[ON HOLD] Implement pull-based design for content decoding

net/filter/sdch_stream_source_delegate.h

Index: net/filter/sdch_stream_source_delegate.h
diff --git a/net/filter/sdch_stream_source_delegate.h b/net/filter/sdch_stream_source_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..9fbc5e4abc1e345364090e83b9e98964ca935d9b
--- /dev/null
+++ b/net/filter/sdch_stream_source_delegate.h
@@ -0,0 +1,60 @@
+// Copyright 2016 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.
+
+#ifndef NET_FILTER_SDCH_STREAM_SOURCE_DELEGATE_H_
+#define NET_FILTER_SDCH_STREAM_SOURCE_DELEGATE_H_
+
+#include <string>
+
+namespace net {
+
+class SdchStreamSource;
+
+// The SdchStreamSourceDelegate class acts as a delegate for
+// SdchStreamSource and is responsible for error recovery and stats gathering.
+// See the methods below for descriptions of which errors the delegate is
+// expected to handle and what it can do to repair them.
+class SdchStreamSourceDelegate {

[Randy Smith (Not in Mondays), 2016/04/26 21:54:01]

Suggestion: My inclination would be to define this as SdchStreamSource::Delegate
in the sdch_stream_source.h file.  I think it's bound tightly with that
interface, and should be part of it.

[xunjieli, 2016/07/20 21:00:47]

Done.

+ public:
+  virtual ~SdchStreamSourceDelegate(){};
+
+  // Called by the SdchStreamSource if an error occurs while parsing the
+  // server-sent dictionary ID, or if the specified dictionary can't be loaded
+  // (i.e., GetDictionary returned false). This method is expected to correct
+  // the error condition by either:
+  //   a) returning true and calling ReplaceOutput or Passthrough, or
+  //   b) returning false, in which case the StreamSource will return an error
+  //      to its caller
+  // Conceptually, the return value is true if the error has been
+  // handled/recovered from and false if not.
+  // This method must not retain a reference to |source| after returning.
+  virtual bool HandleDictionaryError(SdchStreamSource* source) = 0;
+
+  // Called by the SdchStreamSource if an error occurs while decoding the
+  // vcdiff-compressed data stream. Semantics are similar to
+  // HandleDictionaryError above. This method must not retain a reference to
+  // |source| after returning.
+  virtual bool HandleDecodingError(SdchStreamSource* source) = 0;
+
+  // Called by the SdchStreamSource to request the text of the specified
+  // dictionary. This method must either:
+  //   * Fill in |*text| and return true, or
+  //   * Leave |*text| untouched and return false.
+  // The return value is true if the named dictionary could be found and false
+  // otherwise.
+  //
+  // The |server_id| string is guaranteed to be a syntactically valid SDCH
+  // server-id.
+  virtual bool GetDictionary(const std::string& server_id,
+                             const std::string** text) = 0;
+
+  // Called by the SdchStreamSource to notify the delegate that the stream
+  // finished successfully. This method is purely advisory for statistics
+  // gathering.
+  virtual void NotifyStreamDone() = 0;
+};
+
+}  // namespace net
+
+#endif  // NET_FILTER_SDCH_STREAM_SOURCE_DELEGATE_H_