Modularize the whole thing (#16)

* Use channels, add a metric router, split up configuration and use extended version of Influx line protocol internally

* Use central timer for collectors and router. Add expressions to router

* Add expression to router config

* Update entry points

* Start with README

* Update README for CCMetric

* Formatting

* Update README.md

* Add README for MultiChanTicker

* Add README for MultiChanTicker

* Update README.md

* Add README to metric router

* Update main README

* Remove SinkEntity type

* Update README for sinks

* Update go files

* Update README for receivers

* Update collectors README

* Update collectors README

* Use seperate page per collector

* Fix for tempstat page

* Add docs for customcmd collector

* Add docs for ipmistat collector

* Add docs for topprocs collector

* Update customCmdMetric.md

* Use seconds when calculating LIKWID metrics

* Add IB metrics ib_recv_pkts and ib_xmit_pkts

* Drop domain part of host name

* Updated to latest stable version of likwid

* Define source code dependencies in Makefile

* Add GPFS / IBM Spectrum Scale collector

* Add vet and staticcheck make targets

* Add vet and staticcheck make targets

* Avoid go vet warning:
struct field tag `json:"..., omitempty"` not compatible with reflect.StructTag.Get: suspicious space in struct tag value
struct field tag `json:"...", omitempty` not compatible with reflect.StructTag.Get: key:"value" pairs not separated by spaces

* Add sample collector to README.md

* Add CPU frequency collector

* Avoid staticcheck warning: redundant return statement

* Avoid staticcheck warning: unnecessary assignment to the blank identifier

* Simplified code

* Add CPUFreqCollectorCpuinfo
a metric collector to measure the current frequency of the CPUs
as obtained from /proc/cpuinfo
Only measure on the first hyperthread

* Add collector for NFS clients

* Move publication of metrics into Flush() for NatsSink

* Update GitHub actions

* Refactoring

* Avoid vet warning: Println arg list ends with redundant newline

* Avoid vet warning struct field commands has json tag but is not exported

* Avoid vet warning: return copies lock value.

* Corrected typo

* Refactoring

* Add go sources in internal/...

* Bad separator in Makefile

* Fix Infiniband collector

Co-authored-by: Holger Obermaier <40787752+ho-ob@users.noreply.github.com>

internal/multiChanTicker/README.md

@@ -0,0 +1,37 @@
+# MultiChanTicker
+
+The idea of this ticker is to multiply the output channels. The original Golang `time.Ticker` provides only a single output channel, so the signal can only be received by a single other class. This ticker allows to add multiple channels which get all notified about the time tick.
+
+```golang
+type MultiChanTicker interface {
+	Init(duration time.Duration)
+	AddChannel(chan time.Time)
+}
+```
+
+The MultiChanTicker is created similarly to the common `time.Ticker`:
+
+```golang
+NewTicker(duration time.Duration) MultiChanTicker
+```
+
+Afterwards, you can add channels:
+
+```golang
+t := MultiChanTicker(duration)
+c1 := make(chan time.Time)
+c2 := make(chan time.Time)
+t.AddChannel(c1)
+t.AddChannel(c2)
+
+for {
+    select {
+    case t1 := <- c1:
+        log.Print(t1)
+    case t2 := <- c2:
+        log.Print(t2)
+    }
+}
+```
+
+The result should be the same `time.Time` output in both channels, notified "simultaneously".

internal/multiChanTicker/multiChanTicker.go

@@ -0,0 +1,39 @@
+package multiChanTicker
+
+import (
+	"time"
+)
+
+type multiChanTicker struct {
+	ticker   *time.Ticker
+	channels []chan time.Time
+}
+
+type MultiChanTicker interface {
+	Init(duration time.Duration)
+	AddChannel(chan time.Time)
+}
+
+func (t *multiChanTicker) Init(duration time.Duration) {
+	t.ticker = time.NewTicker(duration)
+	go func() {
+		for {
+			select {
+			case ts := <-t.ticker.C:
+				for _, c := range t.channels {
+					c <- ts
+				}
+			}
+		}
+	}()
+}
+
+func (t *multiChanTicker) AddChannel(channel chan time.Time) {
+	t.channels = append(t.channels, channel)
+}
+
+func NewTicker(duration time.Duration) MultiChanTicker {
+	t := &multiChanTicker{}
+	t.Init(duration)
+	return t
+}