net/base/file_stream_context.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 // This file defines FileStream::Context class.
   6 // The general design of FileStream is as follows: file_stream.h defines
   7 // FileStream class which basically is just an "wrapper" not containing any
   8 // specific implementation details. It re-routes all its method calls to
   9 // the instance of FileStream::Context (FileStream holds a scoped_ptr to
  10 // FileStream::Context instance). Context was extracted into a different class
  11 // to be able to do and finish all async operations even when FileStream
  12 // instance is deleted. So FileStream's destructor can schedule file
  13 // closing to be done by Context in WorkerPool (or the TaskRunner passed to
  14 // constructor) and then just return (releasing Context pointer from
  15 // scoped_ptr) without waiting for actual closing to complete.
  16 // Implementation of FileStream::Context is divided in two parts: some methods
  17 // and members are platform-independent and some depend on the platform. This
  18 // header file contains the complete definition of Context class including all
  19 // platform-dependent parts (because of that it has a lot of #if-#else
  20 // branching). Implementations of all platform-independent methods are
  21 // located in file_stream_context.cc, and all platform-dependent methods are
  22 // in file_stream_context_{win,posix}.cc. This separation provides better
  23 // readability of Context's code. And we tried to make as much Context code
  24 // platform-independent as possible. So file_stream_context_{win,posix}.cc are
  25 // much smaller than file_stream_context.cc now.
  26
  27 #ifndef NET_BASE_FILE_STREAM_CONTEXT_H_
  28 #define NET_BASE_FILE_STREAM_CONTEXT_H_
  29
  30 #include "base/files/file.h"
  31 #include "base/message_loop/message_loop.h"
  32 #include "base/move.h"
  33 #include "base/task_runner.h"
  34 #include "net/base/completion_callback.h"
  35 #include "net/base/file_stream.h"
  36 #include "net/base/file_stream_whence.h"
  37
  38 #if defined(OS_POSIX)
  39 #include <errno.h>
  40 #endif
  41
  42 namespace base {
  43 class FilePath;
  44 }
  45
  46 namespace net {
  47
  48 class IOBuffer;
  49
  50 #if defined(OS_WIN)
  51 class FileStream::Context : public base::MessageLoopForIO::IOHandler {
  52 #elif defined(OS_POSIX)
  53 class FileStream::Context {
  54 #endif
  55  public:
  56   ////////////////////////////////////////////////////////////////////////////
  57   // Platform-dependent methods implemented in
  58   // file_stream_context_{win,posix}.cc.
  59   ////////////////////////////////////////////////////////////////////////////
  60
  61   explicit Context(const scoped_refptr<base::TaskRunner>& task_runner);
  62   Context(base::File file, const scoped_refptr<base::TaskRunner>& task_runner);
  63 #if defined(OS_WIN)
  64   virtual ~Context();
  65 #elif defined(OS_POSIX)
  66   ~Context();
  67 #endif
  68
  69   int ReadAsync(IOBuffer* buf,
  70                 int buf_len,
  71                 const CompletionCallback& callback);
  72
  73   int WriteAsync(IOBuffer* buf,
  74                  int buf_len,
  75                  const CompletionCallback& callback);
  76
  77   ////////////////////////////////////////////////////////////////////////////
  78   // Inline methods.
  79   ////////////////////////////////////////////////////////////////////////////
  80
  81   const base::File& file() const { return file_; }
  82   bool async_in_progress() const { return async_in_progress_; }
  83
  84   ////////////////////////////////////////////////////////////////////////////
  85   // Platform-independent methods implemented in file_stream_context.cc.
  86   ////////////////////////////////////////////////////////////////////////////
  87
  88   // Destroys the context. It can be deleted in the method or deletion can be
  89   // deferred if some asynchronous operation is now in progress or if file is
  90   // not closed yet.
  91   void Orphan();
  92
  93   void OpenAsync(const base::FilePath& path,
  94                  int open_flags,
  95                  const CompletionCallback& callback);
  96
  97   void CloseAsync(const CompletionCallback& callback);
  98
  99   void SeekAsync(Whence whence,
 100                  int64 offset,
 101                  const Int64CompletionCallback& callback);
 102
 103   void FlushAsync(const CompletionCallback& callback);
 104
 105  private:
 106   ////////////////////////////////////////////////////////////////////////////
 107   // Platform-independent methods implemented in file_stream_context.cc.
 108   ////////////////////////////////////////////////////////////////////////////
 109
 110   struct IOResult {
 111     IOResult();
 112     IOResult(int64 result, int os_error);
 113     static IOResult FromOSError(int64 os_error);
 114
 115     int64 result;
 116     int os_error;  // Set only when result < 0.
 117   };
 118
 119   struct OpenResult {
 120     MOVE_ONLY_TYPE_FOR_CPP_03(OpenResult, RValue)
 121    public:
 122     OpenResult();
 123     OpenResult(base::File file, IOResult error_code);
 124     // C++03 move emulation of this type.
 125     OpenResult(RValue other);
 126     OpenResult& operator=(RValue other);
 127
 128     base::File file;
 129     IOResult error_code;
 130   };
 131
 132   OpenResult OpenFileImpl(const base::FilePath& path, int open_flags);
 133
 134   IOResult CloseFileImpl();
 135
 136   void OnOpenCompleted(const CompletionCallback& callback,
 137                        OpenResult open_result);
 138
 139   void CloseAndDelete();
 140
 141   Int64CompletionCallback IntToInt64(const CompletionCallback& callback);
 142
 143   // Called when asynchronous Open() or Seek()
 144   // is completed. |result| contains the result or a network error code.
 145   void OnAsyncCompleted(const Int64CompletionCallback& callback,
 146                         const IOResult& result);
 147
 148   ////////////////////////////////////////////////////////////////////////////
 149   // Helper stuff which is platform-dependent but is used in the platform-
 150   // independent code implemented in file_stream_context.cc. These helpers were
 151   // introduced solely to implement as much of the Context methods as
 152   // possible independently from platform.
 153   ////////////////////////////////////////////////////////////////////////////
 154
 155 #if defined(OS_WIN)
 156   int GetLastErrno() { return GetLastError(); }
 157   void OnAsyncFileOpened();
 158 #elif defined(OS_POSIX)
 159   int GetLastErrno() { return errno; }
 160   void OnAsyncFileOpened() {}
 161   void CancelIo(base::PlatformFile) {}
 162 #endif
 163
 164   ////////////////////////////////////////////////////////////////////////////
 165   // Platform-dependent methods implemented in
 166   // file_stream_context_{win,posix}.cc.
 167   ////////////////////////////////////////////////////////////////////////////
 168
 169   // Adjusts the position from where the data is read.
 170   IOResult SeekFileImpl(Whence whence, int64 offset);
 171
 172   // Flushes all data written to the stream.
 173   IOResult FlushFileImpl();
 174
 175 #if defined(OS_WIN)
 176   void IOCompletionIsPending(const CompletionCallback& callback, IOBuffer* buf);
 177
 178   // Implementation of MessageLoopForIO::IOHandler.
 179   virtual void OnIOCompleted(base::MessageLoopForIO::IOContext* context,
 180                              DWORD bytes_read,
 181                              DWORD error) OVERRIDE;
 182 #elif defined(OS_POSIX)
 183   // ReadFileImpl() is a simple wrapper around read() that handles EINTR
 184   // signals and calls RecordAndMapError() to map errno to net error codes.
 185   IOResult ReadFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
 186
 187   // WriteFileImpl() is a simple wrapper around write() that handles EINTR
 188   // signals and calls MapSystemError() to map errno to net error codes.
 189   // It tries to write to completion.
 190   IOResult WriteFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
 191 #endif
 192
 193   base::File file_;
 194   bool async_in_progress_;
 195   bool orphaned_;
 196   scoped_refptr<base::TaskRunner> task_runner_;
 197
 198 #if defined(OS_WIN)
 199   base::MessageLoopForIO::IOContext io_context_;
 200   CompletionCallback callback_;
 201   scoped_refptr<IOBuffer> in_flight_buf_;
 202 #endif
 203
 204   DISALLOW_COPY_AND_ASSIGN(Context);
 205 };
 206
 207 }  // namespace net
 208
 209 #endif  // NET_BASE_FILE_STREAM_CONTEXT_H_