Merge pull request #241 from sahilshekhawat/clean_exit_of_server

Added shutting down calls to the visualization server

pydy/viz/scene.py

@@ -17,7 +17,7 @@
 
 # local
 from .camera import PerspectiveCamera
-from .server import run_server
+from .server import Server
 from .light import PointLight
 from ..system import System
 from ..utils import PyDyImportWarning
@@ -463,7 +463,8 @@ def remove_static_html(self, force=False):
     def display(self):
         """Displays the scene in the default webbrowser."""
         self.create_static_html()
-        run_server(scene_file=self._scene_json_file)
+        server = Server(scene_file=self._scene_json_file)
+        server.run_server()
 
     def _rerun_button_callback(self, btn):
         """Callback for the "Rerun Simulation" button. When executed the

pydy/viz/server.py

@@ -2,36 +2,122 @@
 
 import os
 import sys
+import signal
+import socket
 import webbrowser
+
+# For python 2 and python 3 compatibility
 if sys.version_info < (3, 0):
     from SimpleHTTPServer import SimpleHTTPRequestHandler
     from BaseHTTPServer import HTTPServer
 else:
     from http.server import SimpleHTTPRequestHandler
     from http.server import HTTPServer
+    raw_input = input
+
+__all__ = ['Server']
+
+
+class StoppableHTTPServer(HTTPServer):
+    """
+    Overrides BaseHTTPServer.HTTPServer to include a stop
+    function.
+    """
+
+    def server_bind(self):
+        HTTPServer.server_bind(self)
+        self.socket.settimeout(1)
+        self.run = True
+
+    def get_request(self):
+        while self.run:
+            try:
+                sock, addr = self.socket.accept()
+                sock.settimeout(None)
+                return (sock, addr)
+            except socket.timeout:
+                pass
+
+    def stop(self):
+        self.run = False
+
+    def serve(self):
+        while self.run:
+            try:
+                self.handle_request()
+            except TypeError:
+                # When server is being closed, while loop can run once
+                # after setting self.run = False depending on how it
+                # is scheduled.
+                pass
+
+
+class Server(object):
+    """
+    Parameters
+    ----------
+    port : integer
+        Defines the port on which the server will run. If this port is
+        already bind, then it increment 1 until it finds a free port.
+    scene_file : name of the scene_file generated for visualization
+        A Valid PyDy generated scene file in 'directory' parameter.
+    directory : absolute path of a directory
+        Absolute path to the directory which contains scene_file with
+        all other static files.
 
+    Example
+    -------
+    >>> server = Server(scene_file=_scene_json_file)
+    >>> server.run_server()
 
-__all__ = ['run_server']
+    """
+    def __init__(self, scene_file, directory="static/", port=8000):
+        self.scene_file = scene_file
+        self.port = port
+        self.directory = directory
 
+    def run_server(self):
+        # Change dir to static first.
+        os.chdir(self.directory)
+        # Get a free port
+        while self._check_port(self.port):
+            self.port += 1
+        handler_class = SimpleHTTPRequestHandler
+        server_class = StoppableHTTPServer
+        protocol = "HTTP/1.0"
+        server_address = ('127.0.0.1', self.port)
+        handler_class.protocol_version = protocol
+        self.httpd = server_class(server_address, handler_class)
+        sa = self.httpd.socket.getsockname()
+        print("Serving HTTP on", sa[0], "port", sa[1], "...")
+        print("To view visualization, open:\n")
+        url = "http://localhost:"+str(sa[1]) + "/index.html?load=" + \
+              self.scene_file
+        print(url)
+        webbrowser.open(url)
+        print("Hit Ctrl+C to stop the server...")
+        signal.signal(signal.SIGINT, self._stop_server)
+        self.httpd.serve()
 
-def run_server(port=8000,scene_file="Null"):
-    #change dir to static first.
-    os.chdir("static/")
-    HandlerClass = SimpleHTTPRequestHandler
-    ServerClass  = HTTPServer
-    Protocol     = "HTTP/1.0"
-    server_address = ('127.0.0.1', port)
-    HandlerClass.protocol_version = Protocol
-    httpd = ServerClass(server_address, HandlerClass)
-    sa = httpd.socket.getsockname()
-    print("Serving HTTP on", sa[0], "port", sa[1], "...")
-    print("hit ctrl+c to stop the server..")
-    print("To view visualization, open:\n")
-    url = "http://localhost:"+ str(sa[1]) + "/index.html?load=" + scene_file
-    print(url)
-    webbrowser.open(url)
-    httpd.serve_forever()
+    def _check_port(self, port):
+        soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        result = soc.connect_ex(('127.0.0.1', port))
+        return result == 0
 
+    def _stop_server(self, signal, frame):
+        """
+        Confirms and stops the visulisation server
+        signal:
+            Required by signal.signal
+        frame:
+            Required by signal.signal
 
-if __name__ == "__main__":
-    run_server()
+        """
+        res = raw_input("Shutdown this visualization server ([y]/n)? ")
+        res = res.lower()[0]
+        if res == '' or res == 'y':
+            print("Shutdown confirmed")
+            print("Shutting down server...")
+            self.httpd.stop()
+        else:
+            print("Resuming operations...")