build_scan: Fix exception handling

scripts/slave/build_scan.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Scans a list of masters and saves information in a build_db."""
 
 from contextlib import closing
 import json
 import logging
@@ skipping 26 matching lines @@
   }
 
   attempts = 0
   while True:
     try:
       r = urllib2.Request(url, headers=headers)
       with closing(urllib2.urlopen(r, timeout=URL_TIMEOUT)) as f:
         return json.load(f)
     except (urllib2.URLError, IOError) as f:
       if attempts > MAX_ATTEMPTS:
-        raise
+        # Raise a ValueError because this can be called from multiprocessing,
+        # which can't pickle SSLContext objects, which apparently are
+        # properties of urllib2.URLError (it seems).
+        msg = "Error encountered during URL Fetch: %s" % f
+        logging.error(msg)
+        raise ValueError(msg)
 
       attempts += 1
       time_to_sleep = 2 ** attempts
       logging.info(
         "url fetch encountered %s, sleeping for %d seconds and retrying..." % (
             f, time_to_sleep))
 
       time.sleep(time_to_sleep)
 
 
@@ skipping 98 matching lines @@
 
   # Assumes we have something like https://build.chromium.org/p/chromium.perf
   name = master.rstrip('/').split('/')[-1]
   if name in CBE_WHITELIST:
     url = '%s/p/%s/builders/%s/builds/%d?json=1' % (
         CBE_URL, name, urllib.quote(builder), buildnum)
 
   logging.debug('opening %s...' % url)
   return _url_open_json(url), master, builder, buildnum
 
-
 def get_build_jsons(master_builds, processes):
   """Get all new builds on specified masters.
 
   This takes a dict in the form of [master][builder][build], formats that URL
   and appends that to url_list. Then, it forks out and queries each build_url
   for build information.
   """
   url_list = []
   for master, builder_dict in master_builds.iteritems():
     for builder, new_builds in builder_dict.iteritems():
@@ skipping 52 matching lines @@
 
   if not args:
     parser.error('you need to specify at least one master URL')
 
   args = [url.rstrip('/') for url in args]
 
   return options, args
 
 
 def get_updated_builds(masters, build_db, parallelism):
-  try:
-    new_builds, master_jsons = find_new_builds_per_master(masters, build_db)
-    build_jsons = get_build_jsons(new_builds, parallelism)
-    propagate_build_json_to_db(build_db, build_jsons)
-    return master_jsons, build_jsons
+  new_builds, master_jsons = find_new_builds_per_master(masters, build_db)
+  build_jsons = get_build_jsons(new_builds, parallelism)
+  propagate_build_json_to_db(build_db, build_jsons)
+  return master_jsons, build_jsons
 
-  # Catch this and raise a ValueError because this can be called from
-  # mulitprocessing, which can't pickle SSLContext objects, which apparently are
-  # properties of urllib2.URLError (it seems).
-  except (urllib2.URLError, IOError) as f:
-    msg = "Error encountered during URL Fetch: %s" % f
-    logging.error(msg)
-    raise ValueError(msg)
 
 
 def main():
   options, args = get_options()
 
   logging.basicConfig(level=logging.DEBUG if options.verbose else logging.INFO)
 
   masters = {}
   for m in set(args):
     masters[m] = BUILDER_WILDCARD
@@ skipping 11 matching lines @@
     print '%s:%s:%s' % (master_url, builder, buildnum)
 
   if not options.skip_build_db_update:
     build_scan_db.save_build_db(build_db, {}, options.build_db)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())