Parse output from xcodebuild to make it easier to spot problems with non-incremental builds.

dart/tools/build.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, 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 optparse
 import os
 import shutil
@@ skipping 206 matching lines @@
     with open(build_cookie_path, 'w') as f:
       f.write(target_os)
     GClientRunHooks()
 
 
 def CurrentDirectoryBaseName():
   """Returns the name of the current directory"""
   return os.path.relpath(os.curdir, start=os.pardir)
 
 
+def ParseXcodebuild(args):
+  """
+  Run xcodebuild and returns the process object.
+  Output is parsed to filter out build actions that had no output.
+  """

[kustermann, 2013/04/02 21:13:15]

A small comment explaining the 'output format' of xcodebuild would be nice here.

[ahe, 2013/04/05 15:03:43]

Done.

+
+  def is_empty_chunk(chunk):
+    empty_chunk = ['Check dependencies', '', '']
+    return not chunk or (len(chunk) == 4 and chunk[1:] == empty_chunk)
+
+  process = subprocess.Popen(args,
+                             bufsize=0,

[kustermann, 2013/04/02 21:13:15]

I think 'bufsize=0' is the default -- you could remove this.

Why do you make it unbuffered. Shouldn't it be line buffered (i.e. bufsize=1)?

[ahe, 2013/04/05 15:03:43]

Yes.  In addition it turns out that "for line in process.stdout" has its own
buffer.  I found a way to disable that.

+                             stdin=None,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.STDOUT)
+  section = None
+  chunk = []
+  for line in process.stdout:
+    line = line.rstrip()
+    if line.startswith('=== BUILD ') or line.startswith('** BUILD '):
+      if not is_empty_chunk(chunk):
+        print '\n'.join(chunk)
+      section = line
+      chunk = []
+    if not section:
+      print line
+    else:
+      chunk.append(line)
+  if not is_empty_chunk(chunk):
+    print '\n'.join(chunk)
+  return process
+
+
 def Main():
   utils.ConfigureJava()
   # Parse the options.
   parser = BuildOptions()
   (options, args) = parser.parse_args()
   if not ProcessOptions(options, args):
     parser.print_help()
     return 1
   # Determine which targets to build. By default we build the "all" target.
   if len(args) == 0:
     if HOST_OS == 'macos':
       target = 'All'
     else:
       target = 'all'
   else:
     target = args[0]
 
+  parse_xcodebuild = False

[kustermann, 2013/04/02 21:13:15]

The intention is not to parse the output of xcodebuild but rather to filter
empty sections. So you could rename it to 'filter_xcodebuild_output'.

[ahe, 2013/04/05 15:03:43]

Done.

   # Remember path
   old_path = os.environ['PATH']
   # Build the targets for each requested configuration.
   for target_os in options.os:
     for mode in options.mode:
       for arch in options.arch:
         build_config = utils.GetBuildConf(mode, arch)
         if HOST_OS == 'macos':
+          parse_xcodebuild = True
           project_file = 'dart.xcodeproj'
           if os.path.exists('dart-%s.gyp' % CurrentDirectoryBaseName()):
             project_file = 'dart-%s.xcodeproj' % CurrentDirectoryBaseName()
           args = ['xcodebuild',
                   '-project',
                   project_file,
                   '-target',
                   target,
                   '-configuration',
                   build_config,
@@ skipping 47 matching lines @@
                               % os.environ['ANDROID_TOOLCHAIN'])
         toolsOverride = SetTools(arch, toolchainprefix)
         if toolsOverride:
           printToolOverrides = target_os != 'android'
           for k, v in toolsOverride.iteritems():
             args.append(  k + "=" + v)
             if printToolOverrides:
               print k + " = " + v
 
         print ' '.join(args)
-        process = subprocess.Popen(args)
+        process = None
+        if parse_xcodebuild:
+          process = ParseXcodebuild(args)
+        else:
+          process = subprocess.Popen(args, stdin=None)

[kustermann, 2013/04/02 21:13:15]

You could do something like this:

if filter_xcodebuild_output:
  process = subprocess.Popen(args,
                                               stdin=None,
                                               stdout=subprocess.PIPE,  
                                               stderr=subprocess.STDOUT)
  FilterEmptyXcodebuildSections(process.stdout)
else:
  process = subprocess.Popen(args, stdin=None)

This way the subprocess calls are near to each other and
'FilterEmptyXcodebuildSections' has one responsibility (filtering empty
sections) instead of two.

[ahe, 2013/04/05 15:03:43]

Done.

         process.wait()
         if process.returncode != 0:
           print "BUILD FAILED"
           return 1
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(Main())