do not recrunch if dds is unchanged

tests/runner.py

@@ -7183,6 +7183,25 @@ def test_link_s(self):
       code = open('a.out.js').read()
       assert 'SAFE_HEAP' in code, 'valid -s option had an effect'
 
+    def test_crunch(self):
+      # crunch should not be run if a .crn exists that is more recent than the .dds
+      shutil.copyfile(path_from_root('tests', 'ship.dds'), 'ship.dds')
+      time.sleep(0.1)
+      Popen(['python', FILE_PACKAGER, 'test.data', '--pre-run', '--crunch=32', '--preload', 'ship.dds'], stdout=open('pre.js', 'w')).communicate()
+      assert os.stat('test.data').st_size < 0.25*os.stat('ship.dds').st_size, 'Compressed should be much smaller than dds'
+      crunch_time = os.stat('ship.crn').st_mtime
+      dds_time = os.stat('ship.dds').st_mtime
+      assert crunch_time > dds_time, 'Crunch is more recent'
+      # run again, should not recrunch!
+      time.sleep(0.1)
+      Popen(['python', FILE_PACKAGER, 'test.data', '--pre-run', '--crunch=32', '--preload', 'ship.dds'], stdout=open('pre.js', 'w')).communicate()
+      assert crunch_time == os.stat('ship.crn').st_mtime, 'Crunch is unchanged'
+      # update dds, so should recrunch
+      time.sleep(0.1)
+      os.utime('ship.dds', None)
+      Popen(['python', FILE_PACKAGER, 'test.data', '--pre-run', '--crunch=32', '--preload', 'ship.dds'], stdout=open('pre.js', 'w')).communicate()
+      assert crunch_time < os.stat('ship.crn').st_mtime, 'Crunch was changed'
+
 elif 'browser' in str(sys.argv):
   # Browser tests.
 

tools/file_packager.py

@@ -18,6 +18,8 @@
              be added to convert the crn to dds in the browser.
              crunch-worker.js will be generated in the current directory. You should include that file when
              packaging your site.
+             DDS files will not be crunched if the .crn is more recent than the .dds. This prevents a lot of
+             unneeded computation.
 
 TODO:        You can also provide .crn files yourself, pre-crunched. With this option, they will be decompressed
              to dds files in the browser, exactly the same as if this tool compressed them.
@@ -156,9 +158,13 @@ def was_seen(name):
 
   for file_ in data_files:
     if file_['name'].endswith(CRUNCH_INPUT_SUFFIX):
-      # TODO: do not crunch if crunched version exists and is more recent than dds source
-      Popen([CRUNCH, '-file', file_['name'], '-quality', crunch], stdout=sys.stderr).communicate()
+      # Do not crunch if crunched version exists and is more recent than dds source
       crunch_name = unsuffixed(file_['name']) + CRUNCH_OUTPUT_SUFFIX
+      crunch_time = os.stat(crunch_name).st_mtime
+      dds_time = os.stat(file_['name']).st_mtime
+      if dds_time < crunch_time: continue
+
+      Popen([CRUNCH, '-file', file_['name'], '-quality', crunch], stdout=sys.stderr).communicate()
       shutil.move(os.path.basename(crunch_name), crunch_name) # crunch places files in the current dir
       # prepend the dds header
       crunched = open(crunch_name, 'rb').read()