This patch changes two things in our LZMA compression backend:
- We lower the preset values for all `compression_level_t` values to
ensure that we can run the LZMA decoder with less than 65 MB of memory
available. This seems to have a small impact on the real world usage
and fits well with our needs.
- We set the upper bound of memory usage for the LZMA decoder to 16 MB.
See: https://bugs.torproject.org/21665
This patch adds support for measuring the approximated memory usage by
the individual `tor_lzma_compress_state_t` object instances.
The LZMA library provides the functions `lzma_easy_encoder_memusage()`
and `lzma_easy_decoder_memusage()` which is used to find the estimated
usage in bytes.
See: https://bugs.torproject.org/22066
Since we have a streaming API for each compression backend, we don't
need a non-streaming API for each: we can build a common
non-streaming API at the front-end.
This patch splits up `tor_compress_memory_level()` into static functions
in the individual compression backends, which allows us to tune the
values per compression backend rather than globally.
See: https://bugs.torproject.org/21662
This patch adds `tor_compress_version_str()` and
`tor_compress_header_version_str()` to get the version strings of the
different compression schema providers. Both functions returns `NULL` in
case a given `compress_method_t` is unknown or unsupported.
See: https://bugs.torproject.org/21662
This patch adds support for checking if a given `compress_method_t` is
supported by the currently running Tor instance using
`tor_compress_supports_method()`.
See: https://bugs.torproject.org/21662
