Add API to support mapping cache capacity configurable

[hehechen]

Signed-off-by: hehechen [email protected]
closes: #499

In some scenarios, users may want to increase MAPPINGS_CACHE_SIZE to trade memory for performance improvement.
This PR add some functions:
resolve_frame_customized_cache
resolve_frame_unsynchronized_customized_cache
resolve_customized_cache
resolve_unsynchronized_customized_cache
So that users can modify cache capacity to improve performance.

[hehechen]

Same as #500, but change the source branch.

[workingjubilee]

This complicates things a... lot, in the public API, even, for this performance improvement. Can you elaborate about these "some scenarios", and what is your use case that you want specifically the ability to set a number? In the use-case of std, "backtrace" is usually "one of the last things before the world ends", so yes, we might want to cache more than 4, but I kinda think that we would want to try to lazily cache as many mappings as can fit into memory, because we're going to throw everything away soon anyways? But it sounds a little like you have a different need? Am I mistaken?

[workingjubilee]

Hmm, judging by this issue, some users will be invoking backtrace... a lot:
#365

Interesting. That helps motivate this a little, but I'm still curious about what your use pattern, and thus what you want us to support, is like.

[workingjubilee]

Since this seems to have already been a bit stale by the time I got to this crate, I'm going to close this for now. Feel free to reopen when you're ready to discuss it.