port_server.py

#!/usr/bin/env python2.7
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"""Manage TCP ports for unit tests; started by run_tests.py"""

import argparse
import BaseHTTPServer
import hashlib
import os
import socket
import sys
import time


# increment this number whenever making a change to ensure that
# the changes are picked up by running CI servers
# note that all changes must be backwards compatible
_MY_VERSION = 7


if len(sys.argv) == 2 and sys.argv[1] == 'dump_version':
  print _MY_VERSION
  sys.exit(0)


argp = argparse.ArgumentParser(description='Server for httpcli_test')
argp.add_argument('-p', '--port', default=12345, type=int)
argp.add_argument('-l', '--logfile', default=None, type=str)
args = argp.parse_args()

if args.logfile is not None:
  sys.stdin.close()
  sys.stderr.close()
  sys.stdout.close()
  sys.stderr = open(args.logfile, 'w')
  sys.stdout = sys.stderr

print 'port server running on port %d' % args.port

pool = []
in_use = {}


def refill_pool(max_timeout, req):
  """Scan for ports not marked for being in use"""
  for i in range(1025, 32767):
    if len(pool) > 100: break
    if i in in_use:
      age = time.time() - in_use[i]
      if age < max_timeout:
        continue
      req.log_message("kill old request %d" % i)
      del in_use[i]
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    try:
      s.bind(('localhost', i))
      req.log_message("found available port %d" % i)
      pool.append(i)
    except:
      pass # we really don't care about failures
    finally:
      s.close()


def allocate_port(req):
  global pool
  global in_use
  max_timeout = 600
  while not pool:
    refill_pool(max_timeout, req)
    if not pool:
      req.log_message("failed to find ports: retrying soon")
      time.sleep(1)
      max_timeout /= 2
  port = pool[0]
  pool = pool[1:]
  in_use[port] = time.time()
  return port


keep_running = True


class Handler(BaseHTTPServer.BaseHTTPRequestHandler):

  def do_GET(self):
    global keep_running
    if self.path == '/get':
      # allocate a new port, it will stay bound for ten minutes and until
      # it's unused
      self.send_response(200)
      self.send_header('Content-Type', 'text/plain')
      self.end_headers()
      p = allocate_port(self)
      self.log_message('allocated port %d' % p)
      self.wfile.write('%d' % p)
    elif self.path[0:6] == '/drop/':
      self.send_response(200)
      self.send_header('Content-Type', 'text/plain')
      self.end_headers()
      p = int(self.path[6:])
      if p in in_use:
        del in_use[p]
        pool.append(p)
        self.log_message('drop known port %d' % p)
      else:
        self.log_message('drop unknown port %d' % p)
    elif self.path == '/version_number':
      # fetch a version string and the current process pid
      self.send_response(200)
      self.send_header('Content-Type', 'text/plain')
      self.end_headers()
      self.wfile.write(_MY_VERSION)
    elif self.path == '/dump':
      # yaml module is not installed on Macs and Windows machines by default
      # so we import it lazily (/dump action is only used for debugging)
      import yaml
      self.send_response(200)
      self.send_header('Content-Type', 'text/plain')
      self.end_headers()
      now = time.time()
      self.wfile.write(yaml.dump({'pool': pool, 'in_use': dict((k, now - v) for k, v in in_use.iteritems())}))
    elif self.path == '/quitquitquit':
      self.send_response(200)
      self.end_headers()
      keep_running = False


httpd = BaseHTTPServer.HTTPServer(('', args.port), Handler)
while keep_running:
  httpd.handle_request()
  sys.stderr.flush()

print 'done'