add pymonitor for auto-restart

Author: michaelliao

www/pymonitor.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+import os, sys, time, subprocess
+
+from watchdog.observers import Observer
+from watchdog.events import FileSystemEventHandler
+
+def log(s):
+    print '[Monitor] %s' % s
+
+class MyFileSystemEventHander(FileSystemEventHandler):
+
+    def __init__(self, fn):
+        super(MyFileSystemEventHander, self).__init__()
+        self.restart = fn
+
+    def on_any_event(self, event):
+        if event.src_path.endswith('.py'):
+            log('Python source file changed: %s' % event.src_path)
+            self.restart()
+
+command = ['echo', 'ok']
+process = None
+
+def kill_process():
+    global process
+    if process:
+        log('Kill process [%s]...' % process.pid)
+        process.kill()
+        process.wait()
+        log('Process ended with code %s.' % process.returncode)
+        process = None
+
+def start_process():
+    global process, command
+    log('Start process %s...' % ' '.join(command))
+    process = subprocess.Popen(command, stdin=sys.stdin, stdout=sys.stdout, stderr=sys.stderr)
+
+def restart_process():
+    kill_process()
+    start_process()
+
+def start_watch(path, callback):
+    observer = Observer()
+    observer.schedule(MyFileSystemEventHander(restart_process), path, recursive=True)
+    observer.start()
+    log('Watching directory %s...' % path)
+    start_process()
+    try:
+        while True:
+            time.sleep(0.5)
+    except KeyboardInterrupt:
+        observer.stop()
+    observer.join()
+
+if __name__ == '__main__':
+    argv = sys.argv[1:]
+    if not argv:
+        print('Usage: ./pymonitor your-script.py')
+        exit(0)
+    if argv[0]!='python':
+        argv.insert(0, 'python')
+    command = argv
+    path = os.path.abspath('.')
+    start_watch(path, None)