Rework process collector
This unifies both constructors in one with an options argument. The options argument allows to switch on error reporting, as discussed in #219. The change of the contructor signature is breaking, but only mildly so. Plus, the process collector is rarely used explicitly. I used Sourcegraph to search for public usages, with the following results: - 2 occurrences of NewProcessCollectorPIDFn, once in @discordianfish's glimpse, once in @fabxc's etcd_exporter (deprecated anyway). Both are Prom veterans and will simply do the one line change if needed. - 8 occurrences of NewProcessCollector, of which 7 are of the form NewProcessCollector(os.Getpid(), "") Thus, it's a very easy change, which I even hinted at in the doc comment. Signed-off-by: beorn7 <beorn@soundcloud.com>
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@ -13,11 +13,17 @@
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package prometheus
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import "github.com/prometheus/procfs"
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import (
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"errors"
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"os"
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"github.com/prometheus/procfs"
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)
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type processCollector struct {
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collectFn func(chan<- Metric)
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pidFn func() (int, error)
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reportErrors bool
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cpuTotal *Desc
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openFDs, maxFDs *Desc
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vsize, maxVsize *Desc
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@ -25,34 +31,56 @@ type processCollector struct {
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startTime *Desc
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}
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// ProcessCollectorOpts defines the behavior of a process metrics collector
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// created with NewProcessCollector.
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type ProcessCollectorOpts struct {
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// PidFn returns the PID of the process the collector collects metrics
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// for. It is called upon each collection. By default, the PID of the
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// current process is used, as determined on construction time by
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// calling os.Getpid().
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PidFn func() (int, error)
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// If non-empty, each of the collected metrics is prefixed by the
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// provided string and an underscore ("_").
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Namespace string
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// If true, any error encountered during collection is reported as an
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// invalid metric (see NewInvalidMetric). Otherwise, errors are ignored
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// and the collected metrics will be incomplete. (Possibly, no metrics
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// will be collected at all.) While that's usually not desired, it is
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// appropriate for the common "mix-in" of process metrics, where process
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// metrics are nice to have, but failing to collect them should not
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// disrupt the collection of the remaining metrics.
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ReportErrors bool
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}
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// NewProcessCollector returns a collector which exports the current state of
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// process metrics including CPU, memory and file descriptor usage as well as
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// the process start time for the given process ID under the given namespace.
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// the process start time. The detailed behavior is defined by the provided
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// ProcessCollectorOpts. The zero value of ProcessCollectorOpts creates a
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// collector for the current process with an empty namespace string and no error
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// reporting.
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//
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// Currently, the collector depends on a Linux-style proc filesystem and
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// therefore only exports metrics for Linux.
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func NewProcessCollector(pid int, namespace string) Collector {
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return NewProcessCollectorPIDFn(
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func() (int, error) { return pid, nil },
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namespace,
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)
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}
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// NewProcessCollectorPIDFn works like NewProcessCollector but the process ID is
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// determined on each collect anew by calling the given pidFn function.
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func NewProcessCollectorPIDFn(
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pidFn func() (int, error),
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namespace string,
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) Collector {
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//
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// Note: An older version of this function had the following signature:
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//
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// NewProcessCollector(pid int, namespace string) Collector
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//
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// Most commonly, it was called as
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//
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// NewProcessCollector(os.Getpid(), "")
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//
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// The following call of the current version is equivalent to the above:
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//
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// NewProcessCollector(ProcessCollectorOpts{})
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func NewProcessCollector(opts ProcessCollectorOpts) Collector {
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ns := ""
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if len(namespace) > 0 {
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ns = namespace + "_"
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if len(opts.Namespace) > 0 {
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ns = opts.Namespace + "_"
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}
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c := processCollector{
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pidFn: pidFn,
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collectFn: func(chan<- Metric) {},
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c := &processCollector{
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reportErrors: opts.ReportErrors,
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cpuTotal: NewDesc(
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ns+"process_cpu_seconds_total",
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"Total user and system CPU time spent in seconds.",
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@ -90,12 +118,23 @@ func NewProcessCollectorPIDFn(
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),
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}
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if opts.PidFn == nil {
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pid := os.Getpid()
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c.pidFn = func() (int, error) { return pid, nil }
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} else {
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c.pidFn = opts.PidFn
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}
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// Set up process metric collection if supported by the runtime.
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if _, err := procfs.NewStat(); err == nil {
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c.collectFn = c.processCollect
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} else {
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c.collectFn = func(ch chan<- Metric) {
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c.reportError(ch, nil, errors.New("process metrics not supported on this platform"))
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}
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}
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return &c
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return c
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}
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// Describe returns all descriptions of the collector.
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@ -114,16 +153,16 @@ func (c *processCollector) Collect(ch chan<- Metric) {
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c.collectFn(ch)
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}
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// TODO(ts): Bring back error reporting by reverting 7faf9e7 as soon as the
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// client allows users to configure the error behavior.
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func (c *processCollector) processCollect(ch chan<- Metric) {
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pid, err := c.pidFn()
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if err != nil {
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c.reportError(ch, nil, err)
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return
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}
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p, err := procfs.NewProc(pid)
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if err != nil {
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c.reportError(ch, nil, err)
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return
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}
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@ -133,15 +172,33 @@ func (c *processCollector) processCollect(ch chan<- Metric) {
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ch <- MustNewConstMetric(c.rss, GaugeValue, float64(stat.ResidentMemory()))
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if startTime, err := stat.StartTime(); err == nil {
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ch <- MustNewConstMetric(c.startTime, GaugeValue, startTime)
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} else {
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c.reportError(ch, c.startTime, err)
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}
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} else {
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c.reportError(ch, nil, err)
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}
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if fds, err := p.FileDescriptorsLen(); err == nil {
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ch <- MustNewConstMetric(c.openFDs, GaugeValue, float64(fds))
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} else {
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c.reportError(ch, c.openFDs, err)
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}
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if limits, err := p.NewLimits(); err == nil {
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ch <- MustNewConstMetric(c.maxFDs, GaugeValue, float64(limits.OpenFiles))
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ch <- MustNewConstMetric(c.maxVsize, GaugeValue, float64(limits.AddressSpace))
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} else {
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c.reportError(ch, nil, err)
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}
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}
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func (c *processCollector) reportError(ch chan<- Metric, desc *Desc, err error) {
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if !c.reportErrors {
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return
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}
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if desc == nil {
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desc = NewInvalidDesc(err)
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}
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ch <- NewInvalidMetric(desc, err)
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}
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@ -17,12 +17,15 @@ package prometheus
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import (
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"bytes"
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"errors"
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"os"
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"regexp"
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"testing"
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"github.com/prometheus/common/expfmt"
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"github.com/prometheus/procfs"
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dto "github.com/prometheus/client_model/go"
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)
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func TestProcessCollector(t *testing.T) {
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}
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registry := NewRegistry()
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if err := registry.Register(NewProcessCollector(os.Getpid(), "")); err != nil {
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if err := registry.Register(NewProcessCollector(ProcessCollectorOpts{})); err != nil {
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t.Fatal(err)
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}
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if err := registry.Register(NewProcessCollectorPIDFn(
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func() (int, error) { return os.Getpid(), nil }, "foobar"),
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); err != nil {
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if err := registry.Register(NewProcessCollector(ProcessCollectorOpts{
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PidFn: func() (int, error) { return os.Getpid(), nil },
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Namespace: "foobar",
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ReportErrors: true, // No errors expected, just to see if none are reported.
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})); err != nil {
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t.Fatal(err)
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}
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t.Errorf("want body to match %s\n%s", re, buf.String())
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}
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}
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brokenProcessCollector := NewProcessCollector(ProcessCollectorOpts{
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PidFn: func() (int, error) { return 0, errors.New("boo") },
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ReportErrors: true,
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})
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ch := make(chan Metric)
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go func() {
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brokenProcessCollector.Collect(ch)
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close(ch)
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}()
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n := 0
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for m := range ch {
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n++
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pb := &dto.Metric{}
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err := m.Write(pb)
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if err == nil {
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t.Error("metric collected from broken process collector is unexpectedly valid")
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}
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}
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if n != 1 {
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t.Errorf("%d metrics collected, want 1", n)
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}
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}
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@ -16,7 +16,6 @@ package prometheus
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import (
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"bytes"
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"fmt"
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"os"
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"runtime"
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"sort"
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"strings"
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@ -54,7 +53,7 @@ var (
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)
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func init() {
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MustRegister(NewProcessCollector(os.Getpid(), ""))
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MustRegister(NewProcessCollector(ProcessCollectorOpts{}))
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MustRegister(NewGoCollector())
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}
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