net: Implement canceling of all async operations in FileStream.

net/base/file_stream_posix.cc

 // 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.
 
 // For 64-bit file access (off_t = off64_t, lseek64, etc).
 #define _FILE_OFFSET_BITS 64
 
-#include "net/base/file_stream.h"
+#include "net/base/file_stream_posix.h"
 
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/eintr_wrapper.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
-#include "base/string_util.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/task_runner_util.h"
 #include "base/threading/worker_pool.h"
-#include "base/synchronization/waitable_event.h"
-#include "net/base/file_stream_metrics.h"
-#include "net/base/file_stream_net_log_parameters.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 
 #if defined(OS_ANDROID)
 // Android's bionic libc only supports the LFS transitional API.
 #define off_t off64_t
 #define lseek lseek64
 #define stat stat64
 #define fstat fstat64
 #endif
 
 namespace net {
 
 // We cast back and forth, so make sure it's the size we're expecting.
 COMPILE_ASSERT(sizeof(int64) == sizeof(off_t), off_t_64_bit);
 
 // Make sure our Whence mappings match the system headers.
 COMPILE_ASSERT(FROM_BEGIN   == SEEK_SET &&
                FROM_CURRENT == SEEK_CUR &&
                FROM_END     == SEEK_END, whence_matches_system);
 
-namespace {
-
-int RecordAndMapError(int error,
-                      FileErrorSource source,
-                      bool record_uma,
-                      const net::BoundNetLog& bound_net_log) {
-  net::Error net_error = MapSystemError(error);
-
-  bound_net_log.AddEvent(
-      net::NetLog::TYPE_FILE_STREAM_ERROR,
-      base::Bind(&NetLogFileStreamErrorCallback,
-                 source, error, net_error));
-
-  RecordFileError(error, source, record_uma);
-
-  return net_error;
+FileStream::Context::Context(const BoundNetLog& bound_net_log)
+    : file_(base::kInvalidPlatformFileValue),
+      record_uma_(false),
+      async_in_progress_(false),
+      orphaned_(false),
+      bound_net_log_(bound_net_log) {
 }
 
-// Opens a file with some network logging.
-// The opened file and the result code are written to |file| and |result|.
-void OpenFile(const FilePath& path,
-              int open_flags,
-              bool record_uma,
-              base::PlatformFile* file,
-              int* result,
-              const net::BoundNetLog& bound_net_log) {
-  std::string file_name = path.AsUTF8Unsafe();
-  bound_net_log.BeginEvent(
-      net::NetLog::TYPE_FILE_STREAM_OPEN,
-      NetLog::StringCallback("file_name", &file_name));
-
-  *result = OK;
-  *file = base::CreatePlatformFile(path, open_flags, NULL, NULL);
-  if (*file == base::kInvalidPlatformFileValue) {
-    bound_net_log.EndEvent(net::NetLog::TYPE_FILE_STREAM_OPEN);
-    *result = RecordAndMapError(errno, FILE_ERROR_SOURCE_OPEN, record_uma,
-                                bound_net_log);
-  }
+FileStream::Context::Context(base::PlatformFile file,
+                             const BoundNetLog& bound_net_log,
+                             int /* open_flags */)
+    : file_(file),
+      record_uma_(false),
+      async_in_progress_(false),
+      orphaned_(false),
+      bound_net_log_(bound_net_log) {
 }
 
-// Opens a file using OpenFile() and then signals the completion.
-void OpenFileAndSignal(const FilePath& path,
-                       int open_flags,
-                       bool record_uma,
-                       base::PlatformFile* file,
-                       int* result,
-                       base::WaitableEvent* on_io_complete,
-                       const net::BoundNetLog& bound_net_log) {
-  OpenFile(path, open_flags, record_uma, file, result, bound_net_log);
-  on_io_complete->Signal();
+FileStream::Context::~Context() {
 }
 
-// Closes a file with some network logging.
-void CloseFile(base::PlatformFile file,
-               const net::BoundNetLog& bound_net_log) {
-  bound_net_log.AddEvent(net::NetLog::TYPE_FILE_STREAM_CLOSE);
-  if (file == base::kInvalidPlatformFileValue)
-    return;
+void FileStream::Context::SeekAsync(Whence whence,
+                                    int64 offset,
+                                    const Int64CompletionCallback& callback) {
+  DCHECK(!async_in_progress_);
 
-  if (!base::ClosePlatformFile(file))
-    NOTREACHED();
-  bound_net_log.EndEvent(net::NetLog::TYPE_FILE_STREAM_OPEN);
+  const bool posted = base::PostTaskAndReplyWithResult(
+      base::WorkerPool::GetTaskRunner(true /* task is slow */),
+      FROM_HERE,
+      base::Bind(&Context::SeekFileImpl,
+                 base::Unretained(this), whence, offset),
+      base::Bind(&Context::OnIOCompleted<int64>,
+                 base::Unretained(this), callback, FILE_ERROR_SOURCE_SEEK));
+  DCHECK(posted);
+
+  async_in_progress_ = true;
 }
 
-// Closes a file with CloseFile() and signals the completion.
-void CloseFileAndSignal(base::PlatformFile* file,
-                        base::WaitableEvent* on_io_complete,
-                        const net::BoundNetLog& bound_net_log) {
-  CloseFile(*file, bound_net_log);
-  *file = base::kInvalidPlatformFileValue;
-  on_io_complete->Signal();
+int64 FileStream::Context::SeekSync(Whence whence, int64 offset) {
+  off_t result = SeekFileImpl(whence, offset);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_SEEK);
+  return result;
 }
 
-// Adjusts the position from where the data is read.
-void SeekFile(base::PlatformFile file,
-              Whence whence,
-              int64 offset,
-              int64* result,
-              bool record_uma,
-              const net::BoundNetLog& bound_net_log) {
-  off_t res = lseek(file, static_cast<off_t>(offset),
-                    static_cast<int>(whence));
-  if (res == static_cast<off_t>(-1)) {
-    *result = RecordAndMapError(errno,
-                                FILE_ERROR_SOURCE_SEEK,
-                                record_uma,
-                                bound_net_log);
-    return;
-  }
-  *result = res;
+int64 FileStream::Context::GetFileSize() const {
+  struct stat info;
+  if (fstat(file_, &info) != 0)
+    return RecordAndMapError(errno, FILE_ERROR_SOURCE_GET_SIZE);
+
+  return static_cast<int64>(info.st_size);
 }
 
-// Seeks a file by calling SeekSync() and signals the completion.
-void SeekFileAndSignal(base::PlatformFile file,
-                       Whence whence,
-                       int64 offset,
-                       int64* result,
-                       bool record_uma,
-                       base::WaitableEvent* on_io_complete,
-                       const net::BoundNetLog& bound_net_log) {
-  SeekFile(file, whence, offset, result, record_uma, bound_net_log);
-  on_io_complete->Signal();
+int FileStream::Context::ReadAsync(IOBuffer* in_buf,
+                                   int buf_len,
+                                   const CompletionCallback& callback) {
+  DCHECK(!async_in_progress_);
+
+  scoped_refptr<IOBuffer> buf = in_buf;
+  const bool posted = base::PostTaskAndReplyWithResult(
+      base::WorkerPool::GetTaskRunner(true /* task is slow */),
+      FROM_HERE,
+      base::Bind(&Context::ReadFileImpl,
+                 base::Unretained(this), buf, buf_len),
+      base::Bind(&Context::OnIOCompleted<int>,
+                 base::Unretained(this), callback, FILE_ERROR_SOURCE_READ));
+  DCHECK(posted);
+
+  async_in_progress_ = true;
+  return ERR_IO_PENDING;
 }
 
-// ReadFile() is a simple wrapper around read() that handles EINTR signals and
-// calls MapSystemError() to map errno to net error codes.
-void ReadFile(base::PlatformFile file,
-              char* buf,
-              int buf_len,
-              bool record_uma,
-              int* result,
-              const net::BoundNetLog& bound_net_log) {
-  base::ThreadRestrictions::AssertIOAllowed();
-  // read(..., 0) returns 0 to indicate end-of-file.
-
-  // Loop in the case of getting interrupted by a signal.
-  ssize_t res = HANDLE_EINTR(read(file, buf, static_cast<size_t>(buf_len)));
-  if (res == -1) {
-    res = RecordAndMapError(errno, FILE_ERROR_SOURCE_READ,
-                            record_uma, bound_net_log);
-  }
-  *result = res;
+int FileStream::Context::ReadSync(char* in_buf, int buf_len) {
+  scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(in_buf);
+  int result = ReadFileImpl(buf, buf_len);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_READ);
+  return result;
 }
 
-// Reads a file using ReadFile() and signals the completion.
-void ReadFileAndSignal(base::PlatformFile file,
-                       scoped_refptr<IOBuffer> buf,
-                       int buf_len,
-                       bool record_uma,
-                       int* result,
-                       base::WaitableEvent* on_io_complete,
-                       const net::BoundNetLog& bound_net_log) {
-  ReadFile(file, buf->data(), buf_len, record_uma, result, bound_net_log);
-  on_io_complete->Signal();
+int FileStream::Context::WriteAsync(IOBuffer* in_buf,
+                                    int buf_len,
+                                    const CompletionCallback& callback) {
+  DCHECK(!async_in_progress_);
+
+  scoped_refptr<IOBuffer> buf = in_buf;
+  const bool posted = base::PostTaskAndReplyWithResult(
+      base::WorkerPool::GetTaskRunner(true /* task is slow */),
+      FROM_HERE,
+      base::Bind(&Context::WriteFileImpl,
+                 base::Unretained(this), buf, buf_len),
+      base::Bind(&Context::OnIOCompleted<int>,
+                 base::Unretained(this), callback, FILE_ERROR_SOURCE_WRITE));
+  DCHECK(posted);
+
+  async_in_progress_ = true;
+  return ERR_IO_PENDING;
 }
 
-// WriteFile() 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.
-void WriteFile(base::PlatformFile file,
-               const char* buf,
-               int buf_len,
-               bool record_uma,
-               int* result,
-               const net::BoundNetLog& bound_net_log) {
-  base::ThreadRestrictions::AssertIOAllowed();
-
-  ssize_t res = HANDLE_EINTR(write(file, buf, buf_len));
-  if (res == -1) {
-    res = RecordAndMapError(errno, FILE_ERROR_SOURCE_WRITE, record_uma,
-                            bound_net_log);
-  }
-  *result = res;
+int FileStream::Context::WriteSync(const char* in_buf, int buf_len) {
+  scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(in_buf);
+  int result = WriteFileImpl(buf, buf_len);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_WRITE);
+  return result;
 }
 
-// Writes a file using WriteFile() and signals the completion.
-void WriteFileAndSignal(base::PlatformFile file,
-                        scoped_refptr<IOBuffer> buf,
-                        int buf_len,
-                        bool record_uma,
-                        int* result,
-                        base::WaitableEvent* on_io_complete,
-                        const net::BoundNetLog& bound_net_log) {
-  WriteFile(file, buf->data(), buf_len, record_uma, result, bound_net_log);
-  on_io_complete->Signal();
-}
-
-// FlushFile() is a simple wrapper around fsync() that handles EINTR signals and
-// calls MapSystemError() to map errno to net error codes.  It tries to flush to
-// completion.
-int FlushFile(base::PlatformFile file,
-              bool record_uma,
-              const net::BoundNetLog& bound_net_log) {
-  base::ThreadRestrictions::AssertIOAllowed();
-  ssize_t res = HANDLE_EINTR(fsync(file));
-  if (res == -1) {
-    res = RecordAndMapError(errno, FILE_ERROR_SOURCE_FLUSH, record_uma,
-                            bound_net_log);
-  }
+int FileStream::Context::Flush() {
+  ssize_t res = HANDLE_EINTR(fsync(file_));
+  if (res == -1)
+    res = RecordAndMapError(errno, FILE_ERROR_SOURCE_FLUSH);
   return res;
 }
 
-// Called when Read(), Write() or Seek() is completed.
-// |result| contains the result or a network error code.
-template <typename R>
-void OnIOComplete(const base::WeakPtr<FileStreamPosix>& stream,
-                  const base::Callback<void(R)>& callback,
-                  R* result) {
-  if (!stream.get())
-    return;
+int FileStream::Context::Truncate(int64 bytes) {
+  int result = ftruncate(file_, bytes);
+  if (result == 0)
+    return bytes;
 
-  // Reset this before Run() as Run() may issue a new async operation.
-  stream->ResetOnIOComplete();
-  callback.Run(*result);
+  return RecordAndMapError(errno, FILE_ERROR_SOURCE_SET_EOF);
 }
 
-}  // namespace
+int64 FileStream::Context::SeekFileImpl(Whence whence, int64 offset) {
+  off_t res = lseek(file_, static_cast<off_t>(offset),
+                    static_cast<int>(whence));
+  if (res == static_cast<off_t>(-1))
+    return errno;
 
-// FileStreamPosix ------------------------------------------------------------
-
-FileStreamPosix::FileStreamPosix(net::NetLog* net_log)
-    : file_(base::kInvalidPlatformFileValue),
-      open_flags_(0),
-      auto_closed_(true),
-      record_uma_(false),
-      bound_net_log_(net::BoundNetLog::Make(net_log,
-                                            net::NetLog::SOURCE_FILESTREAM)),
-      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
-  bound_net_log_.BeginEvent(net::NetLog::TYPE_FILE_STREAM_ALIVE);
+  return res;
 }
 
-FileStreamPosix::FileStreamPosix(
-    base::PlatformFile file, int flags, net::NetLog* net_log)
-    : file_(file),
-      open_flags_(flags),
-      auto_closed_(false),
-      record_uma_(false),
-      bound_net_log_(net::BoundNetLog::Make(net_log,
-                                            net::NetLog::SOURCE_FILESTREAM)),
-      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
-  bound_net_log_.BeginEvent(net::NetLog::TYPE_FILE_STREAM_ALIVE);
+int FileStream::Context::ReadFileImpl(scoped_refptr<IOBuffer> buf,
+                                      int buf_len) {
+  // Loop in the case of getting interrupted by a signal.
+  ssize_t res = HANDLE_EINTR(read(file_, buf->data(),
+                                  static_cast<size_t>(buf_len)));
+  if (res == -1)
+    return errno;
+
+  return res;
 }
 
-FileStreamPosix::~FileStreamPosix() {
-  if (open_flags_ & base::PLATFORM_FILE_ASYNC) {
-    // Block until the last open/close/read/write operation is complete.
-    // TODO(satorux): Ideally we should not block. crbug.com/115067
-    WaitForIOCompletion();
-  }
+int FileStream::Context::WriteFileImpl(scoped_refptr<IOBuffer> buf,
+                                       int buf_len) {
+  ssize_t res = HANDLE_EINTR(write(file_, buf->data(), buf_len));
+  if (res == -1)
+    return errno;
 
-  if (auto_closed_) {
-    if (open_flags_ & base::PLATFORM_FILE_ASYNC) {
-      // Close the file in the background.
-      if (IsOpen()) {
-        const bool posted = base::WorkerPool::PostTask(
-            FROM_HERE,
-            base::Bind(&CloseFile, file_, bound_net_log_),
-            true /* task_is_slow */);
-        DCHECK(posted);
-      }
-    } else {
-      CloseSync();
-    }
-  }
-
-  bound_net_log_.EndEvent(net::NetLog::TYPE_FILE_STREAM_ALIVE);
+  return res;
 }
 
-void FileStreamPosix::Close(const CompletionCallback& callback) {
-  DCHECK(open_flags_ & base::PLATFORM_FILE_ASYNC);
-
-  DCHECK(!weak_ptr_factory_.HasWeakPtrs());
-  DCHECK(!on_io_complete_.get());
-  on_io_complete_.reset(new base::WaitableEvent(
-      false  /* manual_reset */, false  /* initially_signaled */));
-
-  // Passing &file_ to a thread pool looks unsafe but it's safe here as the
-  // destructor ensures that the close operation is complete with
-  // WaitForIOCompletion(). See also the destructor.
-  const bool posted = base::WorkerPool::PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&CloseFileAndSignal, &file_, on_io_complete_.get(),
-                 bound_net_log_),
-      base::Bind(&FileStreamPosix::OnClosed,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback),
-      true /* task_is_slow */);
-
-  DCHECK(posted);
+template <typename R>
+void FileStream::Context::CheckForIOError(R* result, FileErrorSource source) {
+  if (*result < 0)
+    *result = RecordAndMapError(static_cast<int>(*result), source);
 }
 
-void FileStreamPosix::CloseSync() {
-  // TODO(satorux): Replace the following async stuff with a
-  // DCHECK(open_flags & ASYNC) once once all async clients are migrated to
-  // use Close(). crbug.com/114783
-
-  // Abort any existing asynchronous operations.
-  weak_ptr_factory_.InvalidateWeakPtrs();
-  // Block until the last open/read/write operation is complete.
-  // TODO(satorux): Ideally we should not block. crbug.com/115067
-  WaitForIOCompletion();
-
-  CloseFile(file_, bound_net_log_);
-  file_ = base::kInvalidPlatformFileValue;
+template <typename R>
+void FileStream::Context::OnIOCompleted(const base::Callback<void(R)>& callback,
+                                        FileErrorSource source,
+                                        R result) {
+  CheckForIOError(&result, source);
+  OnAsyncCompleted(callback, result);
 }
 
-int FileStreamPosix::Open(const FilePath& path, int open_flags,
-                     const CompletionCallback& callback) {
-  if (IsOpen()) {
-    DLOG(FATAL) << "File is already open!";
-    return ERR_UNEXPECTED;
-  }
-
-  open_flags_ = open_flags;
-  DCHECK(open_flags_ & base::PLATFORM_FILE_ASYNC);
-
-  DCHECK(!weak_ptr_factory_.HasWeakPtrs());
-  DCHECK(!on_io_complete_.get());
-  on_io_complete_.reset(new base::WaitableEvent(
-      false  /* manual_reset */, false  /* initially_signaled */));
-
-  // Passing &file_ to a thread pool looks unsafe but it's safe here as the
-  // destructor ensures that the open operation is complete with
-  // WaitForIOCompletion(). See also the destructor.
-  int* result = new int(OK);
-  const bool posted = base::WorkerPool::PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&OpenFileAndSignal,
-                 path, open_flags, record_uma_, &file_, result,
-                 on_io_complete_.get(), bound_net_log_),
-      base::Bind(&OnIOComplete<int>, weak_ptr_factory_.GetWeakPtr(),
-                 callback, base::Owned(result)),
-      true /* task_is_slow */);
-  DCHECK(posted);
-  return ERR_IO_PENDING;
-}
-
-int FileStreamPosix::OpenSync(const FilePath& path, int open_flags) {
-  if (IsOpen()) {
-    DLOG(FATAL) << "File is already open!";
-    return ERR_UNEXPECTED;
-  }
-
-  open_flags_ = open_flags;
-  // TODO(satorux): Put a DCHECK once once all async clients are migrated
-  // to use Open(). crbug.com/114783
-  //
-  // DCHECK(!(open_flags_ & base::PLATFORM_FILE_ASYNC));
-
-  int result = OK;
-  OpenFile(path, open_flags_, record_uma_, &file_, &result, bound_net_log_);
-  return result;
-}
-
-bool FileStreamPosix::IsOpen() const {
-  return file_ != base::kInvalidPlatformFileValue;
-}
-
-int FileStreamPosix::Seek(Whence whence, int64 offset,
-                          const Int64CompletionCallback& callback) {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  // Make sure we're async and we have no other in-flight async operations.
-  DCHECK(open_flags_ & base::PLATFORM_FILE_ASYNC);
-  DCHECK(!weak_ptr_factory_.HasWeakPtrs());
-  DCHECK(!on_io_complete_.get());
-
-  on_io_complete_.reset(new base::WaitableEvent(
-      false  /* manual_reset */, false  /* initially_signaled */));
-
-  int64* result = new int64(-1);
-  const bool posted = base::WorkerPool::PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&SeekFileAndSignal, file_, whence, offset, result,
-                 record_uma_, on_io_complete_.get(), bound_net_log_),
-      base::Bind(&OnIOComplete<int64>,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback, base::Owned(result)),
-      true /* task is slow */);
-  DCHECK(posted);
-  return ERR_IO_PENDING;
-}
-
-int64 FileStreamPosix::SeekSync(Whence whence, int64 offset) {
-  base::ThreadRestrictions::AssertIOAllowed();
-
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  // If we're in async, make sure we don't have a request in flight.
-  DCHECK(!(open_flags_ & base::PLATFORM_FILE_ASYNC) ||
-         !on_io_complete_.get());
-
-  off_t result = -1;
-  SeekFile(file_, whence, offset, &result, record_uma_, bound_net_log_);
-  return result;
-}
-
-int64 FileStreamPosix::Available() {
-  base::ThreadRestrictions::AssertIOAllowed();
-
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  int64 cur_pos = SeekSync(FROM_CURRENT, 0);
-  if (cur_pos < 0)
-    return cur_pos;
-
-  struct stat info;
-  if (fstat(file_, &info) != 0) {
-    return RecordAndMapError(errno,
-                             FILE_ERROR_SOURCE_GET_SIZE,
-                             record_uma_,
-                             bound_net_log_);
-  }
-
-  int64 size = static_cast<int64>(info.st_size);
-  DCHECK_GT(size, cur_pos);
-
-  return size - cur_pos;
-}
-
-int FileStreamPosix::Read(
-    IOBuffer* in_buf, int buf_len, const CompletionCallback& callback) {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  // read(..., 0) will return 0, which indicates end-of-file.
-  DCHECK_GT(buf_len, 0);
-  DCHECK(open_flags_ & base::PLATFORM_FILE_READ);
-  DCHECK(open_flags_ & base::PLATFORM_FILE_ASYNC);
-
-  // Make sure we don't have a request in flight.
-  DCHECK(!weak_ptr_factory_.HasWeakPtrs());
-  DCHECK(!on_io_complete_.get());
-
-  on_io_complete_.reset(new base::WaitableEvent(
-      false  /* manual_reset */, false  /* initially_signaled */));
-
-  int* result = new int(OK);
-  scoped_refptr<IOBuffer> buf = in_buf;
-  const bool posted = base::WorkerPool::PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&ReadFileAndSignal, file_, buf, buf_len,
-                 record_uma_, result, on_io_complete_.get(), bound_net_log_),
-      base::Bind(&OnIOComplete<int>,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback, base::Owned(result)),
-      true /* task is slow */);
-  DCHECK(posted);
-  return ERR_IO_PENDING;
-}
-
-int FileStreamPosix::ReadSync(char* buf, int buf_len) {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  DCHECK(!(open_flags_ & base::PLATFORM_FILE_ASYNC));
-  // read(..., 0) will return 0, which indicates end-of-file.
-  DCHECK_GT(buf_len, 0);
-  DCHECK(open_flags_ & base::PLATFORM_FILE_READ);
-
-  int result = OK;
-  ReadFile(file_, buf, buf_len, record_uma_, &result, bound_net_log_);
-  return result;
-}
-
-int FileStreamPosix::ReadUntilComplete(char *buf, int buf_len) {
-  int to_read = buf_len;
-  int bytes_total = 0;
-
-  do {
-    int bytes_read = ReadSync(buf, to_read);
-    if (bytes_read <= 0) {
-      if (bytes_total == 0)
-        return bytes_read;
-
-      return bytes_total;
-    }
-
-    bytes_total += bytes_read;
-    buf += bytes_read;
-    to_read -= bytes_read;
-  } while (bytes_total < buf_len);
-
-  return bytes_total;
-}
-
-int FileStreamPosix::Write(
-    IOBuffer* in_buf, int buf_len, const CompletionCallback& callback) {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  DCHECK(open_flags_ & base::PLATFORM_FILE_ASYNC);
-  DCHECK(open_flags_ & base::PLATFORM_FILE_WRITE);
-  // write(..., 0) will return 0, which indicates end-of-file.
-  DCHECK_GT(buf_len, 0);
-
-  // Make sure we don't have a request in flight.
-  DCHECK(!weak_ptr_factory_.HasWeakPtrs());
-  DCHECK(!on_io_complete_.get());
-  on_io_complete_.reset(new base::WaitableEvent(
-      false  /* manual_reset */, false  /* initially_signaled */));
-
-  int* result = new int(OK);
-  scoped_refptr<IOBuffer> buf = in_buf;
-  const bool posted = base::WorkerPool::PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&WriteFileAndSignal, file_, buf, buf_len,
-                 record_uma_, result, on_io_complete_.get(), bound_net_log_),
-      base::Bind(&OnIOComplete<int>,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback, base::Owned(result)),
-      true /* task is slow */);
-  DCHECK(posted);
-  return ERR_IO_PENDING;
-}
-
-int FileStreamPosix::WriteSync(
-    const char* buf, int buf_len) {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  DCHECK(!(open_flags_ & base::PLATFORM_FILE_ASYNC));
-  DCHECK(open_flags_ & base::PLATFORM_FILE_WRITE);
-  // write(..., 0) will return 0, which indicates end-of-file.
-  DCHECK_GT(buf_len, 0);
-
-  int result = OK;
-  WriteFile(file_, buf, buf_len, record_uma_, &result, bound_net_log_);
-  return result;
-}
-
-int64 FileStreamPosix::Truncate(int64 bytes) {
-  base::ThreadRestrictions::AssertIOAllowed();
-
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  // We'd better be open for writing.
-  DCHECK(open_flags_ & base::PLATFORM_FILE_WRITE);
-
-  // Seek to the position to truncate from.
-  int64 seek_position = SeekSync(FROM_BEGIN, bytes);
-  if (seek_position != bytes)
-    return ERR_UNEXPECTED;
-
-  // And truncate the file.
-  int result = ftruncate(file_, bytes);
-  if (result == 0)
-    return seek_position;
-
-  return RecordAndMapError(errno,
-                           FILE_ERROR_SOURCE_SET_EOF,
-                           record_uma_,
-                           bound_net_log_);
-}
-
-int FileStreamPosix::Flush() {
-  if (!IsOpen())
-    return ERR_UNEXPECTED;
-
-  return FlushFile(file_, record_uma_, bound_net_log_);
-}
-
-void FileStreamPosix::EnableErrorStatistics() {
-  record_uma_ = true;
-}
-
-void FileStreamPosix::SetBoundNetLogSource(
-    const net::BoundNetLog& owner_bound_net_log) {
-  if ((owner_bound_net_log.source().id == net::NetLog::Source::kInvalidId) &&
-      (bound_net_log_.source().id == net::NetLog::Source::kInvalidId)) {
-    // Both |BoundNetLog|s are invalid.
-    return;
-  }
-
-  // Should never connect to itself.
-  DCHECK_NE(bound_net_log_.source().id, owner_bound_net_log.source().id);
-
-  bound_net_log_.AddEvent(
-      net::NetLog::TYPE_FILE_STREAM_BOUND_TO_OWNER,
-      owner_bound_net_log.source().ToEventParametersCallback());
-
-  owner_bound_net_log.AddEvent(
-      net::NetLog::TYPE_FILE_STREAM_SOURCE,
-      bound_net_log_.source().ToEventParametersCallback());
-}
-
-base::PlatformFile FileStreamPosix::GetPlatformFileForTesting() {
-  return file_;
-}
-
-void FileStreamPosix::ResetOnIOComplete() {
-  on_io_complete_.reset();
-  weak_ptr_factory_.InvalidateWeakPtrs();
-}
-
-void FileStreamPosix::OnClosed(const CompletionCallback& callback) {
-  file_ = base::kInvalidPlatformFileValue;
-
-  // Reset this before Run() as Run() may issue a new async operation.
-  ResetOnIOComplete();
-  callback.Run(OK);
-}
-
-void FileStreamPosix::WaitForIOCompletion() {
-  // http://crbug.com/115067
-  base::ThreadRestrictions::ScopedAllowWait allow_wait;
-  if (on_io_complete_.get()) {
-    on_io_complete_->Wait();
-    on_io_complete_.reset();
-  }
+template <typename R>
+void FileStream::Context::OnAsyncCompleted(
+    const base::Callback<void(R)>& callback,
+    R result) {
+  // Reset this before Run() as Run() may issue a new async operation. Also it
+  // should be reset before CloseAsync() because it shouldn't run if any async
+  // operation is in progress.
+  async_in_progress_ = false;
+  if (orphaned_)
+    CloseAsync(CompletionCallback());
+  else
+    callback.Run(result);
 }
 
 }  // namespace net