Merge pull request #682 from devlights:add-sync-oncevalues-example

Add sync.OnceValues example

Author: devlights

examples/basic/syncs/README.md

@@ -16,3 +16,4 @@
 |use\_once.go|syncs\_use\_once|sync.Onceのサンプルです|
 |use\_oncefunc.go|syncs\_use\_oncefunc|Go 1.21 で追加された sync.OnceFunc() のサンプルです|
 |use\_oncevalue.go|syncs\_use\_oncevalue|Go 1.21 で追加された sync.OnceValue() のサンプルです|
+|use\_oncevalues.go|syncs\_use\_oncevalues|Go 1.21 で追加された sync.OnceValues() のサンプルです|

examples/basic/syncs/examples.go

@@ -25,4 +25,5 @@ func (r *register) Regist(m mapping.ExampleMapping) {
 	m["syncs_use_once"] = UseOnce
 	m["syncs_use_oncefunc"] = UseOnceFunc
 	m["syncs_use_oncevalue"] = UseOnceValue
+	m["syncs_use_oncevalues"] = UseOnceValues
 }

examples/basic/syncs/use_oncevalues.go

@@ -0,0 +1,75 @@
+package syncs
+
+import (
+	"runtime"
+	"sync"
+
+	"github.com/devlights/gomy/output"
+)
+
+// UseOnceValues は、Go 1.21 で追加された sync.OnceValues() のサンプルです。
+//
+// # REFERENCES
+//   - https://pkg.go.dev/sync@go1.21.4#OnceValues
+func UseOnceValues() error {
+	var (
+		v = 0
+		f = sync.OnceValues(func() (int, error) {
+			v++
+			return v, nil
+		})
+	)
+	output.Stdoutl("[before]", v)
+
+	var (
+		numCpu = runtime.NumCPU()
+		done   = make(chan bool, numCpu)
+	)
+	for i := 0; i < numCpu; i++ {
+		i := i
+		go func() {
+			result, err := f()
+			done <- true
+			output.Stderrf("[done]", "result=%d\terr=%v\tgoroutine-%d\n", result, err, i)
+		}()
+	}
+
+	for i := 0; i < numCpu; i++ {
+		<-done
+	}
+
+	output.Stdoutl("[after]", v)
+
+	return nil
+
+	/*
+		$ task
+		task: Task "build" is up to date
+		task: [run] ./try-golang -onetime
+
+		ENTER EXAMPLE NAME: syncs_use_oncevalues
+
+		[Name] "syncs_use_oncevalues"
+		[before]             0
+		[done]               result=1   err=<nil>       goroutine-15
+		[done]               result=1   err=<nil>       goroutine-13
+		[done]               result=1   err=<nil>       goroutine-14
+		[done]               result=1   err=<nil>       goroutine-10
+		[done]               result=1   err=<nil>       goroutine-1
+		[done]               result=1   err=<nil>       goroutine-0
+		[done]               result=1   err=<nil>       goroutine-2
+		[done]               result=1   err=<nil>       goroutine-6
+		[done]               result=1   err=<nil>       goroutine-5
+		[done]               result=1   err=<nil>       goroutine-11
+		[done]               result=1   err=<nil>       goroutine-3
+		[done]               result=1   err=<nil>       goroutine-8
+		[done]               result=1   err=<nil>       goroutine-9
+		[done]               result=1   err=<nil>       goroutine-7
+		[done]               result=1   err=<nil>       goroutine-4
+		[done]               result=1   err=<nil>       goroutine-12
+		[after]              1
+
+
+		[Elapsed] 460.969µs
+	*/
+}