bug fix

batch3.go

@@ -133,20 +133,22 @@ func (c *Controller[Res]) commit(ctx context.Context, err error) (Res, error) {
 again:
 	if err != nil || atomic.LoadInt32(&c.queue) == 0 {
 		c.cnt = -c.cnt
-		c.ready = true
 
 		if ep, ok := err.(PanicError); ok {
 			c.err = err
+			c.ready = true
 			panic(ep.Panic)
 		} else if err != nil {
 			c.err = err
+			c.ready = true
 		} else {
 			func() {
 				var res Res
 				var err error
 
 				defer func() {
 					c.res, c.err = res, err
+					c.ready = true
 
 					if p := recover(); p != nil {
 						c.err = PanicError{Panic: p}
@@ -160,11 +162,15 @@ again:
 			}()
 		}
 	} else {
+	wait:
 		c.cond.Wait()
 
-		if !c.ready {
+		if c.cnt > 0 {
 			goto again
 		}
+		if !c.ready {
+			goto wait
+		}
 	}
 
 	res, err := c.res, c.err
@@ -260,8 +266,15 @@ func (b *Batch[Res]) Rollback(ctx context.Context, err error) (Res, error) {
 	return b.c.commit(ctx, err)
 }
 
+func AsPanicError(err error) (PanicError, bool) {
+	var pe PanicError
+
+	return pe, errors.As(err, &pe)
+}
+
 func (e PanicError) Error() string {
 	return fmt.Sprintf("panic: %v", e.Panic)
 }
 
-func (noCopy) Lock() {}
+func (*noCopy) Lock()   {}
+func (*noCopy) Unlock() {}

batch3_test.go

@@ -266,6 +266,48 @@ func TestBatch(tb *testing.T) {
 			})
 		}
 	})
+
+	tb.Run("okAfterAll", func(tb *testing.T) {
+		const N = 100
+
+		ctx := context.Background()
+
+		var sum int
+
+		b.Commit = func(ctx context.Context, _ int) (int, error) {
+			runtime.Gosched()
+			return sum, nil
+		}
+
+		var wg sync.WaitGroup
+
+		wg.Add(*jobs)
+
+		for j := 0; j < *jobs; j++ {
+			go func() {
+				defer wg.Done()
+
+				for i := 0; i < N; i++ {
+					func() {
+						b, idx := b.Enter(true)
+						defer b.Exit()
+
+						if idx == 0 {
+							sum = 0
+						}
+
+						runtime.Gosched()
+						sum++
+						runtime.Gosched()
+
+						_, _ = b.Commit(ctx)
+					}()
+				}
+			}()
+		}
+
+		wg.Wait()
+	})
 }
 
 func TestBatchNonBlocking(tb *testing.T) {

go.mod

@@ -1,3 +1,5 @@
 module nikand.dev/go/batch
 
 go 1.18
+
+retract v0.4.0 // has a bug

multi.go

@@ -40,7 +40,10 @@ func (c *Multi[Res]) Enter(blocking bool) (b Batch[Res], coach, index int) {
 		for coach := range c.cs {
 			b, idx := c.cs[coach].Enter(false)
 			if idx >= 0 {
-				return b, coach, idx
+				return Batch[Res]{
+					c:     b.c,
+					state: b.state,
+				}, coach, idx
 			}
 		}