Bug 1397722 - [tryselect] Filter 'ccov' tasks out of the target task set (now they must be selected with --full), r=sparky

Usually people don't mean to schedule code coverage tasks on try. But e.g |mach
try fuzzy -q "'mochitest"|, will cause them to be scheduled as a side effect.
This results in wasted resources and superfluous data in ActiveData.

This patch makes it so you need to explicitly pass --full to select ccov tasks
(even though they're technically part of the target task graph).

Differential Revision: https://phabricator.services.mozilla.com/D3917

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

tools/tryselect/tasks.py

@@ -6,6 +6,7 @@ from __future__ import absolute_import, print_function, unicode_literals
 
 import hashlib
 import os
+import re
 import shutil
 import sys
 
@@ -35,6 +36,12 @@ To fix this, either rebase onto the latest mozilla-central or pass in
 https://firefox-source-docs.mozilla.org/taskcluster/taskcluster/mach.html#parameters
 """
 
+# Some tasks show up in the target task set, but are either special cases
+# or uncommon enough that they should only be selectable with --full.
+TARGET_TASK_FILTERS = (
+    '.*-ccov\/.*',
+)
+
 
 def invalidate(cache, root):
     if not os.path.isfile(cache):
@@ -48,6 +55,10 @@ def invalidate(cache, root):
         os.remove(cache)
 
 
+def filter_target_task(task):
+    return not any(re.search(pattern, task) for pattern in TARGET_TASK_FILTERS)
+
+
 def generate_tasks(params, full, root):
     params = params or "project=mozilla-central"
 
@@ -85,6 +96,9 @@ def generate_tasks(params, full, root):
     tg = getattr(TaskGraphGenerator(root_dir=root, parameters=params), attr)
     labels = [label for label in tg.graph.visit_postorder()]
 
+    if not full:
+        labels = filter(filter_target_task, labels)
+
     os.chdir(cwd)
 
     with open(cache, 'w') as fh: