Added memremaining tag

cloudcontrol/node/hypervisor/__init__.py

@@ -125,7 +125,7 @@ class Handler(HostHandler):
 
         # we must refresh those tags only when domains tags are registered to
         # have the calculated values
-        for tag in ('cpualloc', 'cpurunning', 'memalloc', 'memrunning'):
+        for tag in ('cpualloc', 'cpurunning', 'memalloc', 'memrunning', 'memremaining'):
             self.tag_db['__main__'][tag].update_value()
 
         # register libvirt handlers

cloudcontrol/node/hypervisor/tags.py

@@ -20,6 +20,7 @@ from functools import wraps
 import libvirt
 
 from cloudcontrol.node.utils import and_
+from cloudcontrol.common.client.tags import ttl, refresh
 
 
 logger = logging.getLogger(__name__)
@@ -175,3 +176,11 @@ def memalloc(handl):
     """Memory used by all VMs on the hypervisor."""
     return sum(int(vm.tag_db['__main__']['mem'].value) for vm in
                handl.hypervisor.domains.itervalues() if vm.tag_db['__main__']['mem'].value)
+
+
+@_check_virt_connected
+def memremaining(handl):
+    """Allocatable memory remaining on the hypervisor."""
+    mem = int(handl.tag_db['__main__']['mem'].value)
+    memalloc = int(handl.tag_db['__main__']['memalloc'].value)
+    return mem - memalloc
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