highlight: exit early on textual and unknown files (issue3005)
authorAnton Shestakov <av6@dwimlabs.net>
Sun, 02 Aug 2015 19:18:35 +0800
changeset 25899 c35ee1bbbbdc
parent 25898 4dcc9b5d786a
child 25901 0203c50a589f
highlight: exit early on textual and unknown files (issue3005) When highlight extension encountered files that pygments didn't recognize, it used to fall back to text lexer. Also, pygments uses TextLexer for .txt files. This lexer is noop by design. On bigger files, however, doing the noop highlighting resulted in noticeable extra CPU work and memory usage: to show a 1 MB text file, hgweb required about 0.7s more (on top of ~3.8s, Q8400) and consumed about 100 MB of RAM more (on top of ~150 MB). Let's just exit the function when it's clear that nothing will be highlighted. Due to how this pygmentize function works (it modifies the template in-place), we can just return from it and everything else will work as if highlight extension wasn't enabled.
hgext/highlight/highlight.py
--- a/hgext/highlight/highlight.py	Mon Aug 03 14:16:51 2015 -0700
+++ b/hgext/highlight/highlight.py	Sun Aug 02 19:18:35 2015 +0800
@@ -49,7 +49,12 @@
         try:
             lexer = guess_lexer(text[:1024], stripnl=False)
         except (ClassNotFound, ValueError):
-            lexer = TextLexer(stripnl=False)
+            # Don't highlight unknown files
+            return
+
+    # Don't highlight text files
+    if isinstance(lexer, TextLexer):
+        return
 
     formatter = HtmlFormatter(nowrap=True, style=style)