Improve the file server shutdown logic and display the shutdown progress bar in the UI

src/util/GreenletManager.py

@@ -3,17 +3,37 @@ from Debug import Debug
 
 
 class GreenletManager:
-    def __init__(self):
+    # pool is either gevent.pool.Pool or GreenletManager.
+    # if pool is None, new gevent.pool.Pool() is created.
+    def __init__(self, pool=None):
         self.greenlets = set()
+        if not pool:
+            pool = gevent.pool.Pool(None)
+        self.pool = pool
+
+    def _spawn_later(self, seconds, *args, **kwargs):
+        # If pool is another GreenletManager, delegate to it.
+        if hasattr(self.pool, 'spawnLater'):
+            return self.pool.spawnLater(seconds, *args, **kwargs)
+
+        # There's gevent.spawn_later(), but there isn't gevent.pool.Pool.spawn_later().
+        # Doing manually.
+        greenlet = self.pool.greenlet_class(*args, **kwargs)
+        self.pool.add(greenlet)
+        greenlet.start_later(seconds)
+        return greenlet
+
+    def _spawn(self, *args, **kwargs):
+        return self.pool.spawn(*args, **kwargs)
 
     def spawnLater(self, *args, **kwargs):
-        greenlet = gevent.spawn_later(*args, **kwargs)
+        greenlet = self._spawn_later(*args, **kwargs)
         greenlet.link(lambda greenlet: self.greenlets.remove(greenlet))
         self.greenlets.add(greenlet)
         return greenlet
 
     def spawn(self, *args, **kwargs):
-        greenlet = gevent.spawn(*args, **kwargs)
+        greenlet = self._spawn(*args, **kwargs)
         greenlet.link(lambda greenlet: self.greenlets.remove(greenlet))
         self.greenlets.add(greenlet)
         return greenlet