[VOL-2312] Logging - Integrate voltctl with new etcd-based dynamic loglevel mechanism. Testing is in progress

Change-Id: I2e13bb79008c9a49ebb6f58e575f51efebe6dbfd
diff --git a/vendor/github.com/armon/go-metrics/inmem_signal.go b/vendor/github.com/armon/go-metrics/inmem_signal.go
new file mode 100644
index 0000000..0937f4a
--- /dev/null
+++ b/vendor/github.com/armon/go-metrics/inmem_signal.go
@@ -0,0 +1,117 @@
+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)
+			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)
+			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)
+			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()
+}