Bug 1624859 - [taskgraph] Always optimize build tasks with ./mach try auto, r=tomprince

This ensures we don't run every build with every push via ./mach try auto. It
introduces a new 'optimization-overrides' try_config that can be used to
replace optimizations. For now, there is no user interface to pass this in via
the 'mach try' command line.

Differential Revision: https://phabricator.services.mozilla.com/D68207

taskcluster/taskgraph/optimize/__init__.py

@@ -259,6 +259,12 @@ class OptimizationStrategy(object):
         return False
 
 
+@register_strategy('always')
+class Always(OptimizationStrategy):
+    def should_remove_task(self, task, params, arg):
+        return True
+
+
 @six.add_metaclass(ABCMeta)
 class CompositeStrategy(OptimizationStrategy):
 
@@ -369,12 +375,15 @@ import_sibling_modules()
 
 
 # Register composite strategies.
+register_strategy('build', args=('skip-unless-schedules',))(Alias)
 register_strategy('test', args=(Any('skip-unless-schedules', 'seta'), 'backstop'))(All)
 register_strategy('test-inclusive', args=('skip-unless-schedules',))(Alias)
 register_strategy('test-try', args=('skip-unless-schedules',))(Alias)
 register_strategy('fuzzing-builds', args=('skip-unless-schedules', 'seta'))(Any)
 
 
+# Strategy overrides used by |mach try| and/or shadow-scheduler tasks.
+
 class experimental(object):
     """Experimental strategies either under development or used as benchmarks.
 
@@ -425,3 +434,30 @@ class experimental(object):
     }
     """Provides a stable history of SETA's performance in the event we make it
     non-default in the future. Only useful as a benchmark."""
+
+
+class ExperimentalOverride(object):
+    """Overrides dictionaries that are stored in a container with new values.
+
+    This can be used to modify all strategies in a collection the same way,
+    presumably with strategies affecting kinds of tasks tangential to the
+    current context.
+
+    Args:
+        base (object): A container class supporting attribute access.
+        overrides (dict): Values to update any accessed dictionaries with.
+    """
+    def __init__(self, base, overrides):
+        self.base = base
+        self.overrides = overrides
+
+    def __getattr__(self, name):
+        val = getattr(self.base, name).copy()
+        val.update(self.overrides)
+        return val
+
+
+tryselect = ExperimentalOverride(experimental, {
+    'build': Alias('always'),
+    'fuzzing-builds': Alias('always'),
+})

taskcluster/taskgraph/transforms/build_attrs.py

@@ -45,5 +45,5 @@ def set_schedules_optimization(config, jobs):
 
         build_platform = job['attributes']['build_platform']
         job.setdefault('optimization',
-                       {'skip-unless-schedules': [platform_family(build_platform)]})
+                       {'build': [platform_family(build_platform)]})
         yield job

taskcluster/taskgraph/util/schema.py

@@ -197,6 +197,10 @@ class Schema(voluptuous.Schema):
 OptimizationSchema = voluptuous.Any(
     # always run this task (default)
     None,
+    # always optimize this task
+    {'always': None},
+    # optimize strategy aliases for build kind
+    {'build': list(schedules.ALL_COMPONENTS)},
     # search the index for the given index namespaces, and replace this task if found
     # the search occurs in order, with the first match winning
     {'index-search': [text_type]},

tools/tryselect/selectors/auto.py

@@ -29,7 +29,7 @@ def run(message='{msg}', push=True, closed_tree=False, try_config=None):
     # XXX Remove once an intelligent scheduling algorithm is running on
     # autoland by default. This ensures `mach try auto` doesn't run SETA.
     try_config.setdefault('optimize-strategies',
-                          'taskgraph.optimize:experimental.bugbug_debug')
+                          'taskgraph.optimize:tryselect.bugbug_debug')
 
     task_config = {
         'version': 2,

tools/tryselect/task_config.py

@@ -318,7 +318,7 @@ class OptimizeStrategies(TryConfig):
     def try_config(self, strategy, **kwargs):
         if strategy:
             if ':' not in strategy:
-                strategy = "taskgraph.optimize:experimental.{}".format(strategy)
+                strategy = "taskgraph.optimize:tryselect.{}".format(strategy)
 
             try:
                 obj = find_object(strategy)

tools/tryselect/test/test_auto.t

@@ -17,7 +17,7 @@ Test auto selector
           "target_tasks_method": "try_auto",
           "try_mode": "try_auto",
           "try_task_config": {
-              "optimize-strategies": "taskgraph.optimize:experimental.bugbug_debug"
+              "optimize-strategies": "taskgraph.optimize:tryselect.bugbug_debug"
           }
       },
       "version": 2
@@ -37,7 +37,7 @@ Test auto selector
           "target_tasks_method": "try_auto",
           "try_mode": "try_auto",
           "try_task_config": {
-              "optimize-strategies": "taskgraph.optimize:experimental.bugbug_debug"
+              "optimize-strategies": "taskgraph.optimize:tryselect.bugbug_debug"
           }
       },
       "version": 2
@@ -56,7 +56,7 @@ Test auto selector
           "target_tasks_method": "try_auto",
           "try_mode": "try_auto",
           "try_task_config": {
-              "optimize-strategies": "taskgraph.optimize:experimental.bugbug_debug"
+              "optimize-strategies": "taskgraph.optimize:tryselect.bugbug_debug"
           }
       },
       "version": 2

tools/tryselect/test/test_task_configs.py

@@ -42,9 +42,9 @@ TASK_CONFIG_TESTS = {
     ],
     'strategy': [
         ([], None),
-        (['--strategy', 'seta'], {'optimize-strategies': 'taskgraph.optimize:experimental.seta'}),
+        (['--strategy', 'seta'], {'optimize-strategies': 'taskgraph.optimize:tryselect.seta'}),
         (['--strategy', 'taskgraph.optimize:experimental.seta'], {'optimize-strategies': 'taskgraph.optimize:experimental.seta'}),  # noqa
-        (['--strategy', 'taskgraph.optimize:experimental'], SystemExit),
+        (['--strategy', 'taskgraph.optimize:tryselect'], SystemExit),
         (['--strategy', 'foo'], SystemExit),
         (['--strategy', 'foo:bar'], SystemExit),
     ],