make importing matplotlib optional

tools/testing/perf_testing/run_perf_tests.py

 #!/usr/bin/python
 
 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import datetime
 import getpass
 import math
-from matplotlib.font_manager import FontProperties
-import matplotlib.pyplot as plt
+try:
+  from matplotlib.font_manager import FontProperties
+  import matplotlib.pyplot as plt
+except ImportError:
+  pass # Only needed if we want to make graphs.
 import optparse
 import os
 from os.path import dirname, abspath
 import platform
 import re
 import shutil
 import stat
 import subprocess
 import sys
 import time
@@ skipping 346 matching lines @@
     os.chdir(os.path.join('tools', 'testing', 'perf_testing'))
 
     # TODO(efortuna): You will want to make this only use a subset of the files
     # eventually.
     files = os.listdir(self.result_folder_name)
 
     for afile in files:
       if not afile.startswith('.'):
         self.process_file(afile)
 
-    self.plot_results('%s.png' % self.result_folder_name)
+    if 'plt' in globals():
+      # Only run Matplotlib if it is installed.
+      self.plot_results('%s.png' % self.result_folder_name)
+    else:
+      print 'Unable to import Matplotlib and therefore unable to generate ' + \
+          'graphs. Please install it for this version of Python.'
 
 class PerformanceTest(TestRunner):
   """Super class for all performance testing."""
   def __init__(self, result_folder_name, platform_list, platform_type,
                versions, benchmarks):
     super(PerformanceTest, self).__init__(result_folder_name,
         platform_list, versions, benchmarks)
     self.platform_list = platform_list
     self.platform_type = platform_type
     self.versions = versions
@@ skipping 546 matching lines @@
       else:
         print 'Error: Invalid suite %s not in %s' % (name,
                                                      ','.join(SUITES.keys()))
         sys.exit(1)
   return (suites, args.continuous, args.verbose, args.no_build,
           args.graph_only, args.upload)
 
 def run_test_sequence(suites, no_build, graph_only, upload):
   # The buildbot already builds and syncs to a specific revision. Don't fight
   # with it or replicate work.
-  if (not no_build or not graph_only) and sync_and_build() == 1:
+  if not no_build and sync_and_build() == 1:
     return # The build is broken.
 
   for test in suites:
     test().run(graph_only)
 
   if upload:
     upload_to_app_engine(SUITES.keys())
 
 def main():
   global VERBOSE
   (suites, continuous, verbose, no_build, graph_only, upload) = parse_args()
   VERBOSE = verbose
   if continuous:
     while True:
       if has_new_code():
         run_test_sequence(suites, no_build, graph_only, upload)
       else:
         time.sleep(SLEEP_TIME)
   else:
     run_test_sequence(suites, no_build, graph_only, upload)
 
 if __name__ == '__main__':
   main()