Fix macOS support for tss

common/althreads.h

@@ -9,6 +9,10 @@
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
+#elif defined(__APPLE__)
+
+#include <pthread.h>
+
 #else
 
 #include <threads.h>
@@ -23,7 +27,8 @@ class tss {
     static_assert(sizeof(T) <= sizeof(void*));
     static_assert(std::is_trivially_destructible_v<T> && std::is_trivially_copy_constructible_v<T>);
 
-    static void *as_ptr(const T &value) noexcept
+    [[nodiscard]]
+    static auto to_ptr(const T &value) noexcept -> void*
     {
         if constexpr(std::is_pointer_v<T>)
         {
@@ -38,45 +43,67 @@ class tss {
             return al::bit_cast<void*>(static_cast<std::uintptr_t>(value));
     }
 
+    [[nodiscard]]
+    static auto from_ptr(void *ptr) noexcept -> T
+    {
+        if constexpr(std::is_pointer_v<T>)
+            return static_cast<T>(ptr);
+        else if constexpr(sizeof(T) == sizeof(void*))
+            return al::bit_cast<T>(ptr);
+        else if constexpr(std::is_integral_v<T>)
+            return static_cast<T>(al::bit_cast<std::uintptr_t>(ptr));
+    }
+
 #ifdef _WIN32
     DWORD mTss;
 
 public:
-    tss()
+    tss() : mTss{TlsAlloc()}
     {
-        mTss = TlsAlloc();
         if(mTss == TLS_OUT_OF_INDEXES)
             throw std::runtime_error{"al::tss::tss()"};
     }
     explicit tss(const T &init) : tss{}
     {
-        if(TlsSetValue(mTss, as_ptr(init)) == FALSE)
+        if(TlsSetValue(mTss, to_ptr(init)) == FALSE)
             throw std::runtime_error{"al::tss::tss(T)"};
     }
-    tss(const tss&) = delete;
-    tss(tss&&) = delete;
     ~tss() { TlsFree(mTss); }
 
-    void operator=(const tss&) = delete;
-    void operator=(tss&&) = delete;
-
-    void set(const T &value)
+    void set(const T &value) const
     {
-        if(TlsSetValue(mTss, as_ptr(value)) == FALSE)
+        if(TlsSetValue(mTss, to_ptr(value)) == FALSE)
             throw std::runtime_error{"al::tss::set(T)"};
     }
 
     [[nodiscard]]
-    auto get() const noexcept -> T
+    auto get() const noexcept -> T { return from_ptr(TlsGetValue(mTss)); }
+
+#elif defined(__APPLE__)
+
+    pthread_key_t mTss;
+
+public:
+    tss()
     {
-        void *res{TlsGetValue(mTss)};
-        if constexpr(std::is_pointer_v<T>)
-            return static_cast<T>(res);
-        else if constexpr(sizeof(T) == sizeof(void*))
-            return al::bit_cast<T>(res);
-        else if constexpr(std::is_integral_v<T>)
-            return static_cast<T>(al::bit_cast<std::uintptr_t>(res));
+        if(int res{pthread_key_create(&mTss, nullptr)}; res != 0)
+            throw std::runtime_error{"al::tss::tss()"};
     }
+    explicit tss(const T &init) : tss{}
+    {
+        if(int res{pthread_setspecific(mTss, to_ptr(init))}; res != 0)
+            throw std::runtime_error{"al::tss::tss(T)"};
+    }
+    ~tss() { tss_delete(mTss); }
+
+    void set(const T &value) const
+    {
+        if(int res{pthread_setspecific(mTss, to_ptr(value))}; res != 0)
+            throw std::runtime_error{"al::tss::set(T)"};
+    }
+
+    [[nodiscard]]
+    auto get() const noexcept -> T { return from_ptr(pthread_getspecific(mTss)); }
 
 #else
 
@@ -90,34 +117,25 @@ class tss {
     }
     explicit tss(const T &init) : tss{}
     {
-        if(int res{tss_set(mTss, as_ptr(init))}; res != thrd_success)
+        if(int res{tss_set(mTss, to_ptr(init))}; res != thrd_success)
             throw std::runtime_error{"al::tss::tss(T)"};
     }
-    tss(const tss&) = delete;
-    tss(tss&&) = delete;
     ~tss() { tss_delete(mTss); }
 
-    void operator=(const tss&) = delete;
-    void operator=(tss&&) = delete;
-
-    void set(const T &value)
+    void set(const T &value) const
     {
-        if(int res{tss_set(mTss, as_ptr(value))}; res != thrd_success)
+        if(int res{tss_set(mTss, to_ptr(value))}; res != thrd_success)
             throw std::runtime_error{"al::tss::set(T)"};
     }
 
     [[nodiscard]]
-    auto get() const noexcept -> T
-    {
-        void *res{tss_get(mTss)};
-        if constexpr(std::is_pointer_v<T>)
-            return static_cast<T>(res);
-        else if constexpr(sizeof(T) == sizeof(void*))
-            return al::bit_cast<T>(res);
-        else if constexpr(std::is_integral_v<T>)
-            return static_cast<T>(al::bit_cast<std::uintptr_t>(res));
-    }
+    auto get() const noexcept -> T { return from_ptr(tss_get(mTss)); }
 #endif /* _WIN32 */
+
+    tss(const tss&) = delete;
+    tss(tss&&) = delete;
+    void operator=(const tss&) = delete;
+    void operator=(tss&&) = delete;
 };
 
 } // namespace al