WebKitTools/Scripts/webkitpy/layout_tests/port/http_lock.py

   1 #!/usr/bin/env python
   2 # Copyright (C) 2010 Gabor Rapcsanyi (rgabor@inf.u-szeged.hu), University of Szeged
   3 # Copyright (C) 2010 Andras Becsi (abecsi@inf.u-szeged.hu), University of Szeged
   4 #
   5 # All rights reserved.
   6 #
   7 # Redistribution and use in source and binary forms, with or without
   8 # modification, are permitted provided that the following conditions
   9 # are met:
  10 # 1. Redistributions of source code must retain the above copyright
  11 #    notice, this list of conditions and the following disclaimer.
  12 # 2. Redistributions in binary form must reproduce the above copyright
  13 #    notice, this list of conditions and the following disclaimer in the
  14 #    documentation and/or other materials provided with the distribution.
  15 #
  16 # THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
  17 # EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  19 # PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
  20 # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  21 # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  22 # PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  23 # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  24 # OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27
  28 """This class helps to block NRWT threads when more NRWTs run
  29 http and websocket tests in a same time."""
  30
  31 import glob
  32 import os
  33 import sys
  34 import tempfile
  35 import time
  36
  37
  38 class HttpLock(object):
  39
  40     def __init__(self, lock_path, lock_file_prefix="WebKitHttpd.lock.",
  41                  guard_lock="WebKit.lock"):
  42         if not lock_path:
  43             self._lock_path = tempfile.gettempdir()
  44         self._lock_file_prefix = lock_file_prefix
  45         self._lock_file_path_prefix = os.path.join(self._lock_path,
  46                                                    self._lock_file_prefix)
  47         self._guard_lock_file = os.path.join(self._lock_path, guard_lock)
  48         self._process_lock_file_name = ""
  49
  50     def cleanup_http_lock(self):
  51         """Delete the lock file if exists."""
  52         if os.path.exists(self._process_lock_file_name):
  53             os.unlink(self._process_lock_file_name)
  54
  55     def _extract_lock_number(self, lock_file_name):
  56         """Return the lock number from lock file."""
  57         prefix_length = len(self._lock_file_path_prefix)
  58         return int(lock_file_name[prefix_length:])
  59
  60     def _lock_file_list(self):
  61         """Return the list of lock files sequentially."""
  62         lock_list = glob.glob(self._lock_file_path_prefix + '*')
  63         lock_list.sort(key=self._extract_lock_number)
  64         return lock_list
  65
  66     def _next_lock_number(self):
  67         """Return the next available lock number."""
  68         lock_list = self._lock_file_list()
  69         if not lock_list:
  70             return 0
  71         return self._extract_lock_number(lock_list[-1]) + 1
  72
  73     def _check_pid(self, current_pid):
  74         """Return True if pid is alive, otherwise return False.
  75         FIXME: os.kill() doesn't work on Windows for checking if
  76         a pid is alive, so always return True"""
  77         if sys.platform in ('darwin', 'linux2'):
  78             try:
  79                 os.kill(current_pid, 0)
  80             except OSError:
  81                 return False
  82         return True
  83
  84     def _curent_lock_pid(self):
  85         """Return with the current lock pid. If the lock is not valid
  86         it deletes the lock file."""
  87         lock_list = self._lock_file_list()
  88         if not lock_list:
  89             return
  90         try:
  91             current_lock_file = open(lock_list[0], 'r')
  92             current_pid = current_lock_file.readline()
  93             current_lock_file.close()
  94             if not (current_pid and self._check_pid(int(current_pid))):
  95                 os.unlink(lock_list[0])
  96                 return
  97         except IOError, OSError:
  98             return
  99         return int(current_pid)
 100
 101     def _create_lock_file(self):
 102         """The lock files are used to schedule the running test sessions in first
 103         come first served order. The sequential guard lock ensures that the lock
 104         numbers are sequential."""
 105         while(True):
 106             try:
 107                 sequential_guard_lock = os.open(self._guard_lock_file, os.O_CREAT | os.O_EXCL)
 108                 self._process_lock_file_name = (self._lock_file_path_prefix +
 109                                                 str(self._next_lock_number()))
 110                 lock_file = open(self._process_lock_file_name, 'w')
 111                 lock_file.write(str(os.getpid()))
 112                 lock_file.close()
 113                 os.close(sequential_guard_lock)
 114                 os.unlink(self._guard_lock_file)
 115                 break
 116             except OSError:
 117                 pass
 118
 119     def wait_for_httpd_lock(self):
 120         """Create a lock file and wait until it's turn comes."""
 121         self._create_lock_file()
 122         while self._curent_lock_pid() != os.getpid():
 123             time.sleep(1)