blob: 6b445809741f4b28e26e41b6162b88ef428a3b3d [file] [log] [blame]
// 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.
// 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, 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 now.
#include <stdint.h>
#include "base/files/file.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/task_runner.h"
#include "net/base/completion_callback.h"
#include "net/base/file_stream.h"
#if defined(OS_POSIX)
#include <errno.h>
namespace base {
class FilePath;
namespace net {
class IOBuffer;
#if defined(OS_WIN)
class FileStream::Context : public base::MessageLoopForIO::IOHandler {
#elif defined(OS_POSIX)
class FileStream::Context {
// Platform-dependent methods implemented in
// file_stream_context_{win,posix}.cc.
explicit Context(const scoped_refptr<base::TaskRunner>& task_runner);
Context(base::File file, const scoped_refptr<base::TaskRunner>& task_runner);
#if defined(OS_WIN)
~Context() override;
#elif defined(OS_POSIX)
int Read(IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
int Write(IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
bool async_in_progress() const { return async_in_progress_; }
// Platform-independent methods implemented in
// Destroys the context. It can be deleted in the method or deletion can be
// deferred if some asynchronous operation is now in progress or if file is
// not closed yet.
void Orphan();
void Open(const base::FilePath& path,
int open_flags,
const CompletionCallback& callback);
void Close(const CompletionCallback& callback);
// Seeks |offset| bytes from the start of the file.
void Seek(int64_t offset, const Int64CompletionCallback& callback);
void Flush(const CompletionCallback& callback);
bool IsOpen() const;
struct IOResult {
IOResult(int64_t result, logging::SystemErrorCode os_error);
static IOResult FromOSError(logging::SystemErrorCode os_error);
int64_t result;
logging::SystemErrorCode os_error; // Set only when result < 0.
struct OpenResult {
OpenResult(base::File file, IOResult error_code);
OpenResult(OpenResult&& other);
OpenResult& operator=(OpenResult&& other);
base::File file;
IOResult error_code;
// TODO(xunjieli): Remove after is fixed.
enum LastOperation {
// FileStream has a pending Open().
// FileStream has a pending Write().
// FileStream has a pending Read().
// FileStream has a pending Seek().
// FileStream has a pending Flush().
// FileStream has a pending Close().
// FileStream doesn't have any pending operation.
// TODO(xunjieli): Remove after is fixed.
void CheckNoAsyncInProgress() const;
// Platform-independent methods implemented in
OpenResult OpenFileImpl(const base::FilePath& path, int open_flags);
IOResult CloseFileImpl();
IOResult FlushFileImpl();
void OnOpenCompleted(const CompletionCallback& callback,
OpenResult open_result);
void CloseAndDelete();
Int64CompletionCallback IntToInt64(const CompletionCallback& callback);
// Called when Open() or Seek() completes. |result| contains the result or a
// network error code.
void OnAsyncCompleted(const Int64CompletionCallback& callback,
const IOResult& result);
// Platform-dependent methods implemented in
// file_stream_context_{win,posix}.cc.
// Adjusts the position from where the data is read.
IOResult SeekFileImpl(int64_t offset);
void OnFileOpened();
#if defined(OS_WIN)
void IOCompletionIsPending(const CompletionCallback& callback, IOBuffer* buf);
// Implementation of MessageLoopForIO::IOHandler.
void OnIOCompleted(base::MessageLoopForIO::IOContext* context,
DWORD bytes_read,
DWORD error) override;
// Invokes the user callback.
void InvokeUserCallback();
// Deletes an orphaned context.
void DeleteOrphanedContext();
// The ReadFile call on Windows can execute synchonously at times.
// This ends up blocking the calling
// thread which is undesirable. To avoid this we execute the ReadFile call
// on a worker thread.
// The |context| parameter is a pointer to the current Context instance. It
// is safe to pass this as is to the pool as the Context instance should
// remain valid until the pending Read operation completes.
// The |file| parameter is the handle to the file being read.
// The |buf| parameter is the buffer where we want the ReadFile to read the
// data into.
// The |buf_len| parameter contains the number of bytes to be read.
// The |overlapped| parameter is a pointer to the OVERLAPPED structure being
// used.
// The |origin_thread_task_runner| is a task runner instance used to post
// tasks back to the originating thread.
static void ReadAsync(
FileStream::Context* context,
HANDLE file,
scoped_refptr<IOBuffer> buf,
int buf_len,
OVERLAPPED* overlapped,
scoped_refptr<base::SingleThreadTaskRunner> origin_thread_task_runner);
// This callback executes on the main calling thread. It informs the caller
// about the result of the ReadFile call.
// The |read_file_ret| parameter contains the return value of the ReadFile
// call.
// The |bytes_read| contains the number of bytes read from the file, if
// ReadFile succeeds.
// The |os_error| parameter contains the value of the last error returned by
// the ReadFile API.
void ReadAsyncResult(BOOL read_file_ret, DWORD bytes_read, DWORD os_error);
#elif defined(OS_POSIX)
// ReadFileImpl() is a simple wrapper around read() that handles EINTR
// signals and calls RecordAndMapError() to map errno to net error codes.
IOResult ReadFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
// WriteFileImpl() is a simple wrapper around write() that handles EINTR
// signals and calls MapSystemError() to map errno to net error codes.
// It tries to write to completion.
IOResult WriteFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
base::File file_;
bool async_in_progress_;
// TODO(xunjieli): Remove after is fixed.
LastOperation last_operation_;
bool orphaned_;
scoped_refptr<base::TaskRunner> task_runner_;
#if defined(OS_WIN)
base::MessageLoopForIO::IOContext io_context_;
CompletionCallback callback_;
scoped_refptr<IOBuffer> in_flight_buf_;
// This flag is set to true when we receive a Read request which is queued to
// the thread pool.
bool async_read_initiated_;
// This flag is set to true when we receive a notification ReadAsyncResult()
// on the calling thread which indicates that the asynchronous Read
// operation is complete.
bool async_read_completed_;
// This flag is set to true when we receive an IO completion notification for
// an asynchonously initiated Read operaton. OnIOComplete().
bool io_complete_for_read_received_;
// Tracks the result of the IO completion operation. Set in OnIOComplete.
int result_;
} // namespace net