PoC for bugsink-server-unified

bugsink/scripts/bugsink-server-unified.py

@@ -0,0 +1,70 @@
+#!/usr/bin/env python
+import subprocess
+import signal
+import sys
+
+
+class ParentProcess:
+
+    def __init__(self):
+        """
+        This script starts both the server and snappea as children of a single process.
+
+        * Output of the children is passed as our own.
+        * Any (relevant) signals we receive are passed to all the children.
+        * When either of the children exits, a signal is sent to the other child to terminate it.
+        * The script waits for both children to exit before exiting itself.
+
+        The script is written to be able to run the two parts of Bugsink in a single Docker container. It may, however,
+        be useful in other contexts as well, i.e. for [developer] ergonomics when running in a terminal.
+        """
+        self.children = []
+
+        # I think Docker will send a SIGTERM to the main process when it wants to stop the container; SIGINT is for
+        # interactive use and is also supported. SIGKILL is not handle-able, so we can't do anything about that.
+        signal.signal(signal.SIGINT, self.signal_handler)
+        signal.signal(signal.SIGTERM, self.signal_handler)
+
+        # Start the server
+        # Leaving stdout and stderr as None will make the output of the child processes be passed as our own.
+        for args in self.parse_args():
+            self.children.append(subprocess.Popen(args))
+
+        # Check if any of the children have exited
+        children_are_alive = True
+        while children_are_alive:
+            for child in self.children:
+                if child.poll() is not None:
+                    # One of the children has exited
+                    children_are_alive = False
+
+                    for other_child in self.children:
+                        if other_child != child:
+                            other_child.send_signal(signal.SIGTERM)
+
+        for child in self.children:
+            child.wait()
+
+    def parse_args(self):
+        """Splits our own arguments into a list of args for each of the children each, we split on "UNIFIED_WITH"."""
+
+        # We don't want to pass the first argument, as that is the script name
+        args = sys.argv[1:]
+
+        result = [[]]
+        for arg in args:
+            if arg == "UNIFIED_WITH":
+                result.append([])
+            else:
+                result[-1].append(arg)
+
+        return result
+
+    def signal_handler(self, signum, frame):
+        # we resist the urge to print here, as this is discouraged in signal handlers
+        for child in self.children:
+            child.send_signal(signum)
+
+
+if __name__ == "__main__":
+    ParentProcess()