Auto merge of #24478 - alexcrichton:issue-24313, r=aturon

Inspecting the current thread's info may not always work due to the TLS value
having been destroyed (or is actively being destroyed). The code for printing
a panic message assumed, however, that it could acquire the thread's name
through this method.

Instead this commit propagates the `Option` outwards to allow the
`std::panicking` module to handle the case where the current thread isn't
present.

While it solves the immediate issue of #24313, there is still another underlying
issue of panicking destructors in thread locals will abort the process.

Closes #24313
This commit is contained in:
bors 2015-04-28 00:44:56 +00:00
commit 2b8c9b12f9
6 changed files with 55 additions and 31 deletions

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@ -17,7 +17,7 @@ use any::Any;
use cell::RefCell;
use rt::{backtrace, unwind};
use sys::stdio::Stderr;
use thread;
use sys_common::thread_info;
thread_local! {
pub static LOCAL_STDERR: RefCell<Option<Box<Write + Send>>> = {
@ -34,8 +34,8 @@ pub fn on_panic(obj: &(Any+Send), file: &'static str, line: u32) {
}
};
let mut err = Stderr::new();
let thread = thread::current();
let name = thread.name().unwrap_or("<unnamed>");
let thread = thread_info::current_thread();
let name = thread.as_ref().and_then(|t| t.name()).unwrap_or("<unnamed>");
let prev = LOCAL_STDERR.with(|s| s.borrow_mut().take());
match prev {
Some(mut stderr) => {

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@ -25,10 +25,9 @@ struct ThreadInfo {
thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = RefCell::new(None) }
impl ThreadInfo {
fn with<R, F>(f: F) -> R where F: FnOnce(&mut ThreadInfo) -> R {
fn with<R, F>(f: F) -> Option<R> where F: FnOnce(&mut ThreadInfo) -> R {
if THREAD_INFO.state() == LocalKeyState::Destroyed {
panic!("Use of std::thread::current() is not possible after \
the thread's local data has been destroyed");
return None
}
THREAD_INFO.with(move |c| {
@ -38,16 +37,16 @@ impl ThreadInfo {
thread: NewThread::new(None),
})
}
f(c.borrow_mut().as_mut().unwrap())
Some(f(c.borrow_mut().as_mut().unwrap()))
})
}
}
pub fn current_thread() -> Thread {
pub fn current_thread() -> Option<Thread> {
ThreadInfo::with(|info| info.thread.clone())
}
pub fn stack_guard() -> usize {
pub fn stack_guard() -> Option<usize> {
ThreadInfo::with(|info| info.stack_guard)
}

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@ -81,7 +81,7 @@ mod imp {
// We're calling into functions with stack checks
stack::record_sp_limit(0);
let guard = thread_info::stack_guard();
let guard = thread_info::stack_guard().unwrap_or(0);
let addr = (*info).si_addr as usize;
if guard == 0 || addr < guard - PAGE_SIZE || addr >= guard {

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@ -18,7 +18,6 @@ use cell::UnsafeCell;
// Sure wish we had macro hygiene, no?
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub mod __impl {
pub use super::imp::Key as KeyInner;
pub use super::imp::destroy_value;
@ -78,12 +77,10 @@ pub struct LocalKey<T> {
// This is trivially devirtualizable by LLVM because we never store anything
// to this field and rustc can declare the `static` as constant as well.
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub inner: fn() -> &'static __impl::KeyInner<UnsafeCell<Option<T>>>,
// initialization routine to invoke to create a value
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub init: fn() -> T,
}
@ -297,6 +294,7 @@ impl<T: 'static> LocalKey<T> {
}
#[cfg(all(any(target_os = "macos", target_os = "linux"), not(target_arch = "aarch64")))]
#[doc(hidden)]
mod imp {
use prelude::v1::*;
@ -304,8 +302,6 @@ mod imp {
use intrinsics;
use ptr;
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub struct Key<T> {
// Place the inner bits in an `UnsafeCell` to currently get around the
// "only Sync statics" restriction. This allows any type to be placed in
@ -313,20 +309,16 @@ mod imp {
//
// Note that all access requires `T: 'static` so it can't be a type with
// any borrowed pointers still.
#[unstable(feature = "thread_local_internals")]
pub inner: UnsafeCell<T>,
// Metadata to keep track of the state of the destructor. Remember that
// these variables are thread-local, not global.
#[unstable(feature = "thread_local_internals")]
pub dtor_registered: UnsafeCell<bool>, // should be Cell
#[unstable(feature = "thread_local_internals")]
pub dtor_running: UnsafeCell<bool>, // should be Cell
}
unsafe impl<T> ::marker::Sync for Key<T> { }
#[doc(hidden)]
impl<T> Key<T> {
pub unsafe fn get(&'static self) -> Option<&'static T> {
if intrinsics::needs_drop::<T>() && *self.dtor_running.get() {
@ -422,8 +414,6 @@ mod imp {
_tlv_atexit(dtor, t);
}
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub unsafe extern fn destroy_value<T>(ptr: *mut u8) {
let ptr = ptr as *mut Key<T>;
// Right before we run the user destructor be sure to flag the
@ -435,6 +425,7 @@ mod imp {
}
#[cfg(any(not(any(target_os = "macos", target_os = "linux")), target_arch = "aarch64"))]
#[doc(hidden)]
mod imp {
use prelude::v1::*;
@ -444,16 +435,12 @@ mod imp {
use ptr;
use sys_common::thread_local::StaticKey as OsStaticKey;
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub struct Key<T> {
// Statically allocated initialization expression, using an `UnsafeCell`
// for the same reasons as above.
#[unstable(feature = "thread_local_internals")]
pub inner: UnsafeCell<T>,
// OS-TLS key that we'll use to key off.
#[unstable(feature = "thread_local_internals")]
pub os: OsStaticKey,
}
@ -464,7 +451,6 @@ mod imp {
value: T,
}
#[doc(hidden)]
impl<T> Key<T> {
pub unsafe fn get(&'static self) -> Option<&'static T> {
self.ptr().map(|p| &*p)
@ -489,14 +475,12 @@ mod imp {
key: self,
value: mem::transmute_copy(&self.inner),
};
let ptr: *mut Value<T> = boxed::into_raw(ptr);
let ptr = boxed::into_raw(ptr);
self.os.set(ptr as *mut u8);
Some(&mut (*ptr).value as *mut T)
}
}
#[doc(hidden)]
#[unstable(feature = "thread_local_internals")]
pub unsafe extern fn destroy_value<T: 'static>(ptr: *mut u8) {
// 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
@ -505,7 +489,7 @@ mod imp {
//
// Note that to prevent an infinite loop we reset it back to null right
// before we return from the destructor ourselves.
let ptr: Box<Value<T>> = Box::from_raw(ptr as *mut Value<T>);
let ptr = Box::from_raw(ptr as *mut Value<T>);
let key = ptr.key;
key.os.set(1 as *mut u8);
drop(ptr);

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@ -407,7 +407,9 @@ pub fn scoped<'a, T, F>(f: F) -> JoinGuard<'a, T> where
/// Gets a handle to the thread that invokes it.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn current() -> Thread {
thread_info::current_thread()
thread_info::current_thread().expect("use of std::thread::current() is not \
possible after the thread's local \
data has been destroyed")
}
/// Cooperatively gives up a timeslice to the OS scheduler.

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@ -0,0 +1,39 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::thread;
use std::env;
use std::process::Command;
struct Handle(i32);
impl Drop for Handle {
fn drop(&mut self) { panic!(); }
}
thread_local!(static HANDLE: Handle = Handle(0));
fn main() {
let args = env::args().collect::<Vec<_>>();
if args.len() == 1 {
let out = Command::new(&args[0]).arg("test").output().unwrap();
let stderr = std::str::from_utf8(&out.stderr).unwrap();
assert!(stderr.contains("panicked at 'explicit panic'"),
"bad failure message:\n{}\n", stderr);
} else {
// TLS dtors are not always run on process exit
thread::spawn(|| {
HANDLE.with(|h| {
println!("{}", h.0);
});
}).join().unwrap();
}
}