def AcquireManyInstances(num, _cfg=None):
"""Return instances that are not in use.
@type num: int
@param num: Number of instances; can be 0.
@rtype: list of instances
@return: C{num} different instances
"""
if _cfg is None:
cfg = GetConfig()
else:
cfg = _cfg
# Filter out unwanted instances
instances = filter(lambda inst: not inst.used, cfg["instances"])
if len(instances) < num:
raise qa_error.OutOfInstancesError(
"Not enough instances left (%d needed, %d remaining)" %
(num, len(instances)))
instances = []
try:
for _ in range(0, num):
n = AcquireInstance(_cfg=cfg)
instances.append(n)
except qa_error.OutOfInstancesError:
ReleaseManyInstances(instances)
raise
return instances
def AcquireInstance(_cfg=None):
"""Returns an instance which isn't in use.
"""
if _cfg is None:
cfg = GetConfig()
else:
cfg = _cfg
# Filter out unwanted instances
instances = filter(lambda inst: not inst.used, cfg["instances"])
if not instances:
raise qa_error.OutOfInstancesError("No instances left")
instance = instances[0]
instance.Use()
return instance
