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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 "MediaResource.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Logging.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/ErrorNames.h"
#include "mozilla/SchedulerGroup.h"
using mozilla::media::TimeUnit;
#undef ILOG
mozilla::LazyLogModule gMediaResourceIndexLog("MediaResourceIndex");
// Debug logging macro with object pointer and class name.
#define ILOG(msg, ...) \
DDMOZ_LOG(gMediaResourceIndexLog, mozilla::LogLevel::Debug, msg, \
##__VA_ARGS__)
namespace mozilla {
void MediaResource::Destroy() {
// Ensures we only delete the MediaResource on the main thread.
if (NS_IsMainThread()) {
delete this;
return;
}
nsresult rv = SchedulerGroup::Dispatch(
TaskCategory::Other,
NewNonOwningRunnableMethod("MediaResource::Destroy", this,
&MediaResource::Destroy));
MOZ_ALWAYS_SUCCEEDS(rv);
}
static const uint32_t kMediaResourceIndexCacheSize = 8192;
static_assert(IsPowerOfTwo(kMediaResourceIndexCacheSize),
"kMediaResourceIndexCacheSize cache size must be a power of 2");
MediaResourceIndex::MediaResourceIndex(MediaResource* aResource)
: mResource(aResource),
mOffset(0),
mCacheBlockSize(
aResource->ShouldCacheReads() ? kMediaResourceIndexCacheSize : 0),
mCachedOffset(0),
mCachedBytes(0),
mCachedBlock(MakeUnique<char[]>(mCacheBlockSize)) {
DDLINKCHILD("resource", aResource);
}
nsresult MediaResourceIndex::Read(char* aBuffer, uint32_t aCount,
uint32_t* aBytes) {
NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
// We purposefuly don't check that we may attempt to read past
// mResource->GetLength() as the resource's length may change over time.
nsresult rv = ReadAt(mOffset, aBuffer, aCount, aBytes);
if (NS_FAILED(rv)) {
return rv;
}
mOffset += *aBytes;
if (mOffset < 0) {
// Very unlikely overflow; just return to position 0.
mOffset = 0;
}
return NS_OK;
}
static nsCString ResultName(nsresult aResult) {
nsCString name;
GetErrorName(aResult, name);
return name;
}
nsresult MediaResourceIndex::ReadAt(int64_t aOffset, char* aBuffer,
uint32_t aCount, uint32_t* aBytes) {
if (mCacheBlockSize == 0) {
return UncachedReadAt(aOffset, aBuffer, aCount, aBytes);
}
*aBytes = 0;
if (aCount == 0) {
return NS_OK;
}
const int64_t endOffset = aOffset + aCount;
if (aOffset < 0 || endOffset < aOffset) {
return NS_ERROR_ILLEGAL_VALUE;
}
const int64_t lastBlockOffset = CacheOffsetContaining(endOffset - 1);
if (mCachedBytes != 0 && mCachedOffset + mCachedBytes >= aOffset &&
mCachedOffset < endOffset) {
// There is data in the cache that is not completely before aOffset and not
// completely after endOffset, so it could be usable (with potential
// top-up).
if (aOffset < mCachedOffset) {
// We need to read before the cached data.
const uint32_t toRead = uint32_t(mCachedOffset - aOffset);
MOZ_ASSERT(toRead > 0);
MOZ_ASSERT(toRead < aCount);
uint32_t read = 0;
nsresult rv = UncachedReadAt(aOffset, aBuffer, toRead, &read);
if (NS_FAILED(rv)) {
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read before cache -> %s, %" PRIu32,
aCount, aOffset, ResultName(rv).get(), *aBytes);
return rv;
}
*aBytes = read;
if (read < toRead) {
// Could not read everything we wanted, we're done.
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read before cache, incomplete -> OK, %" PRIu32,
aCount, aOffset, *aBytes);
return NS_OK;
}
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read before cache: %" PRIu32 ", remaining: %" PRIu32
"@%" PRId64 "...",
aCount, aOffset, read, aCount - read, aOffset + read);
aOffset += read;
aBuffer += read;
aCount -= read;
// We should have reached the cache.
MOZ_ASSERT(aOffset == mCachedOffset);
}
MOZ_ASSERT(aOffset >= mCachedOffset);
// We've reached our cache.
const uint32_t toCopy =
std::min(aCount, uint32_t(mCachedOffset + mCachedBytes - aOffset));
// Note that we could in fact be just after the last byte of the cache, in
// which case we can't actually read from it! (But we will top-up next.)
if (toCopy != 0) {
memcpy(aBuffer, &mCachedBlock[IndexInCache(aOffset)], toCopy);
*aBytes += toCopy;
aCount -= toCopy;
if (aCount == 0) {
// All done!
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") copied everything (%" PRIu32
") from cache(%" PRIu32 "@%" PRId64 ") :-D -> OK, %" PRIu32,
aCount, aOffset, toCopy, mCachedBytes, mCachedOffset, *aBytes);
return NS_OK;
}
aOffset += toCopy;
aBuffer += toCopy;
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") copied %" PRIu32
" from cache(%" PRIu32 "@%" PRId64 ") :-), remaining: %" PRIu32
"@%" PRId64 "...",
aCount + toCopy, aOffset - toCopy, toCopy, mCachedBytes,
mCachedOffset, aCount, aOffset);
}
if (aOffset - 1 >= lastBlockOffset) {
// We were already reading cached data from the last block, we need more
// from it -> try to top-up, read what we can, and we'll be done.
MOZ_ASSERT(aOffset == mCachedOffset + mCachedBytes);
MOZ_ASSERT(endOffset <= lastBlockOffset + mCacheBlockSize);
return CacheOrReadAt(aOffset, aBuffer, aCount, aBytes);
}
// We were not in the last block (but we may just have crossed the line now)
MOZ_ASSERT(aOffset <= lastBlockOffset);
// Continue below...
} else if (aOffset >= lastBlockOffset) {
// There was nothing we could get from the cache.
// But we're already in the last block -> Cache or read what we can.
// Make sure to invalidate the cache first.
mCachedBytes = 0;
return CacheOrReadAt(aOffset, aBuffer, aCount, aBytes);
}
// If we're here, either there was nothing usable in the cache, or we've just
// read what was in the cache but there's still more to read.
if (aOffset < lastBlockOffset) {
// We need to read before the last block.
// Start with an uncached read up to the last block.
const uint32_t toRead = uint32_t(lastBlockOffset - aOffset);
MOZ_ASSERT(toRead > 0);
MOZ_ASSERT(toRead < aCount);
uint32_t read = 0;
nsresult rv = UncachedReadAt(aOffset, aBuffer, toRead, &read);
if (NS_FAILED(rv)) {
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read before last block failed -> %s, %" PRIu32,
aCount, aOffset, ResultName(rv).get(), *aBytes);
return rv;
}
if (read == 0) {
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read 0 before last block -> OK, %" PRIu32,
aCount, aOffset, *aBytes);
return NS_OK;
}
*aBytes += read;
if (read < toRead) {
// Could not read everything we wanted, we're done.
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") uncached read before last block, incomplete -> OK, %" PRIu32,
aCount, aOffset, *aBytes);
return NS_OK;
}
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") read %" PRIu32
" before last block, remaining: %" PRIu32 "@%" PRId64 "...",
aCount, aOffset, read, aCount - read, aOffset + read);
aOffset += read;
aBuffer += read;
aCount -= read;
}
// We should just have reached the start of the last block.
MOZ_ASSERT(aOffset == lastBlockOffset);
MOZ_ASSERT(aCount <= mCacheBlockSize);
// Make sure to invalidate the cache first.
mCachedBytes = 0;
return CacheOrReadAt(aOffset, aBuffer, aCount, aBytes);
}
nsresult MediaResourceIndex::CacheOrReadAt(int64_t aOffset, char* aBuffer,
uint32_t aCount, uint32_t* aBytes) {
// We should be here because there is more data to read.
MOZ_ASSERT(aCount > 0);
// We should be in the last block, so we shouldn't try to read past it.
MOZ_ASSERT(IndexInCache(aOffset) + aCount <= mCacheBlockSize);
const int64_t length = GetLength();
// If length is unknown (-1), look at resource-cached data.
// If length is known and equal or greater than requested, also look at
// resource-cached data.
// Otherwise, if length is known but same, or less than(!?), requested, don't
// attempt to access resource-cached data, as we're not expecting it to ever
// be greater than the length.
if (length < 0 || length >= aOffset + aCount) {
// Is there cached data covering at least the requested range?
const int64_t cachedDataEnd = mResource->GetCachedDataEnd(aOffset);
if (cachedDataEnd >= aOffset + aCount) {
// Try to read as much resource-cached data as can fill our local cache.
// Assume we can read as much as is cached without blocking.
const uint32_t cacheIndex = IndexInCache(aOffset);
const uint32_t toRead = uint32_t(std::min(
cachedDataEnd - aOffset, int64_t(mCacheBlockSize - cacheIndex)));
MOZ_ASSERT(toRead >= aCount);
uint32_t read = 0;
// We would like `toRead` if possible, but ok with at least `aCount`.
nsresult rv = UncachedRangedReadAt(aOffset, &mCachedBlock[cacheIndex],
aCount, toRead - aCount, &read);
if (NS_SUCCEEDED(rv)) {
if (read == 0) {
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - UncachedRangedReadAt(%" PRIu32
"..%" PRIu32 "@%" PRId64
") to top-up succeeded but read nothing -> OK anyway",
aCount, aOffset, aCount, toRead, aOffset);
// Couldn't actually read anything, but didn't error out, so count
// that as success.
return NS_OK;
}
if (mCachedOffset + mCachedBytes == aOffset) {
// We were topping-up the cache, just update its size.
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - UncachedRangedReadAt(%" PRIu32
"..%" PRIu32 "@%" PRId64 ") to top-up succeeded to read %" PRIu32
"...",
aCount, aOffset, aCount, toRead, aOffset, read);
mCachedBytes += read;
} else {
// We were filling the cache from scratch, save new cache information.
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - UncachedRangedReadAt(%" PRIu32
"..%" PRIu32 "@%" PRId64
") to fill cache succeeded to read %" PRIu32 "...",
aCount, aOffset, aCount, toRead, aOffset, read);
mCachedOffset = aOffset;
mCachedBytes = read;
}
// Copy relevant part into output.
uint32_t toCopy = std::min(aCount, read);
memcpy(aBuffer, &mCachedBlock[cacheIndex], toCopy);
*aBytes += toCopy;
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - copied %" PRIu32 "@%" PRId64
" -> OK, %" PRIu32,
aCount, aOffset, toCopy, aOffset, *aBytes);
// We may not have read all that was requested, but we got everything
// we could get, so we're done.
return NS_OK;
}
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - UncachedRangedReadAt(%" PRIu32
"..%" PRIu32 "@%" PRId64
") failed: %s, will fallback to blocking read...",
aCount, aOffset, aCount, toRead, aOffset, ResultName(rv).get());
// Failure during reading. Note that this may be due to the cache
// changing between `GetCachedDataEnd` and `ReadAt`, so it's not
// totally unexpected, just hopefully rare; but we do need to handle it.
// Invalidate part of cache that may have been partially overridden.
if (mCachedOffset + mCachedBytes == aOffset) {
// We were topping-up the cache, just keep the old untouched data.
// (i.e., nothing to do here.)
} else {
// We were filling the cache from scratch, invalidate cache.
mCachedBytes = 0;
}
} else {
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") - no cached data, will fallback to blocking read...",
aCount, aOffset);
}
} else {
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - length is %" PRId64
" (%s), will fallback to blocking read as the caller requested...",
aCount, aOffset, length, length < 0 ? "unknown" : "too short!");
}
uint32_t read = 0;
nsresult rv = UncachedReadAt(aOffset, aBuffer, aCount, &read);
if (NS_SUCCEEDED(rv)) {
*aBytes += read;
ILOG("ReadAt(%" PRIu32 "@%" PRId64 ") - fallback uncached read got %" PRIu32
" bytes -> %s, %" PRIu32,
aCount, aOffset, read, ResultName(rv).get(), *aBytes);
} else {
ILOG("ReadAt(%" PRIu32 "@%" PRId64
") - fallback uncached read failed -> %s, %" PRIu32,
aCount, aOffset, ResultName(rv).get(), *aBytes);
}
return rv;
}
nsresult MediaResourceIndex::UncachedReadAt(int64_t aOffset, char* aBuffer,
uint32_t aCount,
uint32_t* aBytes) const {
if (aOffset < 0) {
return NS_ERROR_ILLEGAL_VALUE;
}
if (aCount == 0) {
*aBytes = 0;
return NS_OK;
}
return mResource->ReadAt(aOffset, aBuffer, aCount, aBytes);
}
nsresult MediaResourceIndex::UncachedRangedReadAt(int64_t aOffset,
char* aBuffer,
uint32_t aRequestedCount,
uint32_t aExtraCount,
uint32_t* aBytes) const {
uint32_t count = aRequestedCount + aExtraCount;
if (aOffset < 0 || count < aRequestedCount) {
return NS_ERROR_ILLEGAL_VALUE;
}
if (count == 0) {
*aBytes = 0;
return NS_OK;
}
return mResource->ReadAt(aOffset, aBuffer, count, aBytes);
}
nsresult MediaResourceIndex::Seek(int32_t aWhence, int64_t aOffset) {
switch (aWhence) {
case SEEK_SET:
break;
case SEEK_CUR:
aOffset += mOffset;
break;
case SEEK_END: {
int64_t length = mResource->GetLength();
if (length == -1 || length - aOffset < 0) {
return NS_ERROR_FAILURE;
}
aOffset = mResource->GetLength() - aOffset;
} break;
default:
return NS_ERROR_FAILURE;
}
if (aOffset < 0) {
return NS_ERROR_ILLEGAL_VALUE;
}
mOffset = aOffset;
return NS_OK;
}
already_AddRefed<MediaByteBuffer> MediaResourceIndex::MediaReadAt(
int64_t aOffset, uint32_t aCount) const {
NS_ENSURE_TRUE(aOffset >= 0, nullptr);
RefPtr<MediaByteBuffer> bytes = new MediaByteBuffer();
bool ok = bytes->SetLength(aCount, fallible);
NS_ENSURE_TRUE(ok, nullptr);
uint32_t bytesRead = 0;
nsresult rv = mResource->ReadAt(
aOffset, reinterpret_cast<char*>(bytes->Elements()), aCount, &bytesRead);
NS_ENSURE_SUCCESS(rv, nullptr);
bytes->SetLength(bytesRead);
return bytes.forget();
}
already_AddRefed<MediaByteBuffer> MediaResourceIndex::CachedMediaReadAt(
int64_t aOffset, uint32_t aCount) const {
RefPtr<MediaByteBuffer> bytes = new MediaByteBuffer();
bool ok = bytes->SetLength(aCount, fallible);
NS_ENSURE_TRUE(ok, nullptr);
char* curr = reinterpret_cast<char*>(bytes->Elements());
nsresult rv = mResource->ReadFromCache(curr, aOffset, aCount);
NS_ENSURE_SUCCESS(rv, nullptr);
return bytes.forget();
}
// Get the length of the stream in bytes. Returns -1 if not known.
// This can change over time; after a seek operation, a misbehaving
// server may give us a resource of a different length to what it had
// reported previously --- or it may just lie in its Content-Length
// header and give us more or less data than it reported. We will adjust
// the result of GetLength to reflect the data that's actually arriving.
int64_t MediaResourceIndex::GetLength() const { return mResource->GetLength(); }
uint32_t MediaResourceIndex::IndexInCache(int64_t aOffsetInFile) const {
const uint32_t index = uint32_t(aOffsetInFile) & (mCacheBlockSize - 1);
MOZ_ASSERT(index == aOffsetInFile % mCacheBlockSize);
return index;
}
int64_t MediaResourceIndex::CacheOffsetContaining(int64_t aOffsetInFile) const {
const int64_t offset = aOffsetInFile & ~(int64_t(mCacheBlockSize) - 1);
MOZ_ASSERT(offset == aOffsetInFile - IndexInCache(aOffsetInFile));
return offset;
}
} // namespace mozilla
// avoid redefined macro in unified build
#undef ILOG