use pl_capture_reset to save on allocs

trealla/interop.go

@@ -94,9 +94,9 @@ func (pl *prolog) hostCall( /*c *wasmtime.Caller,*/ subquery, msgptr, msgsize, r
 	if err := subq.readOutput(); err != nil {
 		return 0, wasmtime.NewTrap(err.Error())
 	}
-	if _, err := pl.pl_capture.Call(pl.store, pl.ptr); err != nil {
-		return 0, wasmtime.NewTrap(err.Error())
-	}
+	// if _, err := pl.pl_capture.Call(pl.store, pl.ptr); err != nil {
+	// 	return 0, wasmtime.NewTrap(err.Error())
+	// }
 
 	return wasmTrue, nil
 }

trealla/prolog.go

@@ -50,16 +50,17 @@ type prolog struct {
 	spawning map[int32]*query
 	limiter  chan struct{}
 
-	ptr             int32
-	realloc         wasmFunc
-	free            wasmFunc
-	pl_consult      wasmFunc
-	pl_capture      wasmFunc
-	pl_capture_read wasmFunc
-	pl_capture_free wasmFunc
-	pl_query        wasmFunc
-	pl_redo         wasmFunc
-	pl_done         wasmFunc
+	ptr              int32
+	realloc          wasmFunc
+	free             wasmFunc
+	pl_consult       wasmFunc
+	pl_capture       wasmFunc
+	pl_capture_read  wasmFunc
+	pl_capture_reset wasmFunc
+	pl_capture_free  wasmFunc
+	pl_query         wasmFunc
+	pl_redo          wasmFunc
+	pl_done          wasmFunc
 
 	procs map[string]Predicate
 
@@ -182,6 +183,11 @@ func (pl *prolog) init(parent *prolog) error {
 		return err
 	}
 
+	pl.pl_capture_reset, err = pl.function("pl_capture_reset")
+	if err != nil {
+		return err
+	}
+
 	pl.pl_capture_free, err = pl.function("pl_capture_free")
 	if err != nil {
 		return err
@@ -261,6 +267,11 @@ func (pl *prolog) init(parent *prolog) error {
 	}
 	pl.ptr = ptr.(int32)
 
+	_, err = pl.pl_capture.Call(pl.store, pl.ptr)
+	if err != nil {
+		return err
+	}
+
 	if err := pl.loadBuiltins(); err != nil {
 		return fmt.Errorf("trealla: failed to load builtins: %w", err)
 	}

trealla/query.go

@@ -116,6 +116,7 @@ func (q *query) readOutput() error {
 	if err != nil {
 		return err
 	}
+	defer pl.pl_capture_reset.Call(pl.store, pl.ptr)
 
 	stdoutlen := pl.indirect(q.stdoutlen)
 	stdoutptr := pl.indirect(q.stdoutptr)
@@ -134,7 +135,7 @@ func (q *query) readOutput() error {
 	}
 	q.stderr.WriteString(stderr)
 
-	pl.pl_capture_free.Call(pl.store, pl.ptr)
+	// pl.pl_capture_free.Call(pl.store, pl.ptr)
 
 	return nil
 }
@@ -208,11 +209,6 @@ func (pl *prolog) start(ctx context.Context, goal string, options ...QueryOption
 				ch <- fmt.Errorf("trealla: panic: %v", ex)
 			}
 		}()
-		_, err := pl.pl_capture.Call(pl.store, pl.ptr)
-		if err != nil {
-			ch <- err
-			return
-		}
 
 		v, err := pl.pl_query.Call(pl.store, pl.ptr, goalstr.ptr, subqptr, 0)
 		if err == nil {
@@ -294,12 +290,6 @@ func (q *query) redo(ctx context.Context) bool {
 			}
 		}()
 
-		_, err := pl.pl_capture.Call(pl.store, pl.ptr)
-		if err != nil {
-			ch <- err
-			return
-		}
-
 		v, err := pl.pl_redo.Call(pl.store, q.subquery)
 		if err == nil {
 			ret = v.(int32)