WIP (#1460)

src/common/indexed_resources.h

@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <boost/icl/interval_set.hpp>
+
+#include <limits>
+#include <optional>
+#include <shared_mutex>
+#include <unordered_map>
+
+#include <memory>
+
+namespace Common {
+
+template <class Index, class T, Index MaxIndex = std::numeric_limits<Index>::max()>
+class IndexedResources {
+public:
+    IndexedResources() {
+        m_free_indices += boost::icl::interval<Index>::closed(0, MaxIndex);
+    }
+
+    template <class... Types>
+    std::optional<Index> Create(Types&&... args) {
+        std::unique_lock lock{m_mutex};
+        if (m_free_indices.empty()) {
+            return {};
+        }
+        auto index = first(*m_free_indices.begin());
+        m_free_indices -= index;
+        m_container.emplace(index, T(std::forward<Types>(args)...));
+        return index;
+    }
+
+    void Destroy(Index index) {
+        std::unique_lock lock{m_mutex};
+        if (m_container.erase(index) > 0) {
+            m_free_indices += index;
+        }
+    }
+
+    std::optional<std::reference_wrapper<T>> Get(Index index) {
+        std::shared_lock lock{m_mutex};
+        auto it = m_container.find(index);
+        if (it == m_container.end()) {
+            return {};
+        }
+        return it->second;
+    }
+
+private:
+    std::shared_mutex m_mutex;
+    std::unordered_map<Index, T> m_container;
+    boost::icl::interval_set<Index> m_free_indices;
+};
+
+} // namespace Common