Fuchsia: Re-land build of VM with Observatory with better debug output.

tools/observatory_tool.py

 #!/usr/bin/env python
 # Copyright (c) 2015, 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.
 """Helper for building and deploying Observatory"""
 
 import argparse
 import os
 import platform
 import shutil
@@ skipping 20 matching lines @@
     'ShadowDOM.*',
     'webcomponents.*',
     'webcomponents-lite.js',
     'unittest*',
     '*_buildLogs*',
     '*.log',
     '*~')
 
 usage = """observatory_tool.py [options]"""
 
+# Run |command|. If its return code is 0, return 0 and swallow its output.
+# If its return code is non-zero, emit its output unless |always_silent| is
+# True, and return the return code.
+def RunCommand(command, always_silent=False):
+  try:
+    subprocess.check_output(command, stderr=subprocess.STDOUT)
+    return 0
+  except subprocess.CalledProcessError as e:
+    if not always_silent:
+      print ("Command failed: " + ' '.join(command) + "\n" +
+              "output: " + e.output)
+    return e.returncode
+
 def CreateTimestampFile(options):
   if options.stamp != '':
     dir_name = os.path.dirname(options.stamp)
     if dir_name != '':
       if not os.path.exists(dir_name):
         os.mkdir(dir_name)
     open(options.stamp, 'w').close()
 
 def BuildArguments():
   result = argparse.ArgumentParser(usage=usage)
@@ skipping 17 matching lines @@
     return False
 
   if (options.sdk is not None) and (options.sdk == "True"):
     options.sdk = True
   elif (options.sdk is None) or (options.sdk == "False"):
     options.sdk = False
   else:
     print "--sdk expects 'True' or 'False' argument."
     return False
 
-  with open(os.devnull, 'wb') as silent_sink:
-    # Required options.
-    if options.command is None or options.directory is None:
-      return False
+  # Required options.
+  if options.command is None or options.directory is None:
+    return False
 
-    # Set a default value for pub_snapshot.
-    options.pub_snapshot = None
+  # Set a default value for pub_snapshot.
+  options.pub_snapshot = None
 
-    # If we have a working pub executable, try and use that.
-    # TODO(whesse): Drop the pub-executable option if it isn't used.
-    if options.pub_executable is not None:
-      try:
-        if 0 == subprocess.call([options.pub_executable, '--version'],
-                                stdout=silent_sink,
-                                stderr=silent_sink):
-          return True
-      except OSError as e:
-        pass
-    options.pub_executable = None
+  # If we have a working pub executable, try and use that.
+  # TODO(whesse): Drop the pub-executable option if it isn't used.
+  if options.pub_executable is not None:
+    try:
+      if 0 == RunCommand([options.pub_executable, '--version'],
+                         always_silent=True):
+        return True
+    except OSError as e:
+      pass
+  options.pub_executable = None
 
-    if options.sdk and utils.CheckedInSdkCheckExecutable():
-      # Use the checked in pub executable.
-      options.pub_snapshot = os.path.join(utils.CheckedInSdkPath(),
-                                          'bin',
-                                          'snapshots',
-                                          'pub.dart.snapshot');
-      try:
-        if 0 == subprocess.call([utils.CheckedInSdkExecutable(),
-                                 options.pub_snapshot,
-                                 '--version'],
-                                 stdout=silent_sink,
-                                 stderr=silent_sink):
-          return True
-      except OSError as e:
-        pass
-    options.pub_snapshot = None
+  if options.sdk and utils.CheckedInSdkCheckExecutable():
+    # Use the checked in pub executable.
+    options.pub_snapshot = os.path.join(utils.CheckedInSdkPath(),
+                                        'bin',
+                                        'snapshots',
+                                        'pub.dart.snapshot');
+    try:
+      if 0 == RunCommand([utils.CheckedInSdkExecutable(),
+                          options.pub_snapshot,
+                          '--version'], always_silent=True):
+        return True
+    except OSError as e:
+      pass
+  options.pub_snapshot = None
 
-    # We need a dart executable.
-    return (options.dart_executable is not None)
+  # We need a dart executable.
+  return (options.dart_executable is not None)
 
 def ChangeDirectory(directory):
   os.chdir(directory);
 
 def DisplayBootstrapWarning():
   print """\
 
 
 WARNING: Your system cannot run the checked-in Dart SDK. Using the
 bootstrap Dart executable will make debug builds slow.
 Please see the Wiki for instructions on replacing the checked-in Dart SDK.
 
 https://github.com/dart-lang/sdk/wiki/The-checked-in-SDK-in-tools
 
 To use the dart_bootstrap binary please update the PubCommand function
 in the tools/observatory_tool.py script.
 
 """
 
 def PubCommand(dart_executable,
                pub_executable,
                pub_snapshot,
                command,
                silent):
-  with open(os.devnull, 'wb') as silent_sink:
-    if pub_executable is not None:
-      executable = [pub_executable]
-    elif pub_snapshot is not None:
-      executable = [utils.CheckedInSdkExecutable(), pub_snapshot]
-    else:
+  if pub_executable is not None:
+    executable = [pub_executable]
+  elif pub_snapshot is not None:
+    executable = [utils.CheckedInSdkExecutable(), pub_snapshot]
+  else:
+    if not silent:
       DisplayBootstrapWarning()
-      executable = [dart_executable, PUB_PATH]
-      # Prevent the bootstrap Dart executable from running in regular
-      # development flow.
-      # REMOVE THE FOLLOWING LINE TO USE the dart_bootstrap binary.
-      # return False
-    if not silent:
-      print >> sys.stderr, ('Running command "%s"') % (executable + command)
-    return subprocess.call(executable + command,
-                           stdout=silent_sink if silent else None,
-                           stderr=silent_sink if silent else None)
+    executable = [dart_executable, PUB_PATH]
+    # Prevent the bootstrap Dart executable from running in regular
+    # development flow.
+    # REMOVE THE FOLLOWING LINE TO USE the dart_bootstrap binary.
+    # return False
+  if not silent:
+    print >> sys.stderr, ('Running command "%s"') % (executable + command)
+  return RunCommand(executable + command)
 
 def Deploy(input_dir, output_dir):
   shutil.rmtree(output_dir)
   shutil.copytree(input_dir, output_dir, ignore=IGNORE_PATTERNS)
   index_file = os.path.join(output_dir, 'web', 'index.html')
   os.utime(index_file, None)
   return 0
 
 def RewritePubSpec(input_path, output_path, search, replace):
   with open(input_path, 'rb') as input_file:
@@ skipping 52 matching lines @@
   # Pub must be run from the project's root directory.
   ChangeDirectory(options.directory)
   result = ExecuteCommand(options, args)
   if result == 0:
     CreateTimestampFile(options)
   return result
 
 
 if __name__ == '__main__':
   sys.exit(main());