Rollup merge of rust-lang#23267 - alexcrichton:issue-20012, r=brson

 This reverts commit aec67c2.

Closes rust-lang#20012

This is temporarily rebased on rust-lang#23245 as it would otherwise conflict, the last commit is the only one relevant to this PR though.

Author: Manishearth

src/liblog/lib.rs

@@ -184,10 +184,9 @@ use std::old_io::LineBufferedWriter;
 use std::old_io;
 use std::mem;
 use std::env;
-use std::ptr;
 use std::rt;
 use std::slice;
-use std::sync::{Once, ONCE_INIT};
+use std::sync::{Once, ONCE_INIT, StaticMutex, MUTEX_INIT};
 
 use directive::LOG_LEVEL_NAMES;
 
@@ -203,6 +202,8 @@ pub const MAX_LOG_LEVEL: u32 = 255;
 /// The default logging level of a crate if no other is specified.
 const DEFAULT_LOG_LEVEL: u32 = 1;
 
+static LOCK: StaticMutex = MUTEX_INIT;
+
 /// An unsafe constant that is the maximum logging level of any module
 /// specified. This is the first line of defense to determining whether a
 /// logging statement should be run.
@@ -289,9 +290,18 @@ impl Drop for DefaultLogger {
 pub fn log(level: u32, loc: &'static LogLocation, args: fmt::Arguments) {
     // Test the literal string from args against the current filter, if there
     // is one.
-    match unsafe { FILTER.as_ref() } {
-        Some(filter) if !args.to_string().contains(&filter[..]) => return,
-        _ => {}
+    unsafe {
+        let _g = LOCK.lock();
+        match FILTER as uint {
+            0 => {}
+            1 => panic!("cannot log after main thread has exited"),
+            n => {
+                let filter = mem::transmute::<_, &String>(n);
+                if !args.to_string().contains(&filter[..]) {
+                    return
+                }
+            }
+        }
     }
 
     // Completely remove the local logger from TLS in case anyone attempts to
@@ -373,9 +383,15 @@ pub fn mod_enabled(level: u32, module: &str) -> bool {
 
     // This assertion should never get tripped unless we're in an at_exit
     // handler after logging has been torn down and a logging attempt was made.
-    assert!(unsafe { !DIRECTIVES.is_null() });
 
-    enabled(level, module, unsafe { (*DIRECTIVES).iter() })
+    let _g = LOCK.lock();
+    unsafe {
+        assert!(DIRECTIVES as uint != 0);
+        assert!(DIRECTIVES as uint != 1,
+                "cannot log after the main thread has exited");
+
+        enabled(level, module, (*DIRECTIVES).iter())
+    }
 }
 
 fn enabled(level: u32,
@@ -431,14 +447,14 @@ fn init() {
 
         // Schedule the cleanup for the globals for when the runtime exits.
         rt::at_exit(move || {
+            let _g = LOCK.lock();
             assert!(!DIRECTIVES.is_null());
-            let _directives: Box<Vec<directive::LogDirective>> =
-                Box::from_raw(DIRECTIVES);
-            DIRECTIVES = ptr::null_mut();
+            let _directives = Box::from_raw(DIRECTIVES);
+            DIRECTIVES = 1 as *mut _;
 
             if !FILTER.is_null() {
-                let _filter: Box<String> = Box::from_raw(FILTER);
-                FILTER = 0 as *mut _;
+                let _filter = Box::from_raw(FILTER);
+                FILTER = 1 as *mut _;
             }
         });
     }

src/libstd/lib.rs

@@ -273,13 +273,14 @@ pub mod collections;
 pub mod thread;
 pub mod sync;
 
+#[macro_use]
+#[path = "sys/common/mod.rs"] mod sys_common;
+
 #[cfg(unix)]
 #[path = "sys/unix/mod.rs"] mod sys;
 #[cfg(windows)]
 #[path = "sys/windows/mod.rs"] mod sys;
 
-#[path = "sys/common/mod.rs"] mod sys_common;
-
 pub mod rt;
 mod panicking;
 

src/libstd/rt/mod.rs

@@ -108,9 +108,7 @@ fn lang_start(main: *const u8, argc: int, argv: *const *const u8) -> int {
         // but we just do this to name the main thread and to give it correct
         // info about the stack bounds.
         let thread: Thread = NewThread::new(Some("<main>".to_string()));
-        thread_info::set((my_stack_bottom, my_stack_top),
-                         sys::thread::guard::main(),
-                         thread);
+        thread_info::set(sys::thread::guard::main(), thread);
 
         // By default, some platforms will send a *signal* when a EPIPE error
         // would otherwise be delivered. This runtime doesn't install a SIGPIPE
@@ -149,20 +147,14 @@ fn lang_start(main: *const u8, argc: int, argv: *const *const u8) -> int {
     }
 }
 
-/// Enqueues a procedure to run when the runtime is cleaned up
-///
-/// The procedure passed to this function will be executed as part of the
-/// runtime cleanup phase. For normal rust programs, this means that it will run
-/// after all other threads have exited.
-///
-/// The procedure is *not* executed with a local `Thread` available to it, so
-/// primitives like logging, I/O, channels, spawning, etc, are *not* available.
-/// This is meant for "bare bones" usage to clean up runtime details, this is
-/// not meant as a general-purpose "let's clean everything up" function.
+/// Enqueues a procedure to run when the main thread exits.
 ///
 /// It is forbidden for procedures to register more `at_exit` handlers when they
 /// are running, and doing so will lead to a process abort.
-pub fn at_exit<F:FnOnce()+Send+'static>(f: F) {
+///
+/// Note that other threads may still be running when `at_exit` routines start
+/// running.
+pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) {
     at_exit_imp::push(Thunk::new(f));
 }
 
@@ -178,8 +170,5 @@ pub fn at_exit<F:FnOnce()+Send+'static>(f: F) {
 pub unsafe fn cleanup() {
     args::cleanup();
     sys::stack_overflow::cleanup();
-    // FIXME: (#20012): the resources being cleaned up by at_exit
-    // currently are not prepared for cleanup to happen asynchronously
-    // with detached threads using the resources; for now, we leak.
-    // at_exit_imp::cleanup();
+    at_exit_imp::cleanup();
 }

src/libstd/rt/unwind.rs

@@ -69,7 +69,7 @@ use intrinsics;
 use libc::c_void;
 use mem;
 use sync::atomic::{self, Ordering};
-use sync::{Once, ONCE_INIT};
+use sys_common::mutex::{Mutex, MUTEX_INIT};
 
 use rt::libunwind as uw;
 
@@ -534,11 +534,22 @@ pub fn begin_unwind<M: Any + Send>(msg: M, file_line: &(&'static str, uint)) ->
 /// Doing this split took the LLVM IR line counts of `fn main() { panic!()
 /// }` from ~1900/3700 (-O/no opts) to 180/590.
 #[inline(never)] #[cold] // this is the slow path, please never inline this
-fn begin_unwind_inner(msg: Box<Any + Send>, file_line: &(&'static str, uint)) -> ! {
-    // Make sure the default panic handler is registered before we look at the
-    // callbacks.
-    static INIT: Once = ONCE_INIT;
-    INIT.call_once(|| unsafe { register(panicking::on_panic); });
+fn begin_unwind_inner(msg: Box<Any + Send>,
+                      file_line: &(&'static str, uint)) -> ! {
+    // Make sure the default failure handler is registered before we look at the
+    // callbacks. We also use a raw sys-based mutex here instead of a
+    // `std::sync` one as accessing TLS can cause weird recursive problems (and
+    // we don't need poison checking).
+    unsafe {
+        static LOCK: Mutex = MUTEX_INIT;
+        static mut INIT: bool = false;
+        LOCK.lock();
+        if !INIT {
+            register(panicking::on_panic);
+            INIT = true;
+        }
+        LOCK.unlock();
+    }
 
     // First, invoke call the user-defined callbacks triggered on thread panic.
     //

src/libstd/sys/common/helper_thread.rs

@@ -24,7 +24,6 @@ use prelude::v1::*;
 
 use boxed;
 use cell::UnsafeCell;
-use ptr;
 use rt;
 use sync::{StaticMutex, StaticCondvar};
 use sync::mpsc::{channel, Sender, Receiver};
@@ -70,6 +69,17 @@ struct RaceBox(helper_signal::signal);
 unsafe impl Send for RaceBox {}
 unsafe impl Sync for RaceBox {}
 
+macro_rules! helper_init { (static $name:ident: Helper<$m:ty>) => (
+    static $name: Helper<$m> = Helper {
+        lock: ::sync::MUTEX_INIT,
+        cond: ::sync::CONDVAR_INIT,
+        chan: ::cell::UnsafeCell { value: 0 as *mut Sender<$m> },
+        signal: ::cell::UnsafeCell { value: 0 },
+        initialized: ::cell::UnsafeCell { value: false },
+        shutdown: ::cell::UnsafeCell { value: false },
+    };
+) }
+
 impl<M: Send> Helper<M> {
     /// Lazily boots a helper thread, becoming a no-op if the helper has already
     /// been spawned.
@@ -86,7 +96,7 @@ impl<M: Send> Helper<M> {
     {
         unsafe {
             let _guard = self.lock.lock().unwrap();
-            if !*self.initialized.get() {
+            if *self.chan.get() as uint == 0 {
                 let (tx, rx) = channel();
                 *self.chan.get() = boxed::into_raw(box tx);
                 let (receive, send) = helper_signal::new();
@@ -102,8 +112,10 @@ impl<M: Send> Helper<M> {
                     self.cond.notify_one()
                 });
 
-                rt::at_exit(move|| { self.shutdown() });
+                rt::at_exit(move || { self.shutdown() });
                 *self.initialized.get() = true;
+            } else if *self.chan.get() as uint == 1 {
+                panic!("cannot continue usage after shutdown");
             }
         }
     }
@@ -118,7 +130,9 @@ impl<M: Send> Helper<M> {
             // Must send and *then* signal to ensure that the child receives the
             // message. Otherwise it could wake up and go to sleep before we
             // send the message.
-            assert!(!self.chan.get().is_null());
+            assert!(*self.chan.get() as uint != 0);
+            assert!(*self.chan.get() as uint != 1,
+                    "cannot continue usage after shutdown");
             (**self.chan.get()).send(msg).unwrap();
             helper_signal::signal(*self.signal.get() as helper_signal::signal);
         }
@@ -131,9 +145,13 @@ impl<M: Send> Helper<M> {
             // returns.
             let mut guard = self.lock.lock().unwrap();
 
+            let ptr = *self.chan.get();
+            if ptr as uint == 1 {
+                panic!("cannot continue usage after shutdown");
+            }
             // Close the channel by destroying it
-            let chan: Box<Sender<M>> = Box::from_raw(*self.chan.get());
-            *self.chan.get() = ptr::null_mut();
+            let chan = Box::from_raw(*self.chan.get());
+            *self.chan.get() = 1 as *mut Sender<M>;
             drop(chan);
             helper_signal::signal(*self.signal.get() as helper_signal::signal);
 

src/libstd/sys/common/mod.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![allow(missing_docs)]
-#![allow(dead_code)]
 
 use old_io::{self, IoError, IoResult};
 use prelude::v1::*;
@@ -19,9 +18,10 @@ use num::Int;
 use old_path::BytesContainer;
 use collections;
 
+#[macro_use] pub mod helper_thread;
+
 pub mod backtrace;
 pub mod condvar;
-pub mod helper_thread;
 pub mod mutex;
 pub mod net;
 pub mod net2;

src/libstd/sys/common/net.rs

@@ -26,7 +26,9 @@ use str;
 use sys::{self, retry, c, sock_t, last_error, last_net_error, last_gai_error, close_sock,
           wrlen, msglen_t, os, wouldblock, set_nonblocking, timer, ms_to_timeval,
           decode_error_detailed};
-use sync::{Arc, Mutex, MutexGuard};
+use sync::{Arc, Mutex};
+#[cfg(not(target_os = "linux"))]
+use sync::MutexGuard;
 use sys_common::{self, keep_going, short_write, timeout};
 use cmp;
 use old_io;
@@ -620,11 +622,13 @@ impl Drop for Inner {
     fn drop(&mut self) { unsafe { close_sock(self.fd); } }
 }
 
+#[cfg(not(target_os = "linux"))]
 pub struct Guard<'a> {
     pub fd: sock_t,
     pub guard: MutexGuard<'a, ()>,
 }
 
+#[cfg(not(target_os = "linux"))]
 #[unsafe_destructor]
 impl<'a> Drop for Guard<'a> {
     fn drop(&mut self) {

src/libstd/sys/common/net2.rs

@@ -15,7 +15,6 @@ use io::{self, Error, ErrorKind};
 use libc::{self, c_int, c_char, c_void, socklen_t};
 use mem;
 use net::{IpAddr, SocketAddr, Shutdown};
-use num::Int;
 use sys::c;
 use sys::net::{cvt, cvt_r, cvt_gai, Socket, init, wrlen_t};
 use sys_common::{AsInner, FromInner, IntoInner};
@@ -24,9 +23,6 @@ use sys_common::{AsInner, FromInner, IntoInner};
 // sockaddr and misc bindings
 ////////////////////////////////////////////////////////////////////////////////
 
-fn hton<I: Int>(i: I) -> I { i.to_be() }
-fn ntoh<I: Int>(i: I) -> I { Int::from_be(i) }
-
 fn setsockopt<T>(sock: &Socket, opt: c_int, val: c_int,
                      payload: T) -> io::Result<()> {
     unsafe {
@@ -39,7 +35,7 @@ fn setsockopt<T>(sock: &Socket, opt: c_int, val: c_int,
 
 #[allow(dead_code)]
 fn getsockopt<T: Copy>(sock: &Socket, opt: c_int,
-                           val: c_int) -> io::Result<T> {
+                       val: c_int) -> io::Result<T> {
     unsafe {
         let mut slot: T = mem::zeroed();
         let mut len = mem::size_of::<T>() as socklen_t;

src/libstd/sys/common/stack.rs

@@ -121,37 +121,6 @@ pub unsafe fn record_os_managed_stack_bounds(stack_lo: uint, _stack_hi: uint) {
     record_sp_limit(stack_lo + RED_ZONE);
 }
 
-#[inline(always)]
-pub unsafe fn record_rust_managed_stack_bounds(stack_lo: uint, stack_hi: uint) {
-    // When the old runtime had segmented stacks, it used a calculation that was
-    // "limit + RED_ZONE + FUDGE". The red zone was for things like dynamic
-    // symbol resolution, llvm function calls, etc. In theory this red zone
-    // value is 0, but it matters far less when we have gigantic stacks because
-    // we don't need to be so exact about our stack budget. The "fudge factor"
-    // was because LLVM doesn't emit a stack check for functions < 256 bytes in
-    // size. Again though, we have giant stacks, so we round all these
-    // calculations up to the nice round number of 20k.
-    record_sp_limit(stack_lo + RED_ZONE);
-
-    return target_record_stack_bounds(stack_lo, stack_hi);
-
-    #[cfg(not(windows))] #[inline(always)]
-    unsafe fn target_record_stack_bounds(_stack_lo: uint, _stack_hi: uint) {}
-
-    #[cfg(all(windows, target_arch = "x86"))] #[inline(always)]
-    unsafe fn target_record_stack_bounds(stack_lo: uint, stack_hi: uint) {
-        // stack range is at TIB: %fs:0x04 (top) and %fs:0x08 (bottom)
-        asm!("mov $0, %fs:0x04" :: "r"(stack_hi) :: "volatile");
-        asm!("mov $0, %fs:0x08" :: "r"(stack_lo) :: "volatile");
-    }
-    #[cfg(all(windows, target_arch = "x86_64"))] #[inline(always)]
-    unsafe fn target_record_stack_bounds(stack_lo: uint, stack_hi: uint) {
-        // stack range is at TIB: %gs:0x08 (top) and %gs:0x10 (bottom)
-        asm!("mov $0, %gs:0x08" :: "r"(stack_hi) :: "volatile");
-        asm!("mov $0, %gs:0x10" :: "r"(stack_lo) :: "volatile");
-    }
-}
-
 /// Records the current limit of the stack as specified by `end`.
 ///
 /// This is stored in an OS-dependent location, likely inside of the thread