auto merge of #10312 : thestinger/rust/thread_local, r=alexcritchton
This provides a building block for fast thread-local storage. It does not change the safety semantics of `static mut`. Closes #10310
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35ebf03489
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@ -1754,6 +1754,8 @@ names are effectively reserved. Some significant attributes include:
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* The `deriving` attribute, for automatically generating
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implementations of certain traits.
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* The `static_assert` attribute, for asserting that a static bool is true at compiletime
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* The `thread_local` attribute, for defining a `static mut` as a thread-local. Note that this is
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only a low-level building block, and is not local to a *task*, nor does it provide safety.
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Other attributes may be added or removed during development of the language.
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@ -38,6 +38,7 @@ static KNOWN_FEATURES: &'static [(&'static str, Status)] = &[
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("asm", Active),
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("managed_boxes", Active),
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("non_ascii_idents", Active),
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("thread_local", Active),
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// These are used to test this portion of the compiler, they don't actually
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// mean anything
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@ -107,6 +108,17 @@ impl Visitor<()> for Context {
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}
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fn visit_item(&mut self, i: @ast::item, _:()) {
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// NOTE: uncomment after snapshot
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/*
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for attr in i.attrs.iter() {
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if "thread_local" == attr.name() {
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self.gate_feature("thread_local", i.span,
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"`#[thread_local]` is an experimental feature, and does not \
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currently handle destructors. There is no corresponding \
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`#[task_local]` mapping to the task model");
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}
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}
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*/
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match i.node {
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ast::item_enum(ref def, _) => {
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for variant in def.variants.iter() {
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@ -152,8 +164,8 @@ impl Visitor<()> for Context {
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},
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ast::ty_box(_) => {
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self.gate_feature("managed_boxes", t.span,
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"The managed box syntax is being replaced by the `std::gc::Gc`
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and `std::rc::Rc` types. Equivalent functionality to managed
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"The managed box syntax is being replaced by the `std::gc::Gc` \
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and `std::rc::Rc` types. Equivalent functionality to managed \
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trait objects will be implemented but is currently missing.");
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}
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_ => {}
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@ -1749,6 +1749,12 @@ pub fn SetUnnamedAddr(Global: ValueRef, Unnamed: bool) {
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}
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}
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pub fn set_thread_local(global: ValueRef, is_thread_local: bool) {
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unsafe {
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llvm::LLVMSetThreadLocal(global, is_thread_local as Bool);
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}
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}
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pub fn ConstICmp(Pred: IntPredicate, V1: ValueRef, V2: ValueRef) -> ValueRef {
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unsafe {
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llvm::LLVMConstICmp(Pred as c_ushort, V1, V2)
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@ -816,6 +816,7 @@ static obsolete_attrs: &'static [(&'static str, &'static str)] = &[
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static other_attrs: &'static [&'static str] = &[
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// item-level
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"address_insignificant", // can be crate-level too
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"thread_local", // for statics
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"allow", "deny", "forbid", "warn", // lint options
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"deprecated", "experimental", "unstable", "stable", "locked", "frozen", //item stability
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"crate_map", "cfg", "doc", "export_name", "link_section", "no_freeze",
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@ -2544,6 +2544,10 @@ pub fn get_item_val(ccx: @mut CrateContext, id: ast::NodeId) -> ValueRef {
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inlineable = true;
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}
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if attr::contains_name(i.attrs, "thread_local") {
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lib::llvm::set_thread_local(g, true);
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}
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if !inlineable {
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debug!("{} not inlined", sym);
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ccx.non_inlineable_statics.insert(id);
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@ -17,16 +17,35 @@
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use libc::c_void;
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use cast;
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#[cfg(stage0)]
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#[cfg(windows)]
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use ptr;
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use cell::Cell;
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use option::{Option, Some, None};
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use unstable::finally::Finally;
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#[cfg(stage0)]
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#[cfg(windows)]
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use unstable::mutex::{Mutex, MUTEX_INIT};
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#[cfg(stage0)]
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#[cfg(windows)]
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use tls = rt::thread_local_storage;
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#[cfg(not(stage0), not(windows), test)]
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#[thread_local]
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pub use realstd::rt::shouldnt_be_public::RT_TLS_PTR;
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#[cfg(not(stage0), not(windows), not(test))]
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#[thread_local]
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pub static mut RT_TLS_PTR: *mut c_void = 0 as *mut c_void;
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#[cfg(stage0)]
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#[cfg(windows)]
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static mut RT_TLS_KEY: tls::Key = -1;
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/// Initialize the TLS key. Other ops will fail if this isn't executed first.
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#[inline(never)]
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#[cfg(stage0)]
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#[cfg(windows)]
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pub fn init_tls_key() {
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static mut lock: Mutex = MUTEX_INIT;
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static mut initialized: bool = false;
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@ -41,24 +60,42 @@ pub fn init_tls_key() {
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}
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}
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#[cfg(not(stage0), not(windows))]
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pub fn init_tls_key() {}
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/// Give a pointer to thread-local storage.
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///
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/// # Safety note
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///
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/// Does not validate the pointer type.
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#[inline]
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#[cfg(stage0)]
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#[cfg(windows)]
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pub unsafe fn put<T>(sched: ~T) {
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let key = tls_key();
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let void_ptr: *mut c_void = cast::transmute(sched);
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tls::set(key, void_ptr);
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}
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/// Give a pointer to thread-local storage.
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///
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/// # Safety note
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///
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/// Does not validate the pointer type.
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#[inline]
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#[cfg(not(stage0), not(windows))]
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pub unsafe fn put<T>(sched: ~T) {
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RT_TLS_PTR = cast::transmute(sched)
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}
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/// Take ownership of a pointer from thread-local storage.
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///
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/// # Safety note
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///
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/// Does not validate the pointer type.
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#[inline]
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#[cfg(stage0)]
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#[cfg(windows)]
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pub unsafe fn take<T>() -> ~T {
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let key = tls_key();
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let void_ptr: *mut c_void = tls::get(key);
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@ -70,6 +107,19 @@ pub unsafe fn take<T>() -> ~T {
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return ptr;
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}
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/// Take ownership of a pointer from thread-local storage.
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///
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/// # Safety note
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///
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/// Does not validate the pointer type.
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#[inline]
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#[cfg(not(stage0), not(windows))]
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pub unsafe fn take<T>() -> ~T {
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let ptr: ~T = cast::transmute(RT_TLS_PTR);
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RT_TLS_PTR = cast::transmute(0); // can't use `as`, due to type not matching with `cfg(test)`
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ptr
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}
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/// Take ownership of a pointer from thread-local storage.
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///
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/// # Safety note
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@ -77,6 +127,8 @@ pub unsafe fn take<T>() -> ~T {
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/// Does not validate the pointer type.
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/// Leaves the old pointer in TLS for speed.
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#[inline]
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#[cfg(stage0)]
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#[cfg(windows)]
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pub unsafe fn unsafe_take<T>() -> ~T {
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let key = tls_key();
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let void_ptr: *mut c_void = tls::get(key);
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@ -87,7 +139,21 @@ pub unsafe fn unsafe_take<T>() -> ~T {
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return ptr;
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}
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/// Take ownership of a pointer from thread-local storage.
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///
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/// # Safety note
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///
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/// Does not validate the pointer type.
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/// Leaves the old pointer in TLS for speed.
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#[inline]
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#[cfg(not(stage0), not(windows))]
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pub unsafe fn unsafe_take<T>() -> ~T {
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cast::transmute(RT_TLS_PTR)
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}
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/// Check whether there is a thread-local pointer installed.
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#[cfg(stage0)]
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#[cfg(windows)]
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pub fn exists() -> bool {
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unsafe {
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match maybe_tls_key() {
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@ -97,6 +163,14 @@ pub fn exists() -> bool {
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}
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}
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/// Check whether there is a thread-local pointer installed.
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#[cfg(not(stage0), not(windows))]
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pub fn exists() -> bool {
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unsafe {
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RT_TLS_PTR.is_not_null()
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}
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}
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/// Borrow the thread-local value from thread-local storage.
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/// While the value is borrowed it is not available in TLS.
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///
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@ -119,6 +193,8 @@ pub unsafe fn borrow<T>(f: |&mut T|) {
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///
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/// Because this leaves the value in thread-local storage it is possible
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/// For the Scheduler pointer to be aliased
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#[cfg(stage0)]
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#[cfg(windows)]
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pub unsafe fn unsafe_borrow<T>() -> *mut T {
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let key = tls_key();
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let void_ptr = tls::get(key);
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@ -128,6 +204,16 @@ pub unsafe fn unsafe_borrow<T>() -> *mut T {
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void_ptr as *mut T
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}
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#[cfg(not(stage0), not(windows))]
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pub unsafe fn unsafe_borrow<T>() -> *mut T {
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if RT_TLS_PTR.is_null() {
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rtabort!("thread-local pointer is null. bogus!");
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}
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RT_TLS_PTR as *mut T
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}
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#[cfg(stage0)]
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#[cfg(windows)]
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pub unsafe fn try_unsafe_borrow<T>() -> Option<*mut T> {
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match maybe_tls_key() {
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Some(key) => {
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@ -142,7 +228,18 @@ pub unsafe fn try_unsafe_borrow<T>() -> Option<*mut T> {
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}
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}
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#[cfg(not(stage0), not(windows))]
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pub unsafe fn try_unsafe_borrow<T>() -> Option<*mut T> {
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if RT_TLS_PTR.is_null() {
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None
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} else {
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Some(RT_TLS_PTR as *mut T)
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}
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}
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#[inline]
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#[cfg(stage0)]
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#[cfg(windows)]
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fn tls_key() -> tls::Key {
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match maybe_tls_key() {
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Some(key) => key,
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@ -151,7 +248,8 @@ fn tls_key() -> tls::Key {
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}
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#[inline]
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#[cfg(not(test))]
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#[cfg(not(test), stage0)]
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#[cfg(not(test), windows)]
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pub fn maybe_tls_key() -> Option<tls::Key> {
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unsafe {
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// NB: This is a little racy because, while the key is
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@ -172,11 +270,9 @@ pub fn maybe_tls_key() -> Option<tls::Key> {
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}
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}
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// XXX: The boundary between the running runtime and the testing runtime
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// seems to be fuzzy at the moment, and trying to use two different keys
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// results in disaster. This should not be necessary.
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#[inline]
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#[cfg(test)]
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#[cfg(test, stage0)]
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#[cfg(test, windows)]
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pub fn maybe_tls_key() -> Option<tls::Key> {
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unsafe { ::cast::transmute(::realstd::rt::shouldnt_be_public::maybe_tls_key()) }
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}
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@ -95,7 +95,11 @@ pub use self::kill::BlockedTask;
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pub mod shouldnt_be_public {
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pub use super::select::SelectInner;
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pub use super::select::{SelectInner, SelectPortInner};
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#[cfg(stage0)]
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#[cfg(windows)]
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pub use super::local_ptr::maybe_tls_key;
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#[cfg(not(stage0), not(windows))]
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pub use super::local_ptr::RT_TLS_PTR;
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}
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// Internal macros used by the runtime.
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