From e9cd4db258c060a884751e900dc100be5536030a Mon Sep 17 00:00:00 2001
From: bernat <none>
Date: Sun, 5 Dec 2004 13:17:13 +0100
Subject: [PATCH] Amelioration du lock (utilisation de flock pour assurer une
 zone

exclusive).

darcs-hash:20041205121713-d1718-a6be427ecc5876129ad2be67a85154ed747d7fc7.gz
---
 gestion/lock.py | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/gestion/lock.py b/gestion/lock.py
index 3a992c45..efbac31b 100755
--- a/gestion/lock.py
+++ b/gestion/lock.py
@@ -10,12 +10,27 @@ Licence : GPLv2
 import os,string,time,sys, affich_tools
 from commands import getoutput
 from user_tests import getuser
+from fcntl import lockf, LOCK_EX, LOCK_NB, LOCK_UN
+import errno
 
 def make_lock(lock_name, lock_comment='',nowait=1) :
     """ Création d'un lock 
-    si nowait=0 fait un sys.exit(254) quand un ancien lock actif est rencontré
+    si nowait=1 fait un sys.exit(254) quand un ancien lock actif est rencontré
     """
     lock_file = '/var/lock/' + lock_name
+
+    # On créé une zone d'exclusion
+    lock_fd_dl=open("%s-dotlock" % lock_file, "w")
+    # On demande un verrou exclusif
+    try:
+        lockf(lock_fd_dl, LOCK_EX | LOCK_NB)
+    except IOError, e:
+        if e.errno not in [errno.EACCESS, errno.EAGAIN]:
+            raise
+        # La procédure de lock est deja en cours d'execution, on essaie un peu plus tard
+        time.sleep(0.5)
+        return make_lock(lock_name, lock_comment)
+
     if os.path.isfile(lock_file) :
 	### Lock existant
 	
@@ -65,10 +80,15 @@ def make_lock(lock_name, lock_comment='',nowait=1) :
 	    return make_lock(lock_name, lock_comment)
 	    
     ### Prise du lock
-    lock_fd=open(lock_file, "w")
+    lock_fd = file(lock_file,"w")
     lock_fd.write("%s\n%s\n%s" % (os.getpid(), getuser(), lock_comment) )
     lock_fd.close()
 
+    # On enleve le verrou système
+    lockf(lock_fd_dl, LOCK_UN)
+    lock_fd_dl.close()
+    
+
 def remove_lock( lock_name ) :
     """ Destruction du lock """
     lock_file = '/var/lock/' + lock_name