Teach dart_package to understand the packages/ subdirectory

mojo/public/tools/git/dart_pub_get.py

+#!/usr/bin/python
+# Copyright 2015 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.
+
+"""This script runs "pub get" on all directories within the tree that have
+pubspec.yaml files.
+
+See https://www.dartlang.org/tools/pub/get-started.html for information about
+the pub tool."""
+
+import argparse
+import os
+import subprocess
+import sys
+
+def pub_get(dart_sdk_path, target_directory):
+  cmd = [
+    os.path.join(dart_sdk_path, "bin/pub")
+  ]
+  cmd.extend(["get"])
+
+  # Cache the downloaded pubs inside the repo to avoid the chance of multiple
+  # simultaneous builds in different repos stomping on each other.

[tonyg, 2015/04/09 12:55:57]

I wouldn't change anything here for now, but it seems like we'd want to file a
dart bug if multiple `pub get`s can't be run in parallel.

[blundell, 2015/04/09 15:34:36]

This was based on feedback from zra@, fwiw.

[zra, 2015/04/09 16:20:48]

For better or worse, pub was envisioned as a developer tool, not really intended
to run on a builder. By default the pub cache goes under ~/.pub-cache. If there
are multiple pubs running in parallel they could race on reads/writes under that
directory. Since this isn't a use case that pub was originally designed for,
using the PUB_CACHE environment variable is the recommended work-around.

+  env = os.environ.copy()
+  env["PUB_CACHE"] = os.path.join(os.getcwd(), ".pub-cache")
+  subprocess.check_output(cmd, shell=False,
+                          stderr=subprocess.STDOUT,
+                          cwd=target_directory,
+                          env=env)
+
+
+def main(repository_root, dart_sdk_path):
+  os.chdir(repository_root)
+
+  # Relativize dart_sdk_path to repository_root.
+  dart_sdk_path_from_root = os.path.join(repository_root,
+      os.path.relpath(dart_sdk_path, repository_root))
+
+  cmd = ["git", "ls-files", "*pubspec.yaml"]

[tonyg, 2015/04/09 12:55:57]

I don't know the syntax here, but it looks like this might match
"foopubspec.yaml". Is there a way to allow arbitrary directories but not file
prefixes. Like maybe "*/pubspec.yaml"?

[blundell, 2015/04/09 15:34:36]

Done.

+  pubspec_yaml_files = subprocess.check_output(cmd,
+                                               shell=False,
+                                               stderr=subprocess.STDOUT)
+
+  for f in pubspec_yaml_files.split():
+    pub_get(dart_sdk_path_from_root, os.path.dirname(f))
+
+
+if __name__ == '__main__':
+  parser = argparse.ArgumentParser(
+      description="Run 'pub get' on all directories with checked-in "
+                  "pubspec.yaml files")
+  parser.add_argument("--repository-root",
+                      dest="repository_root",

[tonyg, 2015/04/09 12:55:57]

nit: you can omit the dests when the only change is s/-/_/.

[blundell, 2015/04/09 15:34:36]

Done.

+                      metavar="<repository-root>",
+                      type=str,
+                      required=True,
+                      help="Path to the root of the Git repository, "
+                           "specified as a relative path from this directory.")
+  parser.add_argument("--dart-sdk-directory",
+                      dest="dart_sdk_directory",
+                      metavar="<dart-sdk-directory>",
+                      type=str,
+                      required=True,
+                      help="Path to the directory containing the Dart SDK, "
+                           "specified as a relative path from this directory.")
+  args = parser.parse_args()
+  _current_path = os.path.dirname(os.path.realpath(__file__))
+  _repository_root = os.path.join(_current_path, args.repository_root)
+  _dart_sdk_path = os.path.join(_current_path, args.dart_sdk_directory)
+  sys.exit(main(_repository_root, _dart_sdk_path))