Check for the existence of goma before trying to use it

buildbot/buildbot_pnacl_toolchain.py

 #!/usr/bin/python
 # Copyright (c) 2013 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import logging
 import os
 import platform
 import subprocess
@@ skipping 10 matching lines @@
 NACL_DIR = os.path.dirname(SCRIPT_DIR)
 TOOLCHAIN_BUILD_DIR = os.path.join(NACL_DIR, 'toolchain_build')
 TOOLCHAIN_BUILD_OUT_DIR = os.path.join(TOOLCHAIN_BUILD_DIR, 'out')
 
 TEMP_PACKAGES_FILE = os.path.join(TOOLCHAIN_BUILD_OUT_DIR, 'packages.txt')
 
 BUILD_DIR = os.path.join(NACL_DIR, 'build')
 PACKAGE_VERSION_DIR = os.path.join(BUILD_DIR, 'package_version')
 PACKAGE_VERSION_SCRIPT = os.path.join(PACKAGE_VERSION_DIR, 'package_version.py')
 
+GOMA_PATH = '/b/build/goma'
+GOMA_CTL = os.path.join(GOMA_PATH, 'goma_ctl.py')
+
 # As this is a buildbot script, we want verbose logging. Note however, that
 # toolchain_build has its own log settings, controlled by its CLI flags.
 logging.getLogger().setLevel(logging.DEBUG)
 
 parser = argparse.ArgumentParser(description='PNaCl toolchain buildbot script')
 group = parser.add_mutually_exclusive_group()
 group.add_argument('--buildbot', action='store_true',
                  help='Buildbot mode (build and archive the toolchain)')
 group.add_argument('--trybot', action='store_true',
                  help='Trybot mode (build but do not archove the toolchain)')
@@ skipping 24 matching lines @@
 buildbot_lib.SetDefaultContextAttributes(context)
 context['pnacl'] = True
 status = buildbot_lib.BuildStatus(context)
 
 toolchain_install_dir = os.path.join(
     NACL_DIR,
     'toolchain',
     '%s_%s' % (host_os, pynacl.platform.GetArch()),
     'pnacl_newlib')
 
-use_goma = buildbot_lib.RunningOnBuildbot() and not args.no_goma
+use_goma = (buildbot_lib.RunningOnBuildbot() and not args.no_goma
+            and os.path.isfile(GOMA_CTL))
 
 
 def ToolchainBuildCmd(sync=False, extra_flags=[]):
   sync_flag = ['--sync'] if sync else []
   executable_args = [os.path.join('toolchain_build','toolchain_build_pnacl.py'),
                      '--verbose', '--clobber',
                      '--packages-file', TEMP_PACKAGES_FILE]
 
   if pynacl.platform.IsLinux64():
     executable_args.append('--build-sbtc')
@@ skipping 10 matching lines @@
     executable_args.append('--trybot')
 
   # Enabling LLVM assertions have a higher cost on Windows, particularly in the
   # presence of threads. So disable them on windows but leave them on elsewhere
   # to get the extra error checking.
   # See https://code.google.com/p/nativeclient/issues/detail?id=3830
   if host_os == 'win':
     executable_args.append('--disable-llvm-assertions')
 
   if use_goma:
-    executable_args.append('--goma=/b/build/goma')
+    executable_args.append('--goma=' + GOMA_PATH)
 
   return [sys.executable] + executable_args + sync_flag + extra_flags
 
 
 def RunWithLog(cmd):
   logging.info('Running: ' + ' '.join(cmd))
   subprocess.check_call(cmd)
   sys.stdout.flush()
 
 
@@ skipping 14 matching lines @@
 
 if host_os != 'win':
   with buildbot_lib.Step('update clang', status):
     buildbot_lib.Command(
         context,
         [sys.executable,
          os.path.join(
              NACL_DIR, '..', 'tools', 'clang', 'scripts', 'update.py')])
 
 if use_goma:
-  buildbot_lib.Command(context, cmd=[
-      sys.executable, '/b/build/goma/goma_ctl.py', 'restart'])
+  buildbot_lib.Command(context, cmd=[sys.executable, GOMA_CTL, 'restart'])
 
 # toolchain_build outputs its own buildbot annotations, so don't use
 # buildbot_lib.Step to run it here.
 
 # The package_version tools don't have a way to distinguish canonical packages
 # (i.e. those we want to upload) from non-canonical ones; they only know how to
 # process all the archives that are present. We can't just leave out the
 # the non-canonical packages entirely because they are extracted by the
 # package_version tool.
 # First build only the packages that will be uploaded, and upload them.
 RunWithLog(ToolchainBuildCmd(sync=True, extra_flags=['--canonical-only']))
 
 if use_goma:
-  buildbot_lib.Command(context, cmd=[
-      sys.executable, '/b/build/goma/goma_ctl.py', 'stop'])
+  buildbot_lib.Command(context, cmd=[sys.executable, GOMA_CTL, 'stop'])
 
 if args.skip_tests:
   sys.exit(0)
 
 if args.buildbot or args.trybot:
   # Don't upload packages from the 32-bit linux bot to avoid racing on
   # uploading the same packages as the 64-bit linux bot
   if host_os != 'linux' or pynacl.platform.IsArch64Bit():
     packages.UploadPackages(TEMP_PACKAGES_FILE, args.trybot, args.sanitize)
 
@@ skipping 70 matching lines @@
 
   if args.buildbot:
     trybot_mode = 'false'
   else:
     trybot_mode = 'true'
 
   platform_arg = 'mode-buildbot-tc-' + arch + '-linux'
 
   command = ['bash', buildbot_shell, platform_arg,  trybot_mode]
   RunWithLog(command)