AU: Cycle Breaker for directed graphs.

src/platform/update_engine/SConstruct

 # Copyright (c) 2009 The Chromium OS 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 os
 
 # Protobuffer compilation
 """ Inputs:
         target: list of targets to compile to
         source: list of sources to compile
@@ skipping 68 matching lines @@
 env.ProtocolBuffer('update_metadata.pb.cc', 'update_metadata.proto')
 
 if ARGUMENTS.get('debug', 0):
   env['CCFLAGS'] += ' -fprofile-arcs -ftest-coverage'
   env['LIBS'] += ['bz2', 'gcov']
 
 
 
 sources = Split("""action_processor.cc
                    bzip_extent_writer.cc
+                   cycle_breaker.cc
                    decompressing_file_writer.cc
                    delta_diff_parser.cc
                    download_action.cc
                    extent_mapper.cc
                    extent_writer.cc
                    filesystem_copier_action.cc
                    filesystem_iterator.cc
                    file_writer.cc
                    graph_utils.cc
                    gzip.cc
                    libcurl_http_fetcher.cc
                    omaha_hash_calculator.cc
                    omaha_request_prep_action.cc
                    omaha_response_handler_action.cc
                    postinstall_runner_action.cc
                    set_bootable_flag_action.cc
                    subprocess.cc
                    tarjan.cc
                    update_check_action.cc
                                update_metadata.pb.cc
                                utils.cc""")
 main = ['main.cc']
 
 unittest_sources = Split("""action_unittest.cc
                             action_pipe_unittest.cc
                             action_processor_unittest.cc
                             bzip_extent_writer_unittest.cc
+                            cycle_breaker_unittest.cc
                             decompressing_file_writer_unittest.cc
                             delta_diff_generator_unittest.cc
                             download_action_unittest.cc
                             extent_mapper_unittest.cc
                             extent_writer_unittest.cc
                             file_writer_unittest.cc
                             filesystem_copier_action_unittest.cc
                             filesystem_iterator_unittest.cc
                             graph_utils_unittest.cc
                             gzip_unittest.cc
@@ skipping 26 matching lines @@
                                  unittest_sources + test_installer_main)
 
 Clean(unittest_cmd, Glob('*.gcda') + Glob('*.gcno') + Glob('*.gcov') +
                     Split('html app.info'))
 
 delta_generator_cmd = env.Program('delta_generator',
                                   sources + delta_generator_sources +
                                   delta_generator_main)
 
 http_server_cmd = env.Program('test_http_server', 'test_http_server.cc')