From e970ba16827e6f4baf29004ccc1a48d378723f9e Mon Sep 17 00:00:00 2001
From: Albert S <mail@quitesimple.org>
Date: Fri, 8 Oct 2021 00:08:00 +0200
Subject: [PATCH] cache: MapCache: Introduce MapCache, thread-safe cache
 (key/value store)

---
 cache/mapcache.cpp |  1 +
 cache/mapcache.h   | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 cache/mapcache.cpp
 create mode 100644 cache/mapcache.h

diff --git a/cache/mapcache.cpp b/cache/mapcache.cpp
new file mode 100644
index 0000000..19eef95
--- /dev/null
+++ b/cache/mapcache.cpp
@@ -0,0 +1 @@
+#include "mapcache.h"
diff --git a/cache/mapcache.h b/cache/mapcache.h
new file mode 100644
index 0000000..4f0d00f
--- /dev/null
+++ b/cache/mapcache.h
@@ -0,0 +1,37 @@
+#ifndef MAPCACHE_H
+#define MAPCACHE_H
+#include <map>
+#include <set>
+#include <shared_mutex>
+
+/* Thread-Safe Key-Value store */
+template <class T> class MapCache
+{
+  private:
+	std::map<std::string, T> cache;
+	mutable std::shared_mutex sharedMutex;
+
+  public:
+	std::optional<T> find(const std::string &key) const
+	{
+		std::shared_lock<std::shared_mutex> lock(this->sharedMutex);
+		auto it = this->cache.find(key);
+		if(it != this->cache.end())
+		{
+			return it->second;
+		}
+		return {};
+	}
+	void set(const std::string &key, const T &val)
+	{
+		std::lock_guard<std::shared_mutex> lock{sharedMutex};
+		this->cache[key] = val;
+	}
+	void clear()
+	{
+		std::lock_guard<std::shared_mutex> lock{sharedMutex};
+		this->cache.clear();
+	}
+};
+
+#endif // MAPCACHE_H