net/disk_cache/in_flight_backend_io.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_IN_FLIGHT_BACKEND_IO_H_
   6 #define NET_DISK_CACHE_IN_FLIGHT_BACKEND_IO_H_
   7
   8 #include <list>
   9 #include <string>
  10
  11 #include "base/message_loop_proxy.h"
  12 #include "base/time.h"
  13 #include "net/base/completion_callback.h"
  14 #include "net/base/io_buffer.h"
  15 #include "net/disk_cache/in_flight_io.h"
  16
  17 namespace disk_cache {
  18
  19 class BackendImpl;
  20 class Entry;
  21 class EntryImpl;
  22
  23 // This class represents a single asynchronous disk cache IO operation while it
  24 // is being bounced between threads.
  25 class BackendIO : public BackgroundIO {
  26  public:
  27   BackendIO(InFlightIO* controller, BackendImpl* backend,
  28             const net::CompletionCallback& callback);
  29
  30   // Runs the actual operation on the background thread.
  31   void ExecuteOperation();
  32
  33   // Callback implementation.
  34   void OnIOComplete(int result);
  35
  36   // Called when we are finishing this operation. If |cancel| is true, the user
  37   // callback will not be invoked.
  38   void OnDone(bool cancel);
  39
  40   // Returns true if this operation is directed to an entry (vs. the backend).
  41   bool IsEntryOperation();
  42
  43   net::CompletionCallback callback() const { return callback_; }
  44
  45   // Grabs an extra reference of entry_.
  46   void ReferenceEntry();
  47
  48   // The operations we proxy:
  49   void Init();
  50   void OpenEntry(const std::string& key, Entry** entry);
  51   void CreateEntry(const std::string& key, Entry** entry);
  52   void DoomEntry(const std::string& key);
  53   void DoomAllEntries();
  54   void DoomEntriesBetween(const base::Time initial_time,
  55                           const base::Time end_time);
  56   void DoomEntriesSince(const base::Time initial_time);
  57   void OpenNextEntry(void** iter, Entry** next_entry);
  58   void OpenPrevEntry(void** iter, Entry** prev_entry);
  59   void EndEnumeration(void* iterator);
  60   void OnExternalCacheHit(const std::string& key);
  61   void CloseEntryImpl(EntryImpl* entry);
  62   void DoomEntryImpl(EntryImpl* entry);
  63   void FlushQueue();  // Dummy operation.
  64   void RunTask(const base::Closure& task);
  65   void ReadData(EntryImpl* entry, int index, int offset, net::IOBuffer* buf,
  66                 int buf_len);
  67   void WriteData(EntryImpl* entry, int index, int offset, net::IOBuffer* buf,
  68                  int buf_len, bool truncate);
  69   void ReadSparseData(EntryImpl* entry, int64 offset, net::IOBuffer* buf,
  70                       int buf_len);
  71   void WriteSparseData(EntryImpl* entry, int64 offset, net::IOBuffer* buf,
  72                        int buf_len);
  73   void GetAvailableRange(EntryImpl* entry, int64 offset, int len, int64* start);
  74   void CancelSparseIO(EntryImpl* entry);
  75   void ReadyForSparseIO(EntryImpl* entry);
  76
  77  private:
  78   // There are two types of operations to proxy: regular backend operations are
  79   // executed sequentially (queued by the message loop). On the other hand,
  80   // operations targeted to a given entry can be long lived and support multiple
  81   // simultaneous users (multiple reads or writes to the same entry), and they
  82   // are subject to throttling, so we keep an explicit queue.
  83   enum Operation {
  84     OP_NONE = 0,
  85     OP_INIT,
  86     OP_OPEN,
  87     OP_CREATE,
  88     OP_DOOM,
  89     OP_DOOM_ALL,
  90     OP_DOOM_BETWEEN,
  91     OP_DOOM_SINCE,
  92     OP_OPEN_NEXT,
  93     OP_OPEN_PREV,
  94     OP_END_ENUMERATION,
  95     OP_ON_EXTERNAL_CACHE_HIT,
  96     OP_CLOSE_ENTRY,
  97     OP_DOOM_ENTRY,
  98     OP_FLUSH_QUEUE,
  99     OP_RUN_TASK,
 100     OP_MAX_BACKEND,
 101     OP_READ,
 102     OP_WRITE,
 103     OP_READ_SPARSE,
 104     OP_WRITE_SPARSE,
 105     OP_GET_RANGE,
 106     OP_CANCEL_IO,
 107     OP_IS_READY
 108   };
 109
 110   virtual ~BackendIO();
 111
 112   // Returns true if this operation returns an entry.
 113   bool ReturnsEntry();
 114
 115   // Returns the time that has passed since the operation was created.
 116   base::TimeDelta ElapsedTime() const;
 117
 118   void ExecuteBackendOperation();
 119   void ExecuteEntryOperation();
 120
 121   BackendImpl* backend_;
 122   net::CompletionCallback callback_;
 123   Operation operation_;
 124
 125   // The arguments of all the operations we proxy:
 126   std::string key_;
 127   Entry** entry_ptr_;
 128   base::Time initial_time_;
 129   base::Time end_time_;
 130   void** iter_ptr_;
 131   void* iter_;
 132   EntryImpl* entry_;
 133   int index_;
 134   int offset_;
 135   scoped_refptr<net::IOBuffer> buf_;
 136   int buf_len_;
 137   bool truncate_;
 138   int64 offset64_;
 139   int64* start_;
 140   base::TimeTicks start_time_;
 141   base::Closure task_;
 142
 143   DISALLOW_COPY_AND_ASSIGN(BackendIO);
 144 };
 145
 146 // The specialized controller that keeps track of current operations.
 147 class InFlightBackendIO : public InFlightIO {
 148  public:
 149   InFlightBackendIO(BackendImpl* backend,
 150                     base::MessageLoopProxy* background_thread);
 151   virtual ~InFlightBackendIO();
 152
 153   // Proxied operations.
 154   void Init(const net::CompletionCallback& callback);
 155   void OpenEntry(const std::string& key, Entry** entry,
 156                  const net::CompletionCallback& callback);
 157   void CreateEntry(const std::string& key, Entry** entry,
 158                    const net::CompletionCallback& callback);
 159   void DoomEntry(const std::string& key,
 160                  const net::CompletionCallback& callback);
 161   void DoomAllEntries(const net::CompletionCallback& callback);
 162   void DoomEntriesBetween(const base::Time initial_time,
 163                           const base::Time end_time,
 164                           const net::CompletionCallback& callback);
 165   void DoomEntriesSince(const base::Time initial_time,
 166                         const net::CompletionCallback& callback);
 167   void OpenNextEntry(void** iter, Entry** next_entry,
 168                      const net::CompletionCallback& callback);
 169   void OpenPrevEntry(void** iter, Entry** prev_entry,
 170                      const net::CompletionCallback& callback);
 171   void EndEnumeration(void* iterator);
 172   void OnExternalCacheHit(const std::string& key);
 173   void CloseEntryImpl(EntryImpl* entry);
 174   void DoomEntryImpl(EntryImpl* entry);
 175   void FlushQueue(const net::CompletionCallback& callback);
 176   void RunTask(const base::Closure& task,
 177                const net::CompletionCallback& callback);
 178   void ReadData(EntryImpl* entry, int index, int offset, net::IOBuffer* buf,
 179                 int buf_len, const net::CompletionCallback& callback);
 180   void WriteData(
 181       EntryImpl* entry, int index, int offset, net::IOBuffer* buf,
 182       int buf_len, bool truncate, const net::CompletionCallback& callback);
 183   void ReadSparseData(EntryImpl* entry, int64 offset, net::IOBuffer* buf,
 184                       int buf_len, const net::CompletionCallback& callback);
 185   void WriteSparseData(EntryImpl* entry, int64 offset, net::IOBuffer* buf,
 186                        int buf_len, const net::CompletionCallback& callback);
 187   void GetAvailableRange(EntryImpl* entry, int64 offset, int len, int64* start,
 188                          const net::CompletionCallback& callback);
 189   void CancelSparseIO(EntryImpl* entry);
 190   void ReadyForSparseIO(EntryImpl* entry,
 191                         const net::CompletionCallback& callback);
 192
 193   // Blocks until all operations are cancelled or completed.
 194   void WaitForPendingIO();
 195
 196   scoped_refptr<base::MessageLoopProxy> background_thread() {
 197     return background_thread_;
 198   }
 199
 200   // Returns true if the current thread is the background thread.
 201   bool BackgroundIsCurrentThread() {
 202     return background_thread_->BelongsToCurrentThread();
 203   }
 204
 205   base::WeakPtr<InFlightBackendIO> GetWeakPtr();
 206
 207  protected:
 208   virtual void OnOperationComplete(BackgroundIO* operation,
 209                                    bool cancel) OVERRIDE;
 210
 211  private:
 212   void PostOperation(BackendIO* operation);
 213
 214   BackendImpl* backend_;
 215   scoped_refptr<base::MessageLoopProxy> background_thread_;
 216   base::WeakPtrFactory<InFlightBackendIO> ptr_factory_;
 217
 218   DISALLOW_COPY_AND_ASSIGN(InFlightBackendIO);
 219 };
 220
 221 }  // namespace disk_cache
 222
 223 #endif  // NET_DISK_CACHE_IN_FLIGHT_BACKEND_IO_H_