MutableBlobStorage.h

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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 http://mozilla.org/MPL/2.0/. */

#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 {

 public:

  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING

  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 {

 public:

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MutableBlobStorage)

  enum MutableBlobStorageType {

    eOnlyInMemory,

    eCouldBeInTemporaryFile,

};

  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() {

    MOZ_ASSERT(mEventTarget);

    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();

 private:

  ~MutableBlobStorage();

  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);

  Mutex mMutex MOZ_UNANNOTATED;

  // 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 {

    eKeepInMemory,

    eInMemory,

    eWaitingForTemporaryFile,

    eInTemporaryFile,

    eClosed

};

  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