[libcxx] Fix building for windows after 54fa9ecd3088508

[mstorsjo]

Summary

Move the implementation of libcpp_thread_poll_with_backoff and libcpp_timed_backoff_policy::operator() out of the _LIBCPP_HAS_THREAD_API_PTHREAD block. None of the code in these methods is pthreads specific.

Also add "inline _LIBCPP_INLINE_VISIBILITY" to libcpp_timed_backoff_policy::operator(), to avoid errors due to
multiple definitions of the operator. Contrary to libcpp_thread_poll_with_backoff (which is a template function), this is a normal non-templated method.

[ldionne]

Thanks!

libcxx/include/__threading_support

 }
 
 void __libcpp_thread_sleep_for(const chrono::nanoseconds& __ns)
 {
    __libcpp_timespec_t __ts = __thread_detail::__convert_to_timespec(__ns);
    while (nanosleep(&__ts, &__ts) == -1 && errno == EINTR);
 }
 
-bool __libcpp_timed_backoff_policy::operator()(chrono::nanoseconds __elapsed) const
-{
-    if(__elapsed > chrono::milliseconds(128))
-        __libcpp_thread_sleep_for(chrono::milliseconds(8));
-    else if(__elapsed > chrono::microseconds(64))
-        __libcpp_thread_sleep_for(__elapsed / 2);
-    else if(__elapsed > chrono::microseconds(4))
-      __libcpp_thread_yield();
-    else
-      ; // poll
-    return false;
-}
-
-static _LIBCPP_CONSTEXPR const int __libcpp_polling_count = 64;
-
-template<class _Fn, class _BFn>
-bool __libcpp_thread_poll_with_backoff(_Fn && __f, _BFn && __bf, chrono::nanoseconds __max_elapsed)
-{
-    auto const __start = chrono::high_resolution_clock::now();
-    for(int __count = 0;;) {
-      if(__f())
-        return true; // _Fn completion means success
-      if(__count < __libcpp_polling_count) {
-        __count += 1;
-        continue;
-      }
-      chrono::nanoseconds const __elapsed = chrono::high_resolution_clock::now() - __start;
-      if(__max_elapsed != chrono::nanoseconds::zero() && __max_elapsed < __elapsed)
-          return false; // timeout failure
-      if(__bf(__elapsed))
-        return false; // _BFn completion means failure
-    }
-}
-
 // Thread local storage
 int __libcpp_tls_create(__libcpp_tls_key *__key, void (*__at_exit)(void *))
 {
   return pthread_key_create(__key, __at_exit);
 }
 
 void *__libcpp_tls_get(__libcpp_tls_key __key)
 {

 
 int __libcpp_tls_set(__libcpp_tls_key __key, void *__p)
 {
   return tss_set(__key, __p) == thrd_success ? 0 : EINVAL;
 }
 
 #endif
 
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_timed_backoff_policy::operator()(chrono::nanoseconds __elapsed) const
+{
+    if(__elapsed > chrono::milliseconds(128))
+        __libcpp_thread_sleep_for(chrono::milliseconds(8));
+    else if(__elapsed > chrono::microseconds(64))
+        __libcpp_thread_sleep_for(__elapsed / 2);
+    else if(__elapsed > chrono::microseconds(4))
+      __libcpp_thread_yield();
+    else
+      ; // poll
+    return false;
+}
+
+static _LIBCPP_CONSTEXPR const int __libcpp_polling_count = 64;
+
+template<class _Fn, class _BFn>
+bool __libcpp_thread_poll_with_backoff(_Fn && __f, _BFn && __bf, chrono::nanoseconds __max_elapsed)
+{
+    auto const __start = chrono::high_resolution_clock::now();
+    for(int __count = 0;;) {
+      if(__f())
+        return true; // _Fn completion means success
+      if(__count < __libcpp_polling_count) {
+        __count += 1;
+        continue;
+      }
+      chrono::nanoseconds const __elapsed = chrono::high_resolution_clock::now() - __start;
+      if(__max_elapsed != chrono::nanoseconds::zero() && __max_elapsed < __elapsed)
+          return false; // timeout failure
+      if(__bf(__elapsed))
+        return false; // _BFn completion means failure
+    }
+}
+
 #endif // !_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL || _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL
 
 class _LIBCPP_TYPE_VIS thread;
 class _LIBCPP_TYPE_VIS __thread_id;
 
 namespace this_thread
 {