net: Implement canceling of all async operations in FileStream.

net/base/file_stream_context.h

+// 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 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 "base/message_loop.h"
+#include "base/platform_file.h"
+#include "net/base/completion_callback.h"
+#include "net/base/file_stream.h"
+#include "net/base/file_stream_metrics.h"
+#include "net/base/file_stream_whence.h"
+#include "net/base/net_log.h"
+
+#if defined(OS_POSIX)
+#include <errno.h>
+#endif
+
+class FilePath;
+
+namespace net {
+
+class IOBuffer;
+
+#if defined(OS_WIN)
+class FileStream::Context : public MessageLoopForIO::IOHandler {
+#elif defined(OS_POSIX)
+class FileStream::Context {
+#endif
+ public:
+  ////////////////////////////////////////////////////////////////////////////
+  // Platform-dependent methods implemented in
+  // file_stream_context_{win,posix}.cc.
+  ////////////////////////////////////////////////////////////////////////////
+
+  explicit Context(const BoundNetLog& bound_net_log);
+  Context(base::PlatformFile file,
+          const BoundNetLog& bound_net_log,
+          int open_flags);
+#if defined(OS_WIN)
+  virtual ~Context();
+#elif defined(OS_POSIX)
+  ~Context();
+#endif
+
+  int64 GetFileSize() const;
+
+  int ReadAsync(IOBuffer* buf,
+                int buf_len,
+                const CompletionCallback& callback);
+  int ReadSync(char* buf, int buf_len);
+
+  int WriteAsync(IOBuffer* buf,
+                 int buf_len,
+                 const CompletionCallback& callback);
+  int WriteSync(const char* buf, int buf_len);
+
+  int Truncate(int64 bytes);
+
+  ////////////////////////////////////////////////////////////////////////////
+  // Inline methods.
+  ////////////////////////////////////////////////////////////////////////////
+
+  void set_record_uma(bool value) { record_uma_ = value; }
+  base::PlatformFile file() const { return file_; }
+  bool async_in_progress() const { return async_in_progress_; }
+
+  ////////////////////////////////////////////////////////////////////////////
+  // Platform-independent methods implemented in file_stream_context.cc.
+  ////////////////////////////////////////////////////////////////////////////
+
+  // 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 OpenAsync(const FilePath& path,
+                 int open_flags,
+                 const CompletionCallback& callback);
+  int OpenSync(const FilePath& path, int open_flags);
+
+  void CloseSync();
+
+  void SeekAsync(Whence whence,
+                 int64 offset,
+                 const Int64CompletionCallback& callback);
+  int64 SeekSync(Whence whence, int64 offset);
+
+  void FlushAsync(const CompletionCallback& callback);
+  int FlushSync();
+
+ private:
+  ////////////////////////////////////////////////////////////////////////////
+  // Error code that is platform-dependent but is used in the platform-
+  // independent code implemented in file_stream_context.cc.
+  ////////////////////////////////////////////////////////////////////////////
+  enum {
+#if defined(OS_WIN)
+    ERROR_BAD_FILE = ERROR_INVALID_HANDLE
+#elif defined(OS_POSIX)
+    ERROR_BAD_FILE = EBADF
+#endif
+  };
+
+  ////////////////////////////////////////////////////////////////////////////
+  // Platform-independent methods implemented in file_stream_context.cc.
+  ////////////////////////////////////////////////////////////////////////////
+
+  struct OpenResult {
+    base::PlatformFile file;
+    int error_code;
+  };
+
+  // Map system error into network error code and log it with |bound_net_log_|.
+  int RecordAndMapError(int error, FileErrorSource source) const;
+
+  void BeginOpenEvent(const FilePath& path);
+
+  OpenResult OpenFileImpl(const FilePath& path, int open_flags);
+
+  int ProcessOpenError(int error_code);
+  void OnOpenCompleted(const CompletionCallback& callback, OpenResult result);
+
+  void CloseAndDelete();
+  void OnCloseCompleted();
+
+  Int64CompletionCallback IntToInt64(const CompletionCallback& callback);
+
+  // Checks for IO error that probably happened in async methods.
+  // If there was error reports it.
+  void CheckForIOError(int64* result, FileErrorSource source);
+
+  // Called when asynchronous Seek() is completed.
+  // Reports error if needed and calls callback.
+  void ProcessAsyncResult(const Int64CompletionCallback& callback,
+                          FileErrorSource source,
+                          int64 result);
+
+  // Called when asynchronous Open() or Seek()
+  // is completed. |result| contains the result or a network error code.
+  void OnAsyncCompleted(const Int64CompletionCallback& callback, int64 result);
+
+  ////////////////////////////////////////////////////////////////////////////
+  // Helper stuff which is platform-dependent but is used in the platform-
+  // independent code implemented in file_stream_context.cc. These helpers were
+  // introduced solely to implement as much of the Context methods as
+  // possible independently from platform.
+  ////////////////////////////////////////////////////////////////////////////
+
+#if defined(OS_WIN)
+  int GetLastErrno() { return GetLastError(); }
+  void OnAsyncFileOpened();
+#elif defined(OS_POSIX)
+  int GetLastErrno() { return errno; }
+  void OnAsyncFileOpened() {}
+  void CancelIo(base::PlatformFile) {}
+#endif
+
+  ////////////////////////////////////////////////////////////////////////////
+  // Platform-dependent methods implemented in
+  // file_stream_context_{win,posix}.cc.
+  ////////////////////////////////////////////////////////////////////////////
+
+  // Adjusts the position from where the data is read.
+  int64 SeekFileImpl(Whence whence, int64 offset);
+
+  // Flushes all data written to the stream.
+  int64 FlushFileImpl();
+
+#if defined(OS_WIN)
+  void IOCompletionIsPending(const CompletionCallback& callback, IOBuffer* buf);
+
+  // Implementation of MessageLoopForIO::IOHandler
+  virtual void OnIOCompleted(MessageLoopForIO::IOContext* context,
+                             DWORD bytes_read,
+                             DWORD error) OVERRIDE;
+#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.
+  int64 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.
+  int64 WriteFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
+#endif
+
+  base::PlatformFile file_;
+  bool record_uma_;
+  bool async_in_progress_;
+  bool orphaned_;
+  BoundNetLog bound_net_log_;
+
+#if defined(OS_WIN)
+  MessageLoopForIO::IOContext io_context_;
+  CompletionCallback callback_;
+  scoped_refptr<IOBuffer> in_flight_buf_;
+  FileErrorSource error_source_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(Context);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_FILE_STREAM_CONTEXT_H_
+