Cache

Cache.java

import javaslang.Tuple;
import javaslang.Tuple2;
import javaslang.control.Option;

import java.time.LocalDateTime;
import javaslang.collection.LinkedHashMap;

public class Cache<K, V> {
    private LinkedHashMap<K, Tuple2<V, LocalDateTime>> linkedHashMap = LinkedHashMap.empty();
    private final int maxCount;
    private final long timeLength;// 保存時間[s]

    public Cache(int maxCount, long timeLength) {
        this.maxCount = maxCount;
        this.timeLength = timeLength;
    }

    public void add(K key, V value, LocalDateTime now) {
        // すでにあったら消す
        if(linkedHashMap.containsKey(key)) {
            linkedHashMap = linkedHashMap.remove(key);
        }
        // 入れる
        linkedHashMap = linkedHashMap.put(key, Tuple.of(value, now));
        // 上限超えたら消す
        if(linkedHashMap.size() > maxCount) {
            linkedHashMap = linkedHashMap.drop(1);
        }
    }

    public Option<V> get(K key, LocalDateTime now) {
        return linkedHashMap.get(key)
                .filter(v -> v._2().isAfter(now.minusSeconds(timeLength)))// 保存期間内かチェック。外なら削除
                .map(v -> v._1());
    }

    public void clear() {
        linkedHashMap.keySet().toStream().forEach(linkedHashMap::remove);
    }
}

CacheSpec.groovy

import spock.lang.Specification
import spock.lang.Unroll

import java.time.LocalDateTime

@Unroll
class CacheSpec extends Specification {
    def "上限"() {
        setup:
        def sut = new Cache<String, String>(3, 999);
        sut.add("1", "1", LocalDateTime.now())
        sut.add("2", "2", LocalDateTime.now())
        sut.add("3", "3", LocalDateTime.now())
        sut.add("1", "1", LocalDateTime.now())
        sut.add("4", "4", LocalDateTime.now())

        expect:
        sut.get("1", LocalDateTime.now()).isDefined() //後半に入れたから取れる
        sut.get("2", LocalDateTime.now()).isEmpty()
        sut.get("3", LocalDateTime.now()).isDefined()
        sut.get("4", LocalDateTime.now()).isDefined()
    }

    def "時間制限"() {
        setup:
        def sut = new Cache<String, String>(3, 10);
        sut.add("0", "0", LocalDateTime.now().minusSeconds(15))
        sut.add("1", "1", LocalDateTime.now().minusSeconds(11))
        sut.add("2", "2", LocalDateTime.now().minusSeconds(8))
        sut.add("0", "0", LocalDateTime.now())

        expect:
        sut.get("0", LocalDateTime.now()).isDefined() // 後で入れてるから取れる
        sut.get("1", LocalDateTime.now()).isEmpty()// 時間制限外なので取れない
        sut.get("2", LocalDateTime.now()).isDefined()
    }

    def "clear"() {
        setup:
        def sut = new Cache<String, String>(3, 999);
        sut.add("1", "1", LocalDateTime.now())
        sut.clear()

        expect:
        sut.get("1", LocalDateTime.now()).isEmpty()
    }
}