add proper locking for archives

git-svn-id: file:///home/lennart/svn/public/sse/trunk@44 5fbabb74-0606-0410-a5e4-b5cc6a42724e

1 files changed, 48 insertions, 0 deletions

diff --git a/feed/sse_lock.py b/feed/sse_lock.py
new file mode 100755
index 0000000..8fd0459
--- /dev/null
+++ b/feed/sse_lock.py
@@ -0,0 +1,48 @@
+#!/usr/bin/python
+import os, errno, time
+
+def try_lock_file(fn):
+
+    lp = "%s.%i" % (fn, os.getpid())
+    
+    fd = os.open(lp, os.O_RDWR|os.O_CREAT, 0666)
+
+    try:
+        os.link(lp, fn)
+    except OSError, e:
+        os.close(fd)
+        os.unlink(lp)
+
+        if e.errno != errno.EEXIST:
+            raise e
+
+        return False
+
+    t = os.fstat(fd)
+    os.close(fd)
+    os.unlink(lp)
+
+    return t.st_nlink >= 2
+
+def unlock_file(fn):
+
+    os.unlink(fn)
+
+
+if __name__ == "__main__":
+    
+    if not try_lock_file("test.lock"):
+        print "FAILED"
+    else:
+        try:
+            print "LOCKED"
+            time.sleep(60)
+        finally:
+            unlock_file("test.lock")
+            
+        print "UNLOCKED"
+    
+
+    
+    
+