Use tagged struct fields.

storage/metric/curator.go

@@ -298,7 +298,7 @@ func (w watermarkOperator) Operate(key, _ interface{}) (oErr *storage.OperatorEr
 		// An anomaly with the series frontier is severe in the sense that some sort
 		// of an illegal state condition exists in the storage layer, which would
 		// probably signify an illegal disk frontier.
-		return &storage.OperatorError{err, false}
+		return &storage.OperatorError{error: err, Continuable: false}
 	}
 
 	curationState, err := getCurationRemark(w.curationState, w.processor, w.ignoreYoungerThan, fingerprint)
@@ -307,7 +307,7 @@ func (w watermarkOperator) Operate(key, _ interface{}) (oErr *storage.OperatorEr
 		// there was a decoding error with the entity and shouldn't be cause to stop
 		// work.  The process will simply start from a pessimistic work time and
 		// work forward.  With an idempotent processor, this is safe.
-		return &storage.OperatorError{err, true}
+		return &storage.OperatorError{error: err, Continuable: true}
 	}
 
 	startKey := model.SampleKey{
@@ -318,12 +318,12 @@ func (w watermarkOperator) Operate(key, _ interface{}) (oErr *storage.OperatorEr
 	prospectiveKey, err := coding.NewProtocolBuffer(startKey.ToDTO()).Encode()
 	if err != nil {
 		// An encoding failure of a key is no reason to stop.
-		return &storage.OperatorError{err, true}
+		return &storage.OperatorError{error: err, Continuable: true}
 	}
 	if !w.sampleIterator.Seek(prospectiveKey) {
 		// LevelDB is picky about the seek ranges.  If an iterator was invalidated,
 		// no work may occur, and the iterator cannot be recovered.
-		return &storage.OperatorError{fmt.Errorf("Illegal Condition: Iterator invalidated due to seek range."), false}
+		return &storage.OperatorError{error: fmt.Errorf("Illegal Condition: Iterator invalidated due to seek range."), Continuable: false}
 	}
 
 	newestAllowedSample := w.stopAt
@@ -335,7 +335,7 @@ func (w watermarkOperator) Operate(key, _ interface{}) (oErr *storage.OperatorEr
 	if err != nil {
 		// We can't divine the severity of a processor error without refactoring the
 		// interface.
-		return &storage.OperatorError{err, false}
+		return &storage.OperatorError{error: err, Continuable: false}
 	}
 
 	err = w.refreshCurationRemark(fingerprint, lastTime)
@@ -343,7 +343,7 @@ func (w watermarkOperator) Operate(key, _ interface{}) (oErr *storage.OperatorEr
 		// Under the assumption that the processors are idempotent, they can be
 		// re-run; thusly, the commitment of the curation remark is no cause
 		// to cease further progress.
-		return &storage.OperatorError{err, true}
+		return &storage.OperatorError{error: err, Continuable: true}
 	}
 
 	return