From 7bf7bd6a75c38ed71df69cb9149eb7fdce23ced5 Mon Sep 17 00:00:00 2001 From: Aidan Cully Date: Fri, 5 Dec 2014 17:20:44 -0500 Subject: [PATCH 1/2] work around portability issue on FreeBSD, in which the key returned from pthread_key_create can be 0. --- src/libstd/sys/common/thread_local.rs | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/src/libstd/sys/common/thread_local.rs b/src/libstd/sys/common/thread_local.rs index 370d74cc5e189..b33e74248d275 100644 --- a/src/libstd/sys/common/thread_local.rs +++ b/src/libstd/sys/common/thread_local.rs @@ -185,7 +185,23 @@ impl StaticKey { } unsafe fn lazy_init(&self) -> uint { - let key = imp::create(self.dtor); + // POSIX allows the key created here to be 0, but the compare_and_swap + // below relies on using 0 as a sentinel value to check who won the + // race to set the shared TLS key. As far as I know, there is no + // guaranteed value that cannot be returned as a posix_key_create key, + // so there is no value we can initialize the inner key with to + // prove that it has not yet been set. As such, we'll continue using a + // value of 0, but with some gyrations to make sure we have a non-0 + // value returned from the creation routine. + // TODO: this is clearly a hack, and should be cleaned up. + let key1 = imp::create(self.dtor); + let key = if key1 != 0 { + key1 + } else { + let key2 = imp::create(self.dtor); + imp::destroy(key1); + key2 + }; assert!(key != 0); match self.inner.key.compare_and_swap(0, key as uint, atomic::SeqCst) { // The CAS succeeded, so we've created the actual key From c394a6c238a2e981f9092e142029ec5b465c1dcd Mon Sep 17 00:00:00 2001 From: Aidan Cully Date: Fri, 5 Dec 2014 18:39:58 -0500 Subject: [PATCH 2/2] prefer "FIXME" to "TODO". --- src/libstd/sys/common/thread_local.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libstd/sys/common/thread_local.rs b/src/libstd/sys/common/thread_local.rs index b33e74248d275..3eb0e3f46cb90 100644 --- a/src/libstd/sys/common/thread_local.rs +++ b/src/libstd/sys/common/thread_local.rs @@ -193,7 +193,7 @@ impl StaticKey { // prove that it has not yet been set. As such, we'll continue using a // value of 0, but with some gyrations to make sure we have a non-0 // value returned from the creation routine. - // TODO: this is clearly a hack, and should be cleaned up. + // FIXME: this is clearly a hack, and should be cleaned up. let key1 = imp::create(self.dtor); let key = if key1 != 0 { key1