Mercurial > public > mercurial-scm > hg-stable
comparison mercurial/util.py @ 5449:17a4b20eda7b
chunkiter: handle large reads more efficiently
- for large reads, don't attempt to read more than necessary
- if we've gathered the exact number of bytes needed, avoid a string copy
| author | Matt Mackall <mpm@selenic.com> |
|---|---|
| date | Thu, 11 Oct 2007 00:46:52 -0500 |
| parents | 56591846f819 |
| children | c728424d44c6 |
comparison
equal
deleted
inserted
replaced
| 5448:e038738714fd | 5449:17a4b20eda7b |
|---|---|
| 1406 def read(self, l): | 1406 def read(self, l): |
| 1407 """Read L bytes of data from the iterator of chunks of data. | 1407 """Read L bytes of data from the iterator of chunks of data. |
| 1408 Returns less than L bytes if the iterator runs dry.""" | 1408 Returns less than L bytes if the iterator runs dry.""" |
| 1409 if l > len(self.buf) and self.iter: | 1409 if l > len(self.buf) and self.iter: |
| 1410 # Clamp to a multiple of self.targetsize | 1410 # Clamp to a multiple of self.targetsize |
| 1411 targetsize = self.targetsize * ((l // self.targetsize) + 1) | 1411 targetsize = max(l, self.targetsize) |
| 1412 collector = cStringIO.StringIO() | 1412 collector = cStringIO.StringIO() |
| 1413 collector.write(self.buf) | 1413 collector.write(self.buf) |
| 1414 collected = len(self.buf) | 1414 collected = len(self.buf) |
| 1415 for chunk in self.iter: | 1415 for chunk in self.iter: |
| 1416 collector.write(chunk) | 1416 collector.write(chunk) |
| 1418 if collected >= targetsize: | 1418 if collected >= targetsize: |
| 1419 break | 1419 break |
| 1420 if collected < targetsize: | 1420 if collected < targetsize: |
| 1421 self.iter = False | 1421 self.iter = False |
| 1422 self.buf = collector.getvalue() | 1422 self.buf = collector.getvalue() |
| 1423 s, self.buf = self.buf[:l], buffer(self.buf, l) | 1423 if len(self.buf) == l: |
| 1424 s, self.buf = self.buf, '' | |
| 1425 else: | |
| 1426 s, self.buf = self.buf[:l], buffer(self.buf, l) | |
| 1424 return s | 1427 return s |
| 1425 | 1428 |
| 1426 def filechunkiter(f, size=65536, limit=None): | 1429 def filechunkiter(f, size=65536, limit=None): |
| 1427 """Create a generator that produces the data in the file size | 1430 """Create a generator that produces the data in the file size |
| 1428 (default 65536) bytes at a time, up to optional limit (default is | 1431 (default 65536) bytes at a time, up to optional limit (default is |