Merge pull request moby#3732 from sipsma/fix-recompute-digests

llbsolver: Fix performance of recomputeDigests

Author: sipsma

client/client_test.go

@@ -194,6 +194,7 @@ func TestIntegration(t *testing.T) {
 		testMountStubsDirectory,
 		testMountStubsTimestamp,
 		testSourcePolicy,
+		testLLBMountPerformance,
 	)
 }
 
@@ -8991,3 +8992,31 @@ func testSourcePolicy(t *testing.T, sb integration.Sandbox) {
 		require.ErrorContains(t, err, sourcepolicy.ErrSourceDenied.Error())
 	})
 }
+
+func testLLBMountPerformance(t *testing.T, sb integration.Sandbox) {
+	c, err := New(sb.Context(), sb.Address())
+	require.NoError(t, err)
+	defer c.Close()
+
+	mntInput := llb.Image("busybox:latest")
+	st := llb.Image("busybox:latest")
+	var mnts []llb.State
+	for i := 0; i < 20; i++ {
+		execSt := st.Run(
+			llb.Args([]string{"true"}),
+		)
+		mnts = append(mnts, mntInput)
+		for j := range mnts {
+			mnts[j] = execSt.AddMount(fmt.Sprintf("/tmp/bin%d", j), mnts[j], llb.SourcePath("/bin"))
+		}
+		st = execSt.Root()
+	}
+
+	def, err := st.Marshal(sb.Context())
+	require.NoError(t, err)
+
+	timeoutCtx, cancel := context.WithTimeout(sb.Context(), time.Minute)
+	defer cancel()
+	_, err = c.Solve(timeoutCtx, def, SolveOpt{}, nil)
+	require.NoError(t, err)
+}

solver/llbsolver/vertex.go

@@ -210,6 +210,7 @@ func recomputeDigests(ctx context.Context, all map[digest.Digest]*pb.Op, visited
 	}
 
 	if !mutated {
+		visited[dgst] = dgst
 		return dgst, nil
 	}
 
@@ -274,7 +275,7 @@ func loadLLB(ctx context.Context, def *pb.Definition, polEngine SourcePolicyEval
 
 	for {
 		newDgst, ok := mutatedDigests[lastDgst]
-		if !ok {
+		if !ok || newDgst == lastDgst {
 			break
 		}
 		lastDgst = newDgst