extras-buildsys/utils/pushscript LockFile.py,1.2,1.3

[Michael Schwendt]

Author: mschwendt

Update of /cvs/fedora/extras-buildsys/utils/pushscript
In directory cvs1.fedora.phx.redhat.com:/tmp/cvs-serv25913

Modified Files:
	LockFile.py 
Log Message:
switch to a later implementation that adds optional POSIX fcntl() write-lock support


Index: LockFile.py
===================================================================
RCS file: /cvs/fedora/extras-buildsys/utils/pushscript/LockFile.py,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- LockFile.py	8 Feb 2007 18:52:32 -0000	1.2
+++ LockFile.py	29 Sep 2008 15:53:05 -0000	1.3
@@ -14,27 +14,34 @@
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# Author: Michael Schwendt <mschwendt at fedoraproject.org>
+
+import errno, fcntl, os, struct, sys
 
-import os, sys
-import errno, fcntl
 
 class LockFileLocked(Exception):
+    """Exception thrown if a conflicting lock is found in non-blocking mode"""
     pass
 
 
-class LockFile:
+class SimplePosixLock:
+    """An exclusive lock on a file via fcntl()"""
 
     def __init__(self, name, blocking=False):
-        self.name = name
-        self.mode = fcntl.LOCK_EX
-        if not blocking:
-            self.mode |= fcntl.LOCK_NB
+        self._fname = name
+        self._lock = struct.pack('hhqqhh', fcntl.F_WRLCK, os.SEEK_SET, 0, 0, 0, 0)
+        self._unlock = struct.pack('hhqqhh', fcntl.F_UNLCK, os.SEEK_SET, 0, 0, 0, 0)
+        if blocking:
+            self._l_cmd = fcntl.F_SETLKW
+        else:
+            self._l_cmd = fcntl.F_SETLK
 
 
     def lock(self):
         try:
-            self.file = open(self.name,'w')
-            self.rc = fcntl.flock(self.file, self.mode)
+            self._file = open(self._fname,'w')
+            rv = fcntl.fcntl(self._file.fileno(), self._l_cmd, self._lock)
         except IOError, (err, strerr):
             if ( err == errno.EAGAIN ):
                 raise LockFileLocked
@@ -43,44 +50,53 @@
 
 
     def unlock(self):
-        fcntl.flock(self.file, fcntl.LOCK_UN)
-        self.file.close()
-        os.remove(self.name)
+        rv = fcntl.fcntl(self._file.fileno(), self._l_cmd, self._unlock)
+        self._file.close()
 
-## Main
 
-import unittest
+class SimpleFlock:
+    """An exclusive lock on a file via flock()"""
+
+    def __init__(self, name, blocking=False):
+        self._fname = name
+        self._mode = fcntl.LOCK_EX
+        if not blocking:
+            self._mode |= fcntl.LOCK_NB
 
-class TestSequenceFunctions(unittest.TestCase):
 
-    def testnonblocking(self):
-        name = '.test.lock'
-        l1 = LockFile(name,False)
-        l1.lock()
-        l2 = LockFile(name,False)
+    def lock(self):
         try:
-            l2.lock()
-            self.assert_(False)
-        except LockFileLocked:
-            self.assert_(True)
-        l1.unlock()
+            self._file = open(self._fname,'w')
+            rc = fcntl.flock(self._file, self._mode)
+        except IOError, (err, strerr):
+            if ( err == errno.EAGAIN ):
+                raise LockFileLocked
+            else:
+                raise
 
 
-    def testseries(self):
-        name = '.test.lock'
-        l1 = LockFile(name,False)
-        l1.lock()
-        l2 = LockFile(name,False)
-        try:
-            l1.unlock()
-            l2.lock()
-            l2.unlock()
-            l1.lock()
-            l1.unlock()
-            self.assert_(True)
-        except LockFileLocked:
-            self.assert_(False)
+    def unlock(self):
+        fcntl.flock(self._file, fcntl.LOCK_UN)
+        self._file.close()
+
+
+class LockFile:
+
+    def __init__(self, name, blocking=False, type='flock'):
+        if type == 'flock':
+            self._base = SimpleFlock(name,blocking)
+        elif type == 'posix':
+            self._base = SimplePosixLock(name,blocking)
+        else:
+            sys.stderr.write("Invalid LockFile type!\n")
+            self._base = SimpleFlock(name,blocking)
+
+            
+    def lock(self):
+        self._base.lock()
+
+
+    def unlock(self):
+        self._base.unlock()
 
 
-if __name__ == '__main__':
-    unittest.main()