scheduler/metahost_scheduler.py

   1 from autotest_lib.client.common_lib import utils
   2
   3 class HostSchedulingUtility(object):
   4     """Interface to host availability information from the scheduler."""
   5     def hosts_in_label(self, label_id):
   6         """Return potentially usable hosts with the given label."""
   7         raise NotImplementedError
   8
   9
  10     def remove_host_from_label(self, host_id, label_id):
  11         """Remove this host from the internal list of usable hosts in the label.
  12
  13         This is provided as an optimization -- when code gets a host from a
  14         label and concludes it's unusable, it can call this to avoid getting
  15         that host again in the future (within this tick).  This function should
  16         not affect correctness.
  17         """
  18         raise NotImplementedError
  19
  20
  21     def pop_host(self, host_id):
  22         """Remove and return a host from the internal list of available hosts.
  23         """
  24         raise NotImplementedError
  25
  26
  27     def ineligible_hosts_for_entry(self, queue_entry):
  28         """Get the list of hosts ineligible to run the given queue entry."""
  29         raise NotImplementedError
  30
  31
  32     def is_host_usable(self, host_id):
  33         """Determine if the host is currently usable at all."""
  34         raise NotImplementedError
  35
  36
  37     def is_host_eligible_for_job(self, host_id, queue_entry):
  38         """Determine if the host is eligible specifically for this queue entry.
  39
  40         @param queue_entry: a HostQueueEntry DBObject
  41         """
  42         raise NotImplementedError
  43
  44
  45 class MetahostScheduler(object):
  46     def can_schedule_metahost(self, queue_entry):
  47         """Return true if this object can schedule the given queue entry.
  48
  49         At most one MetahostScheduler should return true for any given entry.
  50
  51         @param queue_entry: a HostQueueEntry DBObject
  52         """
  53         raise NotImplementedError
  54
  55
  56     def schedule_metahost(self, queue_entry, scheduling_utility):
  57         """Schedule the given queue entry, if possible.
  58
  59         This method should make necessary database changes culminating in
  60         assigning a host to the given queue entry in the database.  It may
  61         take no action if no host can be assigned currently.
  62
  63         @param queue_entry: a HostQueueEntry DBObject
  64         @param scheduling_utility: a HostSchedulingUtility object
  65         """
  66         raise NotImplementedError
  67
  68
  69     def recovery_on_startup(self):
  70         """Perform any necessary recovery upon scheduler startup."""
  71         pass
  72
  73
  74     def tick(self):
  75         """Called once per scheduler cycle; any actions are allowed."""
  76         pass
  77
  78
  79 class LabelMetahostScheduler(MetahostScheduler):
  80     def can_schedule_metahost(self, queue_entry):
  81         return bool(queue_entry.meta_host)
  82
  83
  84     def schedule_metahost(self, queue_entry, scheduling_utility):
  85         label_id = queue_entry.meta_host
  86         hosts_in_label = scheduling_utility.hosts_in_label(label_id)
  87         ineligible_host_ids = scheduling_utility.ineligible_hosts_for_entry(
  88                 queue_entry)
  89
  90         for host_id in hosts_in_label:
  91             if not scheduling_utility.is_host_usable(host_id):
  92                 scheduling_utility.remove_host_from_label(host_id, label_id)
  93                 continue
  94             if host_id in ineligible_host_ids:
  95                 continue
  96             if not scheduling_utility.is_host_eligible_for_job(host_id,
  97                                                                queue_entry):
  98                 continue
  99
 100             # Remove the host from our cached internal state before returning
 101             scheduling_utility.remove_host_from_label(host_id, label_id)
 102             host = scheduling_utility.pop_host(host_id)
 103             queue_entry.set_host(host)
 104             return
 105
 106
 107 def get_metahost_schedulers():
 108     return [LabelMetahostScheduler()]