From 993c7c3c4e3795a120165a31c3c1c125c9bd60d1 Mon Sep 17 00:00:00 2001
From: Brendan Howell <brendan@howell-ersatz.com>
Date: Sun, 31 Jul 2016 19:03:39 +0200
Subject: [PATCH] refactor management. now reloads all bureaus on HUP, restarts
 crashed ones.

---
 screenless/mgmt.py | 102 ++++++++++++++++++++++++++++++---------------
 1 file changed, 68 insertions(+), 34 deletions(-)

diff --git a/screenless/mgmt.py b/screenless/mgmt.py
index 2feddf9..033bbd7 100644
--- a/screenless/mgmt.py
+++ b/screenless/mgmt.py
@@ -9,51 +9,85 @@ import configparser
 import importlib
 import multiprocessing
 import os
+import signal
 import time
 
-def mgmt():
+
+class Management:
     """
-    Primary management function.  Main loop that starts and runs all bureaus.
-    Some day this will do nice supervisory things like restart crashed buros.
+    Management is the executive of the Screenless Office.  It can start, stop
+    and reconfigure the subordinate bureaus of the office.
     """
-    basepath = os.path.expanduser("~/.screenless")
-    if not os.path.exists(basepath):
-        os.mkdir(basepath)
-    os.chdir(basepath)
-
-    config = configparser.ConfigParser()
-    procs = {}
+    def __init__(self):
+        basepath = os.path.expanduser("~/.screenless")
+        if not os.path.exists(basepath):
+            os.mkdir(basepath)
+        os.chdir(basepath)
 
+        self.procs = {}
+        self.org_chart = []
+        self._load_config()
 
-    try:
-        config.read("mgmt.ini")
-        org_chart = config["mgmt"]["bureaus"].split()
-    except KeyError:
-        config["mgmt"] = {"bureaus":
-                          "ihr typing publicrelations photography jokes"}
-        with open("mgmt.ini", "w") as configfile:
-            config.write(configfile)
-        print("created new mgmt.ini config file.  please modify this to suit.")
-        org_chart = config["mgmt"]["bureaus"].split()
+    def _load_config(self): 
+        config = configparser.ConfigParser()
+        try:
+            config.read("mgmt.ini")
+            self.org_chart = config["mgmt"]["bureaus"].split()
+        except KeyError:
+            config["mgmt"] = {"bureaus":
+                              "ihr typing publicrelations photography jokes"}
+            with open("mgmt.ini", "w") as configfile:
+                config.write(configfile)
+            print("Created new mgmt.ini config file.  Please modify to suit.")
+            self.org_chart = config["mgmt"]["bureaus"].split()
 
-    print("org chart:", org_chart)
+    def _start_bureaus(self):
+        """
+        Initialized and start all child bureaus
+        """
+        for buro in self.org_chart:
+            # TODO: this may need some sanity checking for crash/reload
+            lib = importlib.import_module("bureau." + buro)
+            proc = multiprocessing.Process(target=lib.main)
+            self.procs[buro] = proc
+            proc.start()
 
-    for buro in org_chart:
-        lib = importlib.import_module("bureau." + buro)
-        proc = multiprocessing.Process(target=lib.main)
-        procs[buro] = proc
-        proc.start()
+    def _stop_bureaus(self):
+        """
+        Terminates all running bureau children
+        """
+        for buro in self.org_chart:
+            proc = self.procs[buro]
+            proc.terminate()
 
-    while True:
-        for buro in org_chart:
-            proc = procs[buro]
-            if not proc.is_alive():
-                print("bureau", buro, "has crashed!  Call the consultants!")
-                #TODO this should probably restart in some sensible way
-        time.sleep(1)
+    def reload(self, signum=None, frame=None):
+        """
+        stop all bureaus, reload config, restart all bureaus.
+        Note, this may cause a loss of state in some cases.
+        """
+        self._stop_bureaus()
+        self._load_config()
+        self._start_bureaus()
 
+    def run(self):
+        """
+        main loop for Management, will restart crashed bureaus
+        and reload everything when sent a SIGHUP
+        """
+        signal.signal(signal.SIGHUP, self.reload)
 
+        self._start_bureaus()
+        while True:
+            for buro in self.org_chart:
+                proc = self.procs[buro]
+                if not proc.is_alive():
+                    print("bureau", buro, "has crashed!  Call the consultants!")
+                    print("restarting...")
+                    #TODO this should probably only retry a few times
+                    proc.start()
+            time.sleep(1)
 
 
 if __name__ == "__main__":
-    mgmt()
+    mgmt = Management()
+    mgmt.run()