Test fixes and rebase problems

Note that this removes a number of run-pass tests which are exercising behavior
of the old runtime. This functionality no longer exists and is thoroughly tested
inside of libgreen and libnative. There isn't really the notion of "starting the
runtime" any more. The major notion now is "bootstrapping the initial task".

3 files changed, 96 insertions, 3 deletions

diff --git a/src/libstd/io/test.rs b/src/libstd/io/test.rs
index dd24150e03e..e273aedf7cc 100644
--- a/src/libstd/io/test.rs
+++ b/src/libstd/io/test.rs
@@ -113,3 +113,82 @@ fn base_port() -> u16 {
 
     return final_base;
 }
+
+pub fn raise_fd_limit() {
+    unsafe { darwin_fd_limit::raise_fd_limit() }
+}
+
+#[cfg(target_os="macos")]
+#[allow(non_camel_case_types)]
+mod darwin_fd_limit {
+    /*!
+     * darwin_fd_limit exists to work around an issue where launchctl on Mac OS X defaults the
+     * rlimit maxfiles to 256/unlimited. The default soft limit of 256 ends up being far too low
+     * for our multithreaded scheduler testing, depending on the number of cores available.
+     *
+     * This fixes issue #7772.
+     */
+
+    use libc;
+    type rlim_t = libc::uint64_t;
+    struct rlimit {
+        rlim_cur: rlim_t,
+        rlim_max: rlim_t
+    }
+    #[nolink]
+    extern {
+        // name probably doesn't need to be mut, but the C function doesn't specify const
+        fn sysctl(name: *mut libc::c_int, namelen: libc::c_uint,
+                  oldp: *mut libc::c_void, oldlenp: *mut libc::size_t,
+                  newp: *mut libc::c_void, newlen: libc::size_t) -> libc::c_int;
+        fn getrlimit(resource: libc::c_int, rlp: *mut rlimit) -> libc::c_int;
+        fn setrlimit(resource: libc::c_int, rlp: *rlimit) -> libc::c_int;
+    }
+    static CTL_KERN: libc::c_int = 1;
+    static KERN_MAXFILESPERPROC: libc::c_int = 29;
+    static RLIMIT_NOFILE: libc::c_int = 8;
+
+    pub unsafe fn raise_fd_limit() {
+        // The strategy here is to fetch the current resource limits, read the kern.maxfilesperproc
+        // sysctl value, and bump the soft resource limit for maxfiles up to the sysctl value.
+        use ptr::{to_unsafe_ptr, to_mut_unsafe_ptr, mut_null};
+        use mem::size_of_val;
+        use os::last_os_error;
+
+        // Fetch the kern.maxfilesperproc value
+        let mut mib: [libc::c_int, ..2] = [CTL_KERN, KERN_MAXFILESPERPROC];
+        let mut maxfiles: libc::c_int = 0;
+        let mut size: libc::size_t = size_of_val(&maxfiles) as libc::size_t;
+        if sysctl(to_mut_unsafe_ptr(&mut mib[0]), 2,
+                  to_mut_unsafe_ptr(&mut maxfiles) as *mut libc::c_void,
+                  to_mut_unsafe_ptr(&mut size),
+                  mut_null(), 0) != 0 {
+            let err = last_os_error();
+            error!("raise_fd_limit: error calling sysctl: {}", err);
+            return;
+        }
+
+        // Fetch the current resource limits
+        let mut rlim = rlimit{rlim_cur: 0, rlim_max: 0};
+        if getrlimit(RLIMIT_NOFILE, to_mut_unsafe_ptr(&mut rlim)) != 0 {
+            let err = last_os_error();
+            error!("raise_fd_limit: error calling getrlimit: {}", err);
+            return;
+        }
+
+        // Bump the soft limit to the smaller of kern.maxfilesperproc and the hard limit
+        rlim.rlim_cur = ::cmp::min(maxfiles as rlim_t, rlim.rlim_max);
+
+        // Set our newly-increased resource limit
+        if setrlimit(RLIMIT_NOFILE, to_unsafe_ptr(&rlim)) != 0 {
+            let err = last_os_error();
+            error!("raise_fd_limit: error calling setrlimit: {}", err);
+            return;
+        }
+    }
+}
+
+#[cfg(not(target_os="macos"))]
+mod darwin_fd_limit {
+    pub unsafe fn raise_fd_limit() {}
+}
diff --git a/src/libstd/rt/task.rs b/src/libstd/rt/task.rs
index 91e285b1061..c0e1086483d 100644
--- a/src/libstd/rt/task.rs
+++ b/src/libstd/rt/task.rs
@@ -38,8 +38,13 @@ use task::{TaskResult, TaskOpts};
 use unstable::finally::Finally;
 use unstable::mutex::{Mutex, MUTEX_INIT};
 
-#[cfg(stage0)] pub use rt::unwind::begin_unwind;
+#[cfg(stage0)]
+pub use rt::unwind::begin_unwind;
 
+// These two statics are used as bookeeping to keep track of the rust runtime's
+// count of threads. In 1:1 contexts, this is used to know when to return from
+// the main function, and in M:N contexts this is used to know when to shut down
+// the pool of schedulers.
 static mut TASK_COUNT: AtomicUint = INIT_ATOMIC_UINT;
 static mut TASK_LOCK: Mutex = MUTEX_INIT;
 
@@ -181,10 +186,15 @@ impl Task {
         // Cleanup the dynamic borrowck debugging info
         borrowck::clear_task_borrow_list();
 
-        // TODO: dox
+        // Here we must unsafely borrow the task in order to not remove it from
+        // TLS. When collecting failure, we may attempt to send on a channel (or
+        // just run aribitrary code), so we must be sure to still have a local
+        // task in TLS.
         unsafe {
             let me: *mut Task = Local::unsafe_borrow();
             (*me).death.collect_failure((*me).unwinder.result());
+
+            // see comments on these statics for why they're used
             if TASK_COUNT.fetch_sub(1, SeqCst) == 1 {
                 TASK_LOCK.lock();
                 TASK_LOCK.signal();
@@ -386,6 +396,10 @@ impl Drop for Death {
     }
 }
 
+/// The main function of all rust executables will by default use this function.
+/// This function will *block* the OS thread (hence the `unsafe`) waiting for
+/// all known tasks to complete. Once this function has returned, it is
+/// guaranteed that no more user-defined code is still running.
 pub unsafe fn wait_for_completion() {
     TASK_LOCK.lock();
     while TASK_COUNT.load(SeqCst) > 0 {
diff --git a/src/libstd/sync/arc.rs b/src/libstd/sync/arc.rs
index 7b94a3acc2b..b405104c09a 100644
--- a/src/libstd/sync/arc.rs
+++ b/src/libstd/sync/arc.rs
@@ -32,7 +32,7 @@ use vec;
 /// An atomically reference counted pointer.
 ///
 /// Enforces no shared-memory safety.
-#[unsafe_no_drop_flag]
+//#[unsafe_no_drop_flag] FIXME: #9758
 pub struct UnsafeArc<T> {
     priv data: *mut ArcData<T>,
 }