net/disk_cache/blockfile/entry_impl_v3.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_V3_H_
   6 #define NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_V3_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "net/base/net_log.h"
  12 #include "net/disk_cache/blockfile/disk_format_v3.h"
  13 #include "net/disk_cache/blockfile/storage_block.h"
  14 #include "net/disk_cache/disk_cache.h"
  15
  16 namespace disk_cache {
  17
  18 class BackendImplV3;
  19 class SparseControlV3;
  20
  21 // This class implements the Entry interface. An object of this
  22 // class represents a single entry on the cache.
  23 class NET_EXPORT_PRIVATE EntryImplV3
  24     : public Entry,
  25       public base::RefCounted<EntryImplV3> {
  26   friend class base::RefCounted<EntryImplV3>;
  27   // friend class SparseControlV3;
  28  public:
  29   enum Operation {
  30     kRead,
  31     kWrite,
  32     kSparseRead,
  33     kSparseWrite,
  34     kAsyncIO,
  35     kReadAsync1,
  36     kWriteAsync1
  37   };
  38
  39   EntryImplV3(BackendImplV3* backend, Addr address, bool read_only);
  40
  41   // Performs the initialization of a EntryImplV3 that will be added to the
  42   // cache.
  43   bool CreateEntry(Addr node_address, const std::string& key, uint32 hash);
  44
  45   uint32 GetHash();
  46
  47   uint32 GetHash() const;
  48   Addr GetAddress() const;
  49   int GetReuseCounter() const;
  50   void SetReuseCounter(int count);
  51   int GetRefetchCounter() const;
  52   void SetRefetchCounter(int count);
  53
  54   // Returns true if this entry matches the lookup arguments.
  55   bool IsSameEntry(const std::string& key, uint32 hash);
  56
  57   // Permamently destroys this entry.
  58   void InternalDoom();
  59
  60   // Returns false if the entry is clearly invalid.
  61   bool SanityCheck();
  62   bool DataSanityCheck();
  63
  64   // Attempts to make this entry reachable though the key.
  65   void FixForDelete();
  66
  67   // Set the access times for this entry. This method provides support for
  68   // the upgrade tool.
  69   void SetTimes(base::Time last_used, base::Time last_modified);
  70
  71   // Logs a begin event and enables logging for the EntryImplV3. Will also cause
  72   // an end event to be logged on destruction. The EntryImplV3 must have its key
  73   // initialized before this is called. |created| is true if the Entry was
  74   // created rather than opened.
  75   void BeginLogging(net::NetLog* net_log, bool created);
  76
  77   const net::BoundNetLog& net_log() const;
  78
  79   // Entry interface.
  80   virtual void Doom() OVERRIDE;
  81   virtual void Close() OVERRIDE;
  82   virtual std::string GetKey() const OVERRIDE;
  83   virtual base::Time GetLastUsed() const OVERRIDE;
  84   virtual base::Time GetLastModified() const OVERRIDE;
  85   virtual int32 GetDataSize(int index) const OVERRIDE;
  86   virtual int ReadData(int index, int offset, IOBuffer* buf, int buf_len,
  87                        const CompletionCallback& callback) OVERRIDE;
  88   virtual int WriteData(int index, int offset, IOBuffer* buf, int buf_len,
  89                         const CompletionCallback& callback,
  90                         bool truncate) OVERRIDE;
  91   virtual int ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
  92                              const CompletionCallback& callback) OVERRIDE;
  93   virtual int WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
  94                               const CompletionCallback& callback) OVERRIDE;
  95   virtual int GetAvailableRange(int64 offset, int len, int64* start,
  96                                 const CompletionCallback& callback) OVERRIDE;
  97   virtual bool CouldBeSparse() const OVERRIDE;
  98   virtual void CancelSparseIO() OVERRIDE;
  99   virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
 100
 101  private:
 102   enum {
 103      kNumStreams = 3
 104   };
 105   class UserBuffer;
 106
 107   virtual ~EntryImplV3();
 108
 109   // Do all the work for ReadDataImpl and WriteDataImpl.  Implemented as
 110   // separate functions to make logging of results simpler.
 111   int InternalReadData(int index, int offset, IOBuffer* buf,
 112                        int buf_len, const CompletionCallback& callback);
 113   int InternalWriteData(int index, int offset, IOBuffer* buf, int buf_len,
 114                         const CompletionCallback& callback, bool truncate);
 115
 116   // Initializes the storage for an internal or external data block.
 117   bool CreateDataBlock(int index, int size);
 118
 119   // Initializes the storage for an internal or external generic block.
 120   bool CreateBlock(int size, Addr* address);
 121
 122   // Deletes the data pointed by address, maybe backed by files_[index].
 123   // Note that most likely the caller should delete (and store) the reference to
 124   // |address| *before* calling this method because we don't want to have an
 125   // entry using an address that is already free.
 126   void DeleteData(Addr address, int index);
 127
 128   // Updates ranking information.
 129   void UpdateRank(bool modified);
 130
 131   // Deletes this entry from disk. If |everything| is false, only the user data
 132   // will be removed, leaving the key and control data intact.
 133   void DeleteEntryData(bool everything);
 134
 135   // Prepares the target file or buffer for a write of buf_len bytes at the
 136   // given offset.
 137   bool PrepareTarget(int index, int offset, int buf_len, bool truncate);
 138
 139   // Adjusts the internal buffer and file handle for a write that truncates this
 140   // stream.
 141   bool HandleTruncation(int index, int offset, int buf_len);
 142
 143   // Copies data from disk to the internal buffer.
 144   bool CopyToLocalBuffer(int index);
 145
 146   // Reads from a block data file to this object's memory buffer.
 147   bool MoveToLocalBuffer(int index);
 148
 149   // Loads the external file to this object's memory buffer.
 150   bool ImportSeparateFile(int index, int new_size);
 151
 152   // Makes sure that the internal buffer can handle the a write of |buf_len|
 153   // bytes to |offset|.
 154   bool PrepareBuffer(int index, int offset, int buf_len);
 155
 156   // Flushes the in-memory data to the backing storage. The data destination
 157   // is determined based on the current data length and |min_len|.
 158   bool Flush(int index, int min_len);
 159
 160   // Updates the size of a given data stream.
 161   void UpdateSize(int index, int old_size, int new_size);
 162
 163   // Initializes the sparse control object. Returns a net error code.
 164   int InitSparseData();
 165
 166   // Adds the provided |flags| to the current EntryFlags for this entry.
 167   void SetEntryFlags(uint32 flags);
 168
 169   // Returns the current EntryFlags for this entry.
 170   uint32 GetEntryFlags();
 171
 172   // Gets the data stored at the given index. If the information is in memory,
 173   // a buffer will be allocated and the data will be copied to it (the caller
 174   // can find out the size of the buffer before making this call). Otherwise,
 175   // the cache address of the data will be returned, and that address will be
 176   // removed from the regular book keeping of this entry so the caller is
 177   // responsible for deleting the block (or file) from the backing store at some
 178   // point; there is no need to report any storage-size change, only to do the
 179   // actual cleanup.
 180   void GetData(int index, char** buffer, Addr* address);
 181
 182   // Generates a histogram for the time spent working on this operation.
 183   void ReportIOTime(Operation op, const base::TimeTicks& start);
 184
 185   // Logs this entry to the internal trace buffer.
 186   void Log(const char* msg);
 187
 188   scoped_ptr<EntryRecord> entry_;  // Basic record for this entry.
 189   scoped_ptr<ShortEntryRecord> short_entry_;  // Valid for evicted entries.
 190   base::WeakPtr<BackendImplV3> backend_;  // Back pointer to the cache.
 191   scoped_ptr<UserBuffer> user_buffers_[kNumStreams];  // Stores user data.
 192   mutable std::string key_;           // Copy of the key.
 193   Addr address_;
 194   int unreported_size_[kNumStreams];  // Bytes not reported yet to the backend.
 195   bool doomed_;               // True if this entry was removed from the cache.
 196   bool read_only_;
 197   bool dirty_;                // True if there is something to write.
 198   bool modified_;
 199   // scoped_ptr<SparseControlV3> sparse_;  // Support for sparse entries.
 200
 201   net::BoundNetLog net_log_;
 202
 203   DISALLOW_COPY_AND_ASSIGN(EntryImplV3);
 204 };
 205
 206 }  // namespace disk_cache
 207
 208 #endif  // NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_V3_H_