CDRIVER-3270 update err msg for retry writes

If a retryable write fails with error code 20 and message
starting with "Transaction numbers", rewrite it to an actionable
error message.

Author: kevinAlbs

src/libmongoc/src/mongoc/mongoc-client.c

@@ -1602,6 +1602,10 @@ _mongoc_client_retryable_write_command_with_stream (
    ret = mongoc_cluster_run_command_monitored (
       &client->cluster, &parts->assembled, reply, error);
 
+   if (is_retryable) {
+      _mongoc_write_error_update_if_unsupported_storage_engine (ret, error, reply);
+   }
+
    /* If a retryable error is encountered and the write is retryable, select
     * a new writable stream and retry. If server selection fails or the selected
     * server does not support retryable writes, fall through and allow the

src/libmongoc/src/mongoc/mongoc-collection.c

@@ -3160,6 +3160,11 @@ mongoc_collection_find_and_modify_with_opts (
    ret = mongoc_cluster_run_command_monitored (
       cluster, &parts.assembled, reply_ptr, error);
 
+   if (is_retryable) {
+      _mongoc_write_error_update_if_unsupported_storage_engine (
+         ret, error, reply_ptr);
+   }
+
    /* If a retryable error is encountered and the write is retryable, select
     * a new writable stream and retry. If server selection fails or the selected
     * server does not support retryable writes, fall through and allow the

src/libmongoc/src/mongoc/mongoc-write-command-private.h

@@ -216,6 +216,11 @@ _mongoc_write_error_get_type (bool cmd_ret,
                               const bson_error_t *cmd_err,
                               const bson_t *reply);
 
+bool
+_mongoc_write_error_update_if_unsupported_storage_engine (bool cmd_ret,
+                                                          bson_error_t *cmd_err,
+                                                          bson_t *reply);
+
 BSON_END_DECLS
 
 

src/libmongoc/src/mongoc/mongoc-write-command.c

@@ -594,6 +594,10 @@ _mongoc_write_opmsg (mongoc_write_command_t *command,
           * the selected server does not support retryable writes, fall through
           * and allow the original error to be reported. */
          error_type = _mongoc_write_error_get_type (ret, error, &reply);
+         if (is_retryable) {
+            _mongoc_write_error_update_if_unsupported_storage_engine (
+               ret, error, &reply);
+         }
          if (is_retryable && error_type == MONGOC_WRITE_ERR_RETRY) {
             bson_error_t ignored_error;
 
@@ -1492,3 +1496,41 @@ _mongoc_write_error_get_type (bool cmd_ret,
       return MONGOC_WRITE_ERR_OTHER;
    }
 }
+
+/* Returns true and modifies reply and cmd_err. */
+bool
+_mongoc_write_error_update_if_unsupported_storage_engine (bool cmd_ret,
+                                                          bson_error_t *cmd_err,
+                                                          bson_t *reply)
+{
+   bson_error_t server_error;
+
+   if (cmd_ret) {
+      return false;
+   }
+
+   if (_mongoc_cmd_check_ok_no_wce (
+          reply, MONGOC_ERROR_API_VERSION_2, &server_error)) {
+      return false;
+   }
+
+   if (server_error.code == 20 &&
+       strstr (server_error.message, "Transaction numbers") ==
+          server_error.message) {
+      const char *replacement = "This MongoDB deployment does not support "
+                                "retryable writes. Please add "
+                                "retryWrites=false to your connection string.";
+
+      strcpy (cmd_err->message, replacement);
+
+      if (reply) {
+         bson_t *new_reply = bson_new ();
+         bson_copy_to_excluding_noinit (reply, new_reply, "errmsg", NULL);
+         BSON_APPEND_UTF8 (new_reply, "errmsg", replacement);
+         bson_destroy (reply);
+         bson_steal (reply, new_reply);
+      }
+      return true;
+   }
+   return false;
+}

src/libmongoc/tests/test-mongoc-retryable-writes.c

@@ -496,7 +496,59 @@ test_retry_no_crypto (void *ctx)
    mongoc_uri_destroy (uri);
 }
 
+static void
+test_unsupported_storage_engine_error (void)
+{
+   mock_rs_t *rs;
+   mongoc_client_t *client;
+   mongoc_collection_t *coll;
+   bson_t reply;
+   bson_error_t error;
+   future_t *future;
+   request_t *request;
+   mongoc_client_session_t *session;
+   bson_t opts;
+   const char *expected_msg = "This MongoDB deployment does not support "
+                              "retryable writes. Please add retryWrites=false "
+                              "to your connection string.";
+
+   rs = mock_rs_with_autoismaster (WIRE_VERSION_RETRY_WRITES, true, 0, 0);
+   mock_rs_run (rs);
+   client = mongoc_client_new_from_uri (mock_rs_get_uri (rs));
+   session = mongoc_client_start_session (client, NULL, &error);
+   ASSERT_OR_PRINT (session, error);
+   mongoc_client_set_error_api (client, MONGOC_ERROR_API_VERSION_2);
+   coll = mongoc_client_get_collection (client, "test", "test");
+   bson_init (&opts);
+   ASSERT_OR_PRINT (mongoc_client_session_append (session, &opts, &error),
+                    error);
+   /* findandmodify is retryable through mongoc_client_write_command_with_opts.
+    */
+   future = future_client_write_command_with_opts (
+      client,
+      "test",
+      tmp_bson ("{'findandmodify': 'coll' }"),
+      &opts,
+      &reply,
+      &error);
+   request = mock_rs_receives_request (rs);
+   mock_server_replies_simple (
+      request,
+      "{'ok': 0, 'code': 20, 'errmsg': 'Transaction numbers are great'}");
+   request_destroy (request);
+
+   BSON_ASSERT (!future_get_bool (future));
+   ASSERT_ERROR_CONTAINS (error, MONGOC_ERROR_SERVER, 20, expected_msg);
+   ASSERT_MATCH (&reply, "{'code': 20, 'errmsg': '%s'}", expected_msg);
 
+   bson_destroy (&opts);
+   mongoc_client_session_destroy (session);
+   bson_destroy (&reply);
+   future_destroy (future);
+   mongoc_collection_destroy (coll);
+   mongoc_client_destroy (client);
+   mock_rs_destroy (rs);
+}
 /*
  *-----------------------------------------------------------------------
  *
@@ -558,4 +610,9 @@ test_retryable_writes_install (TestSuite *suite)
                       NULL,
                       NULL,
                       test_framework_skip_if_crypto);
+   TestSuite_AddMockServerTest (
+      suite,
+      "/retryable_writes/unsupported_storage_engine_error",
+      test_unsupported_storage_engine_error,
+      test_framework_skip_if_no_crypto);
 }