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Source code for galaxy.web.stack.handlers
"""Utilities for dealing with the Galaxy 'handler' process pattern.
A 'handler' is a named Python process running the Galaxy application responsible
for some activity such as queuing up jobs or scheduling workflows.
"""
from __future__ import absolute_import
import logging
import os
import random
from collections import namedtuple
from sqlalchemy.orm import object_session
from galaxy.exceptions import HandlerAssignmentError
from galaxy.util import (
ExecutionTimer,
listify
)
log = logging.getLogger(__name__)
_handler_assignment_methods = (
'MEM_SELF', 'DB_SELF', 'DB_PREASSIGN', 'DB_TRANSACTION_ISOLATION', 'DB_SKIP_LOCKED', 'UWSGI_MULE_MESSAGE'
)
HANDLER_ASSIGNMENT_METHODS = namedtuple('JOB_HANDLER_ASSIGNMENT_METHODS', _handler_assignment_methods)(
*[x.lower().replace('_', '-') for x in _handler_assignment_methods]
)
[docs]class HandlerAssignmentSkip(Exception):
"""Exception for handler assignment methods to raise if the next method should be tried.
"""
pass
[docs]class ConfiguresHandlers(object):
DEFAULT_HANDLER_TAG = '_default_'
DEFAULT_BASE_HANDLER_POOLS = ()
UNSUPPORTED_HANDLER_ASSIGNMENT_METHODS = ()
[docs] def add_handler(self, handler_id, tags):
if handler_id not in self.handlers:
self.handlers[handler_id] = (handler_id,)
for tag in tags:
if tag in self.handlers and handler_id not in self.handlers[tag]:
self.handlers[tag].append(handler_id)
else:
self.handlers[tag] = [handler_id]
def _init_handlers(self, config_element):
# Parse handlers
if config_element is not None:
for handler in self._findall_with_required(config_element, 'handler'):
handler_id = handler.get('id')
if handler_id in self.handlers:
log.error("Handler '%s' overlaps handler with the same name, ignoring", handler_id)
else:
log.debug("Read definition for handler '%s'", handler_id)
self._parse_handler(handler_id, handler)
self.add_handler(
handler_id,
[x.strip() for x in handler.get('tags', self.DEFAULT_HANDLER_TAG).split(',')]
)
self.default_handler_id = self._get_default(
self.app.config, config_element, list(self.handlers.keys()), required=False)
def _init_handler_assignment_methods(self, config_element=None):
self.__is_handler = None
# This is set by the stack job handler init code
self.pool_for_tag = {}
self._handler_assignment_method_methods = {
HANDLER_ASSIGNMENT_METHODS.MEM_SELF: self._assign_mem_self_handler,
HANDLER_ASSIGNMENT_METHODS.DB_SELF: self._assign_db_self_handler,
HANDLER_ASSIGNMENT_METHODS.DB_PREASSIGN: self._assign_db_preassign_handler,
HANDLER_ASSIGNMENT_METHODS.DB_TRANSACTION_ISOLATION: self._assign_db_tag,
HANDLER_ASSIGNMENT_METHODS.DB_SKIP_LOCKED: self._assign_db_tag,
HANDLER_ASSIGNMENT_METHODS.UWSGI_MULE_MESSAGE: self._assign_uwsgi_mule_message_handler,
}
if config_element is not None:
for method in listify(config_element.attrib.get('assign_with', []), do_strip=True):
method = method.lower()
assert method in HANDLER_ASSIGNMENT_METHODS, \
"Invalid job handler assignment method '%s', must be one of: %s" % (
method, ', '.join(HANDLER_ASSIGNMENT_METHODS))
try:
self.handler_assignment_methods.append(method)
except AttributeError:
self.handler_assignment_methods_configured = True
self.handler_assignment_methods = [method]
if self.handler_assignment_methods == [HANDLER_ASSIGNMENT_METHODS.MEM_SELF]:
self.app.config.track_jobs_in_database = False
self.handler_max_grab = config_element.attrib.get('max_grab', self.handler_max_grab)
if self.handler_max_grab is not None:
self.handler_max_grab = int(self.handler_max_grab)
def _set_default_handler_assignment_methods(self):
if not self.handler_assignment_methods_configured:
if not self.app.config.track_jobs_in_database and \
HANDLER_ASSIGNMENT_METHODS.MEM_SELF not in self.UNSUPPORTED_HANDLER_ASSIGNMENT_METHODS:
# DEPRECATED: You should just set mem_self as the only method if you want this
log.warning("The `track_jobs_in_database` option is deprecated, please set `%s` as the job"
" handler assignment method in the job handler configuration",
HANDLER_ASSIGNMENT_METHODS.MEM_SELF)
self.handler_assignment_methods = [HANDLER_ASSIGNMENT_METHODS.MEM_SELF]
elif not self.handlers:
# No handlers defined, default is for processes to handle the jobs they create
self.handler_assignment_methods = [HANDLER_ASSIGNMENT_METHODS.DB_SELF]
else:
# Handlers are defined, default is the value if the default attribute, or any untagged handler if
# default attribute is unset
self.handler_assignment_methods = [HANDLER_ASSIGNMENT_METHODS.DB_PREASSIGN]
# If the stack has handler pools it can override these defaults
self.app.application_stack.init_job_handling(self)
log.info("%s: No job handler assignment method is set, defaulting to '%s', set the `assign_with` attribute"
" on <handlers> to override the default", self.__class__.__name__,
self.handler_assignment_methods[0])
def _parse_handler(self, handler_id, handler_def):
pass
def _get_default(self, config, parent, names, auto=False, required=True):
"""
Returns the default attribute set in a parent tag like <handlers> or
<destinations>, or return the ID of the child, if there is no explicit
default and only one child.
:param parent: Object representing a tag that may or may not have a 'default' attribute.
:type parent: ``xml.etree.ElementTree.Element``
:param names: The list of destination or handler IDs or tags that were loaded.
:type names: list of str
:param auto: Automatically set a default if there is no default in the parent tag and there is only one child.
:type auto: bool
:param required: Require a default to be set or determined automatically, else raise Exception
:type required: bool
:returns: str -- id or tag representing the default.
"""
rval = parent.get('default')
if 'default_from_environ' in parent.attrib:
environ_var = parent.attrib['default_from_environ']
rval = os.environ.get(environ_var, rval)
elif 'default_from_config' in parent.attrib:
config_val = parent.attrib['default_from_config']
rval = config.config_dict.get(config_val, rval)
if rval is not None:
# If the parent element has a 'default' attribute, use the id or tag in that attribute
if required and rval not in names:
raise Exception("<%s> default attribute '%s' does not match a defined id or tag in a child element" % (parent.tag, rval))
log.debug("<%s> default set to child with id or tag '%s'" % (parent.tag, rval))
elif auto and len(names) == 1:
log.info("Setting <%s> default to child with id '%s'" % (parent.tag, names[0]))
rval = names[0]
elif required:
raise Exception("No <%s> default specified, please specify a valid id or tag with the 'default' attribute" % parent.tag)
return rval
def _findall_with_required(self, parent, match, attribs=None):
"""Like ``xml.etree.ElementTree.Element.findall()``, except only returns children that have the specified attribs.
:param parent: Parent element in which to find.
:type parent: ``xml.etree.ElementTree.Element``
:param match: Name of child elements to find.
:type match: str
:param attribs: List of required attributes in children elements.
:type attribs: list of str
:returns: list of ``xml.etree.ElementTree.Element``
"""
rval = []
if attribs is None:
attribs = ('id',)
for elem in parent.findall(match):
for attrib in attribs:
if attrib not in elem.attrib:
log.warning("required '%s' attribute is missing from <%s> element" % (attrib, match))
break
else:
rval.append(elem)
return rval
@property
def use_messaging(self):
# The job manager uses this to determine whether the messaging job queue should be used
return HANDLER_ASSIGNMENT_METHODS.UWSGI_MULE_MESSAGE in self.handler_assignment_methods
@property
def deterministic_handler_assignment(self):
return self.handler_assignment_methods and any(
filter(lambda x: x in (
HANDLER_ASSIGNMENT_METHODS.UWSGI_MULE_MESSAGE,
HANDLER_ASSIGNMENT_METHODS.DB_PREASSIGN,
), self.handler_assignment_methods))
def _get_is_handler(self):
"""Indicate whether the current server is configured as a handler.
:return: bool
"""
if self.__is_handler is not None:
return self.__is_handler
if (HANDLER_ASSIGNMENT_METHODS.DB_SELF in self.handler_assignment_methods
or HANDLER_ASSIGNMENT_METHODS.MEM_SELF in self.handler_assignment_methods):
return True
for collection in self.handlers.values():
if self.app.config.server_name in collection:
return True
return False
def _set_is_handler(self, value):
self.__is_handler = value
is_handler = property(_get_is_handler, _set_is_handler)
def _get_single_item(self, collection, index=None):
"""Given a collection of handlers or destinations, return one item from the collection at random.
"""
# Done like this to avoid random under the assumption it's faster to avoid it
if len(collection) == 1:
return collection[0]
elif index is None:
return random.choice(collection)
else:
return collection[index % len(collection)]
@property
def handler_tags(self):
"""Get an iteratable of all configured handler tags.
"""
return filter(lambda k: isinstance(self.handlers[k], list), self.handlers.keys())
@property
def self_handler_tags(self):
"""Get an iterable of the current process's configured handler tags.
"""
return filter(lambda k: self.app.config.server_name in self.handlers[k], self.handler_tags)
# If these get to be any more complex we should probably modularize them, or at least move to a separate class
def _assign_handler_direct(self, obj, configured):
"""Directly assign a handler if the object has been preconfigured to a known single static handler.
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param configured: Same as :method:`ConfiguresHandlers.assign_handler()`.
:returns: str -- A valid handler ID, or False if no handler was assigned.
"""
if self.app.config.track_jobs_in_database and configured:
try:
handlers = self.handlers[configured]
except KeyError:
handlers = None
if handlers == (configured,):
obj.set_handler(configured)
_timed_flush_obj(obj)
return configured
return False
def _assign_mem_self_handler(self, obj, method, configured, queue_callback=None, **kwargs):
"""Assign object to this handler using this process's in-memory queue.
This method ignores all handler configuration.
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param method: Same as :method:`ConfiguresHandlers._assign_db_preassign_handler()`.
:param configured: Ignored.
:param queue_callback: Callback to be executed when the job should be queued (i.e. a callback to the handler's
``put()`` method). No arguments are passed.
:type queue_callback: callable
:returns: str -- This process's server name (handler ID).
"""
assert queue_callback is not None, \
"Cannot perform '%s' handler assignment: `queue_callback` is None" % HANDLER_ASSIGNMENT_METHODS.MEM_SELF
if configured:
log.warning("(%s) Ignoring handler assignment to '%s' because configured handler assignment method"
" '' overrides per-tool handler assignment", obj.log_str(),
HANDLER_ASSIGNMENT_METHODS.MEM_SELF, configured)
_timed_flush_obj(obj)
queue_callback()
return self.app.config.server_name
def _assign_db_self_handler(self, obj, method, configured, **kwargs):
"""Assign object to this process by setting its ``handler`` column in the database to this process.
This only occurs if there is not an explicitly configured handler assignment for the object. Otherwise, it is
passed to the DB_PREASSIGN method for assignment.
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param method: Same as :method:`ConfiguresHandlers._assign_db_preassign_handler()`.
:param configured: Same as :method:`ConfiguresHandlers.assign_handler()`.
:returns: str -- The assigned handler ID.
"""
if configured:
return self._handler_assignment_method_methods[HANDLER_ASSIGNMENT_METHODS.DB_PREASSIGN](
obj, method, configured, **kwargs
)
obj.set_handler(self.app.config.server_name)
_timed_flush_obj(obj)
return self.app.config.server_name
def _assign_db_preassign_handler(self, obj, method, configured, index=None, **kwargs):
"""Assign object to a handler by setting its ``handler`` column in the database to a handler selected at random
from the known handlers in the appropriate tag.
Given a handler ID or tag, return a handler matching it, of those handlers that are statically configured in
the job configuration, or known via preconfigured pools.
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param method: Assignment method currently being checked.
:type method: Value in :data:`HANDLER_ASSIGNMENT_METHODS`.
:param configured: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param index: Generate "consistent" "random" handlers with this index if specified.
:type index: int
:raises KeyError: if the configured or default handler is not a known handler ID or tag.
:returns: str -- A valid job handler ID.
"""
handler = configured
if handler is None:
handler = self.default_handler_id or self.DEFAULT_HANDLER_TAG
# Get a random handler ID from the possible handlers. If the admin has configured a tool with a handler tag that
# does not exist, or if there are no default handlers and configured is None, this will raise KeyError to
# assign_handler, which should log it, try the next method (if any), and if no other methods succeed, raise
# HandlerAssigmentError.
handler_id = self._get_single_item(self.handlers[handler], index=index)
if handler != handler_id:
log.debug("(%s) Selected handler '%s' by random choice from handler tag '%s'", obj.log_str(),
handler_id, handler)
obj.set_handler(handler_id)
_timed_flush_obj(obj)
return handler_id
def _assign_db_tag(self, obj, method, configured, **kwargs):
"""Assign object to a handler by setting its ``handler`` column in the database to either the configured handler
ID or tag, or to the default tag (or ``_default_``)
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param method: Same as :method:`ConfiguresHandlers._assign_db_preassign_handler()`.
:param configured: Same as :method:`ConfiguresHandlers.assign_handler()`.
:returns: str -- The assigned handler pool.
"""
handler = configured
if handler is None:
handler = self.default_handler_id or self.DEFAULT_HANDLER_TAG
obj.set_handler(handler)
_timed_flush_obj(obj)
return handler
def _assign_uwsgi_mule_message_handler(self, obj, method, configured, message_callback=None, **kwargs):
"""Assign object to a handler by sending a setup message to the appropriate handler pool (farm), where a handler
(mule) will receive the message and assign itself.
:param obj: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param method: Same as :method:`ConfiguresHandlers._assign_db_preassign_handler()`.
:param configured: Same as :method:`ConfiguresHandlers.assign_handler()`.
:param queue_callback: Callback returning a setup message to be sent via the stack messaging interface's
``send_message()`` method. No arguments are passed.
:type queue_callback: callable
:raises HandlerAssignmentSkip: if the configured or default handler is not a known handler pool (farm)
:returns: str -- The assigned handler pool.
"""
assert message_callback is not None, \
"Cannot perform '%s' handler assignment: `message_callback` is None" \
% HANDLER_ASSIGNMENT_METHODS.UWSGI_MULE_MESSAGE
tag = configured or self.DEFAULT_HANDLER_TAG
pool = self.pool_for_tag.get(tag)
if pool is None:
log.debug("(%s) No handler pool (uWSGI farm) for '%s' found", obj.log_str(), tag)
raise HandlerAssignmentSkip()
else:
_timed_flush_obj(obj)
message = message_callback()
self.app.application_stack.send_message(pool, message)
return pool
[docs] def assign_handler(self, obj, configured=None, **kwargs):
"""Set a job handler, flush obj
Called assignment methods should raise :exception:`HandlerAssignmentSkip` to indicate that the next method
should be tried.
:param obj: Object to assign a handler to (must be a model object with ``handler`` attribute and
``log_str`` callable).
:type obj: instance of :class:`galaxy.model.Job` or other model object with a ``set_handler()`` method.
:param configured: Preconfigured handler (ID, tag, or None) for the given object.
:type configured: str or None.
:returns: bool -- True on successful assignment, False otherwise.
"""
# It's a bit awkward that the method that actually hands off job execution is in the JobConfiguration, but
# that's currently the best place for it. It's worth noting that this method is also part of the
# WorkflowSchedulingManager, which acts like a combined JobConfiguration and JobManager. Combining those two
# classes would probably be reasonable (and would remove the need for the queue callback).
if self._assign_handler_direct(obj, configured):
log.info("(%s) Skipped handler assignment logic due to explicit configuration to a single handler: %s",
obj.log_str(), configured)
return True
for method in self.handler_assignment_methods:
try:
handler = self._handler_assignment_method_methods[method](
obj, method, configured=configured, **kwargs)
log.info("(%s) Handler '%s' assigned using '%s' assignment method", obj.log_str(), handler, method)
return handler
except HandlerAssignmentSkip:
log.debug("(%s) Handler assignment method '%s' did not assign a handler, trying next method",
obj.log_str(), method)
except Exception:
log.exception("Caught exception in handler assignment method: %s", method)
else:
# Ideally we could just expunge the object from the SA session here, but in most cases, some of its related
# objects have already been created, so instead we'll just have to fail it.
log.error("(%s) Failed to select handler", obj.log_str())
raise HandlerAssignmentError("Job handler assignment failed.", obj=obj)
def _timed_flush_obj(obj):
obj_flush_timer = ExecutionTimer()
sa_session = object_session(obj)
sa_session.flush()
log.info("Flushed transaction for %s %s" % (obj.log_str(), obj_flush_timer))