autolock autoLock(mLock);
+    (new AMessage(kWhatFetchMore, mReflector->id()))->post();
+}
+
+NuCachedSource2::~NuCachedSource2() {
+    mLooper->stop();
+    mLooper->unregisterHandler(mReflector->id());
+
+    delete mCache;
+    mCache = NULL;
+}
+
+status_t NuCachedSource2::initCheck() const {
+    return mSource->initCheck();
+}
+
+status_t NuCachedSource2::getSize(off_t *size) {
+    return mSource->getSize(size);
+}
+
+uint32_t NuCachedSource2::flags() {
+    return mSource->flags();
+}
+
+void NuCachedSource2::onMessageReceived(const sp<AMessage> &msg) {
+    switch (msg->what()) {
+        case kWhatFetchMore:
+        {
+            onFetch();
+            break;
+        }
+
+        case kWhatRead:
+        {
+            onRead(msg);
+            break;
+        }
+
+        default:
+            TRESPASS();
+    }
+}
+
+void NuCachedSource2::fetchInternal() {
+    LOG(VERBOSE) << "fetchInternal";
+
+    CHECK_EQ(mFinalStatus, (status_t)OK);
+
+    PageCache::Page *page = mCache->acquirePage();
+
+    ssize_t n = mSource->readAt(
+            mCacheOffset + mCache->totalSize(), page->mData, kPageSize);
+
+    Mutex::Autolock autoLock(mLock);
+
+    if (n < 0) {
+        LOG(ERROR) << "source returned error " << n;
+        mFinalStatus = n;
+        mCache->releasePage(page);
+    } else if (n == 0) {
+        LOG(INFO) << "ERROR_END_OF_STREAM";
+        mFinalStatus = ERROR_END_OF_STREAM;
+        mCache->releasePage(page);
+    } else {
+        page->mSize = n;
+        mCache->appendPage(page);
+    }
+}
+
+void NuCachedSource2::onFetch() {
+    LOG(VERBOSE) << "onFetch";
+
+    if (mFinalStatus != OK) {
+        LOG(VERBOSE) << "EOS reached, done prefetching for now";
+        mFetching = false;
+    }
+
+    if (mFetching) {
+        fetchInternal();
+
+        if (mCache->totalSize() >= kHighWaterThreshold) {
+            LOG(INFO) << "Cache full, done prefetching for now";
+            mFetching = false;
+        }
+    } else {
+        restartPrefetcherIfNecessary_l();
+    }
+
+    (new AMessage(kWhatFetchMore, mReflector->id()))->post(
+            mFetching ? 0 : 100000ll);
+}
+
+void NuCachedSource2::onRead(const sp<AMessage> &msg) {
+    LOG(VERBOSE) << "onRead";
+
+    int64_t offset;
+    CHECK(msg->findInt64("offset", &offset));
+
+    void *data;
+    CHECK(msg->findPointer("data", &data));
+
+    size_t size;
+    CHECK(msg->findSize("size", &size));
+
+    ssize_t result = readInternal(offset, data, size);
+
+    if (result == -EAGAIN) {
+        msg->post(50000);
+        return;
+    }
+
+    Mutex::Autolock autoLock(mLock);
+
+    CHECK(mAsyncResult == NULL);
+
+    mAsyncResult = new AMessage;
+    mAsyncResult->setInt32("result", result);
+
+    mCondition.signal();
+}
+
+void NuCachedSource2::restartPrefetcherIfNecessary_l() {
+    static const size_t kGrayArea = 256 * 1024;
+
+    if (mFetching || mFinalStatus != OK) {
+        return;
+    }
+
+    if (mCacheOffset + mCache->totalSize() - mLastAccessPos
+            >= kLowWaterThreshold) {
+        return;
+    }
+
+    size_t maxBytes = mLastAccessPos - mCacheOffset;
+    if (maxBytes < kGrayArea) {
+        return;
+    }
+
+    maxBytes -= kGrayArea;
+
+    size_t actualBytes = mCache->releaseFromStart(maxBytes);
+    mCacheOffset += actualBytes;
+
+    LOG(INFO) << "restarting prefetcher, totalSize = " << mCache->totalSize();
+    mFetching = true;
+}
+
+ssize_t NuCachedSource2::readAt(off_t offset, void *data, size_t size) {
+    Mutex::Autolock autoSerializer(mSerializer);
+
+    LOG(VERBOSE) << "readAt offset " << offset << " size " << size;
+
+    Mutex::Autolock autoLock(mLock);
+
+    // If the request can be completely satisfied from the cache, do so.
+
+    if (offset >= mCacheOffset
+            && offset + size <= mCacheOffset + mCache->totalSize()) {
+        size_t delta = offset - mCacheOffset;
+        mCache->copy(delta, data, size);
+
+        mLastAccessPos = offset + size;
+
+        return size;
+    }
+
+    sp<AMessage> msg = new AMessage(kWhatRead, mReflector->id());
+    msg->setInt64("offset", offset);
+    msg->setPointer("data", data);
+    msg->setSize("size", size);
+
+    CHECK(mAsyncResult == NULL);
+    msg->post();
+
+    while (mAsyncResult == NULL) {
+        mCondition.wait(mLock);
+    }
+
+    int32_t result;
+    CHECK(mAsyncResult->findInt32("result", &result));
+
+    mAsyncResult.clear();
+
+    if (result > 0) {
+        mLastAccessPos = offset + result;
+    }
+
+    return (ssize_t)result;
+}
+
+size_t NuCachedSource2::cachedSize() {
+    Mutex::Autolock autoLock(mLock);
+    return mCacheOffset + mCache->totalSize();
+}
+
+size_t NuCachedSource2::approxDataRemaining(bool *eos) {
+    Mutex::Autolock autoLock(mLock);
+    return approxDataRemaining_l(eos);
+}
+
+size_t NuCachedSource2::approxDataRemaining_l(bool *eos) {
+    *eos = (mFinalStatus != OK);
+    off_t lastBytePosCached = mCacheOffset + mCache->totalSize();
+    if (mLastAccessPos < lastBytePosCached) {
+        return lastBytePosCached - mLastAccessPos;
+    }
+    return 0;
+}
+
+ssize_t NuCachedSource2::readInternal(off_t offset, void *data, size_t size) {
+    LOG(VERBOSE) << "readInternal offset " << offset << " size " << size;
+
+    Mutex::Autolock autoLock(mLock);
+
+    if (offset < mCacheOffset
+            || offset >= (off_t)(mCacheOffset + mCache->totalSize())) {
+        static const off_t kPadding = 32768;
+
+        // In the presence of multiple decoded streams, once of them will
+        // trigger this seek request, the other one will request data "nearby"
+        // soon, adjust the seek position so that that subsequent request
+        // does not trigger another seek.
+        off_t seekOffset = (offset > kPadding) ? offset - kPadding : 0;
+
+        seekInternal_l(seekOffset);
+    }
+
+    size_t delta = offset - mCacheOffset;
+
+    if (mFinalStatus != OK) {
+        if (delta >= mCache->totalSize()) {
+            return mFinalStatus;
+        }
+
+        size_t avail = mCache->totalSize() - offset;
+        mCache->copy(delta, data, avail);
+
+        return avail;
+    }
+
+    if (offset + size <= mCacheOffset + mCache->totalSize()) {
+        mCache->copy(delta, data, size);
+
+        return size;
+    }
+
+    LOG(VERBOSE) << "deferring read";
+
+    return -EAGAIN;
+}
+
+status_t NuCachedSource2::seekInternal_l(off_t offset) {
+    mLastAccessPos = offset;
+
+    if (offset >= mCacheOffset
+            && offset <= (off_t)(mCacheOffset + mCache->totalSize())) {
+        return OK;
+    }
+
+    LOG(INFO) << "new range: offset= " << offset;
+
+    mCacheOffset = offset;
+
+    size_t totalSize = mCache->totalSize();
+    CHECK_EQ(mCache->releaseFromStart(totalSize), totalSize);
+
+    mFinalStatus = OK;
+    mFetching = true;
+
+    return OK;
+}
+
+}  // namespace android
+