Fix #80061: Copying large files may have suboptimal performance #6078
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Instead of attempting to map large files into memory at once, we map chunks of at most `PHP_STREAM_MMAP_MAX` bytes, and repeat that until we hit the point where `php_stream_seek()` fails (see bug 54902), and copy the rest of the file by reading and writing small chunks. We also fix the mapping behavior for zero bytes on Windows, which did not error (as with `mmap()`), but would have mapped the remaining file.
cmb69
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nikic
reviewed
Sep 21, 2020
nikic
approved these changes
Sep 21, 2020
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Thanks! Applied as 19c8445. |
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Instead of attempting to map large files into memory at once, we map
chunks of at most
PHP_STREAM_MMAP_MAXbytes, and repeat that until wehit the point where
php_stream_seek()fails (see bug 54902), and copythe rest of the file by reading and writing small chunks.
We also fix the mapping behavior for zero bytes on Windows, which did
not error (as with
mmap()), but would have mapped the remaining file.