added the listpids command

circus/commands/__init__.py

@@ -8,6 +8,7 @@
     incrproc,
     list,
     listen,
+    listpids,
     numprocesses,
     numwatchers,
     options,

circus/commands/listpids.py

@@ -0,0 +1,50 @@
+from circus.commands.base import Command
+from circus.exc import ArgumentError
+
+
+class ListPids(Command):
+    """\
+        Get list of pids in a watcher
+        =============================
+
+        ZMQ Message
+        -----------
+
+
+        To get the list of pid in a watcher::
+
+            {
+                "command": "listpids",
+                "properties": {
+                    "name": "nameofwatcher",
+                }
+            }
+
+
+        The response return the list asked.
+
+        Command line
+        ------------
+
+        ::
+
+            $ circusctl listpids <name>
+    """
+    name = "listpids"
+
+    def message(self, *args, **opts):
+        if len(args) != 1:
+            raise ArgumentError("invalid number of arguments")
+
+        return self.make_message(name=args[0])
+
+    def execute(self, arbiter, props):
+        watcher = self._get_watcher(arbiter, props['name'])
+        pids = [process.pid for process in watcher.processes.values()]
+        pids.sort()
+        return {"pids": pids}
+
+    def console_msg(self, msg):
+        if 'pids' in msg:
+            return ",".join([str(pid) for pid in msg.get('pids')])
+        return self.console_error(msg)