libpthread-330.201.1.tar.gz

[apple/libpthread.git] / src / pthread_dependency.c

diff --git a/src/pthread_dependency.c b/src/pthread_dependency.c
new file mode 100644 (file)
index 0000000..282dfc3
--- /dev/null
+++ b/src/pthread_dependency.c
@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2018 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include "resolver.h"
+#include "internal.h"
+#include "dependency_private.h"
+#include <sys/ulock.h>
+
+#define PREREQUISITE_FULFILLED  (~0u)
+
+PTHREAD_NOEXPORT
+void _pthread_dependency_fulfill_slow(pthread_dependency_t *pr, uint32_t old);
+
+OS_ALWAYS_INLINE
+static inline mach_port_t
+_pthread_dependency_self(void)
+{
+       void *v = _pthread_getspecific_direct(_PTHREAD_TSD_SLOT_MACH_THREAD_SELF);
+       return (mach_port_t)(uintptr_t)v;
+}
+
+void
+pthread_dependency_init_np(pthread_dependency_t *pr, pthread_t pth,
+               pthread_dependency_attr_t *attrs)
+{
+       if (attrs) *(volatile char *)attrs;
+       *pr = (pthread_dependency_t)PTHREAD_DEPENDENCY_INITIALIZER_NP(pth);
+}
+
+OS_NOINLINE
+void
+_pthread_dependency_fulfill_slow(pthread_dependency_t *pr, uint32_t old)
+{
+       if (old == PREREQUISITE_FULFILLED) {
+               PTHREAD_CLIENT_CRASH(0, "Fufilling pthread_dependency_t twice");
+       }
+       if (os_unlikely(old != _pthread_dependency_self())) {
+               PTHREAD_CLIENT_CRASH(old, "Fulfilled a dependency "
+                               "not owned by current thread");
+       }
+
+       int ret = __ulock_wake(UL_UNFAIR_LOCK | ULF_NO_ERRNO, &pr->__pdep_opaque1, 0);
+       switch (-ret) {
+       case 0:
+       case ENOENT:
+               return;
+       default:
+               PTHREAD_INTERNAL_CRASH(-ret, "__ulock_wake() failed");
+       }
+}
+
+
+void
+pthread_dependency_fulfill_np(pthread_dependency_t *pr, void *value)
+{
+       uint32_t old;
+
+       pr->__pdep_opaque2 = (uint64_t)(uintptr_t)value;
+       old = os_atomic_xchg(&pr->__pdep_opaque1, PREREQUISITE_FULFILLED, release);
+
+       if (old != 0) _pthread_dependency_fulfill_slow(pr, old);
+}
+
+void *
+pthread_dependency_wait_np(pthread_dependency_t *pr)
+{
+       if (os_atomic_cmpxchg(&pr->__pdep_opaque1, 0, pr->__pdep_owner, relaxed)) {
+               int ret;
+       again:
+               ret = __ulock_wait(UL_UNFAIR_LOCK | ULF_NO_ERRNO, &pr->__pdep_opaque1,
+                               pr->__pdep_owner, 0);
+               switch (-ret) {
+               case EFAULT:
+                       if (pr->__pdep_opaque1 == pr->__pdep_owner) goto again;
+               case 0:
+                       break;
+               case EOWNERDEAD:
+                       PTHREAD_CLIENT_CRASH(pr->__pdep_owner, "Waiting on orphaned dependency");
+               default:
+                       PTHREAD_CLIENT_CRASH(-ret, "__ulock_wait() failed");
+               }
+       }
+
+       uint32_t cur = os_atomic_load(&pr->__pdep_opaque1, acquire);
+       if (cur == PREREQUISITE_FULFILLED) {
+               return (void *)(uintptr_t)pr->__pdep_opaque2;
+       }
+       PTHREAD_CLIENT_CRASH(cur, "Corrupted pthread_dependency_t");
+}
+