AK+LibCore: Add an IDAllocator and use to allocate timer ids

AK/IDAllocator.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <stdlib.h>
+#include <AK/HashTable.h>
+
+namespace AK {
+
+class IDAllocator {
+
+public:
+    IDAllocator() {}
+    ~IDAllocator() {}
+
+    int allocate()
+    {
+        int r = rand();
+        for (int i = 0; i < 100000; ++i) {
+            int allocated_id = r + i;
+            if (!m_allocated_ids.contains(allocated_id)) {
+                m_allocated_ids.set(allocated_id);
+                return allocated_id;
+            }
+        }
+        ASSERT_NOT_REACHED();
+    }
+
+    void deallocate(int id)
+    {
+        m_allocated_ids.remove(id);
+    }
+
+private:
+    HashTable<int> m_allocated_ids;
+};
+}
+
+using AK::IDAllocator;