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-rw-r--r--net/disk_cache/sparse_control.h147
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diff --git a/net/disk_cache/sparse_control.h b/net/disk_cache/sparse_control.h
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-// 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"
-#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 ReusedIOBuffer;
-}
-
-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:
- // The operation to perform.
- enum SparseOperation {
- kNoOperation,
- kReadOperation,
- kWriteOperation
- };
-
- 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();
-
- // 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 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, net::CompletionCallback* callback);
-
- // Implements Entry::GetAvailableRange().
- int GetAvailableRange(int64 offset, int len, int64* start);
-
- 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();
-
- // Returns true if the required child is tracked by the parent entry, i.e. it
- // was already created.
- bool ChildPresent();
-
- // Starts tracking this child. A new child entry was created so we must set
- // the corresponding bit on the bitmap of children.
- void SetChildBit();
-
- // 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);
-
- // 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 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_;
-
- 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_