jobqueue: handle escaped null bytes in postgres

Postgres doesn't accept `\u0000` in the jsonb datatype. Switch to the
json datatype which is larger and slower, but accepts escaped null
bytes.

As we don't actually query or index the result jsonb directly, the
impact of this should be minimal.

See: https://www.postgresql.org/docs/current/datatype-json.html

internal/jobqueue/jobqueuetest/jobqueuetest.go

@@ -25,6 +25,7 @@ import (
 type MakeJobQueue func() (q jobqueue.JobQueue, stop func(), err error)
 
 type testResult struct {
+	Logs json.RawMessage `json:"logs,omitempty"`
 }
 
 func TestDbURL() string {
@@ -50,6 +51,7 @@ func TestJobQueue(t *testing.T, makeJobQueue MakeJobQueue) {
 	t.Run("cancel", wrap(testCancel))
 	t.Run("requeue", wrap(testRequeue))
 	t.Run("requeue-limit", wrap(testRequeueLimit))
+	t.Run("escaped-null-bytes", wrap(testEscapedNullBytes))
 	t.Run("job-types", wrap(testJobTypes))
 	t.Run("dependencies", wrap(testDependencies))
 	t.Run("multiple-workers", wrap(testMultipleWorkers))
@@ -110,7 +112,8 @@ func testErrors(t *testing.T, q jobqueue.JobQueue) {
 	require.NoError(t, err)
 	require.Equal(t, id, idFromT)
 
-	requeued, err := q.RequeueOrFinishJob(id, 0, nil)
+	require.NoError(t, err)
+	requeued, err := q.RequeueOrFinishJob(id, 0, &testResult{})
 	require.NoError(t, err)
 	require.False(t, requeued)
 
@@ -504,6 +507,18 @@ func testRequeueLimit(t *testing.T, q jobqueue.JobQueue) {
 	require.NotNil(t, result)
 }
 
+func testEscapedNullBytes(t *testing.T, q jobqueue.JobQueue) {
+	pushTestJob(t, q, "octopus", nil, nil, "")
+	id, tok, _, _, _, err := q.Dequeue(context.Background(), uuid.Nil, []string{"octopus"}, []string{""})
+	require.NoError(t, err)
+	require.NotEmpty(t, tok)
+
+	// Ensure postgres accepts escaped null bytes
+	requeued, err := q.RequeueOrFinishJob(id, 0, &testResult{Logs: []byte("{\"blegh\\u0000\": \"\\u0000\"}")})
+	require.NoError(t, err)
+	require.False(t, requeued)
+}
+
 func testHeartbeats(t *testing.T, q jobqueue.JobQueue) {
 	id := pushTestJob(t, q, "octopus", nil, nil, "")
 	// No heartbeats for queued job