Explain our RwLock implementation #71889
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RalfJung
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Amanieu
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May 4, 2020
src/libstd/sys/unix/rwlock.rs
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| self.raw_unlock(); | ||
| } | ||
| panic!("rwlock write lock would result in deadlock"); | ||
| } else { | ||
| debug_assert_eq!(r, 0); | ||
| assert_eq!(r, 0); |
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Why did you change this from a debug assert? The docs for pthread_rwlock_wrlock specify that it only ever returns EDEADLK or 0.
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Consistency -- I did the same in #55865. Seems cheap to check.
But if you want I can also make it a debug assertion again.
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I would prefer making it a debug assert since this is a pretty hot path.
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Okay, I did that and added an appropriate comment.
Is it generally the case that the list of error codes in the POSIX docs is exhaustive? I noticed the docs explicitly say "These functions shall not return an error code of [EINTR]" but do not say that for any of the other error codes.
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They are supposed to be exhaustive in theory.
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@bors r+ |
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📌 Commit f9866f9 has been approved by |
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Explain our RwLock implementation Turns out that [with the latest POSIX docs](https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_wrlock.html), our `RwLock` implementation is actually correct. However, we cannot fully rely on that due to bugs in older glibc (fix released in 2016). Update the comments to explain that. I also clarified our Mutex docs a bit and fixed another instance of rust-lang#55865. r? @Amanieu Fixes rust-lang#53127
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Explain our RwLock implementation Turns out that [with the latest POSIX docs](https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_wrlock.html), our `RwLock` implementation is actually correct. However, we cannot fully rely on that due to bugs in older glibc (fix released in 2016). Update the comments to explain that. I also clarified our Mutex docs a bit and fixed another instance of rust-lang#55865. r? @Amanieu Fixes rust-lang#53127
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Explain our RwLock implementation Turns out that [with the latest POSIX docs](https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_wrlock.html), our `RwLock` implementation is actually correct. However, we cannot fully rely on that due to bugs in older glibc (fix released in 2016). Update the comments to explain that. I also clarified our Mutex docs a bit and fixed another instance of rust-lang#55865. r? @Amanieu Fixes rust-lang#53127
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May 5, 2020
Explain our RwLock implementation Turns out that [with the latest POSIX docs](https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_wrlock.html), our `RwLock` implementation is actually correct. However, we cannot fully rely on that due to bugs in older glibc (fix released in 2016). Update the comments to explain that. I also clarified our Mutex docs a bit and fixed another instance of rust-lang#55865. r? @Amanieu Fixes rust-lang#53127
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Rollup of 6 pull requests Successful merges: - rust-lang#71510 (Btreemap iter intertwined) - rust-lang#71727 (SipHasher with keys initialized to 0 should just use new()) - rust-lang#71889 (Explain our RwLock implementation) - rust-lang#71905 (Add command aliases from Cargo to x.py commands) - rust-lang#71914 (Backport 1.43.1 release notes to master) - rust-lang#71921 (explain the types used in the open64 call) Failed merges: r? @ghost
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Turns out that with the latest POSIX docs, our
RwLockimplementation is actually correct. However, we cannot fully rely on that due to bugs in older glibc (fix released in 2016). Update the comments to explain that.I also clarified our Mutex docs a bit and fixed another instance of #55865.
r? @Amanieu
Fixes #53127