Reorganize net/disk_cache into backend specific directories.

net/disk_cache/mem_entry_impl.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_MEM_ENTRY_IMPL_H_
-#define NET_DISK_CACHE_MEM_ENTRY_IMPL_H_
-
-#include "base/containers/hash_tables.h"
-#include "base/gtest_prod_util.h"
-#include "base/memory/scoped_ptr.h"
-#include "net/base/net_log.h"
-#include "net/disk_cache/disk_cache.h"
-
-namespace disk_cache {
-
-class MemBackendImpl;
-
-// This class implements the Entry interface for the memory-only cache. An
-// object of this class represents a single entry on the cache. We use two
-// types of entries, parent and child to support sparse caching.
-//
-// A parent entry is non-sparse until a sparse method is invoked (i.e.
-// ReadSparseData, WriteSparseData, GetAvailableRange) when sparse information
-// is initialized. It then manages a list of child entries and delegates the
-// sparse API calls to the child entries. It creates and deletes child entries
-// and updates the list when needed.
-//
-// A child entry is used to carry partial cache content, non-sparse methods like
-// ReadData and WriteData cannot be applied to them. The lifetime of a child
-// entry is managed by the parent entry that created it except that the entry
-// can be evicted independently. A child entry does not have a key and it is not
-// registered in the backend's entry map. It is registered in the backend's
-// ranking list to enable eviction of a partial content.
-//
-// A sparse entry has a fixed maximum size and can be partially filled. There
-// can only be one continous filled region in a sparse entry, as illustrated by
-// the following example:
-// | xxx ooooo |
-// x = unfilled region
-// o = filled region
-// It is guranteed that there is at most one unfilled region and one filled
-// region, and the unfilled region (if there is one) is always before the filled
-// region. The book keeping for filled region in a sparse entry is done by using
-// the variable |child_first_pos_| (inclusive).
-
-class MemEntryImpl : public Entry {
- public:
-  enum EntryType {
-    kParentEntry,
-    kChildEntry,
-  };
-
-  explicit MemEntryImpl(MemBackendImpl* backend);
-
-  // Performs the initialization of a EntryImpl that will be added to the
-  // cache.
-  bool CreateEntry(const std::string& key, net::NetLog* net_log);
-
-  // Permanently destroys this entry.
-  void InternalDoom();
-
-  void Open();
-  bool InUse();
-
-  MemEntryImpl* next() const {
-    return next_;
-  }
-
-  MemEntryImpl* prev() const {
-    return prev_;
-  }
-
-  void set_next(MemEntryImpl* next) {
-    next_ = next;
-  }
-
-  void set_prev(MemEntryImpl* prev) {
-    prev_ = prev;
-  }
-
-  EntryType type() const {
-    return parent_ ? kChildEntry : kParentEntry;
-  }
-
-  const net::BoundNetLog& net_log() {
-    return net_log_;
-  }
-
-  // Entry interface.
-  virtual void Doom() OVERRIDE;
-  virtual void Close() OVERRIDE;
-  virtual std::string GetKey() const OVERRIDE;
-  virtual base::Time GetLastUsed() const OVERRIDE;
-  virtual base::Time GetLastModified() const OVERRIDE;
-  virtual int32 GetDataSize(int index) const OVERRIDE;
-  virtual int ReadData(int index, int offset, IOBuffer* buf, int buf_len,
-                       const CompletionCallback& callback) OVERRIDE;
-  virtual int WriteData(int index, int offset, IOBuffer* buf, int buf_len,
-                        const CompletionCallback& callback,
-                        bool truncate) OVERRIDE;
-  virtual int ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
-                             const CompletionCallback& callback) OVERRIDE;
-  virtual int WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
-                              const CompletionCallback& callback) OVERRIDE;
-  virtual int GetAvailableRange(int64 offset, int len, int64* start,
-                                const CompletionCallback& callback) OVERRIDE;
-  virtual bool CouldBeSparse() const OVERRIDE;
-  virtual void CancelSparseIO() OVERRIDE {}
-  virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
-
- private:
-  typedef base::hash_map<int, MemEntryImpl*> EntryMap;
-
-  enum {
-    NUM_STREAMS = 3
-  };
-
-  virtual ~MemEntryImpl();
-
-  // Do all the work for corresponding public functions.  Implemented as
-  // separate functions to make logging of results simpler.
-  int InternalReadData(int index, int offset, IOBuffer* buf, int buf_len);
-  int InternalWriteData(int index, int offset, IOBuffer* buf, int buf_len,
-                        bool truncate);
-  int InternalReadSparseData(int64 offset, IOBuffer* buf, int buf_len);
-  int InternalWriteSparseData(int64 offset, IOBuffer* buf, int buf_len);
-
-  // Old Entry interface.
-  int GetAvailableRange(int64 offset, int len, int64* start);
-
-  // Grows and cleans up the data buffer.
-  void PrepareTarget(int index, int offset, int buf_len);
-
-  // Updates ranking information.
-  void UpdateRank(bool modified);
-
-  // Initializes the children map and sparse info. This method is only called
-  // on a parent entry.
-  bool InitSparseInfo();
-
-  // Performs the initialization of a MemEntryImpl as a child entry.
-  // |parent| is the pointer to the parent entry. |child_id| is the ID of
-  // the new child.
-  bool InitChildEntry(MemEntryImpl* parent, int child_id, net::NetLog* net_log);
-
-  // Returns an entry responsible for |offset|. The returned entry can be a
-  // child entry or this entry itself if |offset| points to the first range.
-  // If such entry does not exist and |create| is true, a new child entry is
-  // created.
-  MemEntryImpl* OpenChild(int64 offset, bool create);
-
-  // Finds the first child located within the range [|offset|, |offset + len|).
-  // Returns the number of bytes ahead of |offset| to reach the first available
-  // bytes in the entry. The first child found is output to |child|.
-  int FindNextChild(int64 offset, int len, MemEntryImpl** child);
-
-  // Removes child indexed by |child_id| from the children map.
-  void DetachChild(int child_id);
-
-  std::string key_;
-  std::vector<char> data_[NUM_STREAMS];  // User data.
-  int32 data_size_[NUM_STREAMS];
-  int ref_count_;
-
-  int child_id_;              // The ID of a child entry.
-  int child_first_pos_;       // The position of the first byte in a child
-                              // entry.
-  MemEntryImpl* next_;        // Pointers for the LRU list.
-  MemEntryImpl* prev_;
-  MemEntryImpl* parent_;      // Pointer to the parent entry.
-  scoped_ptr<EntryMap> children_;
-
-  base::Time last_modified_;  // LRU information.
-  base::Time last_used_;
-  MemBackendImpl* backend_;   // Back pointer to the cache.
-  bool doomed_;               // True if this entry was removed from the cache.
-
-  net::BoundNetLog net_log_;
-
-  DISALLOW_COPY_AND_ASSIGN(MemEntryImpl);
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_MEM_ENTRY_IMPL_H_