Refactor pthread usage of libcxx.

This patch extracts out all the pthread dependencies of libcxx into the
new header __threading_support. The motivation is to make it easy to
re-target libcxx into platforms that do not support pthread.

Original patch from Fulvio Esposito (fulvio.esposito@outlook.com) - D11781

Applied with tweaks - D19412

Change-Id: I301111f0075de93dd8129416e06babc195aa936b

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@268734 91177308-0d34-0410-b5e6-96231b3b80d8

include/__threading_support

@@ -0,0 +1,205 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_THREADING_SUPPORT
+#define _LIBCPP_THREADING_SUPPORT
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
+#pragma GCC system_header
+#endif
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#if defined(_LIBCPP_THREAD_API_PTHREAD)
+#include <pthread.h>
+#include <sched.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if defined(_LIBCPP_THREAD_API_PTHREAD)
+
+// Mutex
+#define _LIBCPP_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
+typedef pthread_mutex_t __libcpp_mutex_t;
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_recursive_mutex_init(__libcpp_mutex_t* __m)
+{
+    pthread_mutexattr_t attr;
+    int __ec = pthread_mutexattr_init(&attr);
+    if (__ec) return __ec;
+    __ec = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+    if (__ec)
+    {
+        pthread_mutexattr_destroy(&attr);
+        return __ec;
+    }
+    __ec = pthread_mutex_init(__m, &attr);
+    if (__ec)
+    {
+        pthread_mutexattr_destroy(&attr);
+        return __ec;
+    }
+    __ec = pthread_mutexattr_destroy(&attr);
+    if (__ec)
+    {
+        pthread_mutex_destroy(__m);
+        return __ec;
+    }
+    return 0;
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_mutex_lock(__libcpp_mutex_t* __m)
+{
+    return pthread_mutex_lock(__m);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_mutex_trylock(__libcpp_mutex_t* __m)
+{
+    return pthread_mutex_trylock(__m);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_mutex_unlock(__libcpp_mutex_t* __m)
+{
+    return pthread_mutex_unlock(__m);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_mutex_destroy(__libcpp_mutex_t* __m)
+{
+    return pthread_mutex_destroy(__m);
+}
+
+// Condition variable
+#define _LIBCPP_CONDVAR_INITIALIZER PTHREAD_COND_INITIALIZER
+typedef pthread_cond_t __libcpp_condvar_t;
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_condvar_signal(__libcpp_condvar_t* __cv)
+{
+    return pthread_cond_signal(__cv);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_condvar_broadcast(__libcpp_condvar_t* __cv)
+{
+    return pthread_cond_broadcast(__cv);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_condvar_wait(__libcpp_condvar_t* __cv, __libcpp_mutex_t* __m)
+{
+    return pthread_cond_wait(__cv, __m);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_condvar_timedwait(__libcpp_condvar_t* __cv, __libcpp_mutex_t* __m, timespec* __ts)
+{
+    return pthread_cond_timedwait(__cv, __m, __ts);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_condvar_destroy(__libcpp_condvar_t* __cv)
+{
+    return pthread_cond_destroy(__cv);
+}
+
+// Thread id
+typedef pthread_t __libcpp_thread_id;
+
+// Returns non-zero if the thread ids are equal, otherwise 0
+inline _LIBCPP_ALWAYS_INLINE
+bool __libcpp_thread_id_equal(__libcpp_thread_id t1, __libcpp_thread_id t2)
+{
+    return pthread_equal(t1, t2) != 0;
+}
+
+// Returns non-zero if t1 < t2, otherwise 0
+inline _LIBCPP_ALWAYS_INLINE
+bool __libcpp_thread_id_less(__libcpp_thread_id t1, __libcpp_thread_id t2)
+{
+    return t1 < t2;
+}
+
+// Thread
+typedef pthread_t __libcpp_thread_t;
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_thread_create(__libcpp_thread_t* __t, void* (*__func)(void*), void* __arg)
+{
+    return pthread_create(__t, 0, __func, __arg);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+__libcpp_thread_id __libcpp_thread_get_current_id()
+{
+    return pthread_self();
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+__libcpp_thread_id __libcpp_thread_get_id(const __libcpp_thread_t* __t)
+{
+    return *__t;
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_thread_join(__libcpp_thread_t* __t)
+{
+    return pthread_join(*__t, 0);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_thread_detach(__libcpp_thread_t* __t)
+{
+    return pthread_detach(*__t);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+void __libcpp_thread_yield()
+{
+    sched_yield();
+}
+
+// Thread local storage
+typedef pthread_key_t __libcpp_tl_key;
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_tl_create(__libcpp_tl_key* __key, void (*__at_exit)(void*))
+{
+    return pthread_key_create(__key, __at_exit);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+void* __libcpp_tl_get(__libcpp_tl_key __key)
+{
+    return pthread_getspecific(__key);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+void __libcpp_tl_set(__libcpp_tl_key __key, void* __p)
+{
+    pthread_setspecific(__key, __p);
+}
+
+#else // !_LIBCPP_THREAD_API_PTHREAD
+  #error "No thread API selected."
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_HAS_NO_THREADS
+
+#endif // _LIBCPP_THREADING_SUPPORT