Add some metric history

The count of connections and count of delivered messages now have 50
minutes of history available in the /about sparklines.

smtpd/listener.go

@@ -1,11 +1,13 @@
 package smtpd
 
 import (
+	"container/list"
 	"expvar"
 	"fmt"
 	"github.com/jhillyerd/inbucket/config"
 	"github.com/jhillyerd/inbucket/log"
 	"net"
+	"time"
 )
 
 // Real server code starts here
@@ -19,7 +21,12 @@ type Server struct {
 
 var expConnectsTotal = new(expvar.Int)
 var expConnectsCurrent = new(expvar.Int)
+var expConnectsHist = new(expvar.String)
 var expDeliveredTotal = new(expvar.Int)
+var expDeliveredHist = new(expvar.String)
+
+var deliveredHist = list.New()
+var connectsHist = list.New()
 
 // Init a new Server object
 func New() *Server {
@@ -60,9 +67,34 @@ func (s *Server) Start() {
 	}
 }
 
+// When the provided Ticker ticks, we update our metrics history
+func metricsTicker(t *time.Ticker) {
+	ok := true
+	for ok {
+		_, ok = <-t.C
+		expDeliveredHist.Set(pushMetric(deliveredHist, expDeliveredTotal))
+		expConnectsHist.Set(pushMetric(connectsHist, expConnectsTotal))
+	}
+}
+
+// pushMetric adds the metric to the end of the list and returns a comma
+// separated string of the previous 50 entries
+func pushMetric(history *list.List, ev expvar.Var) string {
+	history.PushBack(ev.String())
+	if history.Len() > 50 {
+		history.Remove(history.Front())
+	}
+	return JoinStringList(history)
+}
+
 func init() {
 	m := expvar.NewMap("smtp")
 	m.Set("connectsTotal", expConnectsTotal)
+	m.Set("connectsHist", expConnectsHist)
 	m.Set("connectsCurrent", expConnectsCurrent)
 	m.Set("deliveredTotal", expDeliveredTotal)
+	m.Set("deliveredHist", expDeliveredHist)
+
+	t := time.NewTicker(time.Minute)
+	go metricsTicker(t)
 }

smtpd/utils.go

@@ -1,6 +1,7 @@
 package smtpd
 
 import (
+	"container/list"
 	"crypto/sha1"
 	"fmt"
 	"io"
@@ -25,3 +26,15 @@ func HashMailboxName(mailbox string) string {
 	io.WriteString(h, mailbox)
 	return fmt.Sprintf("%x", h.Sum(nil))
 }
+
+// JoinStringList joins a List containing strings by commas
+func JoinStringList(listOfStrings *list.List) string {
+	if listOfStrings.Len() == 0 {
+		return ""
+	}
+	s := make([]string, 0, listOfStrings.Len())
+	for e := listOfStrings.Front(); e != nil; e = e.Next() {
+		s = append(s, e.Value.(string))
+	}
+	return strings.Join(s, ",")
+}

themes/integral/public/main.css

@@ -317,4 +317,13 @@ table.metrics {
 
 .metrics th {
   text-align: left;
+  width: 15em;
+}
+
+.metrics td {
+  width: 10em;
+}
+
+.metrics td.sparkline {
+  width: 170px;
 }

themes/integral/templates/root/about.html

@@ -53,6 +53,20 @@
     }
   }
 
+  function setHistory(name, value) {
+    var h = value.split(",")
+    var prev = parseInt(h[0])
+    for (i=0; i<h.length; i++) {
+      var t = parseInt(h[i])
+      h[i] = t-prev
+      prev = t
+    }
+    el = $('#s-' + name)
+    if (el) {
+      el.sparkline(h)
+    }
+  }
+
   function metric(name, value, filter, chartable) {
     if (chartable) {
       appendHistory(name, value)
@@ -77,6 +91,8 @@
     metric('smtpConnectsTotal', data.smtp.connectsTotal, numberFilter, false)
     metric('smtpConnectsCurrent', data.smtp.connectsCurrent, numberFilter, true)
     metric('smtpDeliveredTotal', data.smtp.deliveredTotal, numberFilter, false)
+    setHistory('smtpConnectsTotal', data.smtp.connectsHist)
+    setHistory('smtpDeliveredTotal', data.smtp.deliveredHist)
   }
 
   function loadMetrics() {
@@ -116,22 +132,26 @@ address and make it available to view without a password.</p>
     <tr>
       <th>System Memory:</th>
       <td><span id="m-memstatsSys">.</span></td>
-      <td><span id="s-memstatsSys">.</span></td>
+      <td class="sparkline"><span id="s-memstatsSys">.</span></td>
+      <td>(5s)</td>
     </tr>
     <tr>
       <th>Heap Capacity:</th>
       <td><span id="m-memstatsHeapSys">.</span></td>
-      <td><span id="s-memstatsHeapSys">.</span></td>
+      <td class="sparkline"><span id="s-memstatsHeapSys">.</span></td>
+      <td>(5s)</td>
     </tr>
     <tr>
       <th>Heap In-Use:</th>
       <td><span id="m-memstatsHeapAlloc">.</span></td>
-      <td><span id="s-memstatsHeapAlloc">.</span></td>
+      <td class="sparkline"><span id="s-memstatsHeapAlloc">.</span></td>
+      <td>(5s)</td>
     </tr>
     <tr>
       <th>Heap # Objects:</th>
       <td><span id="m-memstatsHeapObjects">.</span></td>
-      <td><span id="s-memstatsHeapObjects">.</span></td>
+      <td class="sparkline"><span id="s-memstatsHeapObjects">.</span></td>
+      <td>(5s)</td>
     </tr>
   </table>
   <p class="last">&nbsp;</p>
@@ -142,15 +162,20 @@ address and make it available to view without a password.</p>
     <tr>
       <th>Current Connections:</th>
       <td><span id="m-smtpConnectsCurrent">.</span></td>
-      <td><span id="s-smtpConnectsCurrent">.</span></td>
+      <td class="sparkline"><span id="s-smtpConnectsCurrent">.</span></td>
+      <td>(5s)</td>
     </tr>
     <tr>
       <th>Total Connections:</th>
       <td><span id="m-smtpConnectsTotal">.</span></td>
+      <td class="sparkline"><span id="s-smtpConnectsTotal">.</span></td>
+      <td>(60s)</td>
     </tr>
     <tr>
       <th>Messages Delivered:</th>
       <td><span id="m-smtpDeliveredTotal">.</span></td>
+      <td class="sparkline"><span id="s-smtpDeliveredTotal">.</span></td>
+      <td>(60s)</td>
     </tr>
   </table>
   <p class="last">&nbsp;</p>