Update monet.

tools/go/download.py

Index: tools/go/download.py
diff --git a/tools/go/download.py b/tools/go/download.py
new file mode 100755
index 0000000000000000000000000000000000000000..dbd6f90695153f7b430c9b9f7a727ec280b4c886
--- /dev/null
+++ b/tools/go/download.py
@@ -0,0 +1,91 @@
+#!/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.
+
+"""
+Downloads Go binaries from Google Cloud Storage and extracts them to
+INSTALL_DIR, updating INSTALL_DIR/VERSION stamp file with current version.
+Does nothing if INSTALL_DIR/VERSION is already up to date.
+"""
+
+import os
+import shutil
+import subprocess
+import sys
+import tarfile
+
+# Path constants. (All of these should be absolute paths.)
+THIS_DIR = os.path.abspath(os.path.dirname(__file__))
+MOJO_DIR = os.path.abspath(os.path.join(THIS_DIR, '..', '..'))
+# Should be the same as in upload.py.
+INSTALL_DIR = os.path.join(MOJO_DIR, 'third_party', 'go', 'tool')
+
+sys.path.insert(0, os.path.join(MOJO_DIR, 'tools'))
+import find_depot_tools
+
+DEPOT_PATH = find_depot_tools.add_depot_tools_to_path()
+GSUTIL_PATH = os.path.join(DEPOT_PATH, 'gsutil.py')
+
+def RunCommand(command):
+  """Run command and return success (True) or failure."""
+
+  print 'Running %s' % (str(command))
+  if subprocess.call(command, shell=False) == 0:
+    return True
+  print 'Failed.'
+  return False
+
+def VersionFileName():
+  if sys.platform.startswith('linux'):
+    platform_suffix = 'LINUX'
+  elif sys.platform == 'darwin':
+    platform_suffix = 'MACOSX'
+  else:
+    raise Exception('unsupported platform: ' + sys.platform)
+  return 'VERSION_' + platform_suffix
+
+def GetInstalledVersion():
+  version_file = os.path.join(INSTALL_DIR, VersionFileName())
+  if not os.path.exists(version_file):
+    return None
+  with open(version_file) as f:
+    return f.read().strip()
+
+def InstallGoBinaries(version):
+  """Downloads zipped go binaries from Google Cloud Storage and extracts them,
+     stamping current version."""
+
+  # Remove current installation.
+  if os.path.exists(INSTALL_DIR):
+    shutil.rmtree(INSTALL_DIR)
+  os.makedirs(INSTALL_DIR)
+  # Download go tool binaries from GCS.
+  archive_path = os.path.join(INSTALL_DIR, 'go.tar.gz')
+  download_cmd = ['python', GSUTIL_PATH, 'cp',
+                  'gs://mojo/go/tool/%s.tar.gz' % version,
+                  archive_path]
+  if not RunCommand(download_cmd):
+    print ('WARNING: Failed to download Go tool binaries.')
+    return
+
+  print "Extracting Go binaries."
+  with tarfile.open(archive_path) as arch:
+    arch.extractall(INSTALL_DIR)
+  os.remove(archive_path)
+  # Write version as the last step.
+  with open(os.path.join(INSTALL_DIR, VersionFileName()), 'w+') as f:
+    f.write('%s\n' % version)
+
+def main():
+  # Read latest version.
+  version = ''
+  with open(os.path.join(THIS_DIR, VersionFileName())) as f:
+    version = f.read().strip()
+  # Return if installed binaries are up to date.
+  if version == GetInstalledVersion():
+    return
+  InstallGoBinaries(version)
+
+if __name__ == '__main__':
+  sys.exit(main())