Record UMA statistics for file_stream operations.

net/base/file_stream.h

 // Copyright (c) 2011 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, a basic interface for reading and writing files
 // synchronously or asynchronously with support for seeking to an offset.
 // Note that even when used asynchronously, only one operation is supported at
 // a time.
 
 #ifndef NET_BASE_FILE_STREAM_H_
 #define NET_BASE_FILE_STREAM_H_
 #pragma once
 
 #include "base/memory/scoped_ptr.h"
 #include "base/platform_file.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_api.h"
 
 class FilePath;
 
 namespace net {
 
+enum RecordingClass {

[cbentzel, 2011/08/15 19:49:11]

This CL would be a lot easier without the RecordingClass. It doesn't seem to add
much, and I'd strongly recommend removing it. I definitely want to see the
global removed.

[ahendrickson, 2011/08/15 23:42:26]

Done.

+  RECORDING_CLASS_NONE = 0,
+  RECORDING_CLASS_DOWNLOADS = 1,
+  // Add more flags here as necessary.  Max 31.
+  RECORDING_CLASS_MAX,
+};
+
+enum FileErrorTypes {

[cbentzel, 2011/08/15 19:49:11]

This doesn't need to be exposed in this header - it's internal to the
implementation of file_stream. If you want it to be shared, move it to a
file_stream_metrics.h header which only file_stream_posix and file_stream_win
include.

[cbentzel, 2011/08/15 19:49:11]

Nit: maybe FileError rather than FileErrorTypes

[ahendrickson, 2011/08/15 23:42:26]

Renamed to FileErrorSource.

[ahendrickson, 2011/08/15 23:42:26]

Done.

+  FILE_ERROR_TYPES_IS_NOT_OPEN = 0,
+  FILE_ERROR_TYPES_OPEN,
+  FILE_ERROR_TYPES_WRITE,
+  FILE_ERROR_TYPES_READ,
+  FILE_ERROR_TYPES_SEEK,
+  FILE_ERROR_TYPES_FLUSH,
+  FILE_ERROR_TYPES_SET_EOF,
+  FILE_ERROR_TYPES_GET_SIZE,
+  FILE_ERROR_TYPES_COUNT,
+};
+
+void EnableRecordingForClass(int class_flags);
+
+void RecordFileError(int error, FileErrorTypes type, int class_flags);

[cbentzel, 2011/08/15 19:49:11]

This would also move to the new header.

[ahendrickson, 2011/08/15 23:42:26]

Done.

+
 // TODO(darin): Move this to a more generic location.
 // This explicit mapping matches both FILE_ on Windows and SEEK_ on Linux.
 enum Whence {
   FROM_BEGIN   = 0,
   FROM_CURRENT = 1,
   FROM_END     = 2
 };
 
 class NET_API FileStream {
  public:
   FileStream();
+  explicit FileStream(int class_flags);

[cbentzel, 2011/08/15 19:49:11]

Remove the new constructors and just use EnableRecording. 

[ahendrickson, 2011/08/15 23:42:26]

Done.

 
   // Construct a FileStream with an existing file handle and opening flags.
   // |file| is valid file handle.
   // |flags| is a bitfield of base::PlatformFileFlags when the file handle was
   // opened.
   // The already opened file will not be automatically closed when FileStream
   // is destructed.
   FileStream(base::PlatformFile file, int flags);
 
+  // Construct a FileStream with an existing file handle and opening flags.

[cbentzel, 2011/08/15 19:49:11]

Ditto. 

[ahendrickson, 2011/08/15 23:42:26]

Done.

+  // |file| is valid file handle.
+  // |flags| is a bitfield of base::PlatformFileFlags when the file handle was
+  // opened.
+  // The already opened file will not be automatically closed when FileStream
+  // is destructed.
+  FileStream(base::PlatformFile file, int flags, int class_flags);
+
   ~FileStream();
 
   // Call this method to close the FileStream.  It is OK to call Close
   // multiple times.  Redundant calls are ignored.
   // Note that if there are any pending async operations, they'll be aborted.
   void Close();
 
   // Call this method to open the FileStream.  The remaining methods
   // cannot be used unless this method returns OK.  If the file cannot be
   // opened then an error code is returned.
@@ skipping 72 matching lines @@
   // Forces out a filesystem sync on this file to make sure that the file was
   // written out to disk and is not currently sitting in the buffer. This does
   // not have to be called, it just forces one to happen at the time of
   // calling.
   //
   /// Returns an error code if the operation could not be performed.
   //
   // This method should not be called if the stream was opened READ_ONLY.
   int Flush();
 
+  void EnableRecording(bool enable, int class_flags);

[cbentzel, 2011/08/15 19:49:11]

Just make this 

void EnableRecording();

enable is never non-true by callers. If you really want to include |class_flags|
you can.

Also, document this method.

[ahendrickson, 2011/08/15 23:42:26]

Done.

+
  private:
   class AsyncContext;
   friend class AsyncContext;
 
   // This member is used to support asynchronous reads.  It is non-null when
   // the FileStream was opened with PLATFORM_FILE_ASYNC.
   scoped_ptr<AsyncContext> async_context_;
 
   base::PlatformFile file_;
   int open_flags_;
   bool auto_closed_;
+  int class_flags_;
 
   DISALLOW_COPY_AND_ASSIGN(FileStream);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_FILE_STREAM_H_