svn commit: r1158928 - /subversion/branches/fs-py/subversion/python/svn/_lock.py

[hw...@apache.org]

Author: hwright
Date: Wed Aug 17 21:52:51 2011
New Revision: 1158928

URL: http://svn.apache.org/viewvc?rev=1158928&view=rev
Log:
On the fs-py branch:
Add a simple implementation of os-based locking, which will be useful for
implementation FSFS locks in Python.

This is built such that it should work on multiple OSs, but currently
only has a posix implementation.

* subversion/python/svn/_lock.py:
  New.

Added:
    subversion/branches/fs-py/subversion/python/svn/_lock.py   (with props)

Added: subversion/branches/fs-py/subversion/python/svn/_lock.py
URL: http://svn.apache.org/viewvc/subversion/branches/fs-py/subversion/python/svn/_lock.py?rev=1158928&view=auto
==============================================================================
--- subversion/branches/fs-py/subversion/python/svn/_lock.py (added)
+++ subversion/branches/fs-py/subversion/python/svn/_lock.py Wed Aug 17 21:52:51 2011
@@ -0,0 +1,84 @@
+#!/usr/bin/env python
+#
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import os, errno
+
+import svn
+import svn.err
+
+
+# The system-dependent locking bits
+if os.name == 'posix':
+    import fcntl
+
+    def _lock_file(f, exclusive, blocking):
+        flags = 0
+        if not blocking:
+            flags |= fcntl.LOCK_NB
+        if exclusive:
+            flags |= fcntl.LOCK_EX
+        else:
+            flags |= fcntl.LOCK_SH
+
+        fcntl.lockf(f, flags)
+
+    def _unlock_file(f):
+        fcntl.lockf(f, fcntl.LOCK_UN)
+
+elif os.name == 'nt':
+    # Need to implement os-level locking for Windows
+    raise svn.SubversionException(0, "Locking not supported")
+else:
+    raise svn.SubversionException(0, "Locking not supported")
+
+
+
+class Lock(object):
+    def __init__(self, path, exclusive=True, blocking=True):
+        self._path = path
+        self._exclusive = exclusive
+        self._blocking = blocking
+        self._is_locked = False
+
+    def acquire(self):
+        ###  * Should we add a retry loop of some kind?
+        self._fd = os.open(self._path, os.O_CREAT | os.O_RDWR)
+        _lock_file(self._fd, self._exclusive, self._blocking)
+        self._is_locked = True
+
+    def release(self):
+        if self._is_locked:
+            _unlock_file(self._fd)
+            os.close(self._fd)
+            del self._fd
+            self._is_locked = False
+
+    def __enter__(self):
+        if not self._is_locked:
+            self.acquire()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if self._is_locked:
+            self.release()
+
+    def __del__(self):
+        'Make sure we release the lock if/when it get garbage collected.'
+        self.release()

Propchange: subversion/branches/fs-py/subversion/python/svn/_lock.py
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