Represent targets in a tabular interface.

This commit represents a target group's endpoints in a tabular fashion for better differentiation
of their state in a concise manner.

retrieval/scheduler.go

@@ -25,7 +25,7 @@ const (
 	// The base units for the exponential backoff.
 	DEFAULT_BACKOFF_VALUE_UNIT = time.Second
 	// The maximum allowed backoff time.
-	MAXIMUM_BACKOFF_VALUE = 30 * time.Minute
+	MAXIMUM_BACKOFF_VALUE = 2 * time.Minute
 )
 
 // scheduler is an interface that various scheduling strategies must fulfill

retrieval/target.go

@@ -97,7 +97,7 @@ type Target interface {
 	// time, but it should occur no sooner than it.
 	//
 	// Right now, this is used as the sorting key in TargetPool.
-	scheduledFor() time.Time
+	ScheduledFor() time.Time
 	// Return the last encountered scrape error, if any.
 	LastError() error
 	// The address to which the Target corresponds.  Out of all of the available
@@ -176,11 +176,11 @@ func (t *target) recordScrapeHealth(results chan<- *extraction.Result, timestamp
 	}
 }
 
-func (t *target) Scrape(earliest time.Time, results chan<- *extraction.Result) (err error) {
+func (t *target) Scrape(earliest time.Time, results chan<- *extraction.Result) error {
 	now := time.Now()
 	futureState := t.state
-
-	if err = t.scrape(now, results); err != nil {
+	err := t.scrape(now, results)
+	if err != nil {
 		t.recordScrapeHealth(results, now, false)
 		futureState = UNREACHABLE
 	} else {
@@ -249,23 +249,23 @@ func (t *target) scrape(timestamp time.Time, results chan<- *extraction.Result)
 	return processor.ProcessSingle(buf, results, processOptions)
 }
 
-func (t target) State() TargetState {
+func (t *target) State() TargetState {
 	return t.state
 }
 
-func (t target) scheduledFor() time.Time {
+func (t *target) ScheduledFor() time.Time {
 	return t.scheduler.ScheduledFor()
 }
 
-func (t target) LastError() error {
+func (t *target) LastError() error {
 	return t.lastError
 }
 
-func (t target) Address() string {
+func (t *target) Address() string {
 	return t.address
 }
 
-func (t target) GlobalAddress() string {
+func (t *target) GlobalAddress() string {
 	address := t.address
 	hostname, err := os.Hostname()
 	if err != nil {
@@ -278,7 +278,7 @@ func (t target) GlobalAddress() string {
 	return address
 }
 
-func (t target) BaseLabels() clientmodel.LabelSet {
+func (t *target) BaseLabels() clientmodel.LabelSet {
 	return t.baseLabels
 }
 
@@ -299,7 +299,7 @@ func (t targets) Len() int {
 }
 
 func (t targets) Less(i, j int) bool {
-	return t[i].scheduledFor().Before(t[j].scheduledFor())
+	return t[i].ScheduledFor().Before(t[j].ScheduledFor())
 }
 
 func (t targets) Swap(i, j int) {

retrieval/targetmanager_test.go

@@ -66,7 +66,7 @@ func (t fakeTarget) State() TargetState {
 	return ALIVE
 }
 
-func (t *fakeTarget) scheduledFor() (time time.Time) {
+func (t *fakeTarget) ScheduledFor() (time time.Time) {
 	time = t.schedules[t.scheduleIndex]
 	t.scheduleIndex++
 

retrieval/targetpool.go

@@ -146,7 +146,7 @@ func (p *TargetPool) runIteration(results chan<- *extraction.Result, interval ti
 	for _, target := range p.targets {
 		now := time.Now()
 
-		if target.scheduledFor().After(now) {
+		if target.ScheduledFor().After(now) {
 			// None of the remaining targets are ready to be scheduled. Signal that
 			// we're done processing them in this scrape iteration.
 			continue

web/templates/status.html

@@ -43,17 +43,40 @@
       <ul>
         {{range $job, $pool := .TargetPools}}
         <li>{{$job}}
-            <ul>
+          <table>
+            <thead>
+              <tr>
+                <th>Endpoint</th>
+                <th>State</th>
+                <th>Base Labels</th>
+                <th>Earliest Retrieval</th>
+                <th>Error</th>
+              </tr>
+            </thead>
+            <tbody>
             {{range $pool.Targets}}
-                <li>
-                <a href="{{.GlobalAddress}}">{{.Address}}</a> (State: {{.State}}, Base Labels: {{.BaseLabels}})
+              <tr>
+                <td>
+                  <a href="{{.GlobalAddress}}">{{.Address}}</a>
+                </td>
+                <td>
+                  {{.State}}
+                </td>
+                <td>
+                  {{.BaseLabels}}
+                </td>
+                <td>
+                  {{.ScheduledFor}}
+                </td>
+                <td>
                   {{if .LastError}}
-                <br/>
-                <span class="error_text"><b>Scrape error:</b> "{{.LastError}}"</span>
+                  <span class="error_text">{{.LastError}}</span>
                   {{end}}
-                </li>
+                </td>
+              </tr>
             {{end}}
-            </ul>
+            </tbody>
+          </table>
         </li>
         {{end}}
       </ul>