openstack/mistral
Code Issues Proposed changes

Towards non-locking model: adapt 'join' tasks to work w/o locks

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* Added a scheduled job to check if a 'join' task is allowed to
  start in a separate transaction to prevent phantom reads.
  Architecturally this is done in a generic way with a thought
  in mind that we also need to adapt reverse workflow to work
  similarly. In order to avoid getting duplicates for 'join'
  tasks recently added DB API methods 'insert_or_ignore' is used.

TODO:
* Fix ReverseWorkflowController to work in non-locking model
* Fix 'with-items' so that it can work in non-locking model

Partially implements: blueprint mistral-non-locking-tx-model
Change-Id: Ia319965a65d7b3f09eaf28792104d7fd58e9c82e
This commit is contained in:
Renat Akhmerov
2016-08-05 19:35:51 +07:00
parent ca021e1a63
commit 9f236248c1
13 changed files with 333 additions and 143 deletions
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33
mistral/workflow/base.py
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@@ -86,28 +86,25 @@ class WorkflowController(object):
self.wf_spec = wf_spec
@profiler.trace('workflow-controller-continue-workflow')
def continue_workflow(self):
def continue_workflow(self, task_ex=None):
"""Calculates a list of commands to continue the workflow.
Given a workflow specification this method makes required analysis
according to this workflow type rules and identifies a list of
commands needed to continue the workflow.
:param task_ex: Task execution that caused workflow continuation.
Optional. If not specified, it means that no certain task caused
this operation (e.g. workflow has been just started or resumed
manually).
:return: List of workflow commands (instances of
mistral.workflow.commands.WorkflowCommand).
"""
# TODO(rakhmerov): We now use this method for two cases:
# 1) to handle task completion
# 2) to resume a workflow after it's been paused
# Moving forward we need to introduce a separate method for
# resuming a workflow because it won't be operating with
# any concrete tasks that caused this operation.
if self._is_paused_or_completed():
return []
return self._find_next_commands()
return self._find_next_commands(task_ex)
def rerun_tasks(self, task_execs, reset=True):
"""Gets commands to rerun existing task executions.
@@ -128,11 +125,21 @@ class WorkflowController(object):
return cmds
@abc.abstractmethod
def is_task_start_allowed(self, task_ex):
"""Determines if the given task is allowed to start.
:param task_ex: Task execution.
:return: True if all preconditions are met and the given task
is allowed to start.
"""
raise NotImplementedError
@abc.abstractmethod
def is_error_handled_for(self, task_ex):
"""Determines if error is handled for specific task.
:param task_ex: Task execution perform a check for.
:param task_ex: Task execution.
:return: True if either there is no error at all or
error is considered handled.
"""
@@ -162,7 +169,9 @@ class WorkflowController(object):
"""
raise NotImplementedError
def _get_task_inbound_context(self, task_spec):
def get_task_inbound_context(self, task_spec):
# TODO(rakhmerov): This method should also be able to work with task_ex
# to cover 'split' (aka 'merge') use case.
upstream_task_execs = self._get_upstream_task_executions(task_spec)
upstream_ctx = data_flow.evaluate_upstream_context(upstream_task_execs)
@@ -190,7 +199,7 @@ class WorkflowController(object):
raise NotImplementedError
@abc.abstractmethod
def _find_next_commands(self):
def _find_next_commands(self, task_ex):
"""Finds commands that should run next.
A concrete algorithm of finding such tasks depends on a concrete