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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#ifndef mozilla_dom_MutableBlobStorage_h
#define mozilla_dom_MutableBlobStorage_h
#include "mozilla/RefPtr.h"
#include "mozilla/Mutex.h"
#include "nsCOMPtr.h"
#include "nsString.h"
#include "prio.h"
class nsIEventTarget;
class nsIRunnable;
namespace mozilla {
class TaskQueue;
namespace dom {
class Blob;
class BlobImpl;
class MutableBlobStorage;
class TemporaryIPCBlobChild;
class TemporaryIPCBlobChildCallback;
class MutableBlobStorageCallback {
virtual void BlobStoreCompleted(MutableBlobStorage* aBlobStorage,
BlobImpl* aBlob, nsresult aRv) = 0;
// This class is must be created and used on main-thread, except for Append()
// that can be called on any thread.
class MutableBlobStorage final {
enum MutableBlobStorageType {
explicit MutableBlobStorage(MutableBlobStorageType aType,
nsIEventTarget* aEventTarget = nullptr,
uint32_t aMaxMemory = 0);
nsresult Append(const void* aData, uint32_t aLength);
// This method can be called just once.
// The callback will be called when the BlobImpl is ready.
void GetBlobImplWhenReady(const nsACString& aContentType,
MutableBlobStorageCallback* aCallback);
void TemporaryFileCreated(PRFileDesc* aFD);
void AskForBlob(TemporaryIPCBlobChildCallback* aCallback,
const nsACString& aContentType);
void ErrorPropagated(nsresult aRv);
nsIEventTarget* EventTarget() {
return mEventTarget;
// Returns the heap size in bytes of our internal buffers.
// Note that this intentionally ignores the data in the temp file.
size_t SizeOfCurrentMemoryBuffer();
PRFileDesc* GetFD();
void CloseFD();
bool ExpandBufferSize(const MutexAutoLock& aProofOfLock, uint64_t aSize);
bool ShouldBeTemporaryStorage(const MutexAutoLock& aProofOfLock,
uint64_t aSize) const;
bool MaybeCreateTemporaryFile(const MutexAutoLock& aProofOfLock);
void MaybeCreateTemporaryFileOnMainThread(const MutexAutoLock& aProofOfLock);
[[nodiscard]] nsresult DispatchToIOThread(
already_AddRefed<nsIRunnable> aRunnable);
// All these variables are touched on the main thread only or in the
// retargeted thread when used by Append(). They are protected by mMutex.
void* mData;
uint64_t mDataLen;
uint64_t mDataBufferLen;
enum StorageState {
StorageState mStorageState;
PRFileDesc* mFD;
nsresult mErrorResult;
RefPtr<TaskQueue> mTaskQueue;
nsCOMPtr<nsIEventTarget> mEventTarget;
nsCString mPendingContentType;
RefPtr<MutableBlobStorageCallback> mPendingCallback;
RefPtr<TemporaryIPCBlobChild> mActor;
// This value is used when we go from eInMemory to eWaitingForTemporaryFile
// and eventually eInTemporaryFile. If the size of the buffer is >=
// mMaxMemory, the creation of the temporary file will start.
// It's not used if mStorageState is eKeepInMemory.
uint32_t mMaxMemory;
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_MutableBlobStorage_h