init

errors.go

@@ -0,0 +1,7 @@
+package slowdo
+
+import "errors"
+
+var (
+	ErrWaitTimeTooShort = errors.New("wait time too short")
+)

go.mod

@@ -0,0 +1,3 @@
+module github.com/fumiama/slowdo
+
+go 1.22.1

job.go

@@ -0,0 +1,58 @@
+package slowdo
+
+import (
+	"sync"
+	"time"
+)
+
+type Job[item any] struct {
+	maxmait time.Duration
+	commit  func([]item)
+	itemmu  sync.Mutex
+	items   []item
+	timer   *time.Timer
+}
+
+func NewJob[item any](
+	maxwait time.Duration, commit func([]item),
+) (*Job[item], error) {
+	if maxwait <= time.Millisecond {
+		return nil, ErrWaitTimeTooShort
+	}
+	return &Job[item]{
+		maxmait: maxwait,
+		commit:  commit,
+	}, nil
+}
+
+func (jb *Job[item]) Add(it item) {
+	jb.itemmu.Lock()
+	defer jb.itemmu.Unlock()
+	if len(jb.items) == 0 {
+		defer jb.collect()
+	}
+	jb.items = append(jb.items, it)
+}
+
+func (jb *Job[item]) Commit() {
+	jb.itemmu.Lock()
+	if jb.timer != nil {
+		jb.timer.Stop()
+		jb.timer = nil
+	}
+	if len(jb.items) == 0 {
+		jb.itemmu.Unlock()
+		return
+	}
+	itemscp := make([]item, len(jb.items))
+	copy(itemscp, jb.items)
+	jb.items = jb.items[:0]
+	jb.itemmu.Unlock()
+	jb.commit(itemscp)
+}
+
+func (jb *Job[item]) collect() {
+	jb.itemmu.Lock()
+	defer jb.itemmu.Unlock()
+	jb.timer = time.AfterFunc(jb.maxmait, jb.Commit)
+}