gecko-dev/dom/media/EncodedBufferCache.cpp
2017-06-26 14:19:58 -07:00

134 lines
4.7 KiB
C++

/* -*- 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 "EncodedBufferCache.h"
#include "prio.h"
#include "nsAnonymousTemporaryFile.h"
#include "mozilla/Monitor.h"
#include "mozilla/dom/ContentChild.h"
#include "mozilla/dom/File.h"
#include "nsThreadUtils.h"
#include "nsXULAppAPI.h"
namespace mozilla {
void
EncodedBufferCache::AppendBuffer(nsTArray<uint8_t> & aBuf)
{
MOZ_ASSERT(!NS_IsMainThread());
MutexAutoLock lock(mMutex);
mDataSize += aBuf.Length();
mEncodedBuffers.AppendElement()->SwapElements(aBuf);
if (!mTempFileEnabled && mDataSize > mMaxMemoryStorage) {
nsresult rv;
PRFileDesc* tempFD = nullptr;
{
// Release the mMutex because of the sync dispatch to the main thread.
MutexAutoUnlock unlock(mMutex);
if (XRE_IsParentProcess()) {
// In case we are in the parent process, do a synchronous I/O here to open a
// temporary file.
rv = NS_OpenAnonymousTemporaryFile(&tempFD);
} else {
// In case we are in the child process, we don't have access to open a file
// directly due to sandbox restrictions, so we need to ask the parent process
// to do that for us. In order to initiate the IPC, we need to first go to
// the main thread. This is done by dispatching a runnable to the main thread.
// From there, we start an asynchronous IPC, and we block the current thread
// using a monitor while this async work is in progress. When we receive the
// resulting file descriptor from the parent process, we notify the monitor
// and unblock the current thread and continue.
typedef dom::ContentChild::AnonymousTemporaryFileCallback
AnonymousTemporaryFileCallback;
bool done = false;
Monitor monitor("EncodeBufferCache::AppendBuffer");
RefPtr<dom::ContentChild> cc = dom::ContentChild::GetSingleton();
nsCOMPtr<nsIRunnable> runnable =
NewRunnableMethod<AnonymousTemporaryFileCallback>(
"dom::ContentChild::AsyncOpenAnonymousTemporaryFile",
cc,
&dom::ContentChild::AsyncOpenAnonymousTemporaryFile,
[&](PRFileDesc* aFile) {
rv = aFile ? NS_OK : NS_ERROR_FAILURE;
tempFD = aFile;
MonitorAutoLock lock(monitor);
done = true;
lock.Notify();
});
MonitorAutoLock lock(monitor);
rv = NS_DispatchToMainThread(runnable);
if (NS_SUCCEEDED(rv)) {
while (!done) {
lock.Wait();
}
}
}
}
if (!NS_FAILED(rv)) {
// Check the mDataSize again since we release the mMutex before.
if (mDataSize > mMaxMemoryStorage) {
mFD = tempFD;
mTempFileEnabled = true;
} else {
// Close the tempFD because the data had been taken during the
// MutexAutoUnlock.
PR_Close(tempFD);
}
}
}
if (mTempFileEnabled) {
// has created temporary file, write buffer in it
for (uint32_t i = 0; i < mEncodedBuffers.Length(); i++) {
int32_t amount = PR_Write(mFD, mEncodedBuffers.ElementAt(i).Elements(), mEncodedBuffers.ElementAt(i).Length());
if (amount < 0 || size_t(amount) < mEncodedBuffers.ElementAt(i).Length()) {
NS_WARNING("Failed to write media cache block!");
}
}
mEncodedBuffers.Clear();
}
}
already_AddRefed<dom::Blob>
EncodedBufferCache::ExtractBlob(nsISupports* aParent,
const nsAString &aContentType)
{
MutexAutoLock lock(mMutex);
RefPtr<dom::Blob> blob;
if (mTempFileEnabled) {
// generate new temporary file to write
blob = dom::Blob::CreateTemporaryBlob(aParent, mFD, 0, mDataSize,
aContentType);
// fallback to memory blob
mTempFileEnabled = false;
mDataSize = 0;
mFD = nullptr;
} else {
void* blobData = malloc(mDataSize);
NS_ASSERTION(blobData, "out of memory!!");
if (blobData) {
for (uint32_t i = 0, offset = 0; i < mEncodedBuffers.Length(); i++) {
memcpy((uint8_t*)blobData + offset, mEncodedBuffers.ElementAt(i).Elements(),
mEncodedBuffers.ElementAt(i).Length());
offset += mEncodedBuffers.ElementAt(i).Length();
}
blob = dom::Blob::CreateMemoryBlob(aParent, blobData, mDataSize,
aContentType);
mEncodedBuffers.Clear();
} else
return nullptr;
}
mDataSize = 0;
return blob.forget();
}
} // namespace mozilla