std: Convert the runtime TLS key to a Rust global to avoid FFI

Author: brson

src/libstd/rt/local_ptr.rs

@@ -23,14 +23,16 @@ use option::{Option, Some, None};
 use unstable::finally::Finally;
 use tls = rt::thread_local_storage;
 
+static mut RT_TLS_KEY: tls::Key = -1;
+
 /// Initialize the TLS key. Other ops will fail if this isn't executed first.
 #[fixed_stack_segment]
 #[inline(never)]
 pub fn init_tls_key() {
     unsafe {
-        rust_initialize_rt_tls_key();
+        rust_initialize_rt_tls_key(&mut RT_TLS_KEY);
         extern {
-            fn rust_initialize_rt_tls_key();
+            fn rust_initialize_rt_tls_key(key: *mut tls::Key);
         }
     }
 }
@@ -151,15 +153,10 @@ fn tls_key() -> tls::Key {
     }
 }
 
-#[fixed_stack_segment]
-#[inline(never)]
-fn maybe_tls_key() -> Option<tls::Key> {
+#[inline]
+#[cfg(not(test))]
+pub fn maybe_tls_key() -> Option<tls::Key> {
     unsafe {
-        let key: *mut c_void = rust_get_rt_tls_key();
-        let key: &mut tls::Key = cast::transmute(key);
-        let key = *key;
-        // Check that the key has been initialized.
-
         // NB: This is a little racy because, while the key is
         // initalized under a mutex and it's assumed to be initalized
         // in the Scheduler ctor by any thread that needs to use it,
@@ -170,14 +167,19 @@ fn maybe_tls_key() -> Option<tls::Key> {
         // another thread. I think this is fine since the only action
         // they could take if it was initialized would be to check the
         // thread-local value and see that it's not set.
-        if key != -1 {
-            return Some(key);
+        if RT_TLS_KEY != -1 {
+            return Some(RT_TLS_KEY);
         } else {
             return None;
         }
     }
+}
 
-    extern {
-        fn rust_get_rt_tls_key() -> *mut c_void;
-    }
+// XXX: The boundary between the running runtime and the testing runtime
+// seems to be fuzzy at the moment, and trying to use two different keys
+// results in disaster. This should not be necessary.
+#[inline]
+#[cfg(test)]
+pub fn maybe_tls_key() -> Option<tls::Key> {
+    unsafe { ::cast::transmute(::realstd::rt::local_ptr::maybe_tls_key()) }
 }

src/rt/rust_builtin.cpp

@@ -447,19 +447,14 @@ rust_readdir() {
 #endif
 
 #ifndef _WIN32
-pthread_key_t rt_key = -1;
+typedef pthread_key_t tls_key;
 #else
-DWORD rt_key = -1;
+typedef DWORD tls_key;
 #endif
 
-extern "C" void*
-rust_get_rt_tls_key() {
-    return &rt_key;
-}
-
 // Initialize the TLS key used by the new scheduler
 extern "C" CDECL void
-rust_initialize_rt_tls_key() {
+rust_initialize_rt_tls_key(tls_key *key) {
 
     static lock_and_signal init_lock;
     static bool initialized = false;
@@ -469,10 +464,10 @@ rust_initialize_rt_tls_key() {
     if (!initialized) {
 
 #ifndef _WIN32
-        assert(!pthread_key_create(&rt_key, NULL));
+        assert(!pthread_key_create(key, NULL));
 #else
-        rt_key = TlsAlloc();
-        assert(rt_key != TLS_OUT_OF_INDEXES);
+        *key = TlsAlloc();
+        assert(*key != TLS_OUT_OF_INDEXES);
 #endif
 
         initialized = true;

src/rt/rustrt.def.in

@@ -143,7 +143,6 @@ linenoiseHistoryLoad
 rust_raw_thread_start
 rust_raw_thread_join
 rust_raw_thread_delete
-rust_get_rt_tls_key
 swap_registers
 rust_readdir
 rust_opendir