Bug 1514087: [taskgraph] Add an option to not optimize target tasks in cron graphs; r=dustin

This allows the target tasks to include cached tasks, which by default, get
optimized out of the graph on on-`try` branches.

Differential Revision: https://phabricator.services.mozilla.com/D15278

--HG--
extra : moz-landing-system : lando

.cron.yml

@@ -104,6 +104,7 @@ jobs:
           type: decision-task
           treeherder-symbol: customv8
           target-tasks-method: customv8_update
+          optimize-target-tasks: false
       run-on-projects:
           - mozilla-central
       when:

taskcluster/mach_commands.py

@@ -13,6 +13,7 @@ import os
 import sys
 import traceback
 import re
+from distutils.util import strtobool
 
 from mach.decorators import (
     CommandArgument,
@@ -171,6 +172,12 @@ class MachCommands(MachCommandBase):
                      help='SCM level of this repository')
     @CommandArgument('--target-tasks-method',
                      help='method for selecting the target tasks to generate')
+    @CommandArgument('--optimize-target-tasks',
+                     type=strtobool,
+                     nargs='?', const='true',
+                     help='If specified, this indicates whether the target '
+                          'tasks are eligible for optimization. Otherwise, '
+                          'the default for the project is used.')
     @CommandArgument('--try-task-config-file',
                      help='path to try task configuration file')
     def taskgraph_decision(self, **options):

taskcluster/taskgraph/cron/decision.py

@@ -21,6 +21,10 @@ def run_decision_task(job, params, root):
     arguments = []
     if 'target-tasks-method' in job:
         arguments.append('--target-tasks-method={}'.format(job['target-tasks-method']))
+    if job.get('optimize-target-tasks') is not None:
+        arguments.append('--optimize-target-tasks={}'.format(
+            str(job['optimize-target-tasks']).lower(),
+        ))
     return [
         make_decision_task(
             params,

taskcluster/taskgraph/cron/schema.py

@@ -7,7 +7,7 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
-from voluptuous import Any, Required, All
+from voluptuous import Any, Required, All, Optional
 from taskgraph.util.schema import (
     optionally_keyed_by,
     validate_schema,
@@ -36,6 +36,13 @@ cron_yml_schema = Schema({
 
             # --target-tasks-method './mach taskgraph decision' argument
             'target-tasks-method': basestring,
+
+            Optional(
+                'optimize-target-tasks',
+                description='If specified, this indicates whether the target '
+                            'tasks are eligible for optimization. Otherwise, '
+                            'the default for the project is used.',
+            ): bool,
         },
 
         # when to run it

taskcluster/taskgraph/decision.py

@@ -286,6 +286,9 @@ def get_decision_parameters(config, options):
     if 'try' in project:
         set_try_config(parameters, task_config_file)
 
+    if options.get('optimize_target_tasks') is not None:
+        parameters['optimize_target_tasks'] = options['optimize_target_tasks']
+
     result = Parameters(**parameters)
     result.check()
     return result