feat: add chat

chat/batch.go

@@ -0,0 +1,46 @@
+package chat
+
+import "strings"
+
+type batch struct {
+	lst   *Log
+	items []item
+}
+
+func (l *Log) newbatch(sz int) *batch {
+	if sz == 0 {
+		panic("sz cannot be 0")
+	}
+	return &batch{
+		lst:   l,
+		items: make([]item, 0, sz),
+	}
+}
+
+func (cl *batch) String() string {
+	sb := strings.Builder{}
+	for _, item := range cl.items {
+		sb.WriteString(cl.lst.sep)
+		item.writeToBuilder(&sb, cl.lst.atprefix, cl.lst.namel, cl.lst.namer)
+	}
+	return sb.String()[len(cl.lst.sep):]
+}
+
+// add without mutex
+func (cl *batch) add(item item) *batch {
+	v := cl.items
+	defer func() {
+		cl.items = v
+	}()
+	if cap(v) == 1 {
+		v[0] = item
+		return cl
+	}
+	if len(v) < cap(v) {
+		v = append(v, item)
+		return cl
+	}
+	copy(v, v[1:])
+	v[len(v)-1] = item
+	return cl
+}