bundle2: only emit compressed chunks if they have data
This is similar to
58467204cac0. Not all calls into the compressor
return compressed data, as the compressor may buffer compressed
output internally. It is cheaper to check for empty chunks than to
send empty chunks through the generator.
When generating a gzip-v2 bundle of the mozilla-unified repo, this
change results in 50,093 empty chunks not being sent through the
generator (out of 1,902,996 total input chunks).
--- a/mercurial/bundle2.py Sat Oct 15 15:01:14 2016 -0700
+++ b/mercurial/bundle2.py Sat Oct 15 17:10:53 2016 -0700
@@ -573,7 +573,9 @@
yield param
# starting compression
for chunk in self._getcorechunk():
- yield self._compressor.compress(chunk)
+ data = self._compressor.compress(chunk)
+ if data:
+ yield data
yield self._compressor.flush()
def _paramchunk(self):
@@ -1324,7 +1326,9 @@
def chunkiter():
yield header
for chunk in subchunkiter:
- yield z.compress(chunk)
+ data = z.compress(chunk)
+ if data:
+ yield data
yield z.flush()
chunkiter = chunkiter()