Bug 1420449: Add mach taskgraph -F/--fast r=ahal

Initially this will skip toolchain task optimizations, which avoids hashing
local directory contents and speeds up taskgraph generation by about 25%.

MozReview-Commit-ID: B4LB5BV86nw

--HG--
extra : rebase_source : c41e4d838e8920b865cd62bb8de38e64b85b2d84

taskcluster/mach_commands.py

@@ -51,7 +51,9 @@ class ShowTaskGraphSubCommand(SubCommand):
                             "index (a.k.a. optimize the graph)"),
             CommandArgument('--tasks-regex', '--tasks', default=None,
                             help="only return tasks with labels matching this regular "
-                            "expression.")
+                            "expression."),
+            CommandArgument('-F', '--fast', dest='fast', default=False, action='store_true',
+                            help="enable fast task generation for local debugging.")
 
         ]
         for arg in args:
@@ -316,6 +318,9 @@ class MachCommands(MachCommandBase):
         import taskgraph.parameters
         import taskgraph.target_tasks
         import taskgraph.generator
+        import taskgraph
+        if options['fast']:
+            taskgraph.fast = True
 
         try:
             self.setup_logging(quiet=options['quiet'], verbose=options['verbose'])

taskcluster/taskgraph/__init__.py

@@ -7,3 +7,8 @@ from __future__ import absolute_import, print_function, unicode_literals
 import os
 
 GECKO = os.path.realpath(os.path.join(__file__, '..', '..', '..'))
+
+# Enable fast task generation for local debugging
+# This is normally switched on via the --fast/-F flag to `mach taskgraph`
+# Currently this skips toolchain task optimizations
+fast = False

taskcluster/taskgraph/transforms/job/toolchain.py

@@ -22,6 +22,7 @@ from taskgraph.transforms.job.common import (
 from taskgraph.util.hash import hash_paths
 from taskgraph import GECKO
 from taskgraph.util.cached_tasks import add_optimization
+import taskgraph
 
 
 CACHE_TYPE = 'toolchains.v2'
@@ -155,13 +156,14 @@ def docker_worker_toolchain(config, job, taskdesc):
     if 'toolchain-alias' in run:
         attributes['toolchain-alias'] = run['toolchain-alias']
 
-    name = taskdesc['label'].replace('{}-'.format(config.kind), '', 1)
-    add_optimization(
-        config, taskdesc,
-        cache_type=CACHE_TYPE,
-        cache_name=name,
-        digest_data=get_digest_data(config, run, taskdesc),
-    )
+    if not taskgraph.fast:
+        name = taskdesc['label'].replace('{}-'.format(config.kind), '', 1)
+        add_optimization(
+            config, taskdesc,
+            cache_type=CACHE_TYPE,
+            cache_name=name,
+            digest_data=get_digest_data(config, run, taskdesc),
+        )
 
 
 @run_job_using("generic-worker", "toolchain-script", schema=toolchain_run_schema)
@@ -217,10 +219,11 @@ def windows_toolchain(config, job, taskdesc):
     if 'toolchain-alias' in run:
         attributes['toolchain-alias'] = run['toolchain-alias']
 
-    name = taskdesc['label'].replace('{}-'.format(config.kind), '', 1)
-    add_optimization(
-        config, taskdesc,
-        cache_type=CACHE_TYPE,
-        cache_name=name,
-        digest_data=get_digest_data(config, run, taskdesc),
-    )
+    if not taskgraph.fast:
+        name = taskdesc['label'].replace('{}-'.format(config.kind), '', 1)
+        add_optimization(
+            config, taskdesc,
+            cache_type=CACHE_TYPE,
+            cache_name=name,
+            digest_data=get_digest_data(config, run, taskdesc),
+        )