[NaCl SDK] Don't write generated Makefile if it is identical to the existing one.

If we modify the timestamp of the Makefile, everything gets rebuilt.

BUG=none
R=sbc@chromium.org
NOTRY=true


Review URL: https://chromiumcodereview.appspot.com/12377019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185377 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 27 insertions, 4 deletions

diff --git a/native_client_sdk/src/build_tools/easy_template.py b/native_client_sdk/src/build_tools/easy_template.py
index 6ef2262..b2bfa71 100755
--- a/native_client_sdk/src/build_tools/easy_template.py
+++ b/native_client_sdk/src/build_tools/easy_template.py
@@ -65,6 +65,13 @@ def RunTemplateFile(srcfile, dstfile, template_dict, statement_re=None,
       RunTemplate(src, dst, template_dict, statement_re, expr_re)
 
 
+def RunTemplateString(src, template_dict, statement_re=None, expr_re=None):
+  srcf = cStringIO.StringIO(src)
+  dstf = cStringIO.StringIO()
+  RunTemplate(srcf, dstf, template_dict, statement_re, expr_re)
+  return dstf.getvalue()
+
+
 def main(args):
   parser = optparse.OptionParser()
   _, args = parser.parse_args(args)
diff --git a/native_client_sdk/src/build_tools/generate_make.py b/native_client_sdk/src/build_tools/generate_make.py
index cc1e80f..ef37e97 100755
--- a/native_client_sdk/src/build_tools/generate_make.py
+++ b/native_client_sdk/src/build_tools/generate_make.py
@@ -3,11 +3,12 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import buildbot_common
+import cStringIO
 import optparse
 import os
 import sys
 
+import buildbot_common
 from buildbot_common import ErrorExit
 import easy_template
 from generate_index import LandingPage
@@ -52,6 +53,21 @@ def GenerateSourceCopyList(desc):
   return sources
 
 
+def RunTemplateFile(srcfile, dstfile, replace):
+  dst = cStringIO.StringIO()
+  with open(srcfile) as srcf:
+    easy_template.RunTemplate(srcf, dst, replace)
+
+  if os.path.exists(dstfile):
+    with open(dstfile) as dstf:
+      if dstf.read() == dst.getvalue():
+        Trace('Generated %s is the same. Skipping' % dstfile)
+        return
+
+  with open(dstfile, 'w') as dstf:
+    dstf.write(dst.getvalue())
+
+
 def GetSourcesDict(sources):
   source_map = {}
   for key in ['.c', '.cc']:
@@ -260,7 +276,7 @@ def ProcessHTML(srcroot, dstroot, desc, toolchains):
         'data-name="%s" data-tools="%s" data-configs="%s" data-path="%s"' % (
         name, ' '.join(tools), ' '.join(configs), path),
   }
-  easy_template.RunTemplateFile(srcfile, dstfile, replace)
+  RunTemplateFile(srcfile, dstfile, replace)
 
 
 def LoadProject(filename, toolchains):
@@ -371,7 +387,7 @@ def ProcessProject(srcroot, dstroot, desc, toolchains):
       'tools': tool_list,
       'targets': desc['TARGETS'],
     }
-    easy_template.RunTemplateFile(template, make_path, template_dict)
+    RunTemplateFile(template, make_path, template_dict)
 
   outdir = os.path.dirname(os.path.abspath(make_path))
   pepperdir = os.path.dirname(os.path.dirname(outdir))
@@ -383,7 +399,7 @@ def GenerateMasterMakefile(in_path, out_path, projects):
   """Generate a Master Makefile that builds all examples. """
   project_names = [project['NAME'] for project in projects]
   template_dict = { 'projects': project_names }
-  easy_template.RunTemplateFile(in_path, out_path, template_dict)
+  RunTemplateFile(in_path, out_path, template_dict)
 
   outdir = os.path.dirname(os.path.abspath(out_path))
   pepperdir = os.path.dirname(outdir)