Fix issue with socket length > 108 due to long task names

Ensures that we truncate task names to no more than 60 chars so they
don't exceed the total length limit of 108 that's impose by unix.

Fixes: dagu-org#395

internal/dag/dag.go

@@ -230,6 +230,13 @@ func (d *DAG) SockAddr() string {
 	h := md5.New()
 	_, _ = h.Write([]byte(s))
 	bs := h.Sum(nil)
+	// Socket name length must be shorter than 108 characters,
+	// so we truncate the name to 60 characters.
+	// 108 - 16 (length of the hash) - 32 (length of the prefix) - 2 connectors - 18 safety margin = 40 or 39 with 0 indexing
+	lengthLimit := 39
+	if len(name) > lengthLimit {
+		name = name[:lengthLimit]
+	}
 	return path.Join("/tmp", fmt.Sprintf("@dagu-%s-%x.sock", name, bs))
 }
 

internal/dag/dag_test.go

@@ -42,4 +42,10 @@ func TestDAG_SockAddr(t *testing.T) {
 		d := &DAG{Location: "testdata/testDag.yml"}
 		require.Regexp(t, `^/tmp/@dagu-testDag-[0-9a-f]+\.sock$`, d.SockAddr())
 	})
+	t.Run("Unix Socket", func(t *testing.T) {
+		d := &DAG{Location: "testdata/testDagVeryLongNameThatExceedsUnixSocketLengthMaximum-testDagVeryLongNameThatExceedsUnixSocketLengthMaximum.yml"}
+		// 108 is the maximum length of a unix socket address
+		require.Greater(t, 108, len(d.SockAddr()))
+		require.Equal(t, "/tmp/@dagu-testDagVeryLongNameThatExceedsUnixSocket-b92b711162d6012f025a76d0cf0b40c2.sock", d.SockAddr())
+	})
 }