_message.py: Added Message and MessageType definitions

For transporting messages about plugin instances in the data model,
back from their subprocesses, and controlling message flow.

1 files changed, 52 insertions, 0 deletions

diff --git a/buildstream/_message.py b/buildstream/_message.py
new file mode 100644
index 000000000..4f5de5c1d
--- /dev/null
+++ b/buildstream/_message.py
@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+#
+#  Copyright (C) 2017 Codethink Limited
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU Lesser General Public
+#  License as published by the Free Software Foundation; either
+#  version 2 of the License, or (at your option) any later version.
+#
+#  This library is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+#  Lesser General Public License for more details.
+#
+#  You should have received a copy of the GNU Lesser General Public
+#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
+#
+#  Authors:
+#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
+
+import os
+
+
+# Types of status messages.
+#
+class MessageType():
+    DEBUG = "debug"        # Debugging message
+    STATUS = "status"      # Status message
+    WARN = "warning"       # Warning messages
+    ERROR = "error"        # Error messages
+
+    # The following types are timed, SUCCESS/FAIL have timestamps
+    START = "start"        # Status start message
+    SUCCESS = "success"    # Successful status complete message
+    FAIL = "failure"       # Failing status complete message
+
+
+# Message object
+#
+class Message():
+    def __init__(self, unique_id, message_type, message,
+                 detail=None,
+                 elapsed=None):
+        self.pid = os.getpid()
+        self.unique_id = unique_id
+        self.message_type = message_type
+        self.message = message
+        self.detail = detail
+        self.elapsed = elapsed
+
+        if message_type in (MessageType.SUCCESS, MessageType.FAIL):
+            assert(elapsed is not None)