diff options
Diffstat (limited to 'library/std/src/thread/local.rs')
| -rw-r--r-- | library/std/src/thread/local.rs | 194 |
1 files changed, 0 insertions, 194 deletions
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs index cf7c2e05a2e..c82b5c2284f 100644 --- a/library/std/src/thread/local.rs +++ b/library/std/src/thread/local.rs @@ -173,200 +173,6 @@ macro_rules! thread_local { ); } -#[doc(hidden)] -#[unstable(feature = "thread_local_internals", reason = "should not be necessary", issue = "none")] -#[macro_export] -#[allow_internal_unstable(thread_local_internals, cfg_target_thread_local, thread_local)] -#[allow_internal_unsafe] -macro_rules! __thread_local_inner { - // used to generate the `LocalKey` value for const-initialized thread locals - (@key $t:ty, const $init:expr) => {{ - #[cfg_attr(not(windows), inline)] // see comments below - #[deny(unsafe_op_in_unsafe_fn)] - unsafe fn __getit( - _init: $crate::option::Option<&mut $crate::option::Option<$t>>, - ) -> $crate::option::Option<&'static $t> { - const INIT_EXPR: $t = $init; - - // wasm without atomics maps directly to `static mut`, and dtors - // aren't implemented because thread dtors aren't really a thing - // on wasm right now - // - // FIXME(#84224) this should come after the `target_thread_local` - // block. - #[cfg(all(target_family = "wasm", not(target_feature = "atomics")))] - { - static mut VAL: $t = INIT_EXPR; - unsafe { $crate::option::Option::Some(&VAL) } - } - - // If the platform has support for `#[thread_local]`, use it. - #[cfg(all( - target_thread_local, - not(all(target_family = "wasm", not(target_feature = "atomics"))), - ))] - { - #[thread_local] - static mut VAL: $t = INIT_EXPR; - - // If a dtor isn't needed we can do something "very raw" and - // just get going. - if !$crate::mem::needs_drop::<$t>() { - unsafe { - return $crate::option::Option::Some(&VAL) - } - } - - // 0 == dtor not registered - // 1 == dtor registered, dtor not run - // 2 == dtor registered and is running or has run - #[thread_local] - static mut STATE: $crate::primitive::u8 = 0; - - unsafe extern "C" fn destroy(ptr: *mut $crate::primitive::u8) { - let ptr = ptr as *mut $t; - - unsafe { - $crate::debug_assert_eq!(STATE, 1); - STATE = 2; - $crate::ptr::drop_in_place(ptr); - } - } - - unsafe { - match STATE { - // 0 == we haven't registered a destructor, so do - // so now. - 0 => { - $crate::thread::__FastLocalKeyInner::<$t>::register_dtor( - $crate::ptr::addr_of_mut!(VAL) as *mut $crate::primitive::u8, - destroy, - ); - STATE = 1; - $crate::option::Option::Some(&VAL) - } - // 1 == the destructor is registered and the value - // is valid, so return the pointer. - 1 => $crate::option::Option::Some(&VAL), - // otherwise the destructor has already run, so we - // can't give access. - _ => $crate::option::Option::None, - } - } - } - - // On platforms without `#[thread_local]` we fall back to the - // same implementation as below for os thread locals. - #[cfg(all( - not(target_thread_local), - not(all(target_family = "wasm", not(target_feature = "atomics"))), - ))] - { - #[inline] - const fn __init() -> $t { INIT_EXPR } - static __KEY: $crate::thread::__OsLocalKeyInner<$t> = - $crate::thread::__OsLocalKeyInner::new(); - #[allow(unused_unsafe)] - unsafe { - __KEY.get(move || { - if let $crate::option::Option::Some(init) = _init { - if let $crate::option::Option::Some(value) = init.take() { - return value; - } else if $crate::cfg!(debug_assertions) { - $crate::unreachable!("missing initial value"); - } - } - __init() - }) - } - } - } - - unsafe { - $crate::thread::LocalKey::new(__getit) - } - }}; - - // used to generate the `LocalKey` value for `thread_local!` - (@key $t:ty, $init:expr) => { - { - #[inline] - fn __init() -> $t { $init } - - // When reading this function you might ask "why is this inlined - // everywhere other than Windows?", and that's a very reasonable - // question to ask. The short story is that it segfaults rustc if - // this function is inlined. The longer story is that Windows looks - // to not support `extern` references to thread locals across DLL - // boundaries. This appears to at least not be supported in the ABI - // that LLVM implements. - // - // Because of this we never inline on Windows, but we do inline on - // other platforms (where external references to thread locals - // across DLLs are supported). A better fix for this would be to - // inline this function on Windows, but only for "statically linked" - // components. For example if two separately compiled rlibs end up - // getting linked into a DLL then it's fine to inline this function - // across that boundary. It's only not fine to inline this function - // across a DLL boundary. Unfortunately rustc doesn't currently - // have this sort of logic available in an attribute, and it's not - // clear that rustc is even equipped to answer this (it's more of a - // Cargo question kinda). This means that, unfortunately, Windows - // gets the pessimistic path for now where it's never inlined. - // - // The issue of "should enable on Windows sometimes" is #84933 - #[cfg_attr(not(windows), inline)] - unsafe fn __getit( - init: $crate::option::Option<&mut $crate::option::Option<$t>>, - ) -> $crate::option::Option<&'static $t> { - #[cfg(all(target_family = "wasm", not(target_feature = "atomics")))] - static __KEY: $crate::thread::__StaticLocalKeyInner<$t> = - $crate::thread::__StaticLocalKeyInner::new(); - - #[thread_local] - #[cfg(all( - target_thread_local, - not(all(target_family = "wasm", not(target_feature = "atomics"))), - ))] - static __KEY: $crate::thread::__FastLocalKeyInner<$t> = - $crate::thread::__FastLocalKeyInner::new(); - - #[cfg(all( - not(target_thread_local), - not(all(target_family = "wasm", not(target_feature = "atomics"))), - ))] - static __KEY: $crate::thread::__OsLocalKeyInner<$t> = - $crate::thread::__OsLocalKeyInner::new(); - - // FIXME: remove the #[allow(...)] marker when macros don't - // raise warning for missing/extraneous unsafe blocks anymore. - // See https://github.com/rust-lang/rust/issues/74838. - #[allow(unused_unsafe)] - unsafe { - __KEY.get(move || { - if let $crate::option::Option::Some(init) = init { - if let $crate::option::Option::Some(value) = init.take() { - return value; - } else if $crate::cfg!(debug_assertions) { - $crate::unreachable!("missing default value"); - } - } - __init() - }) - } - } - - unsafe { - $crate::thread::LocalKey::new(__getit) - } - } - }; - ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => { - $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> = - $crate::__thread_local_inner!(@key $t, $($init)*); - } -} - /// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with). #[stable(feature = "thread_local_try_with", since = "1.26.0")] #[non_exhaustive] |