[Findit] Check existence of given targets before running compile in recipe findit/chromium/compile.

scripts/slave/check_target_existence.py

Index: scripts/slave/check_target_existence.py
diff --git a/scripts/slave/check_target_existence.py b/scripts/slave/check_target_existence.py
new file mode 100755
index 0000000000000000000000000000000000000000..ce831a07037c3636e09d7931b6c50321f6d4d47b
--- /dev/null
+++ b/scripts/slave/check_target_existence.py
@@ -0,0 +1,104 @@
+#!/usr/bin/env python

[iannucci, 2016/03/09 19:01:52]

let's add this under the findit module in the 'resources' subdirectory. Then you
can access it in the findit module by doing
self.resource('check_target_existence.py')

[stgao, 2016/03/09 20:09:11]

Nice! I didn't know about self.resource.

+# Copyright (c) 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""A tool to check whether a target exists in the ninja build graph or not.
+
+  Before this is run, ninja build files should already be generated or updated.
+
+  For a list of command line options, call this script with '--help'.
+"""
+
+import json
+import optparse
+import os
+import subprocess
+import sys
+
+
+def targets_exist(targets, target_build_dir):
+  """Returns True if the given targets exist in the ninja build file.
+
+  Args:
+    targets (list): A list of target names.
+    target_build_dir (str): The path to the target build directory.
+  """
+  print 'Checking targets: %s' % ', '.join(targets)
+  cmd = ['ninja', '-C', target_build_dir, '-t', 'query']

[Nico, 2016/03/08 19:41:36]

(i'm assuming you checked that this does the right thing with multiple targets)

[stgao, 2016/03/09 20:09:11]

Yes, it works as the code expected here. I checked the ninja source code and
also tested with the ninja binary.
If all targets exist, ninja will exit with 0; otherwise ninja will complain upon
the first none-existing target and exit with 1 immediately.

+  cmd.extend(targets)
+  with open(os.devnull, 'w') as f:  # Mute normal output, only care about error.
+    p = subprocess.Popen(cmd, stdout=f)
+  return_code = p.wait()
+  print 'return code: %s' % return_code
+  return return_code == 0
+
+
+def check_targets(targets, target_build_dir):
+  """Returns a dict of two lists to indicate which targets exist or not.
+
+  Args:
+    targets (list): A list of target names.
+    target_build_dir (str): The path to the target build directory.
+  """
+  # Check all the targets at once first in one ninja command.
+  # If a target among a few doesn't exist, ninja will exit immediately and not
+  # process the remaining targets. In that case, we have to check them one by
+  # one instead.
+  all_existing = targets_exist(targets, target_build_dir)
+  if all_existing:  # All targets exists.
+    return {'found': targets, 'not_found': []}
+  elif len(targets) == 1:  # None of the targets exists.
+    return {'found': [], 'not_found': targets}
+  else:  # Some targets do not exist.
+    found = []
+    not_found = []
+    for target in targets:
+      if targets_exist([target], target_build_dir):
+        found.append(target)
+      else:
+        not_found.append(target)
+
+    return {
+        'found': found,
+        'not_found': not_found,
+    }
+
+
+def parse_args():
+  option_parser = optparse.OptionParser()
+  option_parser.add_option('--target-build-dir',
+                           help='The target build directory. eg: out/Release.')
+  option_parser.add_option('--target', action='append', default=[],
+                           help='Specify the target to be checked. eg: '
+                                'browser_tests, obj/path/to/Source.o, or '
+                                'gen/path/to/generated.cc, etc.')
+  option_parser.add_option('--json-output',
+                           help='Optional. Specify a file to dump the result '
+                                'as json.')
+  options, _ = option_parser.parse_args()
+  return options.target_build_dir, options.target, options.json_output
+
+
+def main():
+  target_build_dir, targets, json_output = parse_args()
+  if not (target_build_dir and targets):
+    print 'Invalid parameter.'
+    print 'target-build-dir: %s' % target_build_dir
+    print 'targets:'
+    for target in targets:
+      print '  %s' % target
+    return 1
+
+  result = check_targets(targets, target_build_dir)
+  if json_output:
+    with open(json_output, 'wb') as f:
+      json.dump(result, f, indent=2)
+  else:
+    print json.dumps(result, indent=2)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())