solve and pdlp_solve can't read .mps.gz files

[mlubin]

If given an .mps.gz file as input, pdlp_solve crashes with

F0808 08:30:14.141796 288747 quadratic_program_io.cc:70] Check failed: (lp_proto).ok()

and solve crashes with

F0808 08:31:19.341888 289046 solve.cc:130] Check failed: (glop::MPSReader().ParseFile(input, &model_proto)).ok() Error while parsing the mps file '...'

Is zlib linked in correctly?

[lperron]

The gzip and bzip2 file reader code has never been open sourced.

[mlubin]

That's fair, the error messages should be improved in this case.

[stumarcus314]

Could brotli, LZHAM, LZ4, or zstd be used?
https://github.com/google/brotli
https://en.wikipedia.org/wiki/Brotli
https://github.com/richgel999/lzham_codec
https://lz4.github.io/lz4/
https://facebook.github.io/zstd/
https://github.com/facebook/zstd

[stumarcus314]

Could xz be used to compress and decompress MPS files for OR-Tools? The xz compressor (liblzma) and decompressor (xzdec) are both multi-threaded and it seems like they are in the public domain. xz compresses files smaller than gzip (30% smaller) and bzip2 (15% smaller).
https://tukaani.org/xz/
https://git.tukaani.org/?p=xz.git;a=blob;f=COPYING

[mlubin]

gzip and bzip2 are the standard ways to compress MPS files (this is how you'll find them in benchmark libraries). If I/O is really a bottleneck, you'd be better off using an in-memory API instead. You're also welcome to modify pdlp_solve to connect to your favorite decompression library.