threadsafe_queue: Use std::size_t for representing size

Makes it consistent with the regular standard containers in terms of
size representation. This also gets rid of dependence on our own
type aliases, removing the need for an include.

src/common/threadsafe_queue.h

@@ -7,11 +7,10 @@
 // a simple lockless thread-safe,
 // single reader, single writer queue
 
-#include <algorithm>
 #include <atomic>
 #include <cstddef>
 #include <mutex>
-#include "common/common_types.h"
+#include <utility>
 
 namespace Common {
 template <typename T>
@@ -25,7 +24,7 @@ public:
         delete read_ptr;
     }
 
-    u32 Size() const {
+    std::size_t Size() const {
         return size.load();
     }
 
@@ -87,7 +86,7 @@ private:
     // and a pointer to the next ElementPtr
     class ElementPtr {
     public:
-        ElementPtr() : next(nullptr) {}
+        ElementPtr() {}
         ~ElementPtr() {
             ElementPtr* next_ptr = next.load();
 
@@ -96,12 +95,12 @@ private:
         }
 
         T current;
-        std::atomic<ElementPtr*> next;
+        std::atomic<ElementPtr*> next{nullptr};
     };
 
     ElementPtr* write_ptr;
     ElementPtr* read_ptr;
-    std::atomic<u32> size{0};
+    std::atomic_size_t size{0};
 };
 
 // a simple thread-safe,
@@ -110,7 +109,7 @@ private:
 template <typename T>
 class MPSCQueue {
 public:
-    u32 Size() const {
+    std::size_t Size() const {
         return spsc_queue.Size();
     }