locker Namespace Reference

Classes
class	LockFile
	Lock a file. More...
Functions
def	lock
def	unlock
def	_tmpFileName
def	_lckFileName
def	_linkCount
def	_read
def	_sleep
Variables
	LOCK_EX = fcntl.F_WRLCK
	LOCK_SH = fcntl.F_RDLCK
	LOCK_NB = fcntl.F_UNLCK

---

Function Documentation

def locker::_lckFileName

(

fileName

)

[private]

Definition at line 51 of file locker.py.

                              :
        return "%s.lock" % fileName

def locker::_linkCount

(

lockFileName

)

[private]

Definition at line 54 of file locker.py.

00055                                   :
00056         try:
00057             return os.stat(lockFileName).st_nlink
00058         except OSError, e:
00059             if e.errno != errno.ENOENT:
00060                 raise
            return -1

def locker::_read

(

fileName

)

[private]

Definition at line 61 of file locker.py.

00062                        :
00063         try:
00064             fp = open(fileName)
00065             try:     readFileName = fp.read()
00066             finally: fp.close()
00067             return readFileName
00068         except EnvironmentError, e:
00069             if e.errno != errno.ENOENT:
00070                 raise
00071             return None
            

def locker::_sleep

(

)

[private]

Definition at line 72 of file locker.py.

                : time.sleep(8)

def locker::_tmpFileName

(

fileName

)

[private]

Definition at line 49 of file locker.py.

00050                               :
        return "%s.%s.%d" % ( fileName, socket.gethostname(), os.getpid() )

def locker::lock

(

file

)

Lock first 10 bytes of a file.

Definition at line 74 of file locker.py.

00075                   :
00076         fileName = file.name
00077         tmpFileName = _tmpFileName(fileName)
00078         fp = open( tmpFileName, "w" )
00079         fp.write( tmpFileName )
00080         fp.close()
00081 
00082         lockFileName = _lckFileName( fileName )
00083         while True:
00084             if _linkCount(lockFileName) != -1: _sleep()
00085             try:
00086                 os.link( tmpFileName, lockFileName )
00087                 # we acquired the lock
00088                 return
00089             except OSError, e:
00090                 if e.errno == errno.ENOENT:
00091                     pass
00092                 elif e.errno != errno.EEXIST:
00093                     os.unlink(tmpFileName)
00094                     raise
00095                 elif _linkCount( lockFileName ) != 2:
00096                     pass
00097                 elif _read(lockFileName) == tmpFileName:
00098                     raise
00099                 else:
00100                     # someone else owns that lock
00101                     pass
00102             ## didn't get the lock !!
00103             ## say something ?
00104             #print _id_()," failed to acquire the lock ..."
00105             _sleep()
00106             pass
00107         return
    

def locker::unlock

(

file

)

Unlock first 10 bytes of a file.

Definition at line 108 of file locker.py.

                    :
        fileName = file.name
        tmpFileName  = _tmpFileName(fileName)
        lockFileName = _lckFileName( fileName )

        try:
            os.unlink( lockFileName )
        except OSError, e:
            if e.errno != errno.ENOENT:
                raise
        # remove the tmp file
        try:
            os.unlink( tmpFileName )
        except OSError, e:
            if e.errno != errno.ENOENT:
                raise
        return

---

Variable Documentation

locker::LOCK_EX = fcntl.F_WRLCK

Definition at line 12 of file locker.py.

locker::LOCK_NB = fcntl.F_UNLCK

Definition at line 14 of file locker.py.

locker::LOCK_SH = fcntl.F_RDLCK

Definition at line 13 of file locker.py.