Disk Cache: Implement GetAvailableRange for the regular disk cache....

net/disk_cache/sparse_control.h

 // Copyright (c) 2009 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 "base/basictypes.h"
@@ skipping 16 matching lines @@
 // 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:
   // The operation to perform.
   enum SparseOperation {
     kNoOperation,
     kReadOperation,
-    kWriteOperation
+    kWriteOperation,
+    kGetRangeOperation
   };
 
   explicit SparseControl(EntryImpl* entry)
       : entry_(entry), child_(NULL), operation_(kNoOperation), init_(false),
         child_map_(child_data_.bitmap, kNumSparseBits, kNumSparseBits / 32),
         ALLOW_THIS_IN_INITIALIZER_LIST(
             child_callback_(this, &SparseControl::OnChildIOCompleted)),
         user_callback_(NULL) {}
   ~SparseControl();
 
@@ skipping 54 matching lines @@
   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();
 
   EntryImpl* entry_;  // The sparse entry.
   Entry* 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.
 
   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.
 
   net::CompletionCallbackImpl<SparseControl> child_callback_;
   net::CompletionCallback* user_callback_;
   int64 offset_;  // Current sparse offset.
   scoped_refptr<net::ReusedIOBuffer> 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_