Add initial support for `mb run --swarmed`.

This adds the initial support to MB to be able to build and run
a binary under swarming easily. It builds on the existing code
in MB for building and isolating targets, and just adds uploading
the isolate, triggering the task, waiting for and collecting the
results.
e
The end goal is that it should be this easy to reproduce a failure
in a bot config:

    $ fetch chromium && python src\tools\mb\mb.py run --swarmed \
        --master tryserver.chromium.win \
        --builder win-msvc-rel \
        out\Release base_unittests

Adding this gives us a starting framework that we can build on
for the bit.ly/chromium-test-runner-api cleanup work.

R=jbudorick@chromium.org, maruel@chromium.org
BUG=794783

Change-Id: I160706b1a563bceb36b8465857d32692a3ca004d
Reviewed-on: https://chromium-review.googlesource.com/825925
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524568}

tools/mb/docs/user_guide.md

@@ -132,6 +132,13 @@ incorporated into the appropriate flags for GN as needed.
 
 Produces help output on the other subcommands
 
+### `mb isolate`
+
+Builds a given (ninja) target and produces an `.isolated` file suitable
+for then running the command either locally in an isolated environment,
+or remotely by uploading it to an isolate server and running it under
+swarming. See below for more information on isolates and swarming.
+
 ### `mb lookup`
 
 Prints what command will be run by `mb gen` (like `mb gen -n` but does
@@ -141,6 +148,24 @@ The `-b/--builder`, `-c/--config`, `-f/--config-file`, `-m/--master`,
 `--phase`, `-q/--quiet`, and `-v/--verbose` flags work as documented for
 `mb gen`.
 
+### `mb run`
+
+Builds and runs a given (ninja) target. By default the target will
+be run locally but isolated (i.e., outside of the source tree, just
+as it would be run under swarming). If the `-s/--swarming` flag is
+passed, the target will be built, run, uploaded to the isolate server,
+and run under swarming.
+
+By default, a set of dimensions appropriate for running the target in the
+default pool for the build will be provided. You can specify additional
+dimensions with the `-d/--dimension` flags, and you can skip the default
+dimensions with the `--no-default-dimensions` flag (which can be useful
+if you need to run on devices or in a different pool). See below for more
+information on isolates and swarming.
+
+In either case, any flags past `--` will be passed on to the command
+to be run inside the isolate.
+
 ### `mb validate`
 
 Does internal checking to make sure the config file is syntactically

tools/mb/mb.py

@@ -3,7 +3,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""MB - the Meta-Build wrapper around GN
+"""MB - the Meta-Build wrapper around GN.
 
 MB is a wrapper script for GN that can be used to generate build files
 for sets of canned configurations and analyze them.
@@ -17,6 +17,7 @@ import errno
 import json
 import os
 import pipes
+import platform
 import pprint
 import re
 import shutil
@@ -179,7 +180,6 @@ class MetaBuildWrapper(object):
         '    --test-launcher-retry-limit=0'
         '\n'
     )
-
     AddCommonOptions(subp)
     subp.add_argument('-j', '--jobs', dest='jobs', type=int,
                       help='Number of jobs to pass to ninja')
@@ -191,6 +191,14 @@ class MetaBuildWrapper(object):
                             ' This can be either a regular path or a '
                             'GN-style source-relative path like '
                             '//out/Default.'))
+    subp.add_argument('-s', '--swarmed', action='store_true',
+                      help='Run under swarming with the default dimensions')
+    subp.add_argument('-d', '--dimension', default=[], action='append', nargs=2,
+                      dest='dimensions', metavar='FOO bar',
+                      help='dimension to filter on')
+    subp.add_argument('--no-default-dimensions', action='store_false',
+                      dest='default_dimensions', default=True,
+                      help='Do not automatically add dimensions to the task')
     subp.add_argument('target', nargs=1,
                       help='ninja target to build and run')
     subp.add_argument('extra_args', nargs='*',
@@ -313,19 +321,78 @@ class MetaBuildWrapper(object):
     if ret:
       return ret
 
+    if self.args.swarmed:
+      return self._RunUnderSwarming(build_dir, target)
+    else:
+      return self._RunLocallyIsolated(build_dir, target)
+
+  def _RunUnderSwarming(self, build_dir, target):
+    # TODO(dpranke): Look up the information for the target in
+    # the //testing/buildbot.json file, if possible, so that we
+    # can determine the isolate target, command line, and additional
+    # swarming parameters, if possible.
+    #
+    # TODO(dpranke): Also, add support for sharding and merging results.
+    dimensions = []
+    for k, v in self._DefaultDimensions() + self.args.dimensions:
+      dimensions += ['-d', k, v]
+
+    cmd = [
+        self.executable,
+        self.PathJoin('tools', 'swarming_client', 'isolate.py'),
+        'archive',
+        '-s',
+        self.ToSrcRelPath('%s/%s.isolated' % (build_dir, target)),
+        '-I', 'isolateserver.appspot.com',
+      ]
+    ret, out, _ = self.Run(cmd, force_verbose=False)
+    if ret:
+      return ret
+
+    isolated_hash = out.splitlines()[0].split()[0]
+    cmd = [
+        self.executable,
+        self.PathJoin('tools', 'swarming_client', 'swarming.py'),
+          'run',
+          '-s', isolated_hash,
+          '-I', 'isolateserver.appspot.com',
+          '-S', 'chromium-swarm.appspot.com',
+      ] + dimensions
+    if self.args.extra_args:
+      cmd += ['--'] + self.args.extra_args
+    ret, _, _ = self.Run(cmd, force_verbose=True, buffer_output=False)
+    return ret
+
+  def _RunLocallyIsolated(self, build_dir, target):
     cmd = [
         self.executable,
         self.PathJoin('tools', 'swarming_client', 'isolate.py'),
         'run',
         '-s',
         self.ToSrcRelPath('%s/%s.isolated' % (build_dir, target)),
-    ]
+      ]
     if self.args.extra_args:
-        cmd += ['--'] + self.args.extra_args
+      cmd += ['--'] + self.args.extra_args
+    ret, _, _ = self.Run(cmd, force_verbose=True, buffer_output=False)
+    return ret
 
-    ret, _, _ = self.Run(cmd, force_verbose=False, buffer_output=False)
+  def _DefaultDimensions(self):
+    if not self.args.default_dimensions:
+      return []
+
+    # This code is naive and just picks reasonable defaults per platform.
+    if self.platform == 'darwin':
+      os_dim = ('os', 'Mac-10.12')
+    elif self.platform.startswith('linux'):
+      os_dim = ('os', 'Ubuntu-14.04')
+    elif self.platform == 'win32':
+      os_dim = ('os', 'Windows-10-14393')
+    else:
+      raise MBErr('unrecognized platform string "%s"' % self.platform)
 
-    return ret
+    return [('pool', 'Chrome'),
+            ('cpu', 'x86-64'),
+            os_dim]
 
   def CmdBuildbucket(self):
     self.ReadConfigFile()

tools/mb/mb_unittest.py

@@ -478,6 +478,33 @@ class UnitTest(unittest.TestCase):
     self.check(['run', '-c', 'debug_goma', '//out/Default',
                 'base_unittests'], files=files, ret=0)
 
+  def test_run_swarmed(self):
+    files = {
+      '/fake_src/testing/buildbot/gn_isolate_map.pyl': (
+          "{'base_unittests': {"
+          "  'label': '//base:base_unittests',"
+          "  'type': 'raw',"
+          "  'args': [],"
+          "}}\n"
+      ),
+      '/fake_src/out/Default/base_unittests.runtime_deps': (
+          "base_unittests\n"
+      ),
+    }
+
+    def run_stub(cmd, **_kwargs):
+      if 'isolate.py' in cmd[1]:
+        return 0, 'fake_hash base_unittests', ''
+      else:
+        return 0, '', ''
+
+    mbw = self.fake_mbw(files=files)
+    mbw.Run = run_stub
+    self.check(['run', '-s', '-c', 'debug_goma', '//out/Default',
+                'base_unittests'], mbw=mbw, ret=0)
+    self.check(['run', '-s', '-c', 'debug_goma', '-d', 'os', 'Win7',
+                '//out/Default', 'base_unittests'], mbw=mbw, ret=0)
+
   def test_lookup(self):
     self.check(['lookup', '-c', 'debug_goma'], ret=0)