[Sync] Add support for sync Persistence Errors

sync/api/sync_error.h

Index: sync/api/sync_error.h
diff --git a/sync/api/sync_error.h b/sync/api/sync_error.h
index e9ca0f60825c0893cf63c86cf4a8a523762cb1c0..d2508b83eb41233f7b7743e9acd4faa965d853d7 100644
--- a/sync/api/sync_error.h
+++ b/sync/api/sync_error.h
@@ -19,21 +19,41 @@ class Location;
 namespace syncer {
 
 // Sync errors are used for debug purposes and handled internally and/or
-// exposed through Chrome's "about:sync" internal page. They are considered
-// unrecoverable for the datatype creating them, and should only be used as
-// such.
+// exposed through Chrome's "about:sync" internal page.
 // This class is copy-friendly and thread-safe.
 class SYNC_EXPORT SyncError {
  public:
+  // Error types are used to distinguish general datatype errors (which result
+  // in the datatype being disabled) from actionable sync errors (which might
+  // have more complicated results).
+  enum ErrorType {
+    UNSET,                // No error.
+    UNRECOVERABLE_ERROR,  // An unrecoverable runtime error was encountered, and
+                          // sync should be disabled completely.
+    DATATYPE_ERROR,       // A datatype error was encountered, and the datatype
+                          // should be disabled.
+    PERSISTENCE_ERROR,    // A persistence error was detected, and the
+                          // datataype should be associated after a sync update.
+    CRYPTO_ERROR,         // A cryptographer error was detected, and the
+                          // datatype should be associated after it is resolved.
+  };
+
   // Default constructor refers to "no error", and IsSet() will return false.
   SyncError();
 
-  // Create a new Sync error triggered by datatype |type| with debug message
-  // |message| from the specified location. IsSet() will return true.
-  // Will print the new error to LOG(ERROR).
+  // Create a new Sync datatype error triggered by |model_type| with debug
+  // message |message| from the specified location. IsSet() will return true
+  // afterward. Will print the new error to LOG(ERROR).
   SyncError(const tracked_objects::Location& location,
             const std::string& message,
-            ModelType type);
+            ModelType model_type);
+
+  // Create a new Sync error of type |error_type| triggered by |model_type|

[haitaol1, 2013/06/10 22:47:56]

Why don't combine these two constructors?

[Nicolas Zea, 2013/06/20 18:31:33]

This constructor autogenerates the message, to I think it's cleaner to not
provide the message paramater. Otherwise it's ambiguous when the message should
or not should be set.

[haitaol1, 2013/06/20 20:35:51]

I'm not sure how useful the auto-generated message is. Outputting error type has
same effect. And this constructor also accepts datatype error. Seems confusing
to me that there are two ways to create datatype error. Can you just add message
parameter to this constructor? In the future, maybe other types of error can
have customized message, too.

On 2013/06/20 18:31:33, Nicolas Zea wrote:

[Nicolas Zea, 2013/07/01 21:46:21]

Done.

+  // from the specified location. IsSet() will return true afterward. Will
+  // create and print an error specific message to LOG(ERROR).
+  SyncError(const tracked_objects::Location& location,
+            ErrorType error_type,
+            ModelType model_type);
 
   // Copy and assign via deep copy.
   SyncError(const SyncError& other);
@@ -41,8 +61,9 @@ class SYNC_EXPORT SyncError {
 
   ~SyncError();
 
-  // Reset the current error to a new error. May be called irrespective of
-  // whether IsSet() is true. After this is called, IsSet() will return true.
+  // Reset the current error to a new datatype error. May be called
+  // irrespective of whether IsSet() is true. After this is called, IsSet()
+  // will return true.
   // Will print the new error to LOG(ERROR).
   void Reset(const tracked_objects::Location& location,
              const std::string& message,
@@ -54,7 +75,8 @@ class SYNC_EXPORT SyncError {
   // These must only be called if IsSet() is true.
   const tracked_objects::Location& location() const;
   const std::string& message() const;
-  ModelType type() const;
+  ModelType model_type() const;
+  ErrorType error_type() const;
 
   // Returns empty string is IsSet() is false.
   std::string ToString() const;
@@ -70,7 +92,8 @@ class SYNC_EXPORT SyncError {
   // is called, IsSet() will return true.
   void Init(const tracked_objects::Location& location,
             const std::string& message,
-            ModelType type);
+            ModelType model_type,
+            ErrorType error_type);
 
   // Reset the error to it's default (unset) values.
   void Clear();
@@ -78,7 +101,8 @@ class SYNC_EXPORT SyncError {
   // scoped_ptr is necessary because Location objects aren't assignable.
   scoped_ptr<tracked_objects::Location> location_;
   std::string message_;
-  ModelType type_;
+  ModelType model_type_;
+  ErrorType error_type_;
 };
 
 // gmock printer helper.