Disk cache: Add base files for implementation of file format version 3.

net/disk_cache/v3/sparse_control_v3.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>
 
@@ skipping 26 matching lines @@
   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:
+  // 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();
+
   // 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();
+
+  // Continues the current operation (open) without a current child.
+  bool ContinueWithoutChild(const std::string& key);
+
+    // Writes to disk the tracking information for this entry.
+  void WriteSparseData();
+
+  // 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 after a single IO operations finishes.
+  void DoChildIOCompleted(int result);
+
   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();
 
+  // Invoked by the callback of asynchronous operations.
+  void OnChildIOCompleted(int result);
+
   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_