Detect sync server communication errors

chrome/browser/sync/sessions/session_state.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.
 
 // The 'sessions' namespace comprises all the pieces of state that are
 // combined to form a SyncSession instance. In that way, it can be thought of
 // as an extension of the SyncSession type itself. Session scoping gives
 // context to things like "conflict progress", "update progress", etc, and the
 // separation this file provides allows clients to only include the parts they
 // need rather than the entire session stack.
@@ skipping 87 matching lines @@
   // commit.
   int consecutive_transient_error_commits;
 
   // Incremented when get_updates fails, commit fails, and when hitting
   // transient errors. When any of these succeed, this counter is reset.
   // TODO(chron): Reduce number of weird counters we use.
   int consecutive_errors;
 
   // Any protocol errors that we received during this sync session.
   SyncProtocolError sync_protocol_error;
+
+  // Records the most recent results of PostCommit and GetUpdates commands.
+  SyncerError download_updates_result;

[tim (not reviewing), 2012/01/10 17:17:34]

If we only care about the last result, perhaps we should name this
last_download_updates_result to be accurate.

[rlarocque, 2012/01/10 20:40:56]

Done.

It's not that we only care about the most recent result, it's that it would be
difficult to respond to anything but the last error.  We currently don't have
the ability to handle errors during the sync cycle, so we'd have to save all of
them.  What would we do with a list of errors?  I think the only sensible thing
to do would be to ignore all but the most recent error, since we can't do
anything about the older errors.

The best solution would be to handle errors closer to where they occur, but that
won't be happening for a while.  This is a temporary compromise.

+  SyncerError post_commit_result;
+  SyncerError process_commit_response_result;
 };
 
 // Caller takes ownership of the returned dictionary.
 base::DictionaryValue* DownloadProgressMarkersToValue(
     const std::string
         (&download_progress_markers)[syncable::MODEL_TYPE_COUNT]);
 
 // An immutable snapshot of state from a SyncSession.  Convenient to use as
 // part of notifications as it is inherently thread-safe.
 struct SyncSessionSnapshot {
@@ skipping 217 matching lines @@
   ~PerModelSafeGroupState();
 
   UpdateProgress update_progress;
   ConflictProgress conflict_progress;
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_SESSION_STATE_H_