Use gevent.WSGIServer for http introspect

Presently, pysandesh uses WSGIServer defined in wsgiref.simple_server
for http introspect, whose poll_interval is 0.5 seconds by default.
The poll_interval is used to check for server shutdown. Therefore, if
the poll_interval is set to None, it requires external trigger such as
connection to the socket to wakeup the select loop. Polling reduces the
responsiveness and wastes cpu cycle. Use gevent.WSGIServer for
http introspect to avoid the polling issue.

Change-Id: Ic8cf8ec815c422be0d65e77247c67e7002bc91ad
Closes-Bug: #1584160
(cherry picked from commit 8a0b129)

library/python/pysandesh/sandesh_http.py

@@ -18,7 +18,8 @@
 if 'threading' in sys.modules:
     del sys.modules['threading']
 from gevent import monkey; monkey.patch_all()
-from wsgiref.simple_server import make_server, WSGIServer
+from gevent.server import StreamServer
+from gevent.pywsgi import WSGIServer
 import bottle
 import cStringIO
 from transport import TTransport
@@ -27,16 +28,6 @@
 import socket
 
 
-class SandeshWSGIServer(WSGIServer):
-    # patch handle_error() which spews exception log to stdout that
-    # interferes/impacts the functioning of the supervisor.
-    def handle_error(self, request, client_address):
-        sys.stderr.write('Error while handling request from client %s'\
-                         % (str(client_address)))
-        import traceback
-        traceback.print_exc()
-# end class SandeshWSGIServer
-
 class SandeshHttp(object):
 
     _HTTP_SERVER_IP = '0.0.0.0'
@@ -78,7 +69,7 @@ def __init__(self, sandesh, module, port, pkg_list):
         self._jquery_collapse_storage_js_path = None
         self._jquery_collapse_js_path = None
         self._jquery_1_8_1_js_path = None
-        self._svr = None
+        self._http_server = None
         try:
             imp_pysandesh = __import__('pysandesh')
         except ImportError:
@@ -97,26 +88,28 @@ def __init__(self, sandesh, module, port, pkg_list):
     #end __init__
 
     def stop_http_server(self):
-        if self._svr:
-            self._svr.shutdown()
-            self._svr = None
+        if self._http_server:
+            self._http_server.stop()
+            self._http_server = None
             self._logger.error('Stopped http server')
+    # end stop_http_server
 
     def start_http_server(self):
         try:
-            self._svr = make_server(SandeshHttp._HTTP_SERVER_IP,
-                                    self._http_port,
-                                    self._http_app, SandeshWSGIServer)
+            sock = StreamServer.get_listener((SandeshHttp._HTTP_SERVER_IP,
+                self._http_port), family=socket.AF_INET)
         except socket.error as e:
-            self._logger.error('Unable to open HTTP Port %d, %s' % (self._http_port, e))
+            self._logger.error('Unable to open HTTP Port %d, %s' %
+                (self._http_port, e))
             sys.exit()
-        self._http_port = self._svr.server_port
-        self._logger.error('Starting Introspect on HTTP Port %d' % self._http_port)
-        self._sandesh.record_port("http", self._http_port)
-        self._svr.allow_reuse_address = True
-        self._svr.serve_forever()
-
-    #end start_http_server
+        else:
+            self._http_port = sock.getsockname()[1]
+            self._sandesh.record_port("http", self._http_port)
+            self._logger.error('Starting Introspect on HTTP Port %d' %
+                self._http_port)
+            self._http_server = WSGIServer(sock, self._http_app)
+            self._http_server.serve_forever()
+    # end start_http_server
 
     def get_port(self):
         return self._http_port

library/python/pysandesh/test/SConscript

@@ -50,7 +50,7 @@ env.Depends(test_modules_rules, gen_test_pkg)
 
 venv = env.setup_venv('pysandesh_test', 'pysandesh_test')
 env['env_venv'] = venv
-pip_pkgs = ['greenlet==0.4.1', 'gevent==0.13.8', 'eventlet==0.9.17',
+pip_pkgs = ['greenlet==0.4.1', 'gevent==1.1a2', 'eventlet==0.9.17',
         'testtools==0.9.21', 'geventhttpclient==1.0a', 'bottle==0.11.6',
         'mock==1.0.1']