add proper locking for archives

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

1 files changed, 23 insertions, 14 deletions

diff --git a/feed/sse_grab.py b/feed/sse_grab.py
index 302c5a7..b1d11db 100644
--- a/feed/sse_grab.py
+++ b/feed/sse_grab.py
@@ -2,36 +2,42 @@
 
 import sys, urllib2, os, socket
 
-import sse_tar
+import sse_tar, sse_lock
 from sse_defs import *
 from sse_config import *
 
 socket.setdefaulttimeout(SSE_SOCKET_TIMEOUT)
 
 def grab_archive(meta, recid, provider_id = SSE_PROVIDER_NONE):
-
+    
     try:
         os.mkdir("%s/download" % HOME)
     except:
         pass
     
     fn = os.path.join(HOME, "download", recid)
+    lock_fn = fn + ".lock"
 
-    download = False
+    if not sse_lock.try_lock_file(lock_fn):
+        print "Skipping locked archive '%s'." % recid
+        return
 
     try:
-        f = open(fn+".release", "r")
-    except:
-        download = True
-    else:
-        download = f.read(SSE_BLOCK_SIZE) != meta["version"]
-        f.close()
+        download = False
+
+        try:
+            f = open(fn+".release", "r")
+        except IOError:
+            download = True
+        else:
+            download = f.read(SSE_BLOCK_SIZE) != meta["version"]
+            f.close()
 
-    archive_url = meta["archive-url"]
+        archive_url = meta["archive-url"]
 
-    if not download:
-        print "File %s up-to-date." % archive_url
-    else:
+        if not download:
+            print "File %s up-to-date." % archive_url
+            return
 
         print "Downloading %s..." % archive_url
 
@@ -73,7 +79,10 @@ def grab_archive(meta, recid, provider_id = SSE_PROVIDER_NONE):
             f = open(fn+".release", "w")
         except:
             os.unlink(fn)
-
+        
         f.write(meta["version"])
         f.close()
+
+    finally:
+        sse_lock.unlock_file(lock_fn)