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gecko/content/media/nsMediaCache.cpp

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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: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla code.
*
* The Initial Developer of the Original Code is the Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Robert O'Callahan <robert@ocallahan.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "mozilla/XPCOM.h"
#include "nsMediaCache.h"
#include "nsAutoLock.h"
#include "nsContentUtils.h"
#include "nsDirectoryServiceUtils.h"
#include "nsDirectoryServiceDefs.h"
#include "nsNetUtil.h"
#include "prio.h"
#include "nsThreadUtils.h"
#include "nsMediaStream.h"
#include "nsMathUtils.h"
#include "prlog.h"
#ifdef PR_LOGGING
PRLogModuleInfo* gMediaCacheLog;
#define LOG(type, msg) PR_LOG(gMediaCacheLog, type, msg)
#else
#define 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;
// Assume that any replaying or backward seeking will happen
// this far in the future (in seconds). This is a random guess/estimate
// penalty to account for the possibility that we might not replay at
// all.
static const PRUint32 REPLAY_DELAY = 30;
// 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 PRUint32 FREE_BLOCK_SCAN_LIMIT = 16;
using mozilla::TimeStamp;
using mozilla::TimeDuration;
#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 nsMediaCache* gMediaCache;
class nsMediaCache {
public:
friend class nsMediaCacheStream::BlockList;
typedef nsMediaCacheStream::BlockList BlockList;
enum {
BLOCK_SIZE = nsMediaCacheStream::BLOCK_SIZE
};
nsMediaCache() : mNextResourceID(1),
mMonitor(nsAutoMonitor::NewMonitor("media.cache")),
mFD(nsnull), mFDCurrentPos(0), mUpdateQueued(PR_FALSE)
#ifdef DEBUG
, mInUpdate(PR_FALSE)
#endif
{
MOZ_COUNT_CTOR(nsMediaCache);
}
~nsMediaCache() {
NS_ASSERTION(mStreams.IsEmpty(), "Stream(s) still open!");
Truncate();
NS_ASSERTION(mIndex.Length() == 0, "Blocks leaked?");
if (mFD) {
PR_Close(mFD);
}
if (mMonitor) {
nsAutoMonitor::DestroyMonitor(mMonitor);
}
MOZ_COUNT_DTOR(nsMediaCache);
}
// Main thread only. Creates the backing cache file.
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();
// Cache-file access methods. These are the lowest-level cache methods.
// mMonitor must be held; these can be called on any thread.
// This can return partial reads.
nsresult ReadCacheFile(PRInt64 aOffset, void* aData, PRInt32 aLength,
PRInt32* aBytes);
// This will fail if all aLength bytes are not read
nsresult ReadCacheFileAllBytes(PRInt64 aOffset, void* aData, PRInt32 aLength);
// This will fail if all aLength bytes are not written
nsresult WriteCacheFile(PRInt64 aOffset, const void* aData, PRInt32 aLength);
// mMonitor 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(nsMediaCacheStream* aStream);
// Remove aStream from the list of streams.
void ReleaseStream(nsMediaCacheStream* aStream);
// Free all blocks belonging to aStream.
void ReleaseStreamBlocks(nsMediaCacheStream* aStream);
// Find a cache entry for this data, and write the data into it
void AllocateAndWriteBlock(nsMediaCacheStream* aStream, const void* aData,
nsMediaCacheStream::ReadMode aMode);
// mMonitor 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(nsMediaCacheStream* aStream, PRInt64 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(nsMediaCacheStream* aStream, PRInt32 aBlockIndex,
nsMediaCacheStream::ReadMode aMode, TimeStamp aNow);
// Mark aStream as having the block, adding it as an owner.
void AddBlockOwnerAsReadahead(PRInt32 aBlockIndex, nsMediaCacheStream* aStream,
PRInt32 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
PRMonitor* Monitor() { return mMonitor; }
/**
* An iterator that makes it easy to iterate through all streams that
* have a given resource ID and are not closed.
*/
class ResourceStreamIterator {
public:
ResourceStreamIterator(PRInt64 aResourceID) :
mResourceID(aResourceID), mNext(0) {}
nsMediaCacheStream* Next()
{
while (mNext < gMediaCache->mStreams.Length()) {
nsMediaCacheStream* stream = gMediaCache->mStreams[mNext];
++mNext;
if (stream->GetResourceID() == mResourceID && !stream->IsClosed())
return stream;
}
return nsnull;
}
private:
PRInt64 mResourceID;
PRUint32 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.
PRInt32 FindBlockForIncomingData(TimeStamp aNow, nsMediaCacheStream* 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.
PRInt32 FindReusableBlock(TimeStamp aNow,
nsMediaCacheStream* aForStream,
PRInt32 aForStreamBlock,
PRInt32 aMaxSearchBlockIndex);
PRBool BlockIsReusable(PRInt32 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<PRUint32>* aResult,
PRInt32 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(nsnull), mClass(READAHEAD_BLOCK) {}
// The stream that owns this block, or null if the block is free.
nsMediaCacheStream* mStream;
// The block index in the stream. Valid only if mStream is non-null.
PRUint32 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(PRInt32 aBlockIndex, nsMediaCacheStream* aStream);
// Returns true iff the block is free
PRBool IsBlockFree(PRInt32 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(PRInt32 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(PRInt32 aBlockIndex, nsMediaCacheStream* aStream);
// Swap all metadata associated with the two blocks. The caller
// is responsible for swapping up any cache file state.
void SwapBlocks(PRInt32 aBlockIndex1, PRInt32 aBlockIndex2);
// Insert the block into the readahead block list for the stream
// at the right point in the list.
void InsertReadaheadBlock(BlockOwner* aBlockOwner, PRInt32 aBlockIndex);
// Guess the duration until block aBlock will be next used
TimeDuration PredictNextUse(TimeStamp aNow, PRInt32 aBlock);
// Guess the duration until the next incoming data on aStream will be used
TimeDuration PredictNextUseForIncomingData(nsMediaCacheStream* 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.
PRInt64 mNextResourceID;
// This member is main-thread only. It contains all the streams.
nsTArray<nsMediaCacheStream*> mStreams;
// 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.
PRMonitor* mMonitor;
// The Blocks describing the cache entries.
nsTArray<Block> mIndex;
// The file descriptor of the cache file. The file will be deleted
// by the operating system when this is closed.
PRFileDesc* mFD;
// The current file offset in the cache file.
PRInt64 mFDCurrentPos;
// The list of free blocks; they are not ordered.
BlockList mFreeBlocks;
// True if an event to run Update() has been queued but not processed
PRPackedBool mUpdateQueued;
#ifdef DEBUG
PRPackedBool mInUpdate;
#endif
};
void nsMediaCacheStream::BlockList::AddFirstBlock(PRInt32 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 nsMediaCacheStream::BlockList::AddAfter(PRInt32 aBlock, PRInt32 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 nsMediaCacheStream::BlockList::RemoveBlock(PRInt32 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;
}
PRInt32 nsMediaCacheStream::BlockList::GetLastBlock() const
{
if (mFirstBlock < 0)
return -1;
return mEntries.GetEntry(mFirstBlock)->mPrevBlock;
}
PRInt32 nsMediaCacheStream::BlockList::GetNextBlock(PRInt32 aBlock) const
{
PRInt32 block = mEntries.GetEntry(aBlock)->mNextBlock;
if (block == mFirstBlock)
return -1;
return block;
}
PRInt32 nsMediaCacheStream::BlockList::GetPrevBlock(PRInt32 aBlock) const
{
if (aBlock == mFirstBlock)
return -1;
return mEntries.GetEntry(aBlock)->mPrevBlock;
}
#ifdef DEBUG
void nsMediaCacheStream::BlockList::Verify()
{
PRInt32 count = 0;
if (mFirstBlock >= 0) {
PRInt32 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(PRInt32* aBlockIndex,
PRInt32 aBlock1Index, PRInt32 aBlock2Index)
{
PRInt32 index = *aBlockIndex;
if (index == aBlock1Index) {
*aBlockIndex = aBlock2Index;
} else if (index == aBlock2Index) {
*aBlockIndex = aBlock1Index;
}
}
void
nsMediaCacheStream::BlockList::NotifyBlockSwapped(PRInt32 aBlockIndex1,
PRInt32 aBlockIndex2)
{
Entry* e1 = mEntries.GetEntry(aBlockIndex1);
Entry* e2 = mEntries.GetEntry(aBlockIndex2);
PRInt32 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
nsMediaCache::Init()
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
if (!mMonitor) {
// the constructor failed
return NS_ERROR_OUT_OF_MEMORY;
}
nsCOMPtr<nsIFile> tmp;
nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tmp));
if (NS_FAILED(rv))
return rv;
nsCOMPtr<nsILocalFile> tmpFile = do_QueryInterface(tmp);
if (!tmpFile)
return NS_ERROR_FAILURE;
rv = tmpFile->AppendNative(nsDependentCString("moz_media_cache"));
if (NS_FAILED(rv))
return rv;
rv = tmpFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
if (NS_FAILED(rv))
return rv;
rv = tmpFile->OpenNSPRFileDesc(PR_RDWR | nsILocalFile::DELETE_ON_CLOSE,
PR_IRWXU, &mFD);
if (NS_FAILED(rv))
return rv;
#ifdef PR_LOGGING
if (!gMediaCacheLog) {
gMediaCacheLog = PR_NewLogModule("nsMediaCache");
}
#endif
return NS_OK;
}
void
nsMediaCache::MaybeShutdown()
{
NS_ASSERTION(NS_IsMainThread(),
"nsMediaCache::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 = nsnull;
}
static void
InitMediaCache()
{
if (gMediaCache)
return;
gMediaCache = new nsMediaCache();
if (!gMediaCache)
return;
nsresult rv = gMediaCache->Init();
if (NS_FAILED(rv)) {
delete gMediaCache;
gMediaCache = nsnull;
}
}
nsresult
nsMediaCache::ReadCacheFile(PRInt64 aOffset, void* aData, PRInt32 aLength,
PRInt32* aBytes)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
if (!mFD)
return NS_ERROR_FAILURE;
if (mFDCurrentPos != aOffset) {
PROffset64 offset = PR_Seek64(mFD, aOffset, PR_SEEK_SET);
if (offset != aOffset)
return NS_ERROR_FAILURE;
mFDCurrentPos = aOffset;
}
PRInt32 amount = PR_Read(mFD, aData, aLength);
if (amount <= 0)
return NS_ERROR_FAILURE;
mFDCurrentPos += amount;
*aBytes = amount;
return NS_OK;
}
nsresult
nsMediaCache::ReadCacheFileAllBytes(PRInt64 aOffset, void* aData, PRInt32 aLength)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRInt64 offset = aOffset;
PRInt32 count = aLength;
// Cast to char* so we can do byte-wise pointer arithmetic
char* data = static_cast<char*>(aData);
while (count > 0) {
PRInt32 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;
}
nsresult
nsMediaCache::WriteCacheFile(PRInt64 aOffset, const void* aData, PRInt32 aLength)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
if (!mFD)
return NS_ERROR_FAILURE;
if (mFDCurrentPos != aOffset) {
PROffset64 offset = PR_Seek64(mFD, aOffset, PR_SEEK_SET);
if (offset != aOffset)
return NS_ERROR_FAILURE;
mFDCurrentPos = aOffset;
}
const char* data = static_cast<const char*>(aData);
PRInt32 length = aLength;
while (length > 0) {
PRInt32 amount = PR_Write(mFD, data, length);
if (amount <= 0)
return NS_ERROR_FAILURE;
mFDCurrentPos += amount;
length -= amount;
data += amount;
}
return NS_OK;
}
static PRInt32 GetMaxBlocks()
{
// We look up the cache size every time. This means dynamic changes
// to the pref are applied.
// Cache size is in KB
PRInt32 cacheSize = nsContentUtils::GetIntPref("media.cache_size", 50*1024);
PRInt64 maxBlocks = PRInt64(cacheSize)*1024/nsMediaCache::BLOCK_SIZE;
maxBlocks = PR_MAX(maxBlocks, 1);
return PRInt32(PR_MIN(maxBlocks, PR_INT32_MAX));
}
PRInt32
nsMediaCache::FindBlockForIncomingData(TimeStamp aNow,
nsMediaCacheStream* aStream)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRInt32 blockIndex = FindReusableBlock(aNow, aStream,
aStream->mChannelOffset/BLOCK_SIZE, PR_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() < PRUint32(GetMaxBlocks()) || blockIndex < 0 ||
PredictNextUseForIncomingData(aStream) >= PredictNextUse(aNow, blockIndex))) {
blockIndex = mIndex.Length();
if (!mIndex.AppendElement())
return -1;
mFreeBlocks.AddFirstBlock(blockIndex);
return blockIndex;
}
}
return blockIndex;
}
PRBool
nsMediaCache::BlockIsReusable(PRInt32 aBlockIndex)
{
Block* block = &mIndex[aBlockIndex];
for (PRUint32 i = 0; i < block->mOwners.Length(); ++i) {
nsMediaCacheStream* stream = block->mOwners[i].mStream;
if (stream->mPinCount > 0 ||
stream->mStreamOffset/BLOCK_SIZE == block->mOwners[i].mStreamBlock) {
return PR_FALSE;
}
}
return PR_TRUE;
}
void
nsMediaCache::AppendMostReusableBlock(BlockList* aBlockList,
nsTArray<PRUint32>* aResult,
PRInt32 aBlockIndexLimit)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRInt32 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);
}
PRInt32
nsMediaCache::FindReusableBlock(TimeStamp aNow,
nsMediaCacheStream* aForStream,
PRInt32 aForStreamBlock,
PRInt32 aMaxSearchBlockIndex)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRUint32 length = PR_MIN(PRUint32(aMaxSearchBlockIndex), mIndex.Length());
if (aForStream && aForStreamBlock > 0 &&
PRUint32(aForStreamBlock) <= aForStream->mBlocks.Length()) {
PRInt32 prevCacheBlock = aForStream->mBlocks[aForStreamBlock - 1];
if (prevCacheBlock >= 0) {
PRUint32 freeBlockScanEnd =
PR_MIN(length, prevCacheBlock + FREE_BLOCK_SCAN_LIMIT);
for (PRUint32 i = prevCacheBlock; i < freeBlockScanEnd; ++i) {
if (IsBlockFree(i))
return i;
}
}
}
if (!mFreeBlocks.IsEmpty()) {
PRInt32 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<PRUint32,8> candidates;
for (PRUint32 i = 0; i < mStreams.Length(); ++i) {
nsMediaCacheStream* 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->mIsSeekable) {
AppendMostReusableBlock(&stream->mReadaheadBlocks, &candidates, length);
}
}
TimeDuration latestUse;
PRInt32 latestUseBlock = -1;
for (PRUint32 i = 0; i < candidates.Length(); ++i) {
TimeDuration nextUse = PredictNextUse(aNow, candidates[i]);
if (nextUse > latestUse) {
latestUse = nextUse;
latestUseBlock = candidates[i];
}
}
return latestUseBlock;
}
nsMediaCache::BlockList*
nsMediaCache::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 nsnull;
}
}
nsMediaCache::BlockOwner*
nsMediaCache::GetBlockOwner(PRInt32 aBlockIndex, nsMediaCacheStream* aStream)
{
Block* block = &mIndex[aBlockIndex];
for (PRUint32 i = 0; i < block->mOwners.Length(); ++i) {
if (block->mOwners[i].mStream == aStream)
return &block->mOwners[i];
}
return nsnull;
}
void
nsMediaCache::SwapBlocks(PRInt32 aBlockIndex1, PRInt32 aBlockIndex2)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
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 };
PRInt32 blockIndices[] = { aBlockIndex1, aBlockIndex2 };
for (PRInt32 i = 0; i < 2; ++i) {
for (PRUint32 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<nsMediaCacheStream> > visitedStreams;
visitedStreams.Init();
for (PRInt32 i = 0; i < 2; ++i) {
for (PRUint32 j = 0; j < blocks[i]->mOwners.Length(); ++j) {
nsMediaCacheStream* 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
nsMediaCache::RemoveBlockOwner(PRInt32 aBlockIndex, nsMediaCacheStream* aStream)
{
Block* block = &mIndex[aBlockIndex];
for (PRUint32 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
nsMediaCache::AddBlockOwnerAsReadahead(PRInt32 aBlockIndex,
nsMediaCacheStream* aStream,
PRInt32 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
nsMediaCache::FreeBlock(PRInt32 aBlock)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
Block* block = &mIndex[aBlock];
if (block->mOwners.IsEmpty()) {
// already free
return;
}
LOG(PR_LOG_DEBUG, ("Released block %d", aBlock));
for (PRUint32 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
nsMediaCache::PredictNextUse(TimeStamp aNow, PRInt32 aBlock)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
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 (PRUint32 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(PRInt64(bo->mStreamBlock)*BLOCK_SIZE <
bo->mStream->mStreamOffset,
"Played block after the current stream position?");
prediction = aNow - bo->mLastUseTime +
TimeDuration::FromSeconds(REPLAY_DELAY);
break;
case READAHEAD_BLOCK: {
PRInt64 bytesAhead =
PRInt64(bo->mStreamBlock)*BLOCK_SIZE - bo->mStream->mStreamOffset;
NS_ASSERTION(bytesAhead >= 0,
"Readahead block before the current stream position?");
PRInt64 millisecondsAhead =
bytesAhead*1000/bo->mStream->mPlaybackBytesPerSecond;
prediction = TimeDuration::FromMilliseconds(
PR_MIN(millisecondsAhead, PR_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
nsMediaCache::PredictNextUseForIncomingData(nsMediaCacheStream* aStream)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRInt64 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);
PRInt64 millisecondsAhead = bytesAhead*1000/aStream->mPlaybackBytesPerSecond;
return TimeDuration::FromMilliseconds(
PR_MIN(millisecondsAhead, PR_INT32_MAX));
}
enum StreamAction { NONE, SEEK, RESUME, SUSPEND };
void
nsMediaCache::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;
{
nsAutoMonitor mon(mMonitor);
mUpdateQueued = PR_FALSE;
#ifdef DEBUG
mInUpdate = PR_TRUE;
#endif
PRInt32 maxBlocks = GetMaxBlocks();
TimeStamp now = TimeStamp::Now();
PRInt32 freeBlockCount = mFreeBlocks.GetCount();
// 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.
TimeDuration latestPredictedUseForOverflow = 0;
for (PRInt32 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 = PR_MAX(latestPredictedUseForOverflow, predictedUse);
}
// Now try to move overflowing blocks to the main part of the cache.
for (PRInt32 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.
PRInt32 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
char buf[BLOCK_SIZE];
nsresult rv = ReadCacheFileAllBytes(blockIndex*BLOCK_SIZE, buf, sizeof(buf));
if (NS_SUCCEEDED(rv)) {
rv = WriteCacheFile(destinationBlockIndex*BLOCK_SIZE, buf, BLOCK_SIZE);
if (NS_SUCCEEDED(rv)) {
// We successfully copied the file data.
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);
} else {
// If the write fails we may have corrupted the destination
// block. Free it now.
LOG(PR_LOG_DEBUG, ("Released block %d (trimming cache)",
destinationBlockIndex));
FreeBlock(destinationBlockIndex);
}
// Free the overflowing block even if the copy failed.
LOG(PR_LOG_DEBUG, ("Released block %d (trimming cache)",
blockIndex));
FreeBlock(blockIndex);
}
}
}
// 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)
PRInt32 nonSeekableReadaheadBlockCount = 0;
for (PRUint32 i = 0; i < mStreams.Length(); ++i) {
nsMediaCacheStream* stream = mStreams[i];
if (!stream->mIsSeekable) {
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) {
PRInt32 reusableBlock = FindReusableBlock(now, nsnull, 0, maxBlocks);
if (reusableBlock >= 0) {
latestNextUse = PredictNextUse(now, reusableBlock);
}
}
for (PRUint32 i = 0; i < mStreams.Length(); ++i) {
actions.AppendElement(NONE);
nsMediaCacheStream* 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.
PRInt64 dataOffset = stream->GetCachedDataEndInternal(stream->mStreamOffset);
// Compute where we'd actually seek to to read at readOffset
PRInt64 desiredOffset = dataOffset;
if (stream->mIsSeekable) {
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.
PRBool 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.
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.
LOG(PR_LOG_DEBUG, ("Stream %p catching up", stream));
enableReading = PR_TRUE;
} else if (desiredOffset < stream->mStreamOffset + BLOCK_SIZE) {
// The stream reader is waiting for us, or nearly so. Better feed it.
LOG(PR_LOG_DEBUG, ("Stream %p feeding reader", stream));
enableReading = PR_TRUE;
} else if (!stream->mIsSeekable &&
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.
LOG(PR_LOG_DEBUG, ("Stream %p throttling non-seekable readahead", stream));
enableReading = PR_FALSE;
} else if (mIndex.Length() > PRUint32(maxBlocks)) {
// We're in the process of bringing the cache size back to the
// desired limit, so don't bring in more data yet
LOG(PR_LOG_DEBUG, ("Stream %p throttling to reduce cache size", stream));
enableReading = PR_FALSE;
} else if (freeBlockCount > 0 || mIndex.Length() < PRUint32(maxBlocks)) {
// Free blocks in the cache, so keep reading
LOG(PR_LOG_DEBUG, ("Stream %p reading since there are free blocks", stream));
enableReading = PR_TRUE;
} else if (latestNextUse <= TimeDuration(0)) {
// No reusable blocks, so can't read anything
LOG(PR_LOG_DEBUG, ("Stream %p throttling due to no reusable blocks", stream));
enableReading = PR_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
TimeDuration predictedNewDataUse = PredictNextUseForIncomingData(stream);
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 (PRUint32 j = 0; j < i; ++j) {
nsMediaCacheStream* other = mStreams[j];
if (other->mResourceID == stream->mResourceID &&
!other->mCacheSuspended &&
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 = PR_FALSE;
break;
}
}
}
if (stream->mChannelOffset != desiredOffset && enableReading) {
// We need to seek now.
NS_ASSERTION(stream->mIsSeekable || 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] = SEEK;
} else if (enableReading && stream->mCacheSuspended) {
actions[i] = RESUME;
} else if (!enableReading && !stream->mCacheSuspended) {
actions[i] = SUSPEND;
}
}
#ifdef DEBUG
mInUpdate = PR_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
// mCacheSuspended, which can only be written by the main thread (i.e., this
// thread), so we don't have races here.
for (PRUint32 i = 0; i < mStreams.Length(); ++i) {
nsMediaCacheStream* stream = mStreams[i];
nsresult rv = NS_OK;
switch (actions[i]) {
case SEEK:
LOG(PR_LOG_DEBUG, ("Stream %p CacheSeek to %lld (resume=%d)", stream,
(long long)stream->mChannelOffset, stream->mCacheSuspended));
rv = stream->mClient->CacheClientSeek(stream->mChannelOffset,
stream->mCacheSuspended);
stream->mCacheSuspended = PR_FALSE;
break;
case RESUME:
LOG(PR_LOG_DEBUG, ("Stream %p Resumed", stream));
rv = stream->mClient->CacheClientResume();
stream->mCacheSuspended = PR_FALSE;
break;
case SUSPEND:
LOG(PR_LOG_DEBUG, ("Stream %p Suspended", stream));
rv = stream->mClient->CacheClientSuspend();
stream->mCacheSuspended = PR_TRUE;
break;
default:
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.
nsAutoMonitor mon(mMonitor);
stream->CloseInternal(&mon);
}
}
}
class UpdateEvent : public nsRunnable
{
public:
NS_IMETHOD Run()
{
if (gMediaCache) {
gMediaCache->Update();
}
return NS_OK;
}
};
void
nsMediaCache::QueueUpdate()
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
// 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 = PR_TRUE;
nsCOMPtr<nsIRunnable> event = new UpdateEvent();
NS_DispatchToMainThread(event);
}
#ifdef DEBUG_VERIFY_CACHE
void
nsMediaCache::Verify()
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
mFreeBlocks.Verify();
for (PRUint32 i = 0; i < mStreams.Length(); ++i) {
nsMediaCacheStream* stream = mStreams[i];
stream->mReadaheadBlocks.Verify();
stream->mPlayedBlocks.Verify();
stream->mMetadataBlocks.Verify();
// Verify that the readahead blocks are listed in stream block order
PRInt32 block = stream->mReadaheadBlocks.GetFirstBlock();
PRInt32 lastStreamBlock = -1;
while (block >= 0) {
PRUint32 j = 0;
while (mIndex[block].mOwners[j].mStream != stream) {
++j;
}
PRInt32 nextStreamBlock =
PRInt32(mIndex[block].mOwners[j].mStreamBlock);
NS_ASSERTION(lastStreamBlock < nextStreamBlock,
"Blocks not increasing in readahead stream");
lastStreamBlock = nextStreamBlock;
block = stream->mReadaheadBlocks.GetNextBlock(block);
}
}
}
#endif
void
nsMediaCache::InsertReadaheadBlock(BlockOwner* aBlockOwner,
PRInt32 aBlockIndex)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
// Find the last block whose stream block is before aBlockIndex's
// stream block, and insert after it
nsMediaCacheStream* stream = aBlockOwner->mStream;
PRInt32 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
nsMediaCache::AllocateAndWriteBlock(nsMediaCacheStream* aStream, const void* aData,
nsMediaCacheStream::ReadMode aMode)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
PRInt32 streamBlockIndex = aStream->mChannelOffset/BLOCK_SIZE;
// Remove all cached copies of this block
ResourceStreamIterator iter(aStream->mResourceID);
while (nsMediaCacheStream* stream = iter.Next()) {
while (streamBlockIndex >= PRInt32(stream->mBlocks.Length())) {
stream->mBlocks.AppendElement(-1);
}
if (stream->mBlocks[streamBlockIndex] >= 0) {
// We no longer want to own this block
PRInt32 globalBlockIndex = stream->mBlocks[streamBlockIndex];
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();
PRInt32 blockIndex = FindBlockForIncomingData(now, aStream);
if (blockIndex >= 0) {
FreeBlock(blockIndex);
Block* block = &mIndex[blockIndex];
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 (nsMediaCacheStream* 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 == nsMediaCacheStream::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 = WriteCacheFile(blockIndex*BLOCK_SIZE, aData, BLOCK_SIZE);
if (NS_FAILED(rv)) {
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
nsMediaCache::OpenStream(nsMediaCacheStream* aStream)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(mMonitor);
LOG(PR_LOG_DEBUG, ("Stream %p opened", aStream));
mStreams.AppendElement(aStream);
aStream->mResourceID = mNextResourceID++;
}
void
nsMediaCache::ReleaseStream(nsMediaCacheStream* aStream)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(mMonitor);
LOG(PR_LOG_DEBUG, ("Stream %p closed", aStream));
mStreams.RemoveElement(aStream);
}
void
nsMediaCache::ReleaseStreamBlocks(nsMediaCacheStream* aStream)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
// 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
PRUint32 length = aStream->mBlocks.Length();
for (PRUint32 i = 0; i < length; ++i) {
PRInt32 blockIndex = aStream->mBlocks[i];
if (blockIndex >= 0) {
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
nsMediaCache::Truncate()
{
PRUint32 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
nsMediaCache::NoteBlockUsage(nsMediaCacheStream* aStream, PRInt32 aBlockIndex,
nsMediaCacheStream::ReadMode aMode,
TimeStamp aNow)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
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 == nsMediaCacheStream::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
nsMediaCache::NoteSeek(nsMediaCacheStream* aStream, PRInt64 aOldOffset)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mMonitor);
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.
PRInt32 blockIndex = aOldOffset/BLOCK_SIZE;
PRInt32 endIndex =
PR_MIN((aStream->mStreamOffset + BLOCK_SIZE - 1)/BLOCK_SIZE,
aStream->mBlocks.Length());
TimeStamp now = TimeStamp::Now();
while (blockIndex < endIndex) {
PRInt32 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, nsMediaCacheStream::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.
PRInt32 blockIndex =
(aStream->mStreamOffset + BLOCK_SIZE - 1)/BLOCK_SIZE;
PRInt32 endIndex =
PR_MIN((aOldOffset + BLOCK_SIZE - 1)/BLOCK_SIZE,
aStream->mBlocks.Length());
while (blockIndex < endIndex) {
PRInt32 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
nsMediaCacheStream::NotifyDataLength(PRInt64 aLength)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
mStreamLength = aLength;
}
void
nsMediaCacheStream::NotifyDataStarted(PRInt64 aOffset)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
NS_WARN_IF_FALSE(aOffset == mChannelOffset,
"Server is giving us unexpected offset");
mChannelOffset = aOffset;
if (mStreamLength >= 0) {
// If we started reading at a certain offset, then for sure
// the stream is at least that long.
mStreamLength = PR_MAX(mStreamLength, mChannelOffset);
}
}
void
nsMediaCacheStream::UpdatePrincipal(nsIPrincipal* aPrincipal)
{
if (!mPrincipal) {
NS_ASSERTION(!mUsingNullPrincipal, "Are we using a null principal or not?");
if (mUsingNullPrincipal) {
// Don't let mPrincipal be set to anything
return;
}
mPrincipal = aPrincipal;
return;
}
if (mPrincipal == aPrincipal) {
// Common case
NS_ASSERTION(!mUsingNullPrincipal, "We can't receive data from a null principal");
return;
}
if (mUsingNullPrincipal) {
// We've already fallen back to a null principal, so nothing more
// to do.
return;
}
PRBool equal;
nsresult rv = mPrincipal->Equals(aPrincipal, &equal);
if (NS_SUCCEEDED(rv) && equal)
return;
// Principals are not equal, so set mPrincipal to a null principal.
mPrincipal = do_CreateInstance("@mozilla.org/nullprincipal;1");
mUsingNullPrincipal = PR_TRUE;
}
void
nsMediaCacheStream::NotifyDataReceived(PRInt64 aSize, const char* aData,
nsIPrincipal* aPrincipal)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
PRInt64 size = aSize;
const char* data = aData;
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) {
PRUint32 blockIndex = mChannelOffset/BLOCK_SIZE;
PRInt32 blockOffset = PRInt32(mChannelOffset - blockIndex*BLOCK_SIZE);
PRInt32 chunkSize = PRInt32(PR_MIN(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 = nsnull;
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 = PR_FALSE;
}
memcpy(reinterpret_cast<char*>(mPartialBlockBuffer) + blockOffset,
data, chunkSize);
if (blockOffset + chunkSize == BLOCK_SIZE) {
// We completed a block, so lets write it out.
blockDataToStore = reinterpret_cast<char*>(mPartialBlockBuffer);
if (mMetadataInPartialBlockBuffer) {
mode = MODE_METADATA;
}
}
}
if (blockDataToStore) {
gMediaCache->AllocateAndWriteBlock(this, blockDataToStore, mode);
}
mChannelOffset += chunkSize;
size -= chunkSize;
data += chunkSize;
}
nsMediaCache::ResourceStreamIterator iter(mResourceID);
while (nsMediaCacheStream* stream = iter.Next()) {
if (stream->mStreamLength >= 0) {
// The stream is at least as long as what we've read
stream->mStreamLength = PR_MAX(stream->mStreamLength, mChannelOffset);
}
stream->UpdatePrincipal(aPrincipal);
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
nsMediaCacheStream::NotifyDataEnded(nsresult aStatus)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
PRInt32 blockOffset = PRInt32(mChannelOffset%BLOCK_SIZE);
if (blockOffset > 0) {
// Write back the partial block
memset(reinterpret_cast<char*>(mPartialBlockBuffer) + blockOffset, 0,
BLOCK_SIZE - blockOffset);
gMediaCache->AllocateAndWriteBlock(this, mPartialBlockBuffer,
mMetadataInPartialBlockBuffer ? MODE_METADATA : MODE_PLAYBACK);
// Wake up readers who may be waiting for this data
mon.NotifyAll();
}
nsMediaCache::ResourceStreamIterator iter(mResourceID);
while (nsMediaCacheStream* stream = iter.Next()) {
if (NS_SUCCEEDED(aStatus)) {
// We read the whole stream, so remember the true length
stream->mStreamLength = mChannelOffset;
}
stream->mClient->CacheClientNotifyDataEnded(aStatus);
}
}
nsMediaCacheStream::~nsMediaCacheStream()
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
NS_ASSERTION(mClosed, "Stream was not closed");
NS_ASSERTION(!mPinCount, "Unbalanced Pin");
gMediaCache->ReleaseStream(this);
nsMediaCache::MaybeShutdown();
}
void
nsMediaCacheStream::SetSeekable(PRBool aIsSeekable)
{
nsAutoMonitor mon(gMediaCache->Monitor());
NS_ASSERTION(mIsSeekable || aIsSeekable ||
mChannelOffset == 0, "channel offset must be zero when we become non-seekable");
mIsSeekable = aIsSeekable;
// Queue an Update since we may change our strategy for dealing
// with this stream
gMediaCache->QueueUpdate();
}
PRBool
nsMediaCacheStream::IsSeekable()
{
nsAutoMonitor mon(gMediaCache->Monitor());
return mIsSeekable;
}
void
nsMediaCacheStream::Close()
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
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
nsMediaCacheStream::CloseInternal(nsAutoMonitor* aMonitor)
{
NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
if (mClosed)
return;
mClosed = PR_TRUE;
gMediaCache->ReleaseStreamBlocks(this);
// Wake up any blocked readers
aMonitor->NotifyAll();
}
void
nsMediaCacheStream::Pin()
{
nsAutoMonitor mon(gMediaCache->Monitor());
++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
nsMediaCacheStream::Unpin()
{
nsAutoMonitor mon(gMediaCache->Monitor());
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();
}
PRInt64
nsMediaCacheStream::GetLength()
{
nsAutoMonitor mon(gMediaCache->Monitor());
return mStreamLength;
}
PRInt64
nsMediaCacheStream::GetNextCachedData(PRInt64 aOffset)
{
nsAutoMonitor mon(gMediaCache->Monitor());
return GetNextCachedDataInternal(aOffset);
}
PRInt64
nsMediaCacheStream::GetCachedDataEnd(PRInt64 aOffset)
{
nsAutoMonitor mon(gMediaCache->Monitor());
return GetCachedDataEndInternal(aOffset);
}
PRBool
nsMediaCacheStream::IsDataCachedToEndOfStream(PRInt64 aOffset)
{
nsAutoMonitor mon(gMediaCache->Monitor());
if (mStreamLength < 0)
return PR_FALSE;
return GetCachedDataEndInternal(aOffset) >= mStreamLength;
}
PRInt64
nsMediaCacheStream::GetCachedDataEndInternal(PRInt64 aOffset)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(gMediaCache->Monitor());
PRUint32 startBlockIndex = aOffset/BLOCK_SIZE;
PRUint32 blockIndex = startBlockIndex;
while (blockIndex < mBlocks.Length() && mBlocks[blockIndex] != -1) {
++blockIndex;
}
PRInt64 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 = PR_MIN(result, mStreamLength);
}
return PR_MAX(result, aOffset);
}
PRInt64
nsMediaCacheStream::GetNextCachedDataInternal(PRInt64 aOffset)
{
PR_ASSERT_CURRENT_THREAD_IN_MONITOR(gMediaCache->Monitor());
if (aOffset == mStreamLength)
return -1;
PRUint32 startBlockIndex = aOffset/BLOCK_SIZE;
PRUint32 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
PRBool hasPartialBlock = (mChannelOffset % BLOCK_SIZE) != 0;
PRUint32 blockIndex = startBlockIndex + 1;
while (PR_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
nsMediaCacheStream::SetReadMode(ReadMode aMode)
{
nsAutoMonitor mon(gMediaCache->Monitor());
if (aMode == mCurrentMode)
return;
mCurrentMode = aMode;
gMediaCache->QueueUpdate();
}
void
nsMediaCacheStream::SetPlaybackRate(PRUint32 aBytesPerSecond)
{
NS_ASSERTION(aBytesPerSecond > 0, "Zero playback rate not allowed");
nsAutoMonitor mon(gMediaCache->Monitor());
if (aBytesPerSecond == mPlaybackBytesPerSecond)
return;
mPlaybackBytesPerSecond = aBytesPerSecond;
gMediaCache->QueueUpdate();
}
nsresult
nsMediaCacheStream::Seek(PRInt32 aWhence, PRInt64 aOffset)
{
NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
if (mClosed)
return NS_ERROR_FAILURE;
PRInt64 oldOffset = mStreamOffset;
switch (aWhence) {
case PR_SEEK_END:
if (mStreamLength < 0)
return NS_ERROR_FAILURE;
mStreamOffset = mStreamLength + aOffset;
break;
case PR_SEEK_CUR:
mStreamOffset += aOffset;
break;
case PR_SEEK_SET:
mStreamOffset = aOffset;
break;
default:
NS_ERROR("Unknown whence");
return NS_ERROR_FAILURE;
}
LOG(PR_LOG_DEBUG, ("Stream %p Seek to %lld", this, (long long)mStreamOffset));
gMediaCache->NoteSeek(this, oldOffset);
gMediaCache->QueueUpdate();
return NS_OK;
}
PRInt64
nsMediaCacheStream::Tell()
{
NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
return mStreamOffset;
}
nsresult
nsMediaCacheStream::Read(char* aBuffer, PRUint32 aCount, PRUint32* aBytes)
{
NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
nsAutoMonitor mon(gMediaCache->Monitor());
if (mClosed)
return NS_ERROR_FAILURE;
PRUint32 count = 0;
// Read one block (or part of a block) at a time
while (count < aCount) {
PRUint32 streamBlock = PRUint32(mStreamOffset/BLOCK_SIZE);
PRUint32 offsetInStreamBlock =
PRUint32(mStreamOffset - streamBlock*BLOCK_SIZE);
PRInt32 size = PR_MIN(aCount - count, BLOCK_SIZE - offsetInStreamBlock);
if (mStreamLength >= 0) {
// Don't try to read beyond the end of the stream
PRInt64 bytesRemaining = mStreamLength - mStreamOffset;
if (bytesRemaining <= 0) {
// Get out of here and return NS_OK
break;
}
size = PR_MIN(size, PRInt32(bytesRemaining));
}
PRInt32 bytes;
PRUint32 channelBlock = PRUint32(mChannelOffset/BLOCK_SIZE);
PRInt32 cacheBlock = streamBlock < mBlocks.Length() ? mBlocks[streamBlock] : -1;
if (channelBlock == streamBlock && mStreamOffset < 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.
bytes = PR_MIN(size, mChannelOffset - mStreamOffset);
memcpy(aBuffer + count,
reinterpret_cast<char*>(mPartialBlockBuffer) + offsetInStreamBlock, bytes);
if (mCurrentMode == MODE_METADATA) {
mMetadataInPartialBlockBuffer = PR_TRUE;
}
gMediaCache->NoteBlockUsage(this, cacheBlock, mCurrentMode, TimeStamp::Now());
} else {
if (cacheBlock < 0) {
if (count > 0) {
// Some data has been read, so return what we've got instead of
// blocking
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());
PRInt64 offset = cacheBlock*BLOCK_SIZE + offsetInStreamBlock;
nsresult rv = gMediaCache->ReadCacheFile(offset, aBuffer + count, 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();
}
LOG(PR_LOG_DEBUG,
("Stream %p Read at %lld count=%d", this, (long long)(mStreamOffset-count), count));
*aBytes = count;
return NS_OK;
}
nsresult
nsMediaCacheStream::ReadFromCache(char* aBuffer,
PRInt64 aOffset,
PRInt64 aCount)
{
nsAutoMonitor mon(gMediaCache->Monitor());
if (mClosed)
return NS_ERROR_FAILURE;
// Read one block (or part of a block) at a time
PRUint32 count = 0;
PRInt64 streamOffset = aOffset;
while (count < aCount) {
PRUint32 streamBlock = PRUint32(streamOffset/BLOCK_SIZE);
PRUint32 offsetInStreamBlock =
PRUint32(streamOffset - streamBlock*BLOCK_SIZE);
PRInt32 size = PR_MIN(aCount - count, BLOCK_SIZE - offsetInStreamBlock);
if (mStreamLength >= 0) {
// Don't try to read beyond the end of the stream
PRInt64 bytesRemaining = mStreamLength - streamOffset;
if (bytesRemaining <= 0) {
return NS_ERROR_FAILURE;
}
size = PR_MIN(size, PRInt32(bytesRemaining));
}
PRInt32 bytes;
PRUint32 channelBlock = PRUint32(mChannelOffset/BLOCK_SIZE);
PRInt32 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.
bytes = PR_MIN(size, mChannelOffset - streamOffset);
memcpy(aBuffer + count,
reinterpret_cast<char*>(mPartialBlockBuffer) + offsetInStreamBlock, bytes);
} else {
if (cacheBlock < 0) {
// We expect all blocks to be cached! Fail!
return NS_ERROR_FAILURE;
}
PRInt64 offset = cacheBlock*BLOCK_SIZE + offsetInStreamBlock;
nsresult rv = gMediaCache->ReadCacheFile(offset, aBuffer + count, size, &bytes);
if (NS_FAILED(rv)) {
return rv;
}
}
streamOffset += bytes;
count += bytes;
}
return NS_OK;
}
nsresult
nsMediaCacheStream::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 = PR_TRUE;
return NS_OK;
}
nsresult
nsMediaCacheStream::InitAsClone(nsMediaCacheStream* aOriginal)
{
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
nsAutoMonitor mon(gMediaCache->Monitor());
mPrincipal = aOriginal->mPrincipal;
mStreamLength = aOriginal->mStreamLength;
mIsSeekable = aOriginal->mIsSeekable;
// Cloned streams are initially suspended, since there is no channel open
// initially for a clone.
mCacheSuspended = PR_TRUE;
for (PRUint32 i = 0; i < aOriginal->mBlocks.Length(); ++i) {
PRInt32 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;
}
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