Upload first release

README.md

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+# Repeater
+
+A Go library, for easy creation of repeating function calls. Use it for things like checking updates and others periodic actions.
+
+It is also supports aggregation of several repeaters in one manager (see [`MultiRepeater`](#multirepeater)) 
+
+## Exmple usage
+
+### StartRepeater
+
+```Go
+package main
+
+import (
+	"time"
+
+	"github.com/nickname76/repeater"
+)
+
+func main() {
+	stop := repeater.StartRepeater(time.Second, func() {
+		println(1)
+		time.Sleep(time.Second)
+		println(2)
+		time.Sleep(time.Second)
+		println(3)
+	})
+
+	time.Sleep(time.Second * 10)
+
+	println("STOPPIN")
+	stop()
+}
+
+```
+
+### MultiRepeater
+
+```Go
+package main
+
+import (
+	"time"
+
+	"github.com/nickname76/repeater"
+)
+
+func main() {
+	mr := repeater.NewMultiRepeater[int]()
+
+	mr.StartRepeater(1, time.Second, func() {
+		println(1)
+	})
+
+	mr.StartRepeater(2, time.Second, func() {
+		println(2)
+	})
+
+	created := mr.StartRepeater(2, time.Second, func() {
+		println(2)
+	})
+	if !created {
+		println("oops, using same id with the second one repeater")
+	}
+
+	mr.StartRepeater(3, 0, func() {
+		println(3)
+		time.Sleep(time.Second)
+		println(33)
+	})
+
+	time.Sleep(time.Second * 1)
+
+	stopped := mr.StopRepeater(1)
+	if stopped {
+		println("repeater with id 1 is now stopped")
+	}
+
+	time.Sleep(time.Second * 2)
+
+	println("Now stopping repeaters with ids 2 and 3")
+
+	mr.StopAllRepeaters()
+
+	println("All repeaters are now stopped")
+
+}
+
+```

go.mod

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+module github.com/nickname76/repeater
+
+go 1.18

multirepeater.go

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+package repeater
+
+import (
+	"sync"
+	"time"
+)
+
+// Holds any amount of repeaters. Uses StartRepeater. Use this to manage several repeaters by ids. Use NewMultiRepeater to instance MultiRepeater.
+type MultiRepeater[ID comparable] struct {
+	repeaters map[ID]func()
+	mux       sync.Mutex
+}
+
+// Instances MultiRepeater. Pass ID type you'd like to use to manage repeaters.
+func NewMultiRepeater[ID comparable]() *MultiRepeater[ID] {
+	return &MultiRepeater[ID]{
+		repeaters: make(map[ID]func()),
+		mux:       sync.Mutex{},
+	}
+}
+
+// Works almost same as original StartRepeater, but delegates stop function managment to MultiRepeater and requires id for repeater.
+// Returns `true` on success, and `false` if given id is occupied.
+func (mr *MultiRepeater[ID]) StartRepeater(id ID, frequency time.Duration, fnToCall func()) bool {
+	mr.mux.Lock()
+	if mr.repeaters[id] != nil {
+		mr.mux.Unlock()
+		return false
+	}
+	mr.repeaters[id] = StartRepeater(frequency, fnToCall)
+	mr.mux.Unlock()
+	return true
+}
+
+// Stops repeater by ID. Return `true` on success, and `false` if given id is not found.
+func (mr *MultiRepeater[ID]) StopRepeater(id ID) bool {
+	mr.mux.Lock()
+	if mr.repeaters[id] == nil {
+		mr.mux.Unlock()
+		return false
+	}
+	mr.repeaters[id]()
+	delete(mr.repeaters, id)
+	mr.mux.Unlock()
+	return true
+}
+
+// Stops all repeaters managed by this MultiRepeater. Waits until all repeaters are stopped.
+func (mr *MultiRepeater[ID]) StopAllRepeaters() {
+	wg := &sync.WaitGroup{}
+
+	mr.mux.Lock()
+	wg.Add(len(mr.repeaters))
+	for _, stop := range mr.repeaters {
+		go func(stop func()) {
+			stop()
+			wg.Done()
+		}(stop)
+	}
+	mr.repeaters = make(map[ID]func())
+	mr.mux.Unlock()
+
+	wg.Wait()
+}

repeater.go

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+package repeater
+
+import (
+	"time"
+)
+
+// Start repeating fnToCall with given frequency, frequency can be 0, if so, ticker won't be used.
+// Use returned function to stop repeater, this function waits until repeater is stopped.
+func StartRepeater(frequency time.Duration, fnToCall func()) (stop func()) {
+	if fnToCall == nil {
+		panic("fnToCall must not be nil")
+	}
+
+	stopCh := make(chan struct{})
+	waitCh := make(chan struct{})
+
+	go func() {
+		defer close(waitCh)
+
+		if frequency != 0 {
+			ticker := time.NewTicker(frequency)
+
+			for {
+				select {
+				case <-stopCh:
+					ticker.Stop()
+					return
+				case <-ticker.C:
+					fnToCall()
+				}
+			}
+		} else {
+			for {
+				select {
+				case <-stopCh:
+					return
+				default:
+					fnToCall()
+				}
+			}
+		}
+	}()
+
+	return func() {
+		close(stopCh)
+		<-waitCh
+	}
+}