diff options
Diffstat (limited to 'library/std/src/sys/common/thread_local/os_local.rs')
| -rw-r--r-- | library/std/src/sys/common/thread_local/os_local.rs | 215 |
1 files changed, 104 insertions, 111 deletions
diff --git a/library/std/src/sys/common/thread_local/os_local.rs b/library/std/src/sys/common/thread_local/os_local.rs index 1442a397e..5d48ce1e0 100644 --- a/library/std/src/sys/common/thread_local/os_local.rs +++ b/library/std/src/sys/common/thread_local/os_local.rs @@ -1,28 +1,29 @@ +use super::lazy::LazyKeyInner; +use crate::cell::Cell; +use crate::sys_common::thread_local_key::StaticKey as OsStaticKey; +use crate::{fmt, marker, panic, ptr}; + #[doc(hidden)] -#[macro_export] -#[allow_internal_unstable( - thread_local_internals, - cfg_target_thread_local, - thread_local, - libstd_thread_internals -)] +#[allow_internal_unstable(thread_local_internals)] #[allow_internal_unsafe] -macro_rules! __thread_local_inner { +#[unstable(feature = "thread_local_internals", issue = "none")] +#[rustc_macro_transparency = "semitransparent"] +pub macro thread_local_inner { // used to generate the `LocalKey` value for const-initialized thread locals (@key $t:ty, const $init:expr) => {{ - #[cfg_attr(not(bootstrap), inline)] + #[inline] #[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; - // On platforms without `#[thread_local]` we fall back to the + // On platforms without `#[thread_local]` we fall back to the // same implementation as below for os thread locals. #[inline] const fn __init() -> $t { INIT_EXPR } - static __KEY: $crate::thread::__LocalKeyInner<$t> = - $crate::thread::__LocalKeyInner::new(); + static __KEY: $crate::thread::local_impl::Key<$t> = + $crate::thread::local_impl::Key::new(); #[allow(unused_unsafe)] unsafe { __KEY.get(move || { @@ -41,7 +42,7 @@ macro_rules! __thread_local_inner { unsafe { $crate::thread::LocalKey::new(__getit) } - }}; + }}, // used to generate the `LocalKey` value for `thread_local!` (@key $t:ty, $init:expr) => { @@ -55,8 +56,8 @@ macro_rules! __thread_local_inner { unsafe fn __getit( init: $crate::option::Option<&mut $crate::option::Option<$t>>, ) -> $crate::option::Option<&'static $t> { - static __KEY: $crate::thread::__LocalKeyInner<$t> = - $crate::thread::__LocalKeyInner::new(); + static __KEY: $crate::thread::local_impl::Key<$t> = + $crate::thread::local_impl::Key::new(); // FIXME: remove the #[allow(...)] marker when macros don't // raise warning for missing/extraneous unsafe blocks anymore. @@ -80,118 +81,110 @@ macro_rules! __thread_local_inner { $crate::thread::LocalKey::new(__getit) } } - }; + }, ($(#[$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)*); - } + $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*); + }, } -#[doc(hidden)] -pub mod os { - use super::super::lazy::LazyKeyInner; - use crate::cell::Cell; - use crate::sys_common::thread_local_key::StaticKey as OsStaticKey; - use crate::{fmt, marker, panic, ptr}; - - /// Use a regular global static to store this key; the state provided will then be - /// thread-local. - pub struct Key<T> { - // OS-TLS key that we'll use to key off. - os: OsStaticKey, - marker: marker::PhantomData<Cell<T>>, - } +/// Use a regular global static to store this key; the state provided will then be +/// thread-local. +pub struct Key<T> { + // OS-TLS key that we'll use to key off. + os: OsStaticKey, + marker: marker::PhantomData<Cell<T>>, +} - impl<T> fmt::Debug for Key<T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("Key").finish_non_exhaustive() - } +impl<T> fmt::Debug for Key<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Key").finish_non_exhaustive() } +} - unsafe impl<T> Sync for Key<T> {} +unsafe impl<T> Sync for Key<T> {} - struct Value<T: 'static> { - inner: LazyKeyInner<T>, - key: &'static Key<T>, +struct Value<T: 'static> { + inner: LazyKeyInner<T>, + key: &'static Key<T>, +} + +impl<T: 'static> Key<T> { + #[rustc_const_unstable(feature = "thread_local_internals", issue = "none")] + pub const fn new() -> Key<T> { + Key { os: OsStaticKey::new(Some(destroy_value::<T>)), marker: marker::PhantomData } } - impl<T: 'static> Key<T> { - #[rustc_const_unstable(feature = "thread_local_internals", issue = "none")] - pub const fn new() -> Key<T> { - Key { os: OsStaticKey::new(Some(destroy_value::<T>)), marker: marker::PhantomData } + /// It is a requirement for the caller to ensure that no mutable + /// reference is active when this method is called. + pub unsafe fn get(&'static self, init: impl FnOnce() -> T) -> Option<&'static T> { + // SAFETY: See the documentation for this method. + let ptr = unsafe { self.os.get() as *mut Value<T> }; + if ptr.addr() > 1 { + // SAFETY: the check ensured the pointer is safe (its destructor + // is not running) + it is coming from a trusted source (self). + if let Some(ref value) = unsafe { (*ptr).inner.get() } { + return Some(value); + } } + // SAFETY: At this point we are sure we have no value and so + // initializing (or trying to) is safe. + unsafe { self.try_initialize(init) } + } - /// It is a requirement for the caller to ensure that no mutable - /// reference is active when this method is called. - pub unsafe fn get(&'static self, init: impl FnOnce() -> T) -> Option<&'static T> { - // SAFETY: See the documentation for this method. - let ptr = unsafe { self.os.get() as *mut Value<T> }; - if ptr.addr() > 1 { - // SAFETY: the check ensured the pointer is safe (its destructor - // is not running) + it is coming from a trusted source (self). - if let Some(ref value) = unsafe { (*ptr).inner.get() } { - return Some(value); - } - } - // SAFETY: At this point we are sure we have no value and so - // initializing (or trying to) is safe. - unsafe { self.try_initialize(init) } + // `try_initialize` is only called once per os thread local variable, + // except in corner cases where thread_local dtors reference other + // thread_local's, or it is being recursively initialized. + unsafe fn try_initialize(&'static self, init: impl FnOnce() -> T) -> Option<&'static T> { + // SAFETY: No mutable references are ever handed out meaning getting + // the value is ok. + let ptr = unsafe { self.os.get() as *mut Value<T> }; + if ptr.addr() == 1 { + // destructor is running + return None; } - // `try_initialize` is only called once per os thread local variable, - // except in corner cases where thread_local dtors reference other - // thread_local's, or it is being recursively initialized. - unsafe fn try_initialize(&'static self, init: impl FnOnce() -> T) -> Option<&'static T> { - // SAFETY: No mutable references are ever handed out meaning getting - // the value is ok. - let ptr = unsafe { self.os.get() as *mut Value<T> }; - if ptr.addr() == 1 { - // destructor is running - return None; + let ptr = if ptr.is_null() { + // If the lookup returned null, we haven't initialized our own + // local copy, so do that now. + let ptr = Box::into_raw(Box::new(Value { inner: LazyKeyInner::new(), key: self })); + // SAFETY: At this point we are sure there is no value inside + // ptr so setting it will not affect anyone else. + unsafe { + self.os.set(ptr as *mut u8); } - - let ptr = if ptr.is_null() { - // If the lookup returned null, we haven't initialized our own - // local copy, so do that now. - let ptr = Box::into_raw(Box::new(Value { inner: LazyKeyInner::new(), key: self })); - // SAFETY: At this point we are sure there is no value inside - // ptr so setting it will not affect anyone else. - unsafe { - self.os.set(ptr as *mut u8); - } - ptr - } else { - // recursive initialization - ptr - }; - - // SAFETY: ptr has been ensured as non-NUL just above an so can be - // dereferenced safely. - unsafe { Some((*ptr).inner.initialize(init)) } - } + ptr + } else { + // recursive initialization + ptr + }; + + // SAFETY: ptr has been ensured as non-NUL just above an so can be + // dereferenced safely. + unsafe { Some((*ptr).inner.initialize(init)) } } +} - unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) { - // SAFETY: - // - // The OS TLS ensures that this key contains a null value when this - // destructor starts to run. We set it back to a sentinel value of 1 to - // ensure that any future calls to `get` for this thread will return - // `None`. - // - // Note that to prevent an infinite loop we reset it back to null right - // before we return from the destructor ourselves. - // - // Wrap the call in a catch to ensure unwinding is caught in the event - // a panic takes place in a destructor. - if let Err(_) = panic::catch_unwind(|| unsafe { - let ptr = Box::from_raw(ptr as *mut Value<T>); - let key = ptr.key; - key.os.set(ptr::invalid_mut(1)); - drop(ptr); - key.os.set(ptr::null_mut()); - }) { - rtabort!("thread local panicked on drop"); - } +unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) { + // SAFETY: + // + // The OS TLS ensures that this key contains a null value when this + // destructor starts to run. We set it back to a sentinel value of 1 to + // ensure that any future calls to `get` for this thread will return + // `None`. + // + // Note that to prevent an infinite loop we reset it back to null right + // before we return from the destructor ourselves. + // + // Wrap the call in a catch to ensure unwinding is caught in the event + // a panic takes place in a destructor. + if let Err(_) = panic::catch_unwind(|| unsafe { + let ptr = Box::from_raw(ptr as *mut Value<T>); + let key = ptr.key; + key.os.set(ptr::invalid_mut(1)); + drop(ptr); + key.os.set(ptr::null_mut()); + }) { + rtabort!("thread local panicked on drop"); } } |