The Tor Browser: comparison content/media/MediaCache.cpp

--1:000000000000
+:e3f35246c65a
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "mozilla/ReentrantMonitor.h"
+#include "MediaCache.h"
+#include "prio.h"
+#include "nsContentUtils.h"
+#include "nsThreadUtils.h"
+#include "MediaResource.h"
+#include "prlog.h"
+#include "mozilla/Preferences.h"
+#include "FileBlockCache.h"
+#include "nsAnonymousTemporaryFile.h"
+#include "nsIObserverService.h"
+#include "nsISeekableStream.h"
+#include "nsIPrincipal.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Services.h"
+#include <algorithm>
+namespace mozilla {
+#ifdef PR_LOGGING
+PRLogModuleInfo* gMediaCacheLog;
+#define CACHE_LOG(type, msg) PR_LOG(gMediaCacheLog, type, msg)
+#else
+#define CACHE_LOG(type, msg)
+#endif
+// Readahead blocks for non-seekable streams will be limited to this
+// fraction of the cache space. We don't normally evict such blocks
+// because replacing them requires a seek, but we need to make sure
+// they don't monopolize the cache.
+static const double NONSEEKABLE_READAHEAD_MAX = 0.5;
+// Data N seconds before the current playback position is given the same priority
+// as data REPLAY_PENALTY_FACTOR*N seconds ahead of the current playback
+// position. REPLAY_PENALTY_FACTOR is greater than 1 to reflect that
+// data in the past is less likely to be played again than data in the future.
+// We want to give data just behind the current playback position reasonably
+// high priority in case codecs need to retrieve that data (e.g. because
+// tracks haven't been muxed well or are being decoded at uneven rates).
+// 1/REPLAY_PENALTY_FACTOR as much data will be kept behind the
+// current playback position as will be kept ahead of the current playback
+// position.
+static const uint32_t REPLAY_PENALTY_FACTOR = 3;
+// When looking for a reusable block, scan forward this many blocks
+// from the desired "best" block location to look for free blocks,
+// before we resort to scanning the whole cache. The idea is to try to
+// store runs of stream blocks close-to-consecutively in the cache if we
+// can.
+static const uint32_t FREE_BLOCK_SCAN_LIMIT = 16;
+// Try to save power by not resuming paused reads if the stream won't need new
+// data within this time interval in the future
+static const uint32_t CACHE_POWERSAVE_WAKEUP_LOW_THRESHOLD_MS = 10000;
+#ifdef DEBUG
+// Turn this on to do very expensive cache state validation
+// #define DEBUG_VERIFY_CACHE
+#endif
+// There is at most one media cache (although that could quite easily be
+// relaxed if we wanted to manage multiple caches with independent
+// size limits).
+static MediaCache* gMediaCache;
+class MediaCacheFlusher MOZ_FINAL : public nsIObserver,
+public nsSupportsWeakReference {
+MediaCacheFlusher() {}
+~MediaCacheFlusher();
+public:
+NS_DECL_ISUPPORTS
+NS_DECL_NSIOBSERVER
+static void Init();
+};
+static MediaCacheFlusher* gMediaCacheFlusher;
+NS_IMPL_ISUPPORTS(MediaCacheFlusher, nsIObserver, nsISupportsWeakReference)
+MediaCacheFlusher::~MediaCacheFlusher()
+{
+gMediaCacheFlusher = nullptr;
+}
+void MediaCacheFlusher::Init()
+{
+if (gMediaCacheFlusher) {
+return;
+}
+gMediaCacheFlusher = new MediaCacheFlusher();
+NS_ADDREF(gMediaCacheFlusher);
+nsCOMPtr<nsIObserverService> observerService =
+mozilla::services::GetObserverService();
+if (observerService) {
+observerService->AddObserver(gMediaCacheFlusher, "last-pb-context-exited", true);
+observerService->AddObserver(gMediaCacheFlusher, "network-clear-cache-stored-anywhere", true);
+}
+}
+class MediaCache {
+public:
+friend class MediaCacheStream::BlockList;
+typedef MediaCacheStream::BlockList BlockList;
+enum {
+BLOCK_SIZE = MediaCacheStream::BLOCK_SIZE
+};
+MediaCache() : mNextResourceID(1),
+mReentrantMonitor("MediaCache.mReentrantMonitor"),
+mUpdateQueued(false)
+#ifdef DEBUG
+, mInUpdate(false)
+#endif
+{
+MOZ_COUNT_CTOR(MediaCache);
+}
+~MediaCache() {
+NS_ASSERTION(mStreams.IsEmpty(), "Stream(s) still open!");
+Truncate();
+NS_ASSERTION(mIndex.Length() == 0, "Blocks leaked?");
+if (mFileCache) {
+mFileCache->Close();
+mFileCache = nullptr;
+}
+MOZ_COUNT_DTOR(MediaCache);
+}
+// Main thread only. Creates the backing cache file. If this fails,
+// then the cache is still in a semi-valid state; mFD will be null,
+// so all I/O on the cache file will fail.
+nsresult Init();
+// Shut down the global cache if it's no longer needed. We shut down
+// the cache as soon as there are no streams. This means that during
+// normal operation we are likely to start up the cache and shut it down
+// many times, but that's OK since starting it up is cheap and
+// shutting it down cleans things up and releases disk space.
+static void MaybeShutdown();
+// Brutally flush the cache contents. Main thread only.
+static void Flush();
+void FlushInternal();
+// Cache-file access methods. These are the lowest-level cache methods.
+// mReentrantMonitor must be held; these can be called on any thread.
+// This can return partial reads.
+nsresult ReadCacheFile(int64_t aOffset, void* aData, int32_t aLength,
+int32_t* aBytes);
+// This will fail if all aLength bytes are not read
+nsresult ReadCacheFileAllBytes(int64_t aOffset, void* aData, int32_t aLength);
+int64_t AllocateResourceID()
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+return mNextResourceID++;
+}
+// mReentrantMonitor must be held, called on main thread.
+// These methods are used by the stream to set up and tear down streams,
+// and to handle reads and writes.
+// Add aStream to the list of streams.
+void OpenStream(MediaCacheStream* aStream);
+// Remove aStream from the list of streams.
+void ReleaseStream(MediaCacheStream* aStream);
+// Free all blocks belonging to aStream.
+void ReleaseStreamBlocks(MediaCacheStream* aStream);
+// Find a cache entry for this data, and write the data into it
+void AllocateAndWriteBlock(MediaCacheStream* aStream, const void* aData,
+MediaCacheStream::ReadMode aMode);
+// mReentrantMonitor must be held; can be called on any thread
+// Notify the cache that a seek has been requested. Some blocks may
+// need to change their class between PLAYED_BLOCK and READAHEAD_BLOCK.
+// This does not trigger channel seeks directly, the next Update()
+// will do that if necessary. The caller will call QueueUpdate().
+void NoteSeek(MediaCacheStream* aStream, int64_t aOldOffset);
+// Notify the cache that a block has been read from. This is used
+// to update last-use times. The block may not actually have a
+// cache entry yet since Read can read data from a stream's
+// in-memory mPartialBlockBuffer while the block is only partly full,
+// and thus hasn't yet been committed to the cache. The caller will
+// call QueueUpdate().
+void NoteBlockUsage(MediaCacheStream* aStream, int32_t aBlockIndex,
+MediaCacheStream::ReadMode aMode, TimeStamp aNow);
+// Mark aStream as having the block, adding it as an owner.
+void AddBlockOwnerAsReadahead(int32_t aBlockIndex, MediaCacheStream* aStream,
+int32_t aStreamBlockIndex);
+// This queues a call to Update() on the main thread.
+void QueueUpdate();
+// Updates the cache state asynchronously on the main thread:
+// -- try to trim the cache back to its desired size, if necessary
+// -- suspend channels that are going to read data that's lower priority
+// than anything currently cached
+// -- resume channels that are going to read data that's higher priority
+// than something currently cached
+// -- seek channels that need to seek to a new location
+void Update();
+#ifdef DEBUG_VERIFY_CACHE
+// Verify invariants, especially block list invariants
+void Verify();
+#else
+void Verify() {}
+#endif
+ReentrantMonitor& GetReentrantMonitor() { return mReentrantMonitor; }
+/**
+* An iterator that makes it easy to iterate through all streams that
+* have a given resource ID and are not closed.
+* Can be used on the main thread or while holding the media cache lock.
+*/
+class ResourceStreamIterator {
+public:
+ResourceStreamIterator(int64_t aResourceID) :
+mResourceID(aResourceID), mNext(0) {}
+MediaCacheStream* Next()
+{
+while (mNext < gMediaCache->mStreams.Length()) {
+MediaCacheStream* stream = gMediaCache->mStreams[mNext];
+++mNext;
+if (stream->GetResourceID() == mResourceID && !stream->IsClosed())
+return stream;
+}
+return nullptr;
+}
+private:
+int64_t  mResourceID;
+uint32_t mNext;
+};
+protected:
+// Find a free or reusable block and return its index. If there are no
+// free blocks and no reusable blocks, add a new block to the cache
+// and return it. Can return -1 on OOM.
+int32_t FindBlockForIncomingData(TimeStamp aNow, MediaCacheStream* aStream);
+// Find a reusable block --- a free block, if there is one, otherwise
+// the reusable block with the latest predicted-next-use, or -1 if
+// there aren't any freeable blocks. Only block indices less than
+// aMaxSearchBlockIndex are considered. If aForStream is non-null,
+// then aForStream and aForStreamBlock indicate what media data will
+// be placed; FindReusableBlock will favour returning free blocks
+// near other blocks for that point in the stream.
+int32_t FindReusableBlock(TimeStamp aNow,
+MediaCacheStream* aForStream,
+int32_t aForStreamBlock,
+int32_t aMaxSearchBlockIndex);
+bool BlockIsReusable(int32_t aBlockIndex);
+// Given a list of blocks sorted with the most reusable blocks at the
+// end, find the last block whose stream is not pinned (if any)
+// and whose cache entry index is less than aBlockIndexLimit
+// and append it to aResult.
+void AppendMostReusableBlock(BlockList* aBlockList,
+nsTArray<uint32_t>* aResult,
+int32_t aBlockIndexLimit);
+enum BlockClass {
+// block belongs to mMetadataBlockList because data has been consumed
+// from it in "metadata mode" --- in particular blocks read during
+// Ogg seeks go into this class. These blocks may have played data
+// in them too.
+METADATA_BLOCK,
+// block belongs to mPlayedBlockList because its offset is
+// less than the stream's current reader position
+PLAYED_BLOCK,
+// block belongs to the stream's mReadaheadBlockList because its
+// offset is greater than or equal to the stream's current
+// reader position
+READAHEAD_BLOCK
+};
+struct BlockOwner {
+BlockOwner() : mStream(nullptr), mClass(READAHEAD_BLOCK) {}
+// The stream that owns this block, or null if the block is free.
+MediaCacheStream* mStream;
+// The block index in the stream. Valid only if mStream is non-null.
+uint32_t            mStreamBlock;
+// Time at which this block was last used. Valid only if
+// mClass is METADATA_BLOCK or PLAYED_BLOCK.
+TimeStamp           mLastUseTime;
+BlockClass          mClass;
+};
+struct Block {
+// Free blocks have an empty mOwners array
+nsTArray<BlockOwner> mOwners;
+};
+// Get the BlockList that the block should belong to given its
+// current owner
+BlockList* GetListForBlock(BlockOwner* aBlock);
+// Get the BlockOwner for the given block index and owning stream
+// (returns null if the stream does not own the block)
+BlockOwner* GetBlockOwner(int32_t aBlockIndex, MediaCacheStream* aStream);
+// Returns true iff the block is free
+bool IsBlockFree(int32_t aBlockIndex)
+{ return mIndex[aBlockIndex].mOwners.IsEmpty(); }
+// Add the block to the free list and mark its streams as not having
+// the block in cache
+void FreeBlock(int32_t aBlock);
+// Mark aStream as not having the block, removing it as an owner. If
+// the block has no more owners it's added to the free list.
+void RemoveBlockOwner(int32_t aBlockIndex, MediaCacheStream* aStream);
+// Swap all metadata associated with the two blocks. The caller
+// is responsible for swapping up any cache file state.
+void SwapBlocks(int32_t aBlockIndex1, int32_t aBlockIndex2);
+// Insert the block into the readahead block list for the stream
+// at the right point in the list.
+void InsertReadaheadBlock(BlockOwner* aBlockOwner, int32_t aBlockIndex);
+// Guess the duration until block aBlock will be next used
+TimeDuration PredictNextUse(TimeStamp aNow, int32_t aBlock);
+// Guess the duration until the next incoming data on aStream will be used
+TimeDuration PredictNextUseForIncomingData(MediaCacheStream* aStream);
+// Truncate the file and index array if there are free blocks at the
+// end
+void Truncate();
+// This member is main-thread only. It's used to allocate unique
+// resource IDs to streams.
+int64_t                       mNextResourceID;
+// The monitor protects all the data members here. Also, off-main-thread
+// readers that need to block will Wait() on this monitor. When new
+// data becomes available in the cache, we NotifyAll() on this monitor.
+ReentrantMonitor         mReentrantMonitor;
+// This is only written while on the main thread and the monitor is held.
+// Thus, it can be safely read from the main thread or while holding the monitor.
+nsTArray<MediaCacheStream*> mStreams;
+// The Blocks describing the cache entries.
+nsTArray<Block> mIndex;
+// Writer which performs IO, asynchronously writing cache blocks.
+nsRefPtr<FileBlockCache> mFileCache;
+// The list of free blocks; they are not ordered.
+BlockList       mFreeBlocks;
+// True if an event to run Update() has been queued but not processed
+bool            mUpdateQueued;
+#ifdef DEBUG
+bool            mInUpdate;
+#endif
+};
+NS_IMETHODIMP
+MediaCacheFlusher::Observe(nsISupports *aSubject, char const *aTopic, char16_t const *aData)
+{
+if (strcmp(aTopic, "last-pb-context-exited") == 0) {
+MediaCache::Flush();
+}
+if (strcmp(aTopic, "network-clear-cache-stored-anywhere") == 0) {
+MediaCache::Flush();
+}
+return NS_OK;
+}
+MediaCacheStream::MediaCacheStream(ChannelMediaResource* aClient)
+: mClient(aClient),
+mInitialized(false),
+mHasHadUpdate(false),
+mClosed(false),
+mDidNotifyDataEnded(false),
+mResourceID(0),
+mIsTransportSeekable(false),
+mCacheSuspended(false),
+mChannelEnded(false),
+mChannelOffset(0),
+mStreamLength(-1),
+mStreamOffset(0),
+mPlaybackBytesPerSecond(10000),
+mPinCount(0),
+mCurrentMode(MODE_PLAYBACK),
+mMetadataInPartialBlockBuffer(false),
+mPartialBlockBuffer(new int64_t[BLOCK_SIZE/sizeof(int64_t)])
+{
+}
+size_t MediaCacheStream::SizeOfExcludingThis(
+MallocSizeOf aMallocSizeOf) const
+{
+// Looks like these are not owned:
+// - mClient
+// - mPrincipal
+size_t size = mBlocks.SizeOfExcludingThis(aMallocSizeOf);
+size += mReadaheadBlocks.SizeOfExcludingThis(aMallocSizeOf);
+size += mMetadataBlocks.SizeOfExcludingThis(aMallocSizeOf);
+size += mPlayedBlocks.SizeOfExcludingThis(aMallocSizeOf);
+size += mPartialBlockBuffer.SizeOfExcludingThis(aMallocSizeOf);
+return size;
+}
+size_t MediaCacheStream::BlockList::SizeOfExcludingThis(
+MallocSizeOf aMallocSizeOf) const
+{
+return mEntries.SizeOfExcludingThis(/* sizeOfEntryExcludingThis = */ nullptr,
+aMallocSizeOf);
+}
+void MediaCacheStream::BlockList::AddFirstBlock(int32_t aBlock)
+{
+NS_ASSERTION(!mEntries.GetEntry(aBlock), "Block already in list");
+Entry* entry = mEntries.PutEntry(aBlock);
+if (mFirstBlock < 0) {
+entry->mNextBlock = entry->mPrevBlock = aBlock;
+} else {
+entry->mNextBlock = mFirstBlock;
+entry->mPrevBlock = mEntries.GetEntry(mFirstBlock)->mPrevBlock;
+mEntries.GetEntry(entry->mNextBlock)->mPrevBlock = aBlock;
+mEntries.GetEntry(entry->mPrevBlock)->mNextBlock = aBlock;
+}
+mFirstBlock = aBlock;
+++mCount;
+}
+void MediaCacheStream::BlockList::AddAfter(int32_t aBlock, int32_t aBefore)
+{
+NS_ASSERTION(!mEntries.GetEntry(aBlock), "Block already in list");
+Entry* entry = mEntries.PutEntry(aBlock);
+Entry* addAfter = mEntries.GetEntry(aBefore);
+NS_ASSERTION(addAfter, "aBefore not in list");
+entry->mNextBlock = addAfter->mNextBlock;
+entry->mPrevBlock = aBefore;
+mEntries.GetEntry(entry->mNextBlock)->mPrevBlock = aBlock;
+mEntries.GetEntry(entry->mPrevBlock)->mNextBlock = aBlock;
+++mCount;
+}
+void MediaCacheStream::BlockList::RemoveBlock(int32_t aBlock)
+{
+Entry* entry = mEntries.GetEntry(aBlock);
+NS_ASSERTION(entry, "Block not in list");
+if (entry->mNextBlock == aBlock) {
+NS_ASSERTION(entry->mPrevBlock == aBlock, "Linked list inconsistency");
+NS_ASSERTION(mFirstBlock == aBlock, "Linked list inconsistency");
+mFirstBlock = -1;
+} else {
+if (mFirstBlock == aBlock) {
+mFirstBlock = entry->mNextBlock;
+}
+mEntries.GetEntry(entry->mNextBlock)->mPrevBlock = entry->mPrevBlock;
+mEntries.GetEntry(entry->mPrevBlock)->mNextBlock = entry->mNextBlock;
+}
+mEntries.RemoveEntry(aBlock);
+--mCount;
+}
+int32_t MediaCacheStream::BlockList::GetLastBlock() const
+{
+if (mFirstBlock < 0)
+return -1;
+return mEntries.GetEntry(mFirstBlock)->mPrevBlock;
+}
+int32_t MediaCacheStream::BlockList::GetNextBlock(int32_t aBlock) const
+{
+int32_t block = mEntries.GetEntry(aBlock)->mNextBlock;
+if (block == mFirstBlock)
+return -1;
+return block;
+}
+int32_t MediaCacheStream::BlockList::GetPrevBlock(int32_t aBlock) const
+{
+if (aBlock == mFirstBlock)
+return -1;
+return mEntries.GetEntry(aBlock)->mPrevBlock;
+}
+#ifdef DEBUG
+void MediaCacheStream::BlockList::Verify()
+{
+int32_t count = 0;
+if (mFirstBlock >= 0) {
+int32_t block = mFirstBlock;
+do {
+Entry* entry = mEntries.GetEntry(block);
+NS_ASSERTION(mEntries.GetEntry(entry->mNextBlock)->mPrevBlock == block,
+"Bad prev link");
+NS_ASSERTION(mEntries.GetEntry(entry->mPrevBlock)->mNextBlock == block,
+"Bad next link");
+block = entry->mNextBlock;
+++count;
+} while (block != mFirstBlock);
+}
+NS_ASSERTION(count == mCount, "Bad count");
+}
+#endif
+static void UpdateSwappedBlockIndex(int32_t* aBlockIndex,
+int32_t aBlock1Index, int32_t aBlock2Index)
+{
+int32_t index = *aBlockIndex;
+if (index == aBlock1Index) {
+*aBlockIndex = aBlock2Index;
+} else if (index == aBlock2Index) {
+*aBlockIndex = aBlock1Index;
+}
+}
+void
+MediaCacheStream::BlockList::NotifyBlockSwapped(int32_t aBlockIndex1,
+int32_t aBlockIndex2)
+{
+Entry* e1 = mEntries.GetEntry(aBlockIndex1);
+Entry* e2 = mEntries.GetEntry(aBlockIndex2);
+int32_t e1Prev = -1, e1Next = -1, e2Prev = -1, e2Next = -1;
+// Fix mFirstBlock
+UpdateSwappedBlockIndex(&mFirstBlock, aBlockIndex1, aBlockIndex2);
+// Fix mNextBlock/mPrevBlock links. First capture previous/next links
+// so we don't get confused due to aliasing.
+if (e1) {
+e1Prev = e1->mPrevBlock;
+e1Next = e1->mNextBlock;
+}
+if (e2) {
+e2Prev = e2->mPrevBlock;
+e2Next = e2->mNextBlock;
+}
+// Update the entries.
+if (e1) {
+mEntries.GetEntry(e1Prev)->mNextBlock = aBlockIndex2;
+mEntries.GetEntry(e1Next)->mPrevBlock = aBlockIndex2;
+}
+if (e2) {
+mEntries.GetEntry(e2Prev)->mNextBlock = aBlockIndex1;
+mEntries.GetEntry(e2Next)->mPrevBlock = aBlockIndex1;
+}
+// Fix hashtable keys. First remove stale entries.
+if (e1) {
+e1Prev = e1->mPrevBlock;
+e1Next = e1->mNextBlock;
+mEntries.RemoveEntry(aBlockIndex1);
+// Refresh pointer after hashtable mutation.
+e2 = mEntries.GetEntry(aBlockIndex2);
+}
+if (e2) {
+e2Prev = e2->mPrevBlock;
+e2Next = e2->mNextBlock;
+mEntries.RemoveEntry(aBlockIndex2);
+}
+// Put new entries back.
+if (e1) {
+e1 = mEntries.PutEntry(aBlockIndex2);
+e1->mNextBlock = e1Next;
+e1->mPrevBlock = e1Prev;
+}
+if (e2) {
+e2 = mEntries.PutEntry(aBlockIndex1);
+e2->mNextBlock = e2Next;
+e2->mPrevBlock = e2Prev;
+}
+}
+nsresult
+MediaCache::Init()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+NS_ASSERTION(!mFileCache, "Cache file already open?");
+PRFileDesc* fileDesc = nullptr;
+nsresult rv = NS_OpenAnonymousTemporaryFile(&fileDesc);
+NS_ENSURE_SUCCESS(rv,rv);
+mFileCache = new FileBlockCache();
+rv = mFileCache->Open(fileDesc);
+NS_ENSURE_SUCCESS(rv,rv);
+#ifdef PR_LOGGING
+if (!gMediaCacheLog) {
+gMediaCacheLog = PR_NewLogModule("MediaCache");
+}
+#endif
+MediaCacheFlusher::Init();
+return NS_OK;
+}
+void
+MediaCache::Flush()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+if (!gMediaCache)
+return;
+gMediaCache->FlushInternal();
+}
+void
+MediaCache::FlushInternal()
+{
+ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+for (uint32_t blockIndex = 0; blockIndex < mIndex.Length(); ++blockIndex) {
+FreeBlock(blockIndex);
+}
+// Truncate file, close it, and reopen
+Truncate();
+NS_ASSERTION(mIndex.Length() == 0, "Blocks leaked?");
+if (mFileCache) {
+mFileCache->Close();
+mFileCache = nullptr;
+}
+Init();
+}
+void
+MediaCache::MaybeShutdown()
+{
+NS_ASSERTION(NS_IsMainThread(),
+"MediaCache::MaybeShutdown called on non-main thread");
+if (!gMediaCache->mStreams.IsEmpty()) {
+// Don't shut down yet, streams are still alive
+return;
+}
+// Since we're on the main thread, no-one is going to add a new stream
+// while we shut down.
+// This function is static so we don't have to delete 'this'.
+delete gMediaCache;
+gMediaCache = nullptr;
+NS_IF_RELEASE(gMediaCacheFlusher);
+}
+static void
+InitMediaCache()
+{
+if (gMediaCache)
+return;
+gMediaCache = new MediaCache();
+if (!gMediaCache)
+return;
+nsresult rv = gMediaCache->Init();
+if (NS_FAILED(rv)) {
+delete gMediaCache;
+gMediaCache = nullptr;
+}
+}
+nsresult
+MediaCache::ReadCacheFile(int64_t aOffset, void* aData, int32_t aLength,
+int32_t* aBytes)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+if (!mFileCache)
+return NS_ERROR_FAILURE;
+return mFileCache->Read(aOffset, reinterpret_cast<uint8_t*>(aData), aLength, aBytes);
+}
+nsresult
+MediaCache::ReadCacheFileAllBytes(int64_t aOffset, void* aData, int32_t aLength)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+int64_t offset = aOffset;
+int32_t count = aLength;
+// Cast to char* so we can do byte-wise pointer arithmetic
+char* data = static_cast<char*>(aData);
+while (count > 0) {
+int32_t bytes;
+nsresult rv = ReadCacheFile(offset, data, count, &bytes);
+if (NS_FAILED(rv))
+return rv;
+if (bytes == 0)
+return NS_ERROR_FAILURE;
+count -= bytes;
+data += bytes;
+offset += bytes;
+}
+return NS_OK;
+}
+static int32_t GetMaxBlocks()
+{
+// We look up the cache size every time. This means dynamic changes
+// to the pref are applied.
+// Cache size is in KB
+int32_t cacheSize = Preferences::GetInt("media.cache_size", 500*1024);
+int64_t maxBlocks = static_cast<int64_t>(cacheSize)*1024/MediaCache::BLOCK_SIZE;
+maxBlocks = std::max<int64_t>(maxBlocks, 1);
+return int32_t(std::min<int64_t>(maxBlocks, INT32_MAX));
+}
+int32_t
+MediaCache::FindBlockForIncomingData(TimeStamp aNow,
+MediaCacheStream* aStream)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+int32_t blockIndex = FindReusableBlock(aNow, aStream,
+aStream->mChannelOffset/BLOCK_SIZE, INT32_MAX);
+if (blockIndex < 0 || !IsBlockFree(blockIndex)) {
+// The block returned is already allocated.
+// Don't reuse it if a) there's room to expand the cache or
+// b) the data we're going to store in the free block is not higher
+// priority than the data already stored in the free block.
+// The latter can lead us to go over the cache limit a bit.
+if ((mIndex.Length() < uint32_t(GetMaxBlocks()) || blockIndex < 0 ||
+PredictNextUseForIncomingData(aStream) >= PredictNextUse(aNow, blockIndex))) {
+blockIndex = mIndex.Length();
+if (!mIndex.AppendElement())
+return -1;
+mFreeBlocks.AddFirstBlock(blockIndex);
+return blockIndex;
+}
+}
+return blockIndex;
+}
+bool
+MediaCache::BlockIsReusable(int32_t aBlockIndex)
+{
+Block* block = &mIndex[aBlockIndex];
+for (uint32_t i = 0; i < block->mOwners.Length(); ++i) {
+MediaCacheStream* stream = block->mOwners[i].mStream;
+if (stream->mPinCount > 0 ||
+stream->mStreamOffset/BLOCK_SIZE == block->mOwners[i].mStreamBlock) {
+return false;
+}
+}
+return true;
+}
+void
+MediaCache::AppendMostReusableBlock(BlockList* aBlockList,
+nsTArray<uint32_t>* aResult,
+int32_t aBlockIndexLimit)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+int32_t blockIndex = aBlockList->GetLastBlock();
+if (blockIndex < 0)
+return;
+do {
+// Don't consider blocks for pinned streams, or blocks that are
+// beyond the specified limit, or a block that contains a stream's
+// current read position (such a block contains both played data
+// and readahead data)
+if (blockIndex < aBlockIndexLimit && BlockIsReusable(blockIndex)) {
+aResult->AppendElement(blockIndex);
+return;
+}
+blockIndex = aBlockList->GetPrevBlock(blockIndex);
+} while (blockIndex >= 0);
+}
+int32_t
+MediaCache::FindReusableBlock(TimeStamp aNow,
+MediaCacheStream* aForStream,
+int32_t aForStreamBlock,
+int32_t aMaxSearchBlockIndex)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+uint32_t length = std::min(uint32_t(aMaxSearchBlockIndex), mIndex.Length());
+if (aForStream && aForStreamBlock > 0 &&
+uint32_t(aForStreamBlock) <= aForStream->mBlocks.Length()) {
+int32_t prevCacheBlock = aForStream->mBlocks[aForStreamBlock - 1];
+if (prevCacheBlock >= 0) {
+uint32_t freeBlockScanEnd =
+std::min(length, prevCacheBlock + FREE_BLOCK_SCAN_LIMIT);
+for (uint32_t i = prevCacheBlock; i < freeBlockScanEnd; ++i) {
+if (IsBlockFree(i))
+return i;
+}
+}
+}
+if (!mFreeBlocks.IsEmpty()) {
+int32_t blockIndex = mFreeBlocks.GetFirstBlock();
+do {
+if (blockIndex < aMaxSearchBlockIndex)
+return blockIndex;
+blockIndex = mFreeBlocks.GetNextBlock(blockIndex);
+} while (blockIndex >= 0);
+}
+// Build a list of the blocks we should consider for the "latest
+// predicted time of next use". We can exploit the fact that the block
+// linked lists are ordered by increasing time of next use. This is
+// actually the whole point of having the linked lists.
+nsAutoTArray<uint32_t,8> candidates;
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+MediaCacheStream* stream = mStreams[i];
+if (stream->mPinCount > 0) {
+// No point in even looking at this stream's blocks
+continue;
+}
+AppendMostReusableBlock(&stream->mMetadataBlocks, &candidates, length);
+AppendMostReusableBlock(&stream->mPlayedBlocks, &candidates, length);
+// Don't consider readahead blocks in non-seekable streams. If we
+// remove the block we won't be able to seek back to read it later.
+if (stream->mIsTransportSeekable) {
+AppendMostReusableBlock(&stream->mReadaheadBlocks, &candidates, length);
+}
+}
+TimeDuration latestUse;
+int32_t latestUseBlock = -1;
+for (uint32_t i = 0; i < candidates.Length(); ++i) {
+TimeDuration nextUse = PredictNextUse(aNow, candidates[i]);
+if (nextUse > latestUse) {
+latestUse = nextUse;
+latestUseBlock = candidates[i];
+}
+}
+return latestUseBlock;
+}
+MediaCache::BlockList*
+MediaCache::GetListForBlock(BlockOwner* aBlock)
+{
+switch (aBlock->mClass) {
+case METADATA_BLOCK:
+NS_ASSERTION(aBlock->mStream, "Metadata block has no stream?");
+return &aBlock->mStream->mMetadataBlocks;
+case PLAYED_BLOCK:
+NS_ASSERTION(aBlock->mStream, "Metadata block has no stream?");
+return &aBlock->mStream->mPlayedBlocks;
+case READAHEAD_BLOCK:
+NS_ASSERTION(aBlock->mStream, "Readahead block has no stream?");
+return &aBlock->mStream->mReadaheadBlocks;
+default:
+NS_ERROR("Invalid block class");
+return nullptr;
+}
+}
+MediaCache::BlockOwner*
+MediaCache::GetBlockOwner(int32_t aBlockIndex, MediaCacheStream* aStream)
+{
+Block* block = &mIndex[aBlockIndex];
+for (uint32_t i = 0; i < block->mOwners.Length(); ++i) {
+if (block->mOwners[i].mStream == aStream)
+return &block->mOwners[i];
+}
+return nullptr;
+}
+void
+MediaCache::SwapBlocks(int32_t aBlockIndex1, int32_t aBlockIndex2)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+Block* block1 = &mIndex[aBlockIndex1];
+Block* block2 = &mIndex[aBlockIndex2];
+block1->mOwners.SwapElements(block2->mOwners);
+// Now all references to block1 have to be replaced with block2 and
+// vice versa.
+// First update stream references to blocks via mBlocks.
+const Block* blocks[] = { block1, block2 };
+int32_t blockIndices[] = { aBlockIndex1, aBlockIndex2 };
+for (int32_t i = 0; i < 2; ++i) {
+for (uint32_t j = 0; j < blocks[i]->mOwners.Length(); ++j) {
+const BlockOwner* b = &blocks[i]->mOwners[j];
+b->mStream->mBlocks[b->mStreamBlock] = blockIndices[i];
+}
+}
+// Now update references to blocks in block lists.
+mFreeBlocks.NotifyBlockSwapped(aBlockIndex1, aBlockIndex2);
+nsTHashtable<nsPtrHashKey<MediaCacheStream> > visitedStreams;
+for (int32_t i = 0; i < 2; ++i) {
+for (uint32_t j = 0; j < blocks[i]->mOwners.Length(); ++j) {
+MediaCacheStream* stream = blocks[i]->mOwners[j].mStream;
+// Make sure that we don't update the same stream twice --- that
+// would result in swapping the block references back again!
+if (visitedStreams.GetEntry(stream))
+continue;
+visitedStreams.PutEntry(stream);
+stream->mReadaheadBlocks.NotifyBlockSwapped(aBlockIndex1, aBlockIndex2);
+stream->mPlayedBlocks.NotifyBlockSwapped(aBlockIndex1, aBlockIndex2);
+stream->mMetadataBlocks.NotifyBlockSwapped(aBlockIndex1, aBlockIndex2);
+}
+}
+Verify();
+}
+void
+MediaCache::RemoveBlockOwner(int32_t aBlockIndex, MediaCacheStream* aStream)
+{
+Block* block = &mIndex[aBlockIndex];
+for (uint32_t i = 0; i < block->mOwners.Length(); ++i) {
+BlockOwner* bo = &block->mOwners[i];
+if (bo->mStream == aStream) {
+GetListForBlock(bo)->RemoveBlock(aBlockIndex);
+bo->mStream->mBlocks[bo->mStreamBlock] = -1;
+block->mOwners.RemoveElementAt(i);
+if (block->mOwners.IsEmpty()) {
+mFreeBlocks.AddFirstBlock(aBlockIndex);
+}
+return;
+}
+}
+}
+void
+MediaCache::AddBlockOwnerAsReadahead(int32_t aBlockIndex,
+MediaCacheStream* aStream,
+int32_t aStreamBlockIndex)
+{
+Block* block = &mIndex[aBlockIndex];
+if (block->mOwners.IsEmpty()) {
+mFreeBlocks.RemoveBlock(aBlockIndex);
+}
+BlockOwner* bo = block->mOwners.AppendElement();
+bo->mStream = aStream;
+bo->mStreamBlock = aStreamBlockIndex;
+aStream->mBlocks[aStreamBlockIndex] = aBlockIndex;
+bo->mClass = READAHEAD_BLOCK;
+InsertReadaheadBlock(bo, aBlockIndex);
+}
+void
+MediaCache::FreeBlock(int32_t aBlock)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+Block* block = &mIndex[aBlock];
+if (block->mOwners.IsEmpty()) {
+// already free
+return;
+}
+CACHE_LOG(PR_LOG_DEBUG, ("Released block %d", aBlock));
+for (uint32_t i = 0; i < block->mOwners.Length(); ++i) {
+BlockOwner* bo = &block->mOwners[i];
+GetListForBlock(bo)->RemoveBlock(aBlock);
+bo->mStream->mBlocks[bo->mStreamBlock] = -1;
+}
+block->mOwners.Clear();
+mFreeBlocks.AddFirstBlock(aBlock);
+Verify();
+}
+TimeDuration
+MediaCache::PredictNextUse(TimeStamp aNow, int32_t aBlock)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+NS_ASSERTION(!IsBlockFree(aBlock), "aBlock is free");
+Block* block = &mIndex[aBlock];
+// Blocks can be belong to multiple streams. The predicted next use
+// time is the earliest time predicted by any of the streams.
+TimeDuration result;
+for (uint32_t i = 0; i < block->mOwners.Length(); ++i) {
+BlockOwner* bo = &block->mOwners[i];
+TimeDuration prediction;
+switch (bo->mClass) {
+case METADATA_BLOCK:
+// This block should be managed in LRU mode. For metadata we predict
+// that the time until the next use is the time since the last use.
+prediction = aNow - bo->mLastUseTime;
+break;
+case PLAYED_BLOCK: {
+// This block should be managed in LRU mode, and we should impose
+// a "replay delay" to reflect the likelihood of replay happening
+NS_ASSERTION(static_cast<int64_t>(bo->mStreamBlock)*BLOCK_SIZE <
+bo->mStream->mStreamOffset,
+"Played block after the current stream position?");
+int64_t bytesBehind =
+bo->mStream->mStreamOffset - static_cast<int64_t>(bo->mStreamBlock)*BLOCK_SIZE;
+int64_t millisecondsBehind =
+bytesBehind*1000/bo->mStream->mPlaybackBytesPerSecond;
+prediction = TimeDuration::FromMilliseconds(
+std::min<int64_t>(millisecondsBehind*REPLAY_PENALTY_FACTOR, INT32_MAX));
+break;
+}
+case READAHEAD_BLOCK: {
+int64_t bytesAhead =
+static_cast<int64_t>(bo->mStreamBlock)*BLOCK_SIZE - bo->mStream->mStreamOffset;
+NS_ASSERTION(bytesAhead >= 0,
+"Readahead block before the current stream position?");
+int64_t millisecondsAhead =
+bytesAhead*1000/bo->mStream->mPlaybackBytesPerSecond;
+prediction = TimeDuration::FromMilliseconds(
+std::min<int64_t>(millisecondsAhead, INT32_MAX));
+break;
+}
+default:
+NS_ERROR("Invalid class for predicting next use");
+return TimeDuration(0);
+}
+if (i == 0 || prediction < result) {
+result = prediction;
+}
+}
+return result;
+}
+TimeDuration
+MediaCache::PredictNextUseForIncomingData(MediaCacheStream* aStream)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+int64_t bytesAhead = aStream->mChannelOffset - aStream->mStreamOffset;
+if (bytesAhead <= -BLOCK_SIZE) {
+// Hmm, no idea when data behind us will be used. Guess 24 hours.
+return TimeDuration::FromSeconds(24*60*60);
+}
+if (bytesAhead <= 0)
+return TimeDuration(0);
+int64_t millisecondsAhead = bytesAhead*1000/aStream->mPlaybackBytesPerSecond;
+return TimeDuration::FromMilliseconds(
+std::min<int64_t>(millisecondsAhead, INT32_MAX));
+}
+enum StreamAction { NONE, SEEK, SEEK_AND_RESUME, RESUME, SUSPEND };
+void
+MediaCache::Update()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+// The action to use for each stream. We store these so we can make
+// decisions while holding the cache lock but implement those decisions
+// without holding the cache lock, since we need to call out to
+// stream, decoder and element code.
+nsAutoTArray<StreamAction,10> actions;
+{
+ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+mUpdateQueued = false;
+#ifdef DEBUG
+mInUpdate = true;
+#endif
+int32_t maxBlocks = GetMaxBlocks();
+TimeStamp now = TimeStamp::Now();
+int32_t freeBlockCount = mFreeBlocks.GetCount();
+TimeDuration latestPredictedUseForOverflow = 0;
+if (mIndex.Length() > uint32_t(maxBlocks)) {
+// Try to trim back the cache to its desired maximum size. The cache may
+// have overflowed simply due to data being received when we have
+// no blocks in the main part of the cache that are free or lower
+// priority than the new data. The cache can also be overflowing because
+// the media.cache_size preference was reduced.
+// First, figure out what the least valuable block in the cache overflow
+// is. We don't want to replace any blocks in the main part of the
+// cache whose expected time of next use is earlier or equal to that.
+// If we allow that, we can effectively end up discarding overflowing
+// blocks (by moving an overflowing block to the main part of the cache,
+// and then overwriting it with another overflowing block), and we try
+// to avoid that since it requires HTTP seeks.
+// We also use this loop to eliminate overflowing blocks from
+// freeBlockCount.
+for (int32_t blockIndex = mIndex.Length() - 1; blockIndex >= maxBlocks;
+--blockIndex) {
+if (IsBlockFree(blockIndex)) {
+// Don't count overflowing free blocks in our free block count
+--freeBlockCount;
+continue;
+}
+TimeDuration predictedUse = PredictNextUse(now, blockIndex);
+latestPredictedUseForOverflow = std::max(latestPredictedUseForOverflow, predictedUse);
+}
+} else {
+freeBlockCount += maxBlocks - mIndex.Length();
+}
+// Now try to move overflowing blocks to the main part of the cache.
+for (int32_t blockIndex = mIndex.Length() - 1; blockIndex >= maxBlocks;
+--blockIndex) {
+if (IsBlockFree(blockIndex))
+continue;
+Block* block = &mIndex[blockIndex];
+// Try to relocate the block close to other blocks for the first stream.
+// There is no point in trying to make it close to other blocks in
+// *all* the streams it might belong to.
+int32_t destinationBlockIndex =
+FindReusableBlock(now, block->mOwners[0].mStream,
+block->mOwners[0].mStreamBlock, maxBlocks);
+if (destinationBlockIndex < 0) {
+// Nowhere to place this overflow block. We won't be able to
+// place any more overflow blocks.
+break;
+}
+if (IsBlockFree(destinationBlockIndex) ||
+PredictNextUse(now, destinationBlockIndex) > latestPredictedUseForOverflow) {
+// Reuse blocks in the main part of the cache that are less useful than
+// the least useful overflow blocks
+nsresult rv = mFileCache->MoveBlock(blockIndex, destinationBlockIndex);
+if (NS_SUCCEEDED(rv)) {
+// We successfully copied the file data.
+CACHE_LOG(PR_LOG_DEBUG, ("Swapping blocks %d and %d (trimming cache)",
+blockIndex, destinationBlockIndex));
+// Swapping the block metadata here lets us maintain the
+// correct positions in the linked lists
+SwapBlocks(blockIndex, destinationBlockIndex);
+//Free the overflowing block even if the copy failed.
+CACHE_LOG(PR_LOG_DEBUG, ("Released block %d (trimming cache)", blockIndex));
+FreeBlock(blockIndex);
+}
+} else {
+CACHE_LOG(PR_LOG_DEBUG, ("Could not trim cache block %d (destination %d, predicted next use %f, latest predicted use for overflow %f",
+blockIndex, destinationBlockIndex,
+PredictNextUse(now, destinationBlockIndex).ToSeconds(),
+latestPredictedUseForOverflow.ToSeconds()));
+}
+}
+// Try chopping back the array of cache entries and the cache file.
+Truncate();
+// Count the blocks allocated for readahead of non-seekable streams
+// (these blocks can't be freed but we don't want them to monopolize the
+// cache)
+int32_t nonSeekableReadaheadBlockCount = 0;
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+MediaCacheStream* stream = mStreams[i];
+if (!stream->mIsTransportSeekable) {
+nonSeekableReadaheadBlockCount += stream->mReadaheadBlocks.GetCount();
+}
+}
+// If freeBlockCount is zero, then compute the latest of
+// the predicted next-uses for all blocks
+TimeDuration latestNextUse;
+if (freeBlockCount == 0) {
+int32_t reusableBlock = FindReusableBlock(now, nullptr, 0, maxBlocks);
+if (reusableBlock >= 0) {
+latestNextUse = PredictNextUse(now, reusableBlock);
+}
+}
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+actions.AppendElement(NONE);
+MediaCacheStream* stream = mStreams[i];
+if (stream->mClosed)
+continue;
+// Figure out where we should be reading from. It's the first
+// uncached byte after the current mStreamOffset.
+int64_t dataOffset = stream->GetCachedDataEndInternal(stream->mStreamOffset);
+MOZ_ASSERT(dataOffset >= 0);
+// Compute where we'd actually seek to to read at readOffset
+int64_t desiredOffset = dataOffset;
+if (stream->mIsTransportSeekable) {
+if (desiredOffset > stream->mChannelOffset &&
+desiredOffset <= stream->mChannelOffset + SEEK_VS_READ_THRESHOLD) {
+// Assume it's more efficient to just keep reading up to the
+// desired position instead of trying to seek
+desiredOffset = stream->mChannelOffset;
+}
+} else {
+// We can't seek directly to the desired offset...
+if (stream->mChannelOffset > desiredOffset) {
+// Reading forward won't get us anywhere, we need to go backwards.
+// Seek back to 0 (the client will reopen the stream) and then
+// read forward.
+NS_WARNING("Can't seek backwards, so seeking to 0");
+desiredOffset = 0;
+// Flush cached blocks out, since if this is a live stream
+// the cached data may be completely different next time we
+// read it. We have to assume that live streams don't
+// advertise themselves as being seekable...
+ReleaseStreamBlocks(stream);
+} else {
+// otherwise reading forward is looking good, so just stay where we
+// are and don't trigger a channel seek!
+desiredOffset = stream->mChannelOffset;
+}
+}
+// Figure out if we should be reading data now or not. It's amazing
+// how complex this is, but each decision is simple enough.
+bool enableReading;
+if (stream->mStreamLength >= 0 && dataOffset >= stream->mStreamLength) {
+// We want data at the end of the stream, where there's nothing to
+// read. We don't want to try to read if we're suspended, because that
+// might create a new channel and seek unnecessarily (and incorrectly,
+// since HTTP doesn't allow seeking to the actual EOF), and we don't want
+// to suspend if we're not suspended and already reading at the end of
+// the stream, since there just might be more data than the server
+// advertised with Content-Length, and we may as well keep reading.
+// But we don't want to seek to the end of the stream if we're not
+// already there.
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p at end of stream", stream));
+enableReading = !stream->mCacheSuspended &&
+stream->mStreamLength == stream->mChannelOffset;
+} else if (desiredOffset < stream->mStreamOffset) {
+// We're reading to try to catch up to where the current stream
+// reader wants to be. Better not stop.
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p catching up", stream));
+enableReading = true;
+} else if (desiredOffset < stream->mStreamOffset + BLOCK_SIZE) {
+// The stream reader is waiting for us, or nearly so. Better feed it.
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p feeding reader", stream));
+enableReading = true;
+} else if (!stream->mIsTransportSeekable &&
+nonSeekableReadaheadBlockCount >= maxBlocks*NONSEEKABLE_READAHEAD_MAX) {
+// This stream is not seekable and there are already too many blocks
+// being cached for readahead for nonseekable streams (which we can't
+// free). So stop reading ahead now.
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p throttling non-seekable readahead", stream));
+enableReading = false;
+} else if (mIndex.Length() > uint32_t(maxBlocks)) {
+// We're in the process of bringing the cache size back to the
+// desired limit, so don't bring in more data yet
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p throttling to reduce cache size", stream));
+enableReading = false;
+} else {
+TimeDuration predictedNewDataUse = PredictNextUseForIncomingData(stream);
+if (stream->mCacheSuspended &&
+predictedNewDataUse.ToMilliseconds() > CACHE_POWERSAVE_WAKEUP_LOW_THRESHOLD_MS) {
+// Don't need data for a while, so don't bother waking up the stream
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p avoiding wakeup since more data is not needed", stream));
+enableReading = false;
+} else if (freeBlockCount > 0) {
+// Free blocks in the cache, so keep reading
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p reading since there are free blocks", stream));
+enableReading = true;
+} else if (latestNextUse <= TimeDuration(0)) {
+// No reusable blocks, so can't read anything
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p throttling due to no reusable blocks", stream));
+enableReading = false;
+} else {
+// Read ahead if the data we expect to read is more valuable than
+// the least valuable block in the main part of the cache
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p predict next data in %f, current worst block is %f",
+stream, predictedNewDataUse.ToSeconds(), latestNextUse.ToSeconds()));
+enableReading = predictedNewDataUse < latestNextUse;
+}
+}
+if (enableReading) {
+for (uint32_t j = 0; j < i; ++j) {
+MediaCacheStream* other = mStreams[j];
+if (other->mResourceID == stream->mResourceID &&
+!other->mClient->IsSuspended() &&
+other->mChannelOffset/BLOCK_SIZE == desiredOffset/BLOCK_SIZE) {
+// This block is already going to be read by the other stream.
+// So don't try to read it from this stream as well.
+enableReading = false;
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p waiting on same block (%lld) from stream %p",
+stream, desiredOffset/BLOCK_SIZE, other));
+break;
+}
+}
+}
+if (stream->mChannelOffset != desiredOffset && enableReading) {
+// We need to seek now.
+NS_ASSERTION(stream->mIsTransportSeekable || desiredOffset == 0,
+"Trying to seek in a non-seekable stream!");
+// Round seek offset down to the start of the block. This is essential
+// because we don't want to think we have part of a block already
+// in mPartialBlockBuffer.
+stream->mChannelOffset = (desiredOffset/BLOCK_SIZE)*BLOCK_SIZE;
+actions[i] = stream->mCacheSuspended ? SEEK_AND_RESUME : SEEK;
+} else if (enableReading && stream->mCacheSuspended) {
+actions[i] = RESUME;
+} else if (!enableReading && !stream->mCacheSuspended) {
+actions[i] = SUSPEND;
+}
+}
+#ifdef DEBUG
+mInUpdate = false;
+#endif
+}
+// Update the channel state without holding our cache lock. While we're
+// doing this, decoder threads may be running and seeking, reading or changing
+// other cache state. That's OK, they'll trigger new Update events and we'll
+// get back here and revise our decisions. The important thing here is that
+// performing these actions only depends on mChannelOffset and
+// the action, which can only be written by the main thread (i.e., this
+// thread), so we don't have races here.
+// First, update the mCacheSuspended/mCacheEnded flags so that they're all correct
+// when we fire our CacheClient commands below. Those commands can rely on these flags
+// being set correctly for all streams.
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+MediaCacheStream* stream = mStreams[i];
+switch (actions[i]) {
+case SEEK:
+	case SEEK_AND_RESUME:
+stream->mCacheSuspended = false;
+stream->mChannelEnded = false;
+break;
+case RESUME:
+stream->mCacheSuspended = false;
+break;
+case SUSPEND:
+stream->mCacheSuspended = true;
+break;
+default:
+break;
+}
+stream->mHasHadUpdate = true;
+}
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+MediaCacheStream* stream = mStreams[i];
+nsresult rv;
+switch (actions[i]) {
+case SEEK:
+	case SEEK_AND_RESUME:
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p CacheSeek to %lld (resume=%d)", stream,
+(long long)stream->mChannelOffset, actions[i] == SEEK_AND_RESUME));
+rv = stream->mClient->CacheClientSeek(stream->mChannelOffset,
+actions[i] == SEEK_AND_RESUME);
+break;
+case RESUME:
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p Resumed", stream));
+rv = stream->mClient->CacheClientResume();
+break;
+case SUSPEND:
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p Suspended", stream));
+rv = stream->mClient->CacheClientSuspend();
+break;
+default:
+rv = NS_OK;
+break;
+}
+if (NS_FAILED(rv)) {
+// Close the streams that failed due to error. This will cause all
+// client Read and Seek operations on those streams to fail. Blocked
+// Reads will also be woken up.
+ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+stream->CloseInternal(mon);
+}
+}
+}
+class UpdateEvent : public nsRunnable
+{
+public:
+NS_IMETHOD Run()
+{
+if (gMediaCache) {
+gMediaCache->Update();
+}
+return NS_OK;
+}
+};
+void
+MediaCache::QueueUpdate()
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+// Queuing an update while we're in an update raises a high risk of
+// triggering endless events
+NS_ASSERTION(!mInUpdate,
+"Queuing an update while we're in an update");
+if (mUpdateQueued)
+return;
+mUpdateQueued = true;
+nsCOMPtr<nsIRunnable> event = new UpdateEvent();
+NS_DispatchToMainThread(event);
+}
+#ifdef DEBUG_VERIFY_CACHE
+void
+MediaCache::Verify()
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+mFreeBlocks.Verify();
+for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+MediaCacheStream* stream = mStreams[i];
+stream->mReadaheadBlocks.Verify();
+stream->mPlayedBlocks.Verify();
+stream->mMetadataBlocks.Verify();
+// Verify that the readahead blocks are listed in stream block order
+int32_t block = stream->mReadaheadBlocks.GetFirstBlock();
+int32_t lastStreamBlock = -1;
+while (block >= 0) {
+uint32_t j = 0;
+while (mIndex[block].mOwners[j].mStream != stream) {
+++j;
+}
+int32_t nextStreamBlock =
+int32_t(mIndex[block].mOwners[j].mStreamBlock);
+NS_ASSERTION(lastStreamBlock < nextStreamBlock,
+"Blocks not increasing in readahead stream");
+lastStreamBlock = nextStreamBlock;
+block = stream->mReadaheadBlocks.GetNextBlock(block);
+}
+}
+}
+#endif
+void
+MediaCache::InsertReadaheadBlock(BlockOwner* aBlockOwner,
+int32_t aBlockIndex)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+// Find the last block whose stream block is before aBlockIndex's
+// stream block, and insert after it
+MediaCacheStream* stream = aBlockOwner->mStream;
+int32_t readaheadIndex = stream->mReadaheadBlocks.GetLastBlock();
+while (readaheadIndex >= 0) {
+BlockOwner* bo = GetBlockOwner(readaheadIndex, stream);
+NS_ASSERTION(bo, "stream must own its blocks");
+if (bo->mStreamBlock < aBlockOwner->mStreamBlock) {
+stream->mReadaheadBlocks.AddAfter(aBlockIndex, readaheadIndex);
+return;
+}
+NS_ASSERTION(bo->mStreamBlock > aBlockOwner->mStreamBlock,
+"Duplicated blocks??");
+readaheadIndex = stream->mReadaheadBlocks.GetPrevBlock(readaheadIndex);
+}
+stream->mReadaheadBlocks.AddFirstBlock(aBlockIndex);
+Verify();
+}
+void
+MediaCache::AllocateAndWriteBlock(MediaCacheStream* aStream, const void* aData,
+MediaCacheStream::ReadMode aMode)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+int32_t streamBlockIndex = aStream->mChannelOffset/BLOCK_SIZE;
+// Remove all cached copies of this block
+ResourceStreamIterator iter(aStream->mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+while (streamBlockIndex >= int32_t(stream->mBlocks.Length())) {
+stream->mBlocks.AppendElement(-1);
+}
+if (stream->mBlocks[streamBlockIndex] >= 0) {
+// We no longer want to own this block
+int32_t globalBlockIndex = stream->mBlocks[streamBlockIndex];
+CACHE_LOG(PR_LOG_DEBUG, ("Released block %d from stream %p block %d(%lld)",
+globalBlockIndex, stream, streamBlockIndex, (long long)streamBlockIndex*BLOCK_SIZE));
+RemoveBlockOwner(globalBlockIndex, stream);
+}
+}
+// Extend the mBlocks array as necessary
+TimeStamp now = TimeStamp::Now();
+int32_t blockIndex = FindBlockForIncomingData(now, aStream);
+if (blockIndex >= 0) {
+FreeBlock(blockIndex);
+Block* block = &mIndex[blockIndex];
+CACHE_LOG(PR_LOG_DEBUG, ("Allocated block %d to stream %p block %d(%lld)",
+blockIndex, aStream, streamBlockIndex, (long long)streamBlockIndex*BLOCK_SIZE));
+mFreeBlocks.RemoveBlock(blockIndex);
+// Tell each stream using this resource about the new block.
+ResourceStreamIterator iter(aStream->mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+BlockOwner* bo = block->mOwners.AppendElement();
+if (!bo)
+return;
+bo->mStream = stream;
+bo->mStreamBlock = streamBlockIndex;
+bo->mLastUseTime = now;
+stream->mBlocks[streamBlockIndex] = blockIndex;
+if (streamBlockIndex*BLOCK_SIZE < stream->mStreamOffset) {
+bo->mClass = aMode == MediaCacheStream::MODE_PLAYBACK
+? PLAYED_BLOCK : METADATA_BLOCK;
+// This must be the most-recently-used block, since we
+// marked it as used now (which may be slightly bogus, but we'll
+// treat it as used for simplicity).
+GetListForBlock(bo)->AddFirstBlock(blockIndex);
+Verify();
+} else {
+// This may not be the latest readahead block, although it usually
+// will be. We may have to scan for the right place to insert
+// the block in the list.
+bo->mClass = READAHEAD_BLOCK;
+InsertReadaheadBlock(bo, blockIndex);
+}
+}
+nsresult rv = mFileCache->WriteBlock(blockIndex, reinterpret_cast<const uint8_t*>(aData));
+if (NS_FAILED(rv)) {
+CACHE_LOG(PR_LOG_DEBUG, ("Released block %d from stream %p block %d(%lld)",
+blockIndex, aStream, streamBlockIndex, (long long)streamBlockIndex*BLOCK_SIZE));
+FreeBlock(blockIndex);
+}
+}
+// Queue an Update since the cache state has changed (for example
+// we might want to stop loading because the cache is full)
+QueueUpdate();
+}
+void
+MediaCache::OpenStream(MediaCacheStream* aStream)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p opened", aStream));
+mStreams.AppendElement(aStream);
+aStream->mResourceID = AllocateResourceID();
+// Queue an update since a new stream has been opened.
+gMediaCache->QueueUpdate();
+}
+void
+MediaCache::ReleaseStream(MediaCacheStream* aStream)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p closed", aStream));
+mStreams.RemoveElement(aStream);
+// Update MediaCache again for |mStreams| is changed.
+// We need to re-run Update() to ensure streams reading from the same resource
+// as the removed stream get a chance to continue reading.
+gMediaCache->QueueUpdate();
+}
+void
+MediaCache::ReleaseStreamBlocks(MediaCacheStream* aStream)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+// XXX scanning the entire stream doesn't seem great, if not much of it
+// is cached, but the only easy alternative is to scan the entire cache
+// which isn't better
+uint32_t length = aStream->mBlocks.Length();
+for (uint32_t i = 0; i < length; ++i) {
+int32_t blockIndex = aStream->mBlocks[i];
+if (blockIndex >= 0) {
+CACHE_LOG(PR_LOG_DEBUG, ("Released block %d from stream %p block %d(%lld)",
+blockIndex, aStream, i, (long long)i*BLOCK_SIZE));
+RemoveBlockOwner(blockIndex, aStream);
+}
+}
+}
+void
+MediaCache::Truncate()
+{
+uint32_t end;
+for (end = mIndex.Length(); end > 0; --end) {
+if (!IsBlockFree(end - 1))
+break;
+mFreeBlocks.RemoveBlock(end - 1);
+}
+if (end < mIndex.Length()) {
+mIndex.TruncateLength(end);
+// XXX We could truncate the cache file here, but we don't seem
+// to have a cross-platform API for doing that. At least when all
+// streams are closed we shut down the cache, which erases the
+// file at that point.
+}
+}
+void
+MediaCache::NoteBlockUsage(MediaCacheStream* aStream, int32_t aBlockIndex,
+MediaCacheStream::ReadMode aMode,
+TimeStamp aNow)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+if (aBlockIndex < 0) {
+// this block is not in the cache yet
+return;
+}
+BlockOwner* bo = GetBlockOwner(aBlockIndex, aStream);
+if (!bo) {
+// this block is not in the cache yet
+return;
+}
+// The following check has to be <= because the stream offset has
+// not yet been updated for the data read from this block
+NS_ASSERTION(bo->mStreamBlock*BLOCK_SIZE <= bo->mStream->mStreamOffset,
+"Using a block that's behind the read position?");
+GetListForBlock(bo)->RemoveBlock(aBlockIndex);
+bo->mClass =
+(aMode == MediaCacheStream::MODE_METADATA || bo->mClass == METADATA_BLOCK)
+? METADATA_BLOCK : PLAYED_BLOCK;
+// Since this is just being used now, it can definitely be at the front
+// of mMetadataBlocks or mPlayedBlocks
+GetListForBlock(bo)->AddFirstBlock(aBlockIndex);
+bo->mLastUseTime = aNow;
+Verify();
+}
+void
+MediaCache::NoteSeek(MediaCacheStream* aStream, int64_t aOldOffset)
+{
+mReentrantMonitor.AssertCurrentThreadIn();
+if (aOldOffset < aStream->mStreamOffset) {
+// We seeked forward. Convert blocks from readahead to played.
+// Any readahead block that intersects the seeked-over range must
+// be converted.
+int32_t blockIndex = aOldOffset/BLOCK_SIZE;
+int32_t endIndex =
+std::min<int64_t>((aStream->mStreamOffset + BLOCK_SIZE - 1)/BLOCK_SIZE,
+aStream->mBlocks.Length());
+TimeStamp now = TimeStamp::Now();
+while (blockIndex < endIndex) {
+int32_t cacheBlockIndex = aStream->mBlocks[blockIndex];
+if (cacheBlockIndex >= 0) {
+// Marking the block used may not be exactly what we want but
+// it's simple
+NoteBlockUsage(aStream, cacheBlockIndex, MediaCacheStream::MODE_PLAYBACK,
+now);
+}
+++blockIndex;
+}
+} else {
+// We seeked backward. Convert from played to readahead.
+// Any played block that is entirely after the start of the seeked-over
+// range must be converted.
+int32_t blockIndex =
+(aStream->mStreamOffset + BLOCK_SIZE - 1)/BLOCK_SIZE;
+int32_t endIndex =
+std::min<int64_t>((aOldOffset + BLOCK_SIZE - 1)/BLOCK_SIZE,
+aStream->mBlocks.Length());
+while (blockIndex < endIndex) {
+int32_t cacheBlockIndex = aStream->mBlocks[endIndex - 1];
+if (cacheBlockIndex >= 0) {
+BlockOwner* bo = GetBlockOwner(cacheBlockIndex, aStream);
+NS_ASSERTION(bo, "Stream doesn't own its blocks?");
+if (bo->mClass == PLAYED_BLOCK) {
+aStream->mPlayedBlocks.RemoveBlock(cacheBlockIndex);
+bo->mClass = READAHEAD_BLOCK;
+// Adding this as the first block is sure to be OK since
+// this must currently be the earliest readahead block
+// (that's why we're proceeding backwards from the end of
+// the seeked range to the start)
+aStream->mReadaheadBlocks.AddFirstBlock(cacheBlockIndex);
+Verify();
+}
+}
+--endIndex;
+}
+}
+}
+void
+MediaCacheStream::NotifyDataLength(int64_t aLength)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+mStreamLength = aLength;
+}
+void
+MediaCacheStream::NotifyDataStarted(int64_t aOffset)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+NS_WARN_IF_FALSE(aOffset == mChannelOffset,
+"Server is giving us unexpected offset");
+MOZ_ASSERT(aOffset >= 0);
+mChannelOffset = aOffset;
+if (mStreamLength >= 0) {
+// If we started reading at a certain offset, then for sure
+// the stream is at least that long.
+mStreamLength = std::max(mStreamLength, mChannelOffset);
+}
+}
+bool
+MediaCacheStream::UpdatePrincipal(nsIPrincipal* aPrincipal)
+{
+return nsContentUtils::CombineResourcePrincipals(&mPrincipal, aPrincipal);
+}
+void
+MediaCacheStream::NotifyDataReceived(int64_t aSize, const char* aData,
+nsIPrincipal* aPrincipal)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+// Update principals before putting the data in the cache. This is important,
+// we want to make sure all principals are updated before any consumer
+// can see the new data.
+// We do this without holding the cache monitor, in case the client wants
+// to do something that takes a lock.
+{
+MediaCache::ResourceStreamIterator iter(mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+if (stream->UpdatePrincipal(aPrincipal)) {
+stream->mClient->CacheClientNotifyPrincipalChanged();
+}
+}
+}
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+int64_t size = aSize;
+const char* data = aData;
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p DataReceived at %lld count=%lld",
+this, (long long)mChannelOffset, (long long)aSize));
+// We process the data one block (or part of a block) at a time
+while (size > 0) {
+uint32_t blockIndex = mChannelOffset/BLOCK_SIZE;
+int32_t blockOffset = int32_t(mChannelOffset - blockIndex*BLOCK_SIZE);
+int32_t chunkSize = std::min<int64_t>(BLOCK_SIZE - blockOffset, size);
+// This gets set to something non-null if we have a whole block
+// of data to write to the cache
+const char* blockDataToStore = nullptr;
+ReadMode mode = MODE_PLAYBACK;
+if (blockOffset == 0 && chunkSize == BLOCK_SIZE) {
+// We received a whole block, so avoid a useless copy through
+// mPartialBlockBuffer
+blockDataToStore = data;
+} else {
+if (blockOffset == 0) {
+// We've just started filling this buffer so now is a good time
+// to clear this flag.
+mMetadataInPartialBlockBuffer = false;
+}
+memcpy(reinterpret_cast<char*>(mPartialBlockBuffer.get()) + blockOffset,
+data, chunkSize);
+if (blockOffset + chunkSize == BLOCK_SIZE) {
+// We completed a block, so lets write it out.
+blockDataToStore = reinterpret_cast<char*>(mPartialBlockBuffer.get());
+if (mMetadataInPartialBlockBuffer) {
+mode = MODE_METADATA;
+}
+}
+}
+if (blockDataToStore) {
+gMediaCache->AllocateAndWriteBlock(this, blockDataToStore, mode);
+}
+mChannelOffset += chunkSize;
+size -= chunkSize;
+data += chunkSize;
+}
+MediaCache::ResourceStreamIterator iter(mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+if (stream->mStreamLength >= 0) {
+// The stream is at least as long as what we've read
+stream->mStreamLength = std::max(stream->mStreamLength, mChannelOffset);
+}
+stream->mClient->CacheClientNotifyDataReceived();
+}
+// Notify in case there's a waiting reader
+// XXX it would be fairly easy to optimize things a lot more to
+// avoid waking up reader threads unnecessarily
+mon.NotifyAll();
+}
+void
+MediaCacheStream::FlushPartialBlockInternal(bool aNotifyAll)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+int32_t blockOffset = int32_t(mChannelOffset%BLOCK_SIZE);
+if (blockOffset > 0) {
+CACHE_LOG(PR_LOG_DEBUG,
+("Stream %p writing partial block: [%d] bytes; "
+"mStreamOffset [%lld] mChannelOffset[%lld] mStreamLength [%lld] "
+"notifying: [%s]",
+this, blockOffset, mStreamOffset, mChannelOffset, mStreamLength,
+aNotifyAll ? "yes" : "no"));
+// Write back the partial block
+memset(reinterpret_cast<char*>(mPartialBlockBuffer.get()) + blockOffset, 0,
+BLOCK_SIZE - blockOffset);
+gMediaCache->AllocateAndWriteBlock(this, mPartialBlockBuffer,
+mMetadataInPartialBlockBuffer ? MODE_METADATA : MODE_PLAYBACK);
+if (aNotifyAll) {
+// Wake up readers who may be waiting for this data
+mon.NotifyAll();
+}
+}
+}
+void
+MediaCacheStream::FlushPartialBlock()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+// Write the current partial block to memory.
+// Note: This writes a full block, so if data is not at the end of the
+// stream, the decoder must subsequently choose correct start and end offsets
+// for reading/seeking.
+FlushPartialBlockInternal(false);
+gMediaCache->QueueUpdate();
+}
+void
+MediaCacheStream::NotifyDataEnded(nsresult aStatus)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (NS_FAILED(aStatus)) {
+// Disconnect from other streams sharing our resource, since they
+// should continue trying to load. Our load might have been deliberately
+// canceled and that shouldn't affect other streams.
+mResourceID = gMediaCache->AllocateResourceID();
+}
+FlushPartialBlockInternal(true);
+if (!mDidNotifyDataEnded) {
+MediaCache::ResourceStreamIterator iter(mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+if (NS_SUCCEEDED(aStatus)) {
+// We read the whole stream, so remember the true length
+stream->mStreamLength = mChannelOffset;
+}
+NS_ASSERTION(!stream->mDidNotifyDataEnded, "Stream already ended!");
+stream->mDidNotifyDataEnded = true;
+stream->mNotifyDataEndedStatus = aStatus;
+stream->mClient->CacheClientNotifyDataEnded(aStatus);
+}
+}
+mChannelEnded = true;
+gMediaCache->QueueUpdate();
+}
+MediaCacheStream::~MediaCacheStream()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+NS_ASSERTION(!mPinCount, "Unbalanced Pin");
+if (gMediaCache) {
+NS_ASSERTION(mClosed, "Stream was not closed");
+gMediaCache->ReleaseStream(this);
+MediaCache::MaybeShutdown();
+}
+}
+void
+MediaCacheStream::SetTransportSeekable(bool aIsTransportSeekable)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+NS_ASSERTION(mIsTransportSeekable || aIsTransportSeekable ||
+mChannelOffset == 0, "channel offset must be zero when we become non-seekable");
+mIsTransportSeekable = aIsTransportSeekable;
+// Queue an Update since we may change our strategy for dealing
+// with this stream
+gMediaCache->QueueUpdate();
+}
+bool
+MediaCacheStream::IsTransportSeekable()
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+return mIsTransportSeekable;
+}
+bool
+MediaCacheStream::AreAllStreamsForResourceSuspended()
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+MediaCache::ResourceStreamIterator iter(mResourceID);
+// Look for a stream that's able to read the data we need
+int64_t dataOffset = -1;
+while (MediaCacheStream* stream = iter.Next()) {
+if (stream->mCacheSuspended || stream->mChannelEnded || stream->mClosed) {
+continue;
+}
+if (dataOffset < 0) {
+dataOffset = GetCachedDataEndInternal(mStreamOffset);
+}
+// Ignore streams that are reading beyond the data we need
+if (stream->mChannelOffset > dataOffset) {
+continue;
+}
+return false;
+}
+return true;
+}
+void
+MediaCacheStream::Close()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+CloseInternal(mon);
+// Queue an Update since we may have created more free space. Don't do
+// it from CloseInternal since that gets called by Update() itself
+// sometimes, and we try to not to queue updates from Update().
+gMediaCache->QueueUpdate();
+}
+void
+MediaCacheStream::EnsureCacheUpdate()
+{
+if (mHasHadUpdate)
+return;
+gMediaCache->Update();
+}
+void
+MediaCacheStream::CloseInternal(ReentrantMonitorAutoEnter& aReentrantMonitor)
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+if (mClosed)
+return;
+mClosed = true;
+gMediaCache->ReleaseStreamBlocks(this);
+// Wake up any blocked readers
+aReentrantMonitor.NotifyAll();
+}
+void
+MediaCacheStream::Pin()
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+++mPinCount;
+// Queue an Update since we may no longer want to read more into the
+// cache, if this stream's block have become non-evictable
+gMediaCache->QueueUpdate();
+}
+void
+MediaCacheStream::Unpin()
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+NS_ASSERTION(mPinCount > 0, "Unbalanced Unpin");
+--mPinCount;
+// Queue an Update since we may be able to read more into the
+// cache, if this stream's block have become evictable
+gMediaCache->QueueUpdate();
+}
+int64_t
+MediaCacheStream::GetLength()
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+return mStreamLength;
+}
+int64_t
+MediaCacheStream::GetNextCachedData(int64_t aOffset)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+return GetNextCachedDataInternal(aOffset);
+}
+int64_t
+MediaCacheStream::GetCachedDataEnd(int64_t aOffset)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+return GetCachedDataEndInternal(aOffset);
+}
+bool
+MediaCacheStream::IsDataCachedToEndOfStream(int64_t aOffset)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (mStreamLength < 0)
+return false;
+return GetCachedDataEndInternal(aOffset) >= mStreamLength;
+}
+int64_t
+MediaCacheStream::GetCachedDataEndInternal(int64_t aOffset)
+{
+gMediaCache->GetReentrantMonitor().AssertCurrentThreadIn();
+uint32_t startBlockIndex = aOffset/BLOCK_SIZE;
+uint32_t blockIndex = startBlockIndex;
+while (blockIndex < mBlocks.Length() && mBlocks[blockIndex] != -1) {
+++blockIndex;
+}
+int64_t result = blockIndex*BLOCK_SIZE;
+if (blockIndex == mChannelOffset/BLOCK_SIZE) {
+// The block containing mChannelOffset may be partially read but not
+// yet committed to the main cache
+result = mChannelOffset;
+}
+if (mStreamLength >= 0) {
+// The last block in the cache may only be partially valid, so limit
+// the cached range to the stream length
+result = std::min(result, mStreamLength);
+}
+return std::max(result, aOffset);
+}
+int64_t
+MediaCacheStream::GetNextCachedDataInternal(int64_t aOffset)
+{
+gMediaCache->GetReentrantMonitor().AssertCurrentThreadIn();
+if (aOffset == mStreamLength)
+return -1;
+uint32_t startBlockIndex = aOffset/BLOCK_SIZE;
+uint32_t channelBlockIndex = mChannelOffset/BLOCK_SIZE;
+if (startBlockIndex == channelBlockIndex &&
+aOffset < mChannelOffset) {
+// The block containing mChannelOffset is partially read, but not
+// yet committed to the main cache. aOffset lies in the partially
+// read portion, thus it is effectively cached.
+return aOffset;
+}
+if (startBlockIndex >= mBlocks.Length())
+return -1;
+// Is the current block cached?
+if (mBlocks[startBlockIndex] != -1)
+return aOffset;
+// Count the number of uncached blocks
+bool hasPartialBlock = (mChannelOffset % BLOCK_SIZE) != 0;
+uint32_t blockIndex = startBlockIndex + 1;
+while (true) {
+if ((hasPartialBlock && blockIndex == channelBlockIndex) ||
+(blockIndex < mBlocks.Length() && mBlocks[blockIndex] != -1)) {
+// We at the incoming channel block, which has has data in it,
+// or are we at a cached block. Return index of block start.
+return blockIndex * BLOCK_SIZE;
+}
+// No more cached blocks?
+if (blockIndex >= mBlocks.Length())
+return -1;
+++blockIndex;
+}
+NS_NOTREACHED("Should return in loop");
+return -1;
+}
+void
+MediaCacheStream::SetReadMode(ReadMode aMode)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (aMode == mCurrentMode)
+return;
+mCurrentMode = aMode;
+gMediaCache->QueueUpdate();
+}
+void
+MediaCacheStream::SetPlaybackRate(uint32_t aBytesPerSecond)
+{
+NS_ASSERTION(aBytesPerSecond > 0, "Zero playback rate not allowed");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (aBytesPerSecond == mPlaybackBytesPerSecond)
+return;
+mPlaybackBytesPerSecond = aBytesPerSecond;
+gMediaCache->QueueUpdate();
+}
+nsresult
+MediaCacheStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (mClosed)
+return NS_ERROR_FAILURE;
+int64_t oldOffset = mStreamOffset;
+int64_t newOffset = mStreamOffset;
+switch (aWhence) {
+case PR_SEEK_END:
+if (mStreamLength < 0)
+return NS_ERROR_FAILURE;
+newOffset = mStreamLength + aOffset;
+break;
+case PR_SEEK_CUR:
+newOffset += aOffset;
+break;
+case PR_SEEK_SET:
+newOffset = aOffset;
+break;
+default:
+NS_ERROR("Unknown whence");
+return NS_ERROR_FAILURE;
+}
+if (newOffset < 0)
+return NS_ERROR_FAILURE;
+mStreamOffset = newOffset;
+CACHE_LOG(PR_LOG_DEBUG, ("Stream %p Seek to %lld", this, (long long)mStreamOffset));
+gMediaCache->NoteSeek(this, oldOffset);
+gMediaCache->QueueUpdate();
+return NS_OK;
+}
+int64_t
+MediaCacheStream::Tell()
+{
+NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+return mStreamOffset;
+}
+nsresult
+MediaCacheStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aBytes)
+{
+NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (mClosed)
+return NS_ERROR_FAILURE;
+uint32_t count = 0;
+// Read one block (or part of a block) at a time
+while (count < aCount) {
+uint32_t streamBlock = uint32_t(mStreamOffset/BLOCK_SIZE);
+uint32_t offsetInStreamBlock =
+uint32_t(mStreamOffset - streamBlock*BLOCK_SIZE);
+int64_t size = std::min(aCount - count, BLOCK_SIZE - offsetInStreamBlock);
+if (mStreamLength >= 0) {
+// Don't try to read beyond the end of the stream
+int64_t bytesRemaining = mStreamLength - mStreamOffset;
+if (bytesRemaining <= 0) {
+// Get out of here and return NS_OK
+break;
+}
+size = std::min(size, bytesRemaining);
+// Clamp size until 64-bit file size issues are fixed.
+size = std::min(size, int64_t(INT32_MAX));
+}
+int32_t cacheBlock = streamBlock < mBlocks.Length() ? mBlocks[streamBlock] : -1;
+if (cacheBlock < 0) {
+// We don't have a complete cached block here.
+if (count > 0) {
+// Some data has been read, so return what we've got instead of
+// blocking or trying to find a stream with a partial block.
+break;
+}
+// See if the data is available in the partial cache block of any
+// stream reading this resource. We need to do this in case there is
+// another stream with this resource that has all the data to the end of
+// the stream but the data doesn't end on a block boundary.
+MediaCacheStream* streamWithPartialBlock = nullptr;
+MediaCache::ResourceStreamIterator iter(mResourceID);
+while (MediaCacheStream* stream = iter.Next()) {
+if (uint32_t(stream->mChannelOffset/BLOCK_SIZE) == streamBlock &&
+mStreamOffset < stream->mChannelOffset) {
+streamWithPartialBlock = stream;
+break;
+}
+}
+if (streamWithPartialBlock) {
+// We can just use the data in mPartialBlockBuffer. In fact we should
+// use it rather than waiting for the block to fill and land in
+// the cache.
+int64_t bytes = std::min<int64_t>(size, streamWithPartialBlock->mChannelOffset - mStreamOffset);
+// Clamp bytes until 64-bit file size issues are fixed.
+bytes = std::min(bytes, int64_t(INT32_MAX));
+NS_ABORT_IF_FALSE(bytes >= 0 && bytes <= aCount, "Bytes out of range.");
+memcpy(aBuffer,
+reinterpret_cast<char*>(streamWithPartialBlock->mPartialBlockBuffer.get()) + offsetInStreamBlock, bytes);
+if (mCurrentMode == MODE_METADATA) {
+streamWithPartialBlock->mMetadataInPartialBlockBuffer = true;
+}
+mStreamOffset += bytes;
+count = bytes;
+break;
+}
+// No data has been read yet, so block
+mon.Wait();
+if (mClosed) {
+// We may have successfully read some data, but let's just throw
+// that out.
+return NS_ERROR_FAILURE;
+}
+continue;
+}
+gMediaCache->NoteBlockUsage(this, cacheBlock, mCurrentMode, TimeStamp::Now());
+int64_t offset = cacheBlock*BLOCK_SIZE + offsetInStreamBlock;
+int32_t bytes;
+NS_ABORT_IF_FALSE(size >= 0 && size <= INT32_MAX, "Size out of range.");
+nsresult rv = gMediaCache->ReadCacheFile(offset, aBuffer + count, int32_t(size), &bytes);
+if (NS_FAILED(rv)) {
+if (count == 0)
+return rv;
+// If we did successfully read some data, may as well return it
+break;
+}
+mStreamOffset += bytes;
+count += bytes;
+}
+if (count > 0) {
+// Some data was read, so queue an update since block priorities may
+// have changed
+gMediaCache->QueueUpdate();
+}
+CACHE_LOG(PR_LOG_DEBUG,
+("Stream %p Read at %lld count=%d", this, (long long)(mStreamOffset-count), count));
+*aBytes = count;
+return NS_OK;
+}
+nsresult
+MediaCacheStream::ReadAt(int64_t aOffset, char* aBuffer,
+uint32_t aCount, uint32_t* aBytes)
+{
+NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+nsresult rv = Seek(nsISeekableStream::NS_SEEK_SET, aOffset);
+if (NS_FAILED(rv)) return rv;
+return Read(aBuffer, aCount, aBytes);
+}
+nsresult
+MediaCacheStream::ReadFromCache(char* aBuffer, int64_t aOffset, int64_t aCount)
+{
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+if (mClosed)
+return NS_ERROR_FAILURE;
+// Read one block (or part of a block) at a time
+uint32_t count = 0;
+int64_t streamOffset = aOffset;
+while (count < aCount) {
+uint32_t streamBlock = uint32_t(streamOffset/BLOCK_SIZE);
+uint32_t offsetInStreamBlock =
+uint32_t(streamOffset - streamBlock*BLOCK_SIZE);
+int64_t size = std::min<int64_t>(aCount - count, BLOCK_SIZE - offsetInStreamBlock);
+if (mStreamLength >= 0) {
+// Don't try to read beyond the end of the stream
+int64_t bytesRemaining = mStreamLength - streamOffset;
+if (bytesRemaining <= 0) {
+return NS_ERROR_FAILURE;
+}
+size = std::min(size, bytesRemaining);
+// Clamp size until 64-bit file size issues are fixed.
+size = std::min(size, int64_t(INT32_MAX));
+}
+int32_t bytes;
+uint32_t channelBlock = uint32_t(mChannelOffset/BLOCK_SIZE);
+int32_t cacheBlock = streamBlock < mBlocks.Length() ? mBlocks[streamBlock] : -1;
+if (channelBlock == streamBlock && streamOffset < mChannelOffset) {
+// We can just use the data in mPartialBlockBuffer. In fact we should
+// use it rather than waiting for the block to fill and land in
+// the cache.
+// Clamp bytes until 64-bit file size issues are fixed.
+int64_t toCopy = std::min<int64_t>(size, mChannelOffset - streamOffset);
+bytes = std::min(toCopy, int64_t(INT32_MAX));
+NS_ABORT_IF_FALSE(bytes >= 0 && bytes <= toCopy, "Bytes out of range.");
+memcpy(aBuffer + count,
+reinterpret_cast<char*>(mPartialBlockBuffer.get()) + offsetInStreamBlock, bytes);
+} else {
+if (cacheBlock < 0) {
+// We expect all blocks to be cached! Fail!
+return NS_ERROR_FAILURE;
+}
+int64_t offset = cacheBlock*BLOCK_SIZE + offsetInStreamBlock;
+NS_ABORT_IF_FALSE(size >= 0 && size <= INT32_MAX, "Size out of range.");
+nsresult rv = gMediaCache->ReadCacheFile(offset, aBuffer + count, int32_t(size), &bytes);
+if (NS_FAILED(rv)) {
+return rv;
+}
+}
+streamOffset += bytes;
+count += bytes;
+}
+return NS_OK;
+}
+nsresult
+MediaCacheStream::Init()
+{
+NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
+if (mInitialized)
+return NS_OK;
+InitMediaCache();
+if (!gMediaCache)
+return NS_ERROR_FAILURE;
+gMediaCache->OpenStream(this);
+mInitialized = true;
+return NS_OK;
+}
+nsresult
+MediaCacheStream::InitAsClone(MediaCacheStream* aOriginal)
+{
+if (!aOriginal->IsAvailableForSharing())
+return NS_ERROR_FAILURE;
+if (mInitialized)
+return NS_OK;
+nsresult rv = Init();
+if (NS_FAILED(rv))
+return rv;
+mResourceID = aOriginal->mResourceID;
+// Grab cache blocks from aOriginal as readahead blocks for our stream
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+mPrincipal = aOriginal->mPrincipal;
+mStreamLength = aOriginal->mStreamLength;
+mIsTransportSeekable = aOriginal->mIsTransportSeekable;
+// Cloned streams are initially suspended, since there is no channel open
+// initially for a clone.
+mCacheSuspended = true;
+mChannelEnded = true;
+if (aOriginal->mDidNotifyDataEnded) {
+mNotifyDataEndedStatus = aOriginal->mNotifyDataEndedStatus;
+mDidNotifyDataEnded = true;
+mClient->CacheClientNotifyDataEnded(mNotifyDataEndedStatus);
+}
+for (uint32_t i = 0; i < aOriginal->mBlocks.Length(); ++i) {
+int32_t cacheBlockIndex = aOriginal->mBlocks[i];
+if (cacheBlockIndex < 0)
+continue;
+while (i >= mBlocks.Length()) {
+mBlocks.AppendElement(-1);
+}
+// Every block is a readahead block for the clone because the clone's initial
+// stream offset is zero
+gMediaCache->AddBlockOwnerAsReadahead(cacheBlockIndex, this, i);
+}
+return NS_OK;
+}
+nsresult MediaCacheStream::GetCachedRanges(nsTArray<MediaByteRange>& aRanges)
+{
+// Take the monitor, so that the cached data ranges can't grow while we're
+// trying to loop over them.
+ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
+// We must be pinned while running this, otherwise the cached data ranges may
+// shrink while we're trying to loop over them.
+NS_ASSERTION(mPinCount > 0, "Must be pinned");
+int64_t startOffset = GetNextCachedData(0);
+while (startOffset >= 0) {
+int64_t endOffset = GetCachedDataEnd(startOffset);
+NS_ASSERTION(startOffset < endOffset, "Buffered range must end after its start");
+// Bytes [startOffset..endOffset] are cached.
+aRanges.AppendElement(MediaByteRange(startOffset, endOffset));
+startOffset = GetNextCachedData(endOffset);
+NS_ASSERTION(startOffset == -1 || startOffset > endOffset,
+"Must have advanced to start of next range, or hit end of stream");
+}
+return NS_OK;
+}
+} // namespace mozilla

The Tor Browser / file comparison

comparison: content/media/MediaCache.cpp

content/media/MediaCache.cpp