alt Hacker NewsYou know it often is the case that APIs like this both in C++ and Rust don't offer you enough knobs when your usecase deviates from being trivial.
It happens with locking APIs, it happens with socket APIs, anything platform dependent.
Does the C++ standard give you an idiomatic way to set PTHREAD_RWLOCK_PREFER_READER_NP or PTHREAD_RWLOCK_PREFER_WRITER_NP explicitly when initializing a rwlock? Nope. Then you either roll your own or in Rust you reach for a crate where someone did the work of making a smarter primitive for you.
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One thing I appreciate about Rust's stdlib is that it exposes enough platform details to allow writing the missing knobs without reimplementing the entire wrapper (e.g. File, TcpStream, etc. allows access to raw file descriptors, OpenOptionsExt allows me to use FILE_FLAG_DELETE_ON_CLOSE on windows, etc.)
Because usually that is OS specific and not portable to be part of standard library that is supposed to work everywhere.
NP means the API is not portable. There are Linux specific extensions for many things but not everything has it. This is also nothing wrong with needing to use an alternative to the standard library if you have more niche requirements.
Yeah, you can't enable priority inheritance for mutexes in std of either C++ or Rust. Which is a show stopper for hard realtime (my dayjob).
And then you have mutexes internally inside some dependency still (e.g. grpc or what have you). What I would really like is the ability to change defaults for all mutexes created in the program, and have everyone use the same std mutexes.
By the way: rwlocks are often a bad idea, since you still get cache contention between readers on the counter for number of active readers. Unless the time you hold the lock for is really long (several milliseconds at least) it usually doesn't improve performance compared to mutexes. Consider alternatives like seqlocks, RCU, hazard pointers etc instead, depending on the specifics of your situation (there is no silver bullet when it comes to performance in concurrent primtitves).