Make cr build run goma_ctl.py ensure_start before building.

tools/cr/cr/actions/ninja.py

Index: tools/cr/cr/actions/ninja.py
diff --git a/tools/cr/cr/actions/ninja.py b/tools/cr/cr/actions/ninja.py
index 404e6caea26e11360bf1b874e72c8de38f3fd697..6a8bd1900ba9def5d628aa1d12ea91355d947606 100644
--- a/tools/cr/cr/actions/ninja.py
+++ b/tools/cr/cr/actions/ninja.py
@@ -30,6 +30,26 @@ class NinjaBuilder(cr.Builder):
     self._targets = []
 
   def Build(self, context, targets, arguments):
+    # Make sure Goma is started, if Ninja is set to use it.
+    # This may be redundant, but it currently improves reliability.
+    try:

[ian_cottrell, 2014/01/09 17:00:21]

I would change how you build paths.
Use
  NINJA_BUILD_FILE=os.path.join('GOMA_DIR', 'build.ninja'),
  GOMA_CTL=os.path.join('{GOMA_DIR}', 'goma_clt.py'),
  GOMA_CC=os.path.join('{GOMA_DIR}', 'gomacc'),
  NINJA_GOMA_LINE='cc = {GOMA_CC} $',
up in the ENABLED block
also, just try to open the file, and trust the IOError to tell you if the
filename was bad because the variables did not expand, so
  try:
    with open(context.Get('NINJA_BUILD_FILE'), 'r') as f:
      ....
  except IOError:
    pass
and cr.Host.Execute will expand variales for you, so just run 
  '{GOMA_CTL}', 'ensure_start'

[johnme, 2014/01/09 19:06:11]

Done.

+      goma_dir = context.Get('GOMA_DIR', raise_errors=True)
+      build_dir = context.Get('CR_BUILD_DIR', raise_errors=True)
+      build_ninja = os.path.join(build_dir, 'build.ninja')
+      if os.path.exists(build_ninja):
+        goma_cc = 'cc = {} $\n'.format(os.path.join(goma_dir, 'gomacc'))
+        with open(build_ninja, 'r') as f:

[ian_cottrell, 2014/01/09 17:00:21]

This is vile, but I don't have a better suggestion.
I guess it's kind of safe because worst case things underneath change and we
stop detecting goma when we should be, it's never going to try to run goma when
it should not.

+          if f.readline() == goma_cc:
+            # Goma is active, so make sure it's started.
+            cr.Host.ExecuteSilently(
+                context,
+                os.path.join('{GOMA_DIR}', 'goma_ctl.py'),
+                'ensure_start'
+            )
+    except KeyError:
+      pass
+
+
     build_arguments = [target.build_target for target in targets]
     build_arguments.extend(arguments)
     cr.Host.Execute(