Now using a more efficient data structure in the prometheus code for saving the last state to improve efficiency and minimize copying even more.

cmd/converge/prometheus.go

@@ -12,10 +12,30 @@ import (
 
 const NAMESPACE = "converge"
 
+// more efficient state representation for state
+type PrometheusState struct {
+	agents  map[string]*models.Agent
+	clients map[string]*models.Client
+}
+
+func NewPrometheusState(state *models.State) *PrometheusState {
+	res := PrometheusState{
+		agents:  make(map[string]*models.Agent),
+		clients: make(map[string]*models.Client),
+	}
+	for i, _ := range state.Agents {
+		res.agents[state.Agents[i].Guid] = &state.Agents[i]
+	}
+	for i, _ := range state.Clients {
+		res.clients[state.Clients[i].Guid] = &state.Clients[i]
+	}
+	return &res
+}
+
 var (
 	// remember previous values of agent guids and clients so that we can increment
 	// the cumulative counters.
-	lastState *models.State = &models.State{}
+	lastState *PrometheusState = NewPrometheusState(&models.State{})
 
 	cumulativeAgentCount = promauto.NewCounter(prometheus.CounterOpts{
 		Namespace: NAMESPACE,
@@ -129,7 +149,7 @@ func clientLabels(client *models.Client) prometheus.Labels {
 }
 
 func agentActive(agent *models.Agent) {
-	prevAgent, ok := findAgent(lastState, agent.Guid)
+	prevAgent, ok := lastState.agents[agent.Guid]
 	if ok && *prevAgent != *agent {
 		removeAgentInfoMetrics(prevAgent)
 	}
@@ -142,26 +162,8 @@ func agentActive(agent *models.Agent) {
 		Set(float64(time.Now().Sub(agent.StartTime).Seconds()))
 }
 
-func findAgent(state *models.State, guid string) (*models.Agent, bool) {
-	for i := range state.Agents {
-		if state.Agents[i].Guid == guid {
-			return &state.Agents[i], true
-		}
-	}
-	return nil, false
-}
-
-func findClient(state *models.State, guid string) (*models.Client, bool) {
-	for i := range state.Clients {
-		if state.Clients[i].Guid == guid {
-			return &state.Clients[i], true
-		}
-	}
-	return nil, false
-}
-
 func clientActive(client *models.Client) {
-	prevClient, ok := findClient(lastState, client.Guid)
+	prevClient, ok := lastState.clients[client.Guid]
 	if ok && *prevClient != *client {
 		removeClientInfoMetrics(prevClient)
 	}
@@ -214,38 +216,35 @@ var prometheusChannel = make(chan func())
 
 func updateMetrics(state *models.State) {
 	prometheusChannel <- func() {
-		updateMetricsImpl(state)
+		updateMetricsImpl(NewPrometheusState(state))
 	}
 }
 
 func updateDurations() {
-	for i := range lastState.Agents {
+	for _, agent := range lastState.agents {
-		agent := &lastState.Agents[i]
 		agentDuration.
 			With(prometheus.Labels{"agent_guid": agent.Guid}).
 			Set(float64(time.Now().Sub(agent.StartTime).Seconds()))
 	}
-	for i := range lastState.Clients {
+	for _, client := range lastState.clients {
-		client := &lastState.Clients[i]
 		clientDuration.
 			With(prometheus.Labels{"client_guid": client.Guid}).
 			Set(float64(time.Now().Sub(client.StartTime).Seconds()))
 	}
 }
 
-func updateMetricsImpl(state *models.State) {
+func updateMetricsImpl(state *PrometheusState) {
+
 	agentGuids := make(map[string]*models.Agent)
 	clientGuids := make(map[string]*models.Client)
 
-	agentCount.Set(float64(len(state.Agents)))
+	agentCount.Set(float64(len(state.agents)))
 	disconnectedAgents := make(map[string]*models.Agent)
-	for i := range lastState.Agents {
+	for _, agent := range lastState.agents {
-		agent := &lastState.Agents[i]
 		disconnectedAgents[agent.Guid] = agent
 	}
-	for i := range state.Agents {
+	for _, agent := range state.agents {
-		agent := &state.Agents[i]
+		if lastState.agents[agent.Guid] == nil {
-		if _, ok := findAgent(lastState, agent.Guid); !ok {
 			cumulativeAgentCount.Inc()
 		}
 		delete(disconnectedAgents, agent.Guid)
@@ -256,17 +255,15 @@ func updateMetricsImpl(state *models.State) {
 		removeAgentMetrics(agent)
 	}
 
-	clientCount.Set(float64(len(state.Clients)))
+	clientCount.Set(float64(len(state.clients)))
 
 	// with this app
 	disconnectedClients := make(map[string]*models.Client)
-	for i := range lastState.Clients {
+	for _, client := range lastState.clients {
-		client := &lastState.Clients[i]
 		disconnectedClients[client.Guid] = client
 	}
-	for i := range state.Clients {
+	for _, client := range state.clients {
-		client := &state.Clients[i]
+		if lastState.clients[client.Guid] == nil {
-		if _, ok := findClient(lastState, client.Guid); !ok {
 			cumulativeClientCount.Inc()
 		}
 		delete(disconnectedClients, client.Guid)