routing: add mission control import functionality

routing/missioncontrol.go

@@ -342,6 +342,27 @@ func (m *MissionControl) GetHistorySnapshot() *MissionControlSnapshot {
 	return m.state.getSnapshot()
 }
 
+// ImportHistory imports the set of mission control results provided to our
+// in-memory state. These results are not persisted, so will not survive
+// restarts.
+func (m *MissionControl) ImportHistory(history *MissionControlSnapshot) error {
+	if history == nil {
+		return errors.New("cannot import nil history")
+	}
+
+	m.Lock()
+	defer m.Unlock()
+
+	log.Infof("Importing history snapshot with %v pairs to mission control",
+		len(history.Pairs))
+
+	imported := m.state.importSnapshot(history)
+
+	log.Infof("Imported %v results to mission control", imported)
+
+	return nil
+}
+
 // GetPairHistorySnapshot returns the stored history for a given node pair.
 func (m *MissionControl) GetPairHistorySnapshot(
 	fromNode, toNode route.Vertex) TimedPairResult {

routing/missioncontrol_state.go

@@ -209,3 +209,53 @@ func (m *missionControlState) getSnapshot() *MissionControlSnapshot {
 
 	return &snapshot
 }
+
+// importSnapshot takes an existing snapshot and merges it with our current
+// state if the result provided are fresher than our current results. It returns
+// the number of pairs that were used.
+func (m *missionControlState) importSnapshot(snapshot *MissionControlSnapshot) int {
+	var imported int
+
+	for _, pair := range snapshot.Pairs {
+		fromNode := pair.Pair.From
+		toNode := pair.Pair.To
+
+		results, found := m.getLastPairResult(fromNode)
+		if !found {
+			results = make(map[route.Vertex]TimedPairResult)
+		}
+
+		lastResult := results[toNode]
+
+		failResult := failPairResult(pair.FailAmt)
+		imported += m.importResult(
+			lastResult.FailTime, pair.FailTime, failResult,
+			fromNode, toNode,
+		)
+
+		successResult := successPairResult(pair.SuccessAmt)
+		imported += m.importResult(
+			lastResult.SuccessTime, pair.SuccessTime, successResult,
+			fromNode, toNode,
+		)
+	}
+
+	return imported
+}
+
+func (m *missionControlState) importResult(currentTs, importedTs time.Time,
+	importedResult pairResult, fromNode, toNode route.Vertex) int {
+
+	if currentTs.After(importedTs) {
+		log.Debugf("Not setting pair result for %v->%v (%v) "+
+			"success=%v, timestamp %v older than last result %v",
+			fromNode, toNode, importedResult.amt,
+			importedResult.success, importedTs, currentTs)
+
+		return 0
+	}
+
+	m.setLastPairResult(fromNode, toNode, importedTs, &importedResult)
+
+	return 1
+}