Tracking issue for sync::Semaphore #27798

alexcrichton · 2015-08-13T05:37:45Z

This is a tracking issue for the unstable semaphore feature of the standard library.

Should we have this kind of semaphore?
Should we allow negative counts?
Should there be an RAII guard for a "resource"?

Decision!

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alexcrichton · 2015-12-17T22:38:48Z

🔔 This issue is now entering its final comment period for deprecation 🔔

If this is used widely, however, we can reconsider!

aturon · 2015-12-17T23:19:08Z

The long-term vision of concurrency support within std is a bit unclear. The deprecation here reflects a general desire to stick to binding system primitives (as we do with locks). For now, user-space synchronization can live out of tree. (Under this rubric, channels don't really belong either, and in hindsight that would probably have been a reasonable call.)

All that said, in the long run I believe that it's important for Rust to have some official user-space concurrency constructs. This could be a rust-lang crate, or eventually land in std.

fritzsche · 2016-01-05T23:38:13Z

Was looking for names Semaphore for Intra-Process synchronization like in your repo:
http://alexcrichton.com/ipc-rs/ipc/struct.Semaphore.html
This seems to be just a counter protected by a Mutex?

sfackler · 2016-01-06T00:19:38Z

@fritzsche a semaphore is a standard synchronization primitive: https://en.wikipedia.org/wiki/Semaphore_(programming)

alexcrichton · 2016-01-11T07:53:51Z

@fritzsche yeah that repo is for OS semaphores which are normally some form of IPC as well, but as @sfackler mentioned a semaphore is also a synchronization primitive.

This is also partly why I'd like to deprecate for now to avoid confusion about what it is.

alexcrichton · 2016-01-15T17:58:28Z

The libs team discussed this in triage yesterday and the decision was to deprecate

This commit stabilizes and deprecates the FCP (final comment period) APIs for the upcoming 1.7 beta release. The specific APIs which changed were: Stabilized * `Path::strip_prefix` (renamed from `relative_from`) * `path::StripPrefixError` (new error type returned from `strip_prefix`) * `Ipv4Addr::is_loopback` * `Ipv4Addr::is_private` * `Ipv4Addr::is_link_local` * `Ipv4Addr::is_multicast` * `Ipv4Addr::is_broadcast` * `Ipv4Addr::is_documentation` * `Ipv6Addr::is_unspecified` * `Ipv6Addr::is_loopback` * `Ipv6Addr::is_unique_local` * `Ipv6Addr::is_multicast` * `Vec::as_slice` * `Vec::as_mut_slice` * `String::as_str` * `String::as_mut_str` * `<[T]>::clone_from_slice` - the `usize` return value is removed * `<[T]>::sort_by_key` * `i32::checked_rem` (and other signed types) * `i32::checked_neg` (and other signed types) * `i32::checked_shl` (and other signed types) * `i32::checked_shr` (and other signed types) * `i32::saturating_mul` (and other signed types) * `i32::overflowing_add` (and other signed types) * `i32::overflowing_sub` (and other signed types) * `i32::overflowing_mul` (and other signed types) * `i32::overflowing_div` (and other signed types) * `i32::overflowing_rem` (and other signed types) * `i32::overflowing_neg` (and other signed types) * `i32::overflowing_shl` (and other signed types) * `i32::overflowing_shr` (and other signed types) * `u32::checked_rem` (and other unsigned types) * `u32::checked_neg` (and other unsigned types) * `u32::checked_shl` (and other unsigned types) * `u32::saturating_mul` (and other unsigned types) * `u32::overflowing_add` (and other unsigned types) * `u32::overflowing_sub` (and other unsigned types) * `u32::overflowing_mul` (and other unsigned types) * `u32::overflowing_div` (and other unsigned types) * `u32::overflowing_rem` (and other unsigned types) * `u32::overflowing_neg` (and other unsigned types) * `u32::overflowing_shl` (and other unsigned types) * `u32::overflowing_shr` (and other unsigned types) * `ffi::IntoStringError` * `CString::into_string` * `CString::into_bytes` * `CString::into_bytes_with_nul` * `From<CString> for Vec<u8>` * `From<CString> for Vec<u8>` * `IntoStringError::into_cstring` * `IntoStringError::utf8_error` * `Error for IntoStringError` Deprecated * `Path::relative_from` - renamed to `strip_prefix` * `Path::prefix` - use `components().next()` instead * `os::unix::fs` constants - moved to the `libc` crate * `fmt::{radix, Radix, RadixFmt}` - not used enough to stabilize * `IntoCow` - conflicts with `Into` and may come back later * `i32::{BITS, BYTES}` (and other integers) - not pulling their weight * `DebugTuple::formatter` - will be removed * `sync::Semaphore` - not used enough and confused with system semaphores Closes rust-lang#23284 cc rust-lang#27709 (still lots more methods though) Closes rust-lang#27712 Closes rust-lang#27722 Closes rust-lang#27728 Closes rust-lang#27735 Closes rust-lang#27729 Closes rust-lang#27755 Closes rust-lang#27782 Closes rust-lang#27798

This commit stabilizes and deprecates the FCP (final comment period) APIs for the upcoming 1.7 beta release. The specific APIs which changed were: Stabilized * `Path::strip_prefix` (renamed from `relative_from`) * `path::StripPrefixError` (new error type returned from `strip_prefix`) * `Ipv4Addr::is_loopback` * `Ipv4Addr::is_private` * `Ipv4Addr::is_link_local` * `Ipv4Addr::is_multicast` * `Ipv4Addr::is_broadcast` * `Ipv4Addr::is_documentation` * `Ipv6Addr::is_unspecified` * `Ipv6Addr::is_loopback` * `Ipv6Addr::is_unique_local` * `Ipv6Addr::is_multicast` * `Vec::as_slice` * `Vec::as_mut_slice` * `String::as_str` * `String::as_mut_str` * `<[T]>::clone_from_slice` - the `usize` return value is removed * `<[T]>::sort_by_key` * `i32::checked_rem` (and other signed types) * `i32::checked_neg` (and other signed types) * `i32::checked_shl` (and other signed types) * `i32::checked_shr` (and other signed types) * `i32::saturating_mul` (and other signed types) * `i32::overflowing_add` (and other signed types) * `i32::overflowing_sub` (and other signed types) * `i32::overflowing_mul` (and other signed types) * `i32::overflowing_div` (and other signed types) * `i32::overflowing_rem` (and other signed types) * `i32::overflowing_neg` (and other signed types) * `i32::overflowing_shl` (and other signed types) * `i32::overflowing_shr` (and other signed types) * `u32::checked_rem` (and other unsigned types) * `u32::checked_shl` (and other unsigned types) * `u32::saturating_mul` (and other unsigned types) * `u32::overflowing_add` (and other unsigned types) * `u32::overflowing_sub` (and other unsigned types) * `u32::overflowing_mul` (and other unsigned types) * `u32::overflowing_div` (and other unsigned types) * `u32::overflowing_rem` (and other unsigned types) * `u32::overflowing_neg` (and other unsigned types) * `u32::overflowing_shl` (and other unsigned types) * `u32::overflowing_shr` (and other unsigned types) * `ffi::IntoStringError` * `CString::into_string` * `CString::into_bytes` * `CString::into_bytes_with_nul` * `From<CString> for Vec<u8>` * `From<CString> for Vec<u8>` * `IntoStringError::into_cstring` * `IntoStringError::utf8_error` * `Error for IntoStringError` Deprecated * `Path::relative_from` - renamed to `strip_prefix` * `Path::prefix` - use `components().next()` instead * `os::unix::fs` constants - moved to the `libc` crate * `fmt::{radix, Radix, RadixFmt}` - not used enough to stabilize * `IntoCow` - conflicts with `Into` and may come back later * `i32::{BITS, BYTES}` (and other integers) - not pulling their weight * `DebugTuple::formatter` - will be removed * `sync::Semaphore` - not used enough and confused with system semaphores Closes rust-lang#23284 cc rust-lang#27709 (still lots more methods though) Closes rust-lang#27712 Closes rust-lang#27722 Closes rust-lang#27728 Closes rust-lang#27735 Closes rust-lang#27729 Closes rust-lang#27755 Closes rust-lang#27782 Closes rust-lang#27798

aarroyoc · 2017-11-21T22:05:44Z

How about re-adding Semaphores? It's a very useful synchronization method and sometimes works better than Mutexes + CondVar. I've seen many crates implementing Semaphores, people are interested. It would be great if they were supported in std.

kim366 · 2020-02-01T15:01:10Z

In C++ semaphores are missing, so we resorted to POSIX semaphores. It would be nice if Rust supported them out of the box

alexcrichton added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. B-unstable Blocker: Implemented in the nightly compiler and unstable. labels Aug 13, 2015

alexcrichton added the I-nominated label Dec 16, 2015

alexcrichton added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed I-nominated labels Dec 17, 2015

alexcrichton mentioned this issue Jan 15, 2016

std: Stabilize APIs for the 1.7 release #30943

Merged

bors closed this as completed in #30943 Jan 17, 2016

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Tracking issue for sync::Semaphore #27798

Tracking issue for sync::Semaphore #27798

alexcrichton commented Aug 13, 2015

alexcrichton commented Dec 17, 2015

aturon commented Dec 17, 2015

fritzsche commented Jan 5, 2016

sfackler commented Jan 6, 2016

alexcrichton commented Jan 11, 2016

alexcrichton commented Jan 15, 2016

aarroyoc commented Nov 21, 2017

kim366 commented Feb 1, 2020

Tracking issue for sync::Semaphore #27798

Tracking issue for sync::Semaphore #27798

Comments

alexcrichton commented Aug 13, 2015

alexcrichton commented Dec 17, 2015

aturon commented Dec 17, 2015

fritzsche commented Jan 5, 2016

sfackler commented Jan 6, 2016

alexcrichton commented Jan 11, 2016

alexcrichton commented Jan 15, 2016

aarroyoc commented Nov 21, 2017

kim366 commented Feb 1, 2020