Reorganize net/disk_cache into backend specific directories.

net/disk_cache/sparse_control.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef NET_DISK_CACHE_SPARSE_CONTROL_H_
-#define NET_DISK_CACHE_SPARSE_CONTROL_H_
-
-#include <string>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/compiler_specific.h"
-#include "net/base/completion_callback.h"
-#include "net/disk_cache/bitmap.h"
-#include "net/disk_cache/disk_format.h"
-
-namespace net {
-class IOBuffer;
-class DrainableIOBuffer;
-}
-
-namespace disk_cache {
-
-class Entry;
-class EntryImpl;
-
-// This class provides support for the sparse capabilities of the disk cache.
-// Basically, sparse IO is directed from EntryImpl to this class, and we split
-// the operation into multiple small pieces, sending each one to the
-// appropriate entry. An instance of this class is asociated with each entry
-// used directly for sparse operations (the entry passed in to the constructor).
-class SparseControl {
- public:
-  typedef net::CompletionCallback CompletionCallback;
-
-  // The operation to perform.
-  enum SparseOperation {
-    kNoOperation,
-    kReadOperation,
-    kWriteOperation,
-    kGetRangeOperation
-  };
-
-  explicit SparseControl(EntryImpl* entry);
-  ~SparseControl();
-
-  // Initializes the object for the current entry. If this entry already stores
-  // sparse data, or can be used to do it, it updates the relevant information
-  // on disk and returns net::OK. Otherwise it returns a net error code.
-  int Init();
-
-  // Performs a quick test to see if the entry is sparse or not, without
-  // generating disk IO (so the answer provided is only a best effort).
-  bool CouldBeSparse() const;
-
-  // Performs an actual sparse read or write operation for this entry. |op| is
-  // the operation to perform, |offset| is the desired sparse offset, |buf| and
-  // |buf_len| specify the actual data to use and |callback| is the callback
-  // to use for asynchronous operations. See the description of the Read /
-  // WriteSparseData for details about the arguments. The return value is the
-  // number of bytes read or written, or a net error code.
-  int StartIO(SparseOperation op, int64 offset, net::IOBuffer* buf,
-              int buf_len, const CompletionCallback& callback);
-
-  // Implements Entry::GetAvailableRange().
-  int GetAvailableRange(int64 offset, int len, int64* start);
-
-  // Cancels the current sparse operation (if any).
-  void CancelIO();
-
-  // Returns OK if the entry can be used for new IO or ERR_IO_PENDING if we are
-  // busy. If the entry is busy, we'll invoke the callback when we are ready
-  // again. See disk_cache::Entry::ReadyToUse() for more info.
-  int ReadyToUse(const CompletionCallback& completion_callback);
-
-  // Deletes the children entries of |entry|.
-  static void DeleteChildren(EntryImpl* entry);
-
- private:
-  // Creates a new sparse entry or opens an aready created entry from disk.
-  // These methods just read / write the required info from disk for the current
-  // entry, and verify that everything is correct. The return value is a net
-  // error code.
-  int CreateSparseEntry();
-  int OpenSparseEntry(int data_len);
-
-  // Opens and closes a child entry. A child entry is a regular EntryImpl object
-  // with a key derived from the key of the resource to store and the range
-  // stored by that child.
-  bool OpenChild();
-  void CloseChild();
-  std::string GenerateChildKey();
-
-  // Deletes the current child and continues the current operation (open).
-  bool KillChildAndContinue(const std::string& key, bool fatal);
-
-  // Continues the current operation (open) without a current child.
-  bool ContinueWithoutChild(const std::string& key);
-
-  // Returns true if the required child is tracked by the parent entry, i.e. it
-  // was already created.
-  bool ChildPresent();
-
-  // Sets the bit for the current child to the provided |value|. In other words,
-  // starts or stops tracking this child.
-  void SetChildBit(bool value);
-
-  // Writes to disk the tracking information for this entry.
-  void WriteSparseData();
-
-  // Verify that the range to be accessed for the current child is appropriate.
-  // Returns false if an error is detected or there is no need to perform the
-  // current IO operation (for instance if the required range is not stored by
-  // the child).
-  bool VerifyRange();
-
-  // Updates the contents bitmap for the current range, based on the result of
-  // the current operation.
-  void UpdateRange(int result);
-
-  // Returns the number of bytes stored at |block_index|, if its allocation-bit
-  // is off (because it is not completely filled).
-  int PartialBlockLength(int block_index) const;
-
-  // Initializes the sparse info for the current child.
-  void InitChildData();
-
-  // Iterates through all the children needed to complete the current operation.
-  void DoChildrenIO();
-
-  // Performs a single operation with the current child. Returns true when we
-  // should move on to the next child and false when we should interrupt our
-  // work.
-  bool DoChildIO();
-
-  // Performs the required work for GetAvailableRange for one child.
-  int DoGetAvailableRange();
-
-  // Performs the required work after a single IO operations finishes.
-  void DoChildIOCompleted(int result);
-
-  // Invoked by the callback of asynchronous operations.
-  void OnChildIOCompleted(int result);
-
-  // Reports to the user that we are done.
-  void DoUserCallback();
-  void DoAbortCallbacks();
-
-  EntryImpl* entry_;  // The sparse entry.
-  EntryImpl* child_;  // The current child entry.
-  SparseOperation operation_;
-  bool pending_;  // True if any child IO operation returned pending.
-  bool finished_;
-  bool init_;
-  bool range_found_;  // True if GetAvailableRange found something.
-  bool abort_;  // True if we should abort the current operation ASAP.
-
-  SparseHeader sparse_header_;  // Data about the children of entry_.
-  Bitmap children_map_;  // The actual bitmap of children.
-  SparseData child_data_;  // Parent and allocation map of child_.
-  Bitmap child_map_;  // The allocation map as a bitmap.
-
-  CompletionCallback user_callback_;
-  std::vector<CompletionCallback> abort_callbacks_;
-  int64 offset_;  // Current sparse offset.
-  scoped_refptr<net::DrainableIOBuffer> user_buf_;
-  int buf_len_;  // Bytes to read or write.
-  int child_offset_;  // Offset to use for the current child.
-  int child_len_;  // Bytes to read or write for this child.
-  int result_;
-
-  DISALLOW_COPY_AND_ASSIGN(SparseControl);
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_SPARSE_CONTROL_H_