file_stream_context.h | Explore in Territory

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file defines FileStream::Context class.
// The general design of FileStream is as follows: file_stream.h defines
// FileStream class which basically is just an "wrapper" not containing any
// specific implementation details. It re-routes all its method calls to
// the instance of FileStream::Context (FileStream holds a scoped_ptr to
// FileStream::Context instance). Context was extracted into a different class
// to be able to do and finish all async operations even when FileStream
// instance is deleted. So FileStream's destructor can schedule file
// closing to be done by Context in WorkerPool (or the TaskRunner passed to
// constructor) and then just return (releasing Context pointer from
// scoped_ptr) without waiting for actual closing to complete.
// Implementation of FileStream::Context is divided in two parts: some methods
// and members are platform-independent and some depend on the platform. This
// header file contains the complete definition of Context class including all
// platform-dependent parts (because of that it has a lot of #if-#else
// branching). Implementations of all platform-independent methods are
// located in file_stream_context.cc, and all platform-dependent methods are
// in file_stream_context_{win,posix}.cc. This separation provides better
// readability of Context's code. And we tried to make as much Context code
// platform-independent as possible. So file_stream_context_{win,posix}.cc are
// much smaller than file_stream_context.cc now.

#ifndef NET_BASE_FILE_STREAM_CONTEXT_H_
#define NET_BASE_FILE_STREAM_CONTEXT_H_

#include <stdint.h>

#include "base/files/file.h"
#include "base/logging.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_pump_for_io.h"
#include "base/task/single_thread_task_runner.h"
#include "base/task/task_runner.h"
#include "build/build_config.h"
#include "net/base/completion_once_callback.h"
#include "net/base/file_stream.h"

#if BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
#include <errno.h>
#endif

namespace base {
class FilePath;
}

namespace net {

class IOBuffer;

// Implementation for a FileStream. See file_stream.h for documentation.
#if BUILDFLAG(IS_WIN)
class FileStream::Context : public base::MessagePumpForIO::IOHandler {
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
class FileStream::Context { … };

}  // namespace net

#endif  // NET_BASE_FILE_STREAM_CONTEXT_H_
chromium/net/base/file_stream_context.h
