Always build the procfs collector.

prometheus/process_collector.go

@@ -13,6 +13,8 @@
 
 package prometheus
 
+import "github.com/prometheus/procfs"
+
 type processCollector struct {
 	pid             int
 	collectFn       func(chan<- Metric)
@@ -100,3 +102,48 @@ func (c *processCollector) Describe(ch chan<- *Desc) {
 func (c *processCollector) Collect(ch chan<- Metric) {
 	c.collectFn(ch)
 }
+
+func processCollectSupported() bool {
+	if _, err := procfs.NewStat(); err == nil {
+		return true
+	}
+	return false
+}
+
+// TODO(ts): Bring back error reporting by reverting 7faf9e7 as soon as the
+// client allows users to configure the error behavior.
+func (c *processCollector) processCollect(ch chan<- Metric) {
+	pid, err := c.pidFn()
+	if err != nil {
+		return
+	}
+
+	p, err := procfs.NewProc(pid)
+	if err != nil {
+		return
+	}
+
+	if stat, err := p.NewStat(); err == nil {
+		c.cpuTotal.Set(stat.CPUTime())
+		ch <- c.cpuTotal
+		c.vsize.Set(float64(stat.VirtualMemory()))
+		ch <- c.vsize
+		c.rss.Set(float64(stat.ResidentMemory()))
+		ch <- c.rss
+
+		if startTime, err := stat.StartTime(); err == nil {
+			c.startTime.Set(startTime)
+			ch <- c.startTime
+		}
+	}
+
+	if fds, err := p.FileDescriptorsLen(); err == nil {
+		c.openFDs.Set(float64(fds))
+		ch <- c.openFDs
+	}
+
+	if limits, err := p.NewLimits(); err == nil {
+		c.maxFDs.Set(float64(limits.OpenFiles))
+		ch <- c.maxFDs
+	}
+}