From 7faf9e76efa0d84fd537cdb9c2372ce4c3df14f1 Mon Sep 17 00:00:00 2001
From: Tobias Schmidt <ts@soundcloud.com>
Date: Tue, 10 Feb 2015 16:19:27 -0500
Subject: [PATCH] Handle process collector errors gracefully

As it is expected that the process collector can fail under certain
conditions (proc information for a process only readable by root or
other user for example) and as there is currently no option to configure
the error behavior of the client, this change reverts the error
reporting introduced in 159e96f. This effectively means that errors are
simply ignored and there won't be any samples for the process_* metrics
in case of an error.

Once a user can control how to behave in case of errors returned by
collectors, this change should probably be reverted.
---
 prometheus/process_collector_procfs.go | 31 ++++----------------------
 1 file changed, 4 insertions(+), 27 deletions(-)

diff --git a/prometheus/process_collector_procfs.go b/prometheus/process_collector_procfs.go
index fab1f03..a15a75f 100644
--- a/prometheus/process_collector_procfs.go
+++ b/prometheus/process_collector_procfs.go
@@ -27,23 +27,15 @@ func processCollectSupported() bool {
 func (c *processCollector) processCollect(ch chan<- Metric) {
 	pid, err := c.pidFn()
 	if err != nil {
-		c.reportCollectErrors(ch, err)
 		return
 	}
 
 	p, err := procfs.NewProc(pid)
 	if err != nil {
-		c.reportCollectErrors(ch, err)
 		return
 	}
 
-	if stat, err := p.NewStat(); err != nil {
-		// Report collect errors for metrics depending on stat.
-		ch <- NewInvalidMetric(c.vsize.Desc(), err)
-		ch <- NewInvalidMetric(c.rss.Desc(), err)
-		ch <- NewInvalidMetric(c.startTime.Desc(), err)
-		ch <- NewInvalidMetric(c.cpuTotal.Desc(), err)
-	} else {
+	if stat, err := p.NewStat(); err == nil {
 		c.cpuTotal.Set(stat.CPUTime())
 		ch <- c.cpuTotal
 		c.vsize.Set(float64(stat.VirtualMemory()))
@@ -51,34 +43,19 @@ func (c *processCollector) processCollect(ch chan<- Metric) {
 		c.rss.Set(float64(stat.ResidentMemory()))
 		ch <- c.rss
 
-		if startTime, err := stat.StartTime(); err != nil {
-			ch <- NewInvalidMetric(c.startTime.Desc(), err)
-		} else {
+		if startTime, err := stat.StartTime(); err == nil {
 			c.startTime.Set(startTime)
 			ch <- c.startTime
 		}
 	}
 
-	if fds, err := p.FileDescriptorsLen(); err != nil {
-		ch <- NewInvalidMetric(c.openFDs.Desc(), err)
-	} else {
+	if fds, err := p.FileDescriptorsLen(); err == nil {
 		c.openFDs.Set(float64(fds))
 		ch <- c.openFDs
 	}
 
-	if limits, err := p.NewLimits(); err != nil {
-		ch <- NewInvalidMetric(c.maxFDs.Desc(), err)
-	} else {
+	if limits, err := p.NewLimits(); err == nil {
 		c.maxFDs.Set(float64(limits.OpenFiles))
 		ch <- c.maxFDs
 	}
 }
-
-func (c *processCollector) reportCollectErrors(ch chan<- Metric, err error) {
-	ch <- NewInvalidMetric(c.cpuTotal.Desc(), err)
-	ch <- NewInvalidMetric(c.openFDs.Desc(), err)
-	ch <- NewInvalidMetric(c.maxFDs.Desc(), err)
-	ch <- NewInvalidMetric(c.vsize.Desc(), err)
-	ch <- NewInvalidMetric(c.rss.Desc(), err)
-	ch <- NewInvalidMetric(c.startTime.Desc(), err)
-}