Create CacheStoreWithTTL.cpp

Author: rachitiitr

CacheStoreWithTTL.cpp

@@ -0,0 +1,57 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int getCurrentTimeStamp(){
+	return 0; //assume this is a system function that returns the current timestamp	
+}
+
+//Implement a CacheStore that can store key values with some TTL info as well
+template <typename K, typename V>
+class CacheStore
+{
+	//mapping key to value as well as a timestamp till its valid
+	unordered_map<K, pair<V, int>> _mep;
+	public:
+	void Add(K key, V value, int ttl) {
+		if(_mep.find(key) == _mep.end()) {
+			int expirationTime = getCurrentTimeStamp() + ttl;
+			_mep[key] = {value, expirationTime};
+		}
+		else {
+			//depends on business logic how to handle this case
+			//one approach is we can overwrite the value
+		}
+	}
+	
+	//returns true if key existed and also alive
+	bool Get(K key, V* out) {
+		int currentTime = getCurrentTimeStamp();
+		if(_mep.find(key) == _mep.end()) {
+			out = NULL;
+			return 0;
+		}
+		else {
+			pair<V, int> cur = _mep[key];
+			if (cur.second < currentTime) {
+				//expired
+				out = NULL;
+				return 0;
+			}
+			else {
+				*out = cur.first;
+				return 1;
+			}
+		}
+	}
+};
+
+int main() {
+	CacheStore<string, int> M;
+	M.Add("rachit", 1, 10);
+	M.Add("Uber", 2, 100);
+	int* res = new int;
+	if(M.Get("rachit", res)) cout << *res << endl;
+	if(M.Get("Uber", res)) cout << *res << endl;
+	
+	return 0;
+}