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1 from __future__ import absolute_import, division
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2
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3 import time
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4 import os
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5 import sys
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6 import errno
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7
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8 from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout,
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9 AlreadyLocked)
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10
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11 class MkdirLockFile(LockBase):
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12 """Lock file by creating a directory."""
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13 def __init__(self, path, threaded=True, timeout=None):
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14 """
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15 >>> lock = MkdirLockFile('somefile')
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16 >>> lock = MkdirLockFile('somefile', threaded=False)
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17 """
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18 LockBase.__init__(self, path, threaded, timeout)
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19 # Lock file itself is a directory. Place the unique file name into
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20 # it.
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21 self.unique_name = os.path.join(self.lock_file,
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22 "%s.%s%s" % (self.hostname,
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23 self.tname,
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24 self.pid))
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25
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26 def acquire(self, timeout=None):
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27 timeout = timeout is not None and timeout or self.timeout
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28 end_time = time.time()
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29 if timeout is not None and timeout > 0:
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30 end_time += timeout
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31
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32 if timeout is None:
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33 wait = 0.1
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34 else:
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35 wait = max(0, timeout / 10)
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36
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37 while True:
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38 try:
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39 os.mkdir(self.lock_file)
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40 except OSError:
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41 err = sys.exc_info()[1]
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42 if err.errno == errno.EEXIST:
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43 # Already locked.
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44 if os.path.exists(self.unique_name):
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45 # Already locked by me.
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46 return
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47 if timeout is not None and time.time() > end_time:
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48 if timeout > 0:
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49 raise LockTimeout("Timeout waiting to acquire"
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50 " lock for %s" %
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51 self.path)
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52 else:
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53 # Someone else has the lock.
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54 raise AlreadyLocked("%s is already locked" %
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55 self.path)
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56 time.sleep(wait)
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57 else:
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58 # Couldn't create the lock for some other reason
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59 raise LockFailed("failed to create %s" % self.lock_file)
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60 else:
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61 open(self.unique_name, "wb").close()
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62 return
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63
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64 def release(self):
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65 if not self.is_locked():
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66 raise NotLocked("%s is not locked" % self.path)
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67 elif not os.path.exists(self.unique_name):
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68 raise NotMyLock("%s is locked, but not by me" % self.path)
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69 os.unlink(self.unique_name)
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70 os.rmdir(self.lock_file)
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71
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72 def is_locked(self):
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73 return os.path.exists(self.lock_file)
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74
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75 def i_am_locking(self):
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76 return (self.is_locked() and
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77 os.path.exists(self.unique_name))
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78
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79 def break_lock(self):
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80 if os.path.exists(self.lock_file):
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81 for name in os.listdir(self.lock_file):
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82 os.unlink(os.path.join(self.lock_file, name))
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83 os.rmdir(self.lock_file)
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