bug 11302: more efficient caching of keyword

scripts/vm/hypervisor/xenserver/vmops

@@ -405,6 +405,9 @@ def can_bridge_firewall(session, args):
     allow_egress_traffic(session)
     if not os.path.exists('/var/run/cloud'):
         os.makedirs('/var/run/cloud')
+    if not os.path.exists('/var/cache/cloud'):
+        os.makedirs('/var/cache/cloud')
+    get_ipset_keyword()
  
     cleanup_rules_for_dead_vms(session)
     cleanup_rules(session, args)
@@ -1152,9 +1155,8 @@ def inflate_rules (zipped):
    return zlib.decompress(base64.b64decode(zipped))
 
 @echo
-def get_ipset_keyword():
+def cache_ipset_keyword():
     tmpname = 'ipsetqzvxtmp'
-    keyword = 'match-set'
     try:
         util.pread2(['/bin/bash', '-c', 'ipset -N ' + tmpname + ' iptreemap'])
     except:
@@ -1172,6 +1174,32 @@ def get_ipset_keyword():
     except:
        pass
        
+    cachefile = "/var/cache/cloud/ipset.keyword"
+    util.SMlog("Writing ipset keyword to " + cachefile)
+    cachef = open(cachefile, 'w')
+    try:
+        cachef.write(keyword)
+        cachef.write('\n')
+    except:
+        util.SMlog("Failed to write to cache file " + cachef)
+        
+    cachef.close()
+    return keyword
+    
+@echo
+def get_ipset_keyword():
+    cachefile = "/var/cache/cloud/ipset.keyword"
+    keyword = 'match-set'
+    
+    if not os.path.exists(cachefile):
+        util.SMlog("Failed to find ipset keyword cachefile %s" %cachefile)
+        keyword = cache_ipset_keyword()
+    else:
+        lines = (line.rstrip() for line in open(cachefile))
+        for line in lines:
+            keyword = line
+            break
+
     return keyword
 
 @echo