tinyproxy: explicitly flush logged messages

On Windows, output streams are buffered when redirected to a file, and
TerminateProcess() apparently doesn't trigger a flush.  This left
test-http-proxy.t missing part of the last line when it cat'd proxy.log[1].

Flushing stderr is all that is needed (on py27 anyway).  I originally flushed
stdout too, but that added additional output to the log:

     $ cat proxy.log
  +  Accept: $LOCALIP (localhost)\r (esc)
  +  Serving HTTP on 0.0.0.0 port 20810 ...\r (esc)
  +       connect to localhost:$HGPORT\r (esc)
     * - - [*] "GET http://localhost:$HGPORT/?cmd=capabilities HTTP/1.1" - - (glob)
  +       bye\r (esc)
  +       connect to localhost:$HGPORT\r (esc)
     * - - [*] "GET http://localhost:$HGPORT/?cmd=branchmap HTTP/1.1" - - x-hgproto-1:0.1 0.2 comp=*zlib,none,bzip2 (glob)
  +       bye\r (esc)
  +       connect to localhost:$HGPORT\r (esc)
     * - - [*] "GET http://localhost:$HGPORT/?cmd=stream_out HTTP/1.1" - - x-hgproto-1:0.1 0.2 comp=*zlib,none,bzip2 (glob)
  +       bye\r (esc)
  +       connect to localhost:$HGPORT\r (esc)
 ...

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096987.html

tests/tinyproxy.py

@@ -1,189 +1,191 b''
 #!/usr/bin/env python
 
 from __future__ import absolute_import, print_function
 
 __doc__ = """Tiny HTTP Proxy.
 
 This module implements GET, HEAD, POST, PUT and DELETE methods
 on BaseHTTPServer, and behaves as an HTTP proxy.  The CONNECT
 method is also implemented experimentally, but has not been
 tested yet.
 
 Any help will be greatly appreciated.           SUZUKI Hisao
 """
 
 __version__ = "0.2.1"
 
 import optparse
 import os
 import select
 import socket
 import sys
 
 from mercurial import util
 
 httpserver = util.httpserver
 socketserver = util.socketserver
 urlreq = util.urlreq
 
 if os.environ.get('HGIPV6', '0') == '1':
     family = socket.AF_INET6
 else:
     family = socket.AF_INET
 
 class ProxyHandler (httpserver.basehttprequesthandler):
     __base = httpserver.basehttprequesthandler
     __base_handle = __base.handle
 
     server_version = "TinyHTTPProxy/" + __version__
     rbufsize = 0                        # self.rfile Be unbuffered
 
     def handle(self):
         (ip, port) = self.client_address
         allowed = getattr(self, 'allowed_clients', None)
         if allowed is not None and ip not in allowed:
             self.raw_requestline = self.rfile.readline()
             if self.parse_request():
                 self.send_error(403)
         else:
             self.__base_handle()
 
     def log_request(self, code='-', size='-'):
         xheaders = [h for h in self.headers.items() if h[0].startswith('x-')]
         self.log_message('"%s" %s %s%s',
                          self.requestline, str(code), str(size),
                          ''.join([' %s:%s' % h for h in sorted(xheaders)]))
+        # Flush for Windows, so output isn't lost on TerminateProcess()
+        sys.stderr.flush()
 
     def _connect_to(self, netloc, soc):
         i = netloc.find(':')
         if i >= 0:
             host_port = netloc[:i], int(netloc[i + 1:])
         else:
             host_port = netloc, 80
         print("\t" "connect to %s:%d" % host_port)
         try: soc.connect(host_port)
         except socket.error as arg:
             try: msg = arg[1]
             except (IndexError, TypeError): msg = arg
             self.send_error(404, msg)
             return 0
         return 1
 
     def do_CONNECT(self):
         soc = socket.socket(family, socket.SOCK_STREAM)
         try:
             if self._connect_to(self.path, soc):
                 self.log_request(200)
                 self.wfile.write(self.protocol_version +
                                  " 200 Connection established\r\n")
                 self.wfile.write("Proxy-agent: %s\r\n" % self.version_string())
                 self.wfile.write("\r\n")
                 self._read_write(soc, 300)
         finally:
             print("\t" "bye")
             soc.close()
             self.connection.close()
 
     def do_GET(self):
         (scm, netloc, path, params, query, fragment) = urlreq.urlparse(
             self.path, 'http')
         if scm != 'http' or fragment or not netloc:
             self.send_error(400, "bad url %s" % self.path)
             return
         soc = socket.socket(family, socket.SOCK_STREAM)
         try:
             if self._connect_to(netloc, soc):
                 self.log_request()
                 soc.send("%s %s %s\r\n" % (
                     self.command,
                     urlreq.urlunparse(('', '', path, params, query, '')),
                     self.request_version))
                 self.headers['Connection'] = 'close'
                 del self.headers['Proxy-Connection']
                 for key_val in self.headers.items():
                     soc.send("%s: %s\r\n" % key_val)
                 soc.send("\r\n")
                 self._read_write(soc)
         finally:
             print("\t" "bye")
             soc.close()
             self.connection.close()
 
     def _read_write(self, soc, max_idling=20):
         iw = [self.connection, soc]
         ow = []
         count = 0
         while True:
             count += 1
             (ins, _, exs) = select.select(iw, ow, iw, 3)
             if exs:
                 break
             if ins:
                 for i in ins:
                     if i is soc:
                         out = self.connection
                     else:
                         out = soc
                     try:
                         data = i.recv(8192)
                     except socket.error:
                         break
                     if data:
                         out.send(data)
                         count = 0
             else:
                 print("\t" "idle", count)
             if count == max_idling:
                 break
 
     do_HEAD = do_GET
     do_POST = do_GET
     do_PUT  = do_GET
     do_DELETE = do_GET
 
 class ThreadingHTTPServer (socketserver.ThreadingMixIn,
                            httpserver.httpserver):
     def __init__(self, *args, **kwargs):
         httpserver.httpserver.__init__(self, *args, **kwargs)
         a = open("proxy.pid", "w")
         a.write(str(os.getpid()) + "\n")
         a.close()
 
 def runserver(port=8000, bind=""):
     server_address = (bind, port)
     ProxyHandler.protocol_version = "HTTP/1.0"
     httpd = ThreadingHTTPServer(server_address, ProxyHandler)
     sa = httpd.socket.getsockname()
     print("Serving HTTP on", sa[0], "port", sa[1], "...")
     try:
         httpd.serve_forever()
     except KeyboardInterrupt:
         print("\nKeyboard interrupt received, exiting.")
         httpd.server_close()
         sys.exit(0)
 
 if __name__ == '__main__':
     argv = sys.argv
     if argv[1:] and argv[1] in ('-h', '--help'):
         print(argv[0], "[port [allowed_client_name ...]]")
     else:
         if argv[2:]:
             allowed = []
             for name in argv[2:]:
                 client = socket.gethostbyname(name)
                 allowed.append(client)
                 print("Accept: %s (%s)" % (client, name))
             ProxyHandler.allowed_clients = allowed
             del argv[2:]
         else:
             print("Any clients will be served...")
 
         parser = optparse.OptionParser()
         parser.add_option('-b', '--bind', metavar='ADDRESS',
                           help='Specify alternate bind address '
                                '[default: all interfaces]', default='')
         (options, args) = parser.parse_args()
         port = 8000
         if len(args) == 1:
             port = int(args[0])
         runserver(port, options.bind)