open-consul/vendor/github.com/armon/go-metrics/inmem_signal.go

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package metrics
import (
"bytes"
"fmt"
"io"
"os"
"os/signal"
"strings"
"sync"
"syscall"
)
// InmemSignal is used to listen for a given signal, and when received,
// to dump the current metrics from the InmemSink to an io.Writer
type InmemSignal struct {
signal syscall.Signal
inm *InmemSink
w io.Writer
sigCh chan os.Signal
stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// NewInmemSignal creates a new InmemSignal which listens for a given signal,
// and dumps the current metrics out to a writer
func NewInmemSignal(inmem *InmemSink, sig syscall.Signal, w io.Writer) *InmemSignal {
i := &InmemSignal{
signal: sig,
inm: inmem,
w: w,
sigCh: make(chan os.Signal, 1),
stopCh: make(chan struct{}),
}
signal.Notify(i.sigCh, sig)
go i.run()
return i
}
// DefaultInmemSignal returns a new InmemSignal that responds to SIGUSR1
// and writes output to stderr. Windows uses SIGBREAK
func DefaultInmemSignal(inmem *InmemSink) *InmemSignal {
return NewInmemSignal(inmem, DefaultSignal, os.Stderr)
}
// Stop is used to stop the InmemSignal from listening
func (i *InmemSignal) Stop() {
i.stopLock.Lock()
defer i.stopLock.Unlock()
if i.stop {
return
}
i.stop = true
close(i.stopCh)
signal.Stop(i.sigCh)
}
// run is a long running routine that handles signals
func (i *InmemSignal) run() {
for {
select {
case <-i.sigCh:
i.dumpStats()
case <-i.stopCh:
return
}
}
}
// dumpStats is used to dump the data to output writer
func (i *InmemSignal) dumpStats() {
buf := bytes.NewBuffer(nil)
data := i.inm.Data()
// Skip the last period which is still being aggregated
for j := 0; j < len(data)-1; j++ {
intv := data[j]
intv.RLock()
for _, val := range intv.Gauges {
name := i.flattenLabels(val.Name, val.Labels)
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fmt.Fprintf(buf, "[%v][G] '%s': %0.3f\n", intv.Interval, name, val.Value)
}
for name, vals := range intv.Points {
for _, val := range vals {
fmt.Fprintf(buf, "[%v][P] '%s': %0.3f\n", intv.Interval, name, val)
}
}
for _, agg := range intv.Counters {
name := i.flattenLabels(agg.Name, agg.Labels)
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fmt.Fprintf(buf, "[%v][C] '%s': %s\n", intv.Interval, name, agg.AggregateSample)
}
for _, agg := range intv.Samples {
name := i.flattenLabels(agg.Name, agg.Labels)
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fmt.Fprintf(buf, "[%v][S] '%s': %s\n", intv.Interval, name, agg.AggregateSample)
}
intv.RUnlock()
}
// Write out the bytes
i.w.Write(buf.Bytes())
}
// Flattens the key for formatting along with its labels, removes spaces
func (i *InmemSignal) flattenLabels(name string, labels []Label) string {
buf := bytes.NewBufferString(name)
replacer := strings.NewReplacer(" ", "_", ":", "_")
for _, label := range labels {
replacer.WriteString(buf, ".")
replacer.WriteString(buf, label.Value)
}
return buf.String()
}