client_golang/prometheus/go_collector_test.go

112 lines
2.0 KiB
Go
Raw Normal View History

package prometheus
import (
2015-04-30 07:27:14 +03:00
"runtime/debug"
"testing"
"time"
2015-02-27 18:12:59 +03:00
dto "github.com/prometheus/client_model/go"
)
func TestGoCollector(t *testing.T) {
var (
c = NewGoCollector()
ch = make(chan Metric)
waitc = make(chan struct{})
closec = make(chan struct{})
old = -1
)
defer close(closec)
go func() {
c.Collect(ch)
go func(c <-chan struct{}) {
<-c
}(closec)
<-waitc
c.Collect(ch)
}()
for {
select {
case metric := <-ch:
switch m := metric.(type) {
Allow error reporting during metrics collection and simplify Register(). Both are interface changes I want to get in before public announcement. They only break rare usage cases, and are always easy to fix, but still we want to avoid breaking changes after a wider announcement of the project. The change of Register() simply removes the return of the Collector, which nobody was using in practice. It was just bloating the call syntax. Note that this is different from RegisterOrGet(), which is used at various occasions where you want to register something that might or might not be registered already, but if it is, you want the previously registered Collector back (because that's the relevant one). WRT error reporting: I first tried the obvious way of letting the Collector methods Describe() and Collect() return error. However, I had to conclude that that bloated _many_ calls and their handling in very obnoxious ways. On the other hand, the case where you actually want to report errors during registration or collection is very rare. Hence, this approach has the wrong trade-off. The approach taken here might at first appear clunky but is in practice quite handy, mostly because there is almost no change for the "normal" case of "no special error handling", but also because it plays well with the way descriptors and metrics are handled (via channels). Explaining the approach in more detail: - During registration / describe: Error handling was actually already in place (for invalid descriptors, which carry an error anyway). I only added a convenience function to create an invalid descriptor with a given error on purpose. - Metrics are now treated in a similar way. The Write method returns an error now (the only change in interface). An "invalid metric" is provided that can be sent via the channel to signal that that metric could not be collected. It alse transports an error. NON-GOALS OF THIS COMMIT: This is NOT yet the major improvement of the whole registry part, where we want a public Registry interface and plenty of modular configurations (for error handling, various auto-metrics, http instrumentation, testing, ...). However, we can do that whole thing without breaking existing interfaces. For now (which is a significant issue) any error during collection will either cause a 500 HTTP response or a panic (depending on registry config). Later, we definitely want to have a possibility to skip (and only report somehow) non-collectible metrics instead of aborting the whole scrape.
2015-01-12 21:16:09 +03:00
// Attention, this also catches Counter...
case Gauge:
pb := &dto.Metric{}
m.Write(pb)
2015-04-30 07:27:14 +03:00
if pb.GetGauge() == nil {
continue
}
if old == -1 {
old = int(pb.GetGauge().GetValue())
close(waitc)
continue
}
if diff := int(pb.GetGauge().GetValue()) - old; diff != 1 {
// TODO: This is flaky in highly concurrent situations.
Allow error reporting during metrics collection and simplify Register(). Both are interface changes I want to get in before public announcement. They only break rare usage cases, and are always easy to fix, but still we want to avoid breaking changes after a wider announcement of the project. The change of Register() simply removes the return of the Collector, which nobody was using in practice. It was just bloating the call syntax. Note that this is different from RegisterOrGet(), which is used at various occasions where you want to register something that might or might not be registered already, but if it is, you want the previously registered Collector back (because that's the relevant one). WRT error reporting: I first tried the obvious way of letting the Collector methods Describe() and Collect() return error. However, I had to conclude that that bloated _many_ calls and their handling in very obnoxious ways. On the other hand, the case where you actually want to report errors during registration or collection is very rare. Hence, this approach has the wrong trade-off. The approach taken here might at first appear clunky but is in practice quite handy, mostly because there is almost no change for the "normal" case of "no special error handling", but also because it plays well with the way descriptors and metrics are handled (via channels). Explaining the approach in more detail: - During registration / describe: Error handling was actually already in place (for invalid descriptors, which carry an error anyway). I only added a convenience function to create an invalid descriptor with a given error on purpose. - Metrics are now treated in a similar way. The Write method returns an error now (the only change in interface). An "invalid metric" is provided that can be sent via the channel to signal that that metric could not be collected. It alse transports an error. NON-GOALS OF THIS COMMIT: This is NOT yet the major improvement of the whole registry part, where we want a public Registry interface and plenty of modular configurations (for error handling, various auto-metrics, http instrumentation, testing, ...). However, we can do that whole thing without breaking existing interfaces. For now (which is a significant issue) any error during collection will either cause a 500 HTTP response or a panic (depending on registry config). Later, we definitely want to have a possibility to skip (and only report somehow) non-collectible metrics instead of aborting the whole scrape.
2015-01-12 21:16:09 +03:00
t.Errorf("want 1 new goroutine, got %d", diff)
}
return
2015-04-30 07:27:14 +03:00
}
case <-time.After(1 * time.Second):
t.Fatalf("expected collect timed out")
}
}
}
func TestGCCollector(t *testing.T) {
var (
c = NewGoCollector()
ch = make(chan Metric)
waitc = make(chan struct{})
closec = make(chan struct{})
oldGC uint64
oldPause float64
)
defer close(closec)
go func() {
c.Collect(ch)
// force GC
debug.FreeOSMemory()
<-waitc
c.Collect(ch)
}()
first := true
for {
select {
case metric := <-ch:
switch m := metric.(type) {
case *constSummary, *value:
pb := &dto.Metric{}
m.Write(pb)
if pb.GetSummary() == nil {
continue
}
if first {
first = false
oldGC = *pb.GetSummary().SampleCount
oldPause = *pb.GetSummary().SampleSum
close(waitc)
continue
}
if diff := *pb.GetSummary().SampleCount - oldGC; diff != 1 {
t.Errorf("want 1 new garbage collection run, got %d", diff)
}
if diff := *pb.GetSummary().SampleSum - oldPause; diff <= 0 {
t.Errorf("want moar pause, got %f", diff)
}
return
}
case <-time.After(1 * time.Second):
t.Fatalf("expected collect timed out")
}
}
}