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gecko-dev/dom/media/MediaCache.cpp
Chris Pearce cabb78f52e Bug 1347031 - Move the MediaCache off of opening its temporary file fd synchronously in the content process. r=jwwang 
In bug 1346987 we're attempting to remove uses of the
NS_OpenAnonymousTemporaryFile() in the content process as it sends a
synchronous IPC to the parent process on the main thread, which can cause UI
jank. This patch makes the MediaCache use the async anonymous temporary file
creation function added in bug 1346987.

The file descriptor is held by the FileBlockCache. This object buffers data
passed to it in memory, and defers writing of said data to another thread. I
added the async wait for the file descriptor to be inside that async "defer to
other thread" step.

This means that while the content process is waiting for the file descriptor to
come down from the parent process, we'll buffer media data being streamed in
memory. Given that our MSE implementation will buffer up to 100MB of media data
in memory anyway, it seems that more buffering in the src=url case while we
wait for an async IPC to do a round trip to the main process is acceptable.

MozReview-Commit-ID: 3OTBTWw5pr0

--HG--
extra : rebase_source : 56e0a1f1473db3c9722330254f7a4bf3a1f5caa3
2017-03-17 09:54:23 +13:00

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/* -*- 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 "mozilla/Logging.h"
#include "mozilla/Preferences.h"
#include "FileBlockCache.h"
#include "nsIObserverService.h"
#include "nsISeekableStream.h"
#include "nsIPrincipal.h"
#include "mozilla/Attributes.h"
#include "mozilla/Services.h"
#include <algorithm>
namespace mozilla {
LazyLogModule gMediaCacheLog("MediaCache");
#define CACHE_LOG(type, msg) MOZ_LOG(gMediaCacheLog, type, msg)
// 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;
#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 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, "cacheservice:empty-cache", true);
}
}
class MediaCache {
public:
friend class MediaCacheStream::BlockList;
typedef MediaCacheStream::BlockList BlockList;
static const int64_t 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,
int64_t aStreamOffset,
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();
// Notify all streams for the resource ID that the suspended status changed
// at the end of MediaCache::Update.
void QueueSuspendedStatusUpdate(int64_t aResourceID);
// 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:
explicit 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 {
constexpr BlockOwner() {}
// The stream that owns this block, or null if the block is free.
MediaCacheStream* mStream = nullptr;
// The block index in the stream. Valid only if mStream is non-null.
// Initialized to an insane value to highlight misuse.
uint32_t mStreamBlock = UINT32_MAX;
// Time at which this block was last used. Valid only if
// mClass is METADATA_BLOCK or PLAYED_BLOCK.
TimeStamp mLastUseTime;
BlockClass mClass = READAHEAD_BLOCK;
};
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.
RefPtr<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
// A list of resource IDs to notify about the change in suspended status.
nsTArray<int64_t> mSuspendedStatusToNotify;
};
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, "cacheservice:empty-cache") == 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(MakeUnique<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.ShallowSizeOfExcludingThis(aMallocSizeOf);
size += mReadaheadBlocks.SizeOfExcludingThis(aMallocSizeOf);
size += mMetadataBlocks.SizeOfExcludingThis(aMallocSizeOf);
size += mPlayedBlocks.SizeOfExcludingThis(aMallocSizeOf);
size += aMallocSizeOf(mPartialBlockBuffer.get());
return size;
}
size_t MediaCacheStream::BlockList::SizeOfExcludingThis(
MallocSizeOf aMallocSizeOf) const
{
return mEntries.ShallowSizeOfExcludingThis(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(entry);
--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?");
mFileCache = new FileBlockCache();
nsresult rv = mFileCache->Init();
NS_ENSURE_SUCCESS(rv,rv);
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();
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), uint32_t(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.
AutoTArray<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(LogLevel::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.
AutoTArray<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(LogLevel::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(LogLevel::Debug, ("Released block %d (trimming cache)", blockIndex));
FreeBlock(blockIndex);
}
} else {
CACHE_LOG(LogLevel::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);
}
}
int32_t resumeThreshold = Preferences::GetInt("media.cache_resume_threshold", 10);
int32_t readaheadLimit = Preferences::GetInt("media.cache_readahead_limit", 30);
for (uint32_t i = 0; i < mStreams.Length(); ++i) {
actions.AppendElement(NONE);
MediaCacheStream* stream = mStreams[i];
if (stream->mClosed) {
CACHE_LOG(LogLevel::Debug, ("Stream %p closed", stream));
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(LogLevel::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(LogLevel::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(LogLevel::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(LogLevel::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(LogLevel::Debug, ("Stream %p throttling to reduce cache size", stream));
enableReading = false;
} else {
TimeDuration predictedNewDataUse = PredictNextUseForIncomingData(stream);
if (stream->mCacheSuspended &&
predictedNewDataUse.ToSeconds() > resumeThreshold) {
// Don't need data for a while, so don't bother waking up the stream
CACHE_LOG(LogLevel::Debug, ("Stream %p avoiding wakeup since more data is not needed", stream));
enableReading = false;
} else if (predictedNewDataUse.ToSeconds() > readaheadLimit) {
// Don't read ahead more than this much
CACHE_LOG(LogLevel::Debug, ("Stream %p throttling to avoid reading ahead too far", stream));
enableReading = false;
} else if (freeBlockCount > 0) {
// Free blocks in the cache, so keep reading
CACHE_LOG(LogLevel::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(LogLevel::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(LogLevel::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->mClosed && !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(LogLevel::Debug, ("Stream %p waiting on same block (%"
PRId64 ") 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(LogLevel::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(LogLevel::Debug, ("Stream %p Resumed", stream));
rv = stream->mClient->CacheClientResume();
QueueSuspendedStatusUpdate(stream->mResourceID);
break;
case SUSPEND:
CACHE_LOG(LogLevel::Debug, ("Stream %p Suspended", stream));
rv = stream->mClient->CacheClientSuspend();
QueueSuspendedStatusUpdate(stream->mResourceID);
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);
}
}
// Notify streams about the suspended status changes.
for (uint32_t i = 0; i < mSuspendedStatusToNotify.Length(); ++i) {
MediaCache::ResourceStreamIterator iter(mSuspendedStatusToNotify[i]);
while (MediaCacheStream* stream = iter.Next()) {
stream->mClient->CacheClientNotifySuspendedStatusChanged();
}
}
mSuspendedStatusToNotify.Clear();
}
class UpdateEvent : public Runnable
{
public:
UpdateEvent() : Runnable("MediaCache::UpdateEvent") {}
NS_IMETHOD Run() override
{
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;
// XXX MediaCache does updates when decoders are still running at
// shutdown and get freed in the final cycle-collector cleanup. So
// don't leak a runnable in that case.
nsCOMPtr<nsIRunnable> event = new UpdateEvent();
SystemGroup::Dispatch("MediaCache::UpdateEvent",
TaskCategory::Other,
event.forget());
}
void
MediaCache::QueueSuspendedStatusUpdate(int64_t aResourceID)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
if (!mSuspendedStatusToNotify.Contains(aResourceID)) {
mSuspendedStatusToNotify.AppendElement(aResourceID);
}
}
#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(LogLevel::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(LogLevel::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(LogLevel::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(LogLevel::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(LogLevel::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(LogLevel::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,
int64_t aStreamOffset,
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 <= aStreamOffset,
"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, aStream->mStreamOffset,
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) {
MOZ_ASSERT(endIndex > 0);
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_WARNING_ASSERTION(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(LogLevel::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,
ReentrantMonitorAutoEnter& aReentrantMonitor)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
int32_t blockOffset = int32_t(mChannelOffset%BLOCK_SIZE);
if (blockOffset > 0) {
CACHE_LOG(LogLevel::Debug,
("Stream %p writing partial block: [%d] bytes; "
"mStreamOffset [%" PRId64 "] mChannelOffset[%"
PRId64 "] mStreamLength [%" PRId64 "] 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.get(),
mMetadataInPartialBlockBuffer ? MODE_METADATA : MODE_PLAYBACK);
}
// |mChannelOffset == 0| means download ends with no bytes received.
// We should also wake up those readers who are waiting for data
// that will never come.
if ((blockOffset > 0 || mChannelOffset == 0) && aNotifyAll) {
// Wake up readers who may be waiting for this data
aReentrantMonitor.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, mon);
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();
}
// It is prudent to update channel/cache status before calling
// CacheClientNotifyDataEnded() which will read |mChannelEnded|.
FlushPartialBlockInternal(true, mon);
mChannelEnded = true;
gMediaCache->QueueUpdate();
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;
}
if (!stream->mDidNotifyDataEnded) {
stream->mDidNotifyDataEnded = true;
stream->mNotifyDataEndedStatus = aStatus;
stream->mClient->CacheClientNotifyDataEnded(aStatus);
}
}
}
void
MediaCacheStream::NotifyChannelRecreated()
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
ReentrantMonitorAutoEnter mon(gMediaCache->GetReentrantMonitor());
mChannelEnded = false;
mDidNotifyDataEnded = false;
}
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");
if (!mInitialized)
return;
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;
// Closing a stream will change the return value of
// MediaCacheStream::AreAllStreamsForResourceSuspended as well as
// ChannelMediaResource::IsSuspendedByCache. Let's notify it.
gMediaCache->QueueSuspendedStatusUpdate(mResourceID);
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(LogLevel::Debug, ("Stream %p Seek to %lld", this, (long long)mStreamOffset));
gMediaCache->NoteSeek(this, oldOffset);
gMediaCache->QueueUpdate();
return NS_OK;
}
int64_t
MediaCacheStream::Tell()
{
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;
// Cache the offset in case it is changed again when we are waiting for the
// monitor to be notified to avoid reading at the wrong position.
auto streamOffset = mStreamOffset;
uint32_t count = 0;
// Read one block (or part of a block) at a time
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) {
// 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 &&
streamOffset < 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 - streamOffset);
// Clamp bytes until 64-bit file size issues are fixed.
bytes = std::min(bytes, int64_t(INT32_MAX));
MOZ_ASSERT(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;
}
streamOffset += 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, streamOffset, mCurrentMode, TimeStamp::Now());
int64_t offset = cacheBlock*BLOCK_SIZE + offsetInStreamBlock;
int32_t bytes;
MOZ_ASSERT(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;
}
streamOffset += bytes;
count += bytes;
}
if (count > 0) {
// Some data was read, so queue an update since block priorities may
// have changed
gMediaCache->QueueUpdate();
}
CACHE_LOG(LogLevel::Debug, ("Stream %p Read at %" PRId64 " count=%d", this, streamOffset-count, count));
*aBytes = count;
mStreamOffset = streamOffset;
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));
MOZ_ASSERT(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;
MOZ_ASSERT(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(MediaByteRangeSet& 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 = GetNextCachedDataInternal(0);
while (startOffset >= 0) {
int64_t endOffset = GetCachedDataEndInternal(startOffset);
NS_ASSERTION(startOffset < endOffset, "Buffered range must end after its start");
// Bytes [startOffset..endOffset] are cached.
aRanges += MediaByteRange(startOffset, endOffset);
startOffset = GetNextCachedDataInternal(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
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