gecko-dev/netwerk/cache2/CacheFileChunk.h

/* 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 CacheFileChunk__h__
#define CacheFileChunk__h__

#include "CacheFileIOManager.h"
#include "CacheStorageService.h"
#include "CacheHashUtils.h"
#include "CacheFileUtils.h"
#include "nsAutoPtr.h"
#include "mozilla/Mutex.h"

namespace mozilla {
namespace net {

#define kChunkSize        (256 * 1024)
#define kEmptyChunkHash   0x1826

class CacheFileChunk;
class CacheFile;

class CacheFileChunkBuffer
{
public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CacheFileChunkBuffer)

  explicit CacheFileChunkBuffer(CacheFileChunk *aChunk);

  nsresult EnsureBufSize(uint32_t aSize);
  void     CopyFrom(CacheFileChunkBuffer *aOther);
  nsresult FillInvalidRanges(CacheFileChunkBuffer *aOther,
                             CacheFileUtils::ValidityMap *aMap);
  size_t   SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

  char *   Buf() const { return mBuf; }
  void     SetDataSize(uint32_t aDataSize);
  uint32_t DataSize() const { return mDataSize; }
  uint32_t ReadHandlesCount() const { return mReadHandlesCount; }
  bool     WriteHandleExists() const { return mWriteHandleExists; }

private:
  friend class CacheFileChunkHandle;
  friend class CacheFileChunkReadHandle;
  friend class CacheFileChunkWriteHandle;

  ~CacheFileChunkBuffer();

  void AssertOwnsLock() const;

  void RemoveReadHandle();
  void RemoveWriteHandle();

  // We keep a weak reference to the chunk to not create a reference cycle. The
  // buffer is referenced only by chunk and handles. Handles are always
  // destroyed before the chunk so it is guaranteed that mChunk is a valid
  // pointer for the whole buffer's lifetime.
  CacheFileChunk *mChunk;
  char           *mBuf;
  uint32_t        mBufSize;
  uint32_t        mDataSize;
  uint32_t        mReadHandlesCount;
  bool            mWriteHandleExists;
};

class CacheFileChunkHandle
{
public:
  uint32_t DataSize();
  uint32_t Offset();

protected:
  RefPtr<CacheFileChunkBuffer> mBuf;
};

class CacheFileChunkReadHandle : public CacheFileChunkHandle
{
public:
  explicit CacheFileChunkReadHandle(CacheFileChunkBuffer *aBuf);
  ~CacheFileChunkReadHandle();

  const char *Buf();
};

class CacheFileChunkWriteHandle : public CacheFileChunkHandle
{
public:
  explicit CacheFileChunkWriteHandle(CacheFileChunkBuffer *aBuf);
  ~CacheFileChunkWriteHandle();

  char *Buf();
  void UpdateDataSize(uint32_t aOffset, uint32_t aLen);
};

#define CACHEFILECHUNKLISTENER_IID \
{ /* baf16149-2ab5-499c-a9c2-5904eb95c288 */       \
  0xbaf16149,                                      \
  0x2ab5,                                          \
  0x499c,                                          \
  {0xa9, 0xc2, 0x59, 0x04, 0xeb, 0x95, 0xc2, 0x88} \
}

class CacheFileChunkListener : public nsISupports
{
public:
  NS_DECLARE_STATIC_IID_ACCESSOR(CACHEFILECHUNKLISTENER_IID)

  NS_IMETHOD OnChunkRead(nsresult aResult, CacheFileChunk *aChunk) = 0;
  NS_IMETHOD OnChunkWritten(nsresult aResult, CacheFileChunk *aChunk) = 0;
  NS_IMETHOD OnChunkAvailable(nsresult aResult, uint32_t aChunkIdx,
                              CacheFileChunk *aChunk) = 0;
  NS_IMETHOD OnChunkUpdated(CacheFileChunk *aChunk) = 0;
};

NS_DEFINE_STATIC_IID_ACCESSOR(CacheFileChunkListener,
                              CACHEFILECHUNKLISTENER_IID)


class ChunkListenerItem {
public:
  ChunkListenerItem()  { MOZ_COUNT_CTOR(ChunkListenerItem); }
  ~ChunkListenerItem() { MOZ_COUNT_DTOR(ChunkListenerItem); }

  nsCOMPtr<nsIEventTarget>         mTarget;
  nsCOMPtr<CacheFileChunkListener> mCallback;
};

class ChunkListeners {
public:
  ChunkListeners()  { MOZ_COUNT_CTOR(ChunkListeners); }
  ~ChunkListeners() { MOZ_COUNT_DTOR(ChunkListeners); }

  nsTArray<ChunkListenerItem *> mItems;
};

class CacheFileChunk : public CacheFileIOListener
                     , public CacheMemoryConsumer
{
public:
  NS_DECL_THREADSAFE_ISUPPORTS
  bool DispatchRelease();

  CacheFileChunk(CacheFile *aFile, uint32_t aIndex, bool aInitByWriter);

  void     InitNew();
  nsresult Read(CacheFileHandle *aHandle, uint32_t aLen,
                CacheHash::Hash16_t aHash,
                CacheFileChunkListener *aCallback);
  nsresult Write(CacheFileHandle *aHandle, CacheFileChunkListener *aCallback);
  void     WaitForUpdate(CacheFileChunkListener *aCallback);
  nsresult CancelWait(CacheFileChunkListener *aCallback);
  nsresult NotifyUpdateListeners();

  uint32_t            Index() const;
  CacheHash::Hash16_t Hash() const;
  uint32_t            DataSize() const;

  NS_IMETHOD OnFileOpened(CacheFileHandle *aHandle, nsresult aResult) override;
  NS_IMETHOD OnDataWritten(CacheFileHandle *aHandle, const char *aBuf,
                           nsresult aResult) override;
  NS_IMETHOD OnDataRead(CacheFileHandle *aHandle, char *aBuf, nsresult aResult) override;
  NS_IMETHOD OnFileDoomed(CacheFileHandle *aHandle, nsresult aResult) override;
  NS_IMETHOD OnEOFSet(CacheFileHandle *aHandle, nsresult aResult) override;
  NS_IMETHOD OnFileRenamed(CacheFileHandle *aHandle, nsresult aResult) override;
  virtual bool IsKilled() override;

  bool   IsReady() const;
  bool   IsDirty() const;

  nsresult GetStatus();
  void     SetError(nsresult aStatus);

  CacheFileChunkReadHandle  GetReadHandle();
  CacheFileChunkWriteHandle GetWriteHandle(uint32_t aEnsuredBufSize);

  // Memory reporting
  size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
  size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

private:
  friend class CacheFileChunkBuffer;
  friend class CacheFileChunkWriteHandle;
  friend class CacheFileInputStream;
  friend class CacheFileOutputStream;
  friend class CacheFile;

  virtual ~CacheFileChunk();

  void AssertOwnsLock() const;

  void UpdateDataSize(uint32_t aOffset, uint32_t aLen);
  nsresult Truncate(uint32_t aOffset);

  bool CanAllocate(uint32_t aSize) const;
  void BuffersAllocationChanged(uint32_t aFreed, uint32_t aAllocated);

  mozilla::Atomic<uint32_t, ReleaseAcquire>& ChunksMemoryUsage() const;

  enum EState {
    INITIAL = 0,
    READING = 1,
    WRITING = 2,
    READY   = 3
  };

  uint32_t mIndex;
  EState   mState;
  nsresult mStatus;

  Atomic<bool> mActiveChunk; // Is true iff the chunk is in CacheFile::mChunks.
                             // Adding/removing chunk to/from mChunks as well as
                             // changing this member happens under the
                             // CacheFile's lock.
  bool mIsDirty : 1;
  bool mDiscardedChunk : 1;

  uint32_t   mBuffersSize;
  bool const mLimitAllocation : 1; // Whether this chunk respects limit for disk
                                   // chunks memory usage.
  bool const mIsPriority : 1;

  // Buffer containing the chunk data. Multiple read handles can access the same
  // buffer. When write handle is created and some read handle exists a new copy
  // of the buffer is created. This prevents invalidating the buffer when
  // CacheFileInputStream::ReadSegments calls the handler outside the lock.
  RefPtr<CacheFileChunkBuffer> mBuf;

  // We need to keep pointers of the old buffers for memory reporting.
  nsTArray<RefPtr<CacheFileChunkBuffer>> mOldBufs;

  // Read handle that is used during writing the chunk to the disk.
  nsAutoPtr<CacheFileChunkReadHandle> mWritingStateHandle;

  // Buffer that is used to read the chunk from the disk. It is allowed to write
  // a new data to chunk while we wait for the data from the disk. In this case
  // this buffer is merged with mBuf in OnDataRead().
  RefPtr<CacheFileChunkBuffer> mReadingStateBuf;
  CacheHash::Hash16_t          mExpectedHash;

  RefPtr<CacheFile>                mFile; // is null if chunk is cached to
                                          // prevent reference cycles
  nsCOMPtr<CacheFileChunkListener> mListener;
  nsTArray<ChunkListenerItem *>    mUpdateListeners;
  CacheFileUtils::ValidityMap      mValidityMap;
};


} // namespace net
} // namespace mozilla

#endif