package lru

// golang -lru
// https://github.com/hashicorp/golang-lru
import (
	"sync"
	"time"
)

// EvictCallback is used to get a callback when a cache entry is evicted
type EvictCallback[K comparable, V any] func(key K, value V)

// LRU implements a thread-safe LRU with expirable entries.
type LRU[K comparable, V any] struct {
	size      int
	evictList *LruList[K, V]
	items     map[K]*Entry[K, V]
	onEvict   EvictCallback[K, V]

	lru *lru.LRU[string, *Stmt]
}

func (s *lruStore) Keys() []string {
	return s.lru.Keys()
}

func (s *lruStore) Get(key string) (*Stmt, bool) {
	stmt, ok := s.lru.Get(key)
	if ok && stmt != nil {
		<-stmt.prepared
	}
	return stmt, ok
}

func (s *lruStore) Set(key string, value *Stmt) {
	s.lru.Add(key, value)
}

func (s *lruStore) Delete(key string) {
	s.lru.Remove(key)
}

	lru := lru.NewLRU[string, int](0, nil, time.Hour)
	lru.Add("key1", 1)
	lru.Add("key2", 2)
	lru.Add("key3", 3)

	if _, ok := lru.Get("key1"); !ok {
		t.Errorf("Expected key1 to exist, but it was evicted")
	}
}

func TestLRU_Add_Eviction(t *testing.T) {
	lru := lru.NewLRU[string, int](0, nil, time.Second*2)
	lru.Add("key1", 1)
	lru.Add("key2", 2)
	lru.Add("key3", 3)

     */
    @Test
    public void testAll() throws Exception {
        final LruHashMap<String, String> lru = new LruHashMap<String, String>(3);
        lru.put("aaa", "111");
        lru.put("bbb", "222");
        lru.put("ccc", "333");
        assertThat(lru.get("aaa"), is("111"));
        Iterator<String> i = lru.keySet().iterator();
        assertThat(i.next(), is("bbb"));
        assertThat(i.next(), is("ccc"));

	lens := len(conn.Stmts.Keys())
	// Check if the number of stored statement keys is 0.
	if lens == 0 {
		// If the number is 0, it means there are no statements stored in the LRU cache.
		// The test fails and an error message is output.
		t.Fatalf("lru should not be empty")
	}
	// Wait for 40 seconds to give the statements in the cache enough time to expire.
	time.Sleep(time.Second * 40)

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * {@link HashMap} with an upper limit on the number of entries. When a new entry is added, the oldest entry is discarded using LRU if the limit is exceeded.
 *
 * @author koichik
 * @param <K> the key type
 * @param <V> the value type
 */
public class LruHashMap<K, V> extends LinkedHashMap<K, V> {

            Integer key = entry.getKey();
            cache.invalidate(key);
          }
        });
  }

  public void testEviction_lru() {
    // test lru within a single segment
    IdentityLoader<Integer> loader = identityLoader();
    LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder().concurrencyLevel(1).maximumSize(10).build(loader);

            .ticker(ticker)
            .build(loader);
    runRemovalScheduler(cache, removalListener, loader, ticker, KEY_PREFIX, EXPIRING_TIME);
  }

  public void testExpirationOrder_access() {
    // test lru within a single segment
    FakeTicker ticker = new FakeTicker();
    IdentityLoader<Integer> loader = identityLoader();
    LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder()

 */
public class LruHashSet<E> extends AbstractSet<E> implements Set<E>, java.io.Serializable {
    private static final long serialVersionUID = 1L;

    /**
     * The internal LRU hash map used to store elements.
     */
    private final LruHashMap<E, Object> map;

    // Dummy value to associate with an Object in the backing Map
    private static final Object PRESENT = new Object();

    /**

- **Collections** (`org.codelibs.core.collection`) - Enhanced collection utilities, array operations, and specialized map/set implementations including LRU caches and case-insensitive collections
- **I/O Operations** (`org.codelibs.core.io`) - File handling, resource management, stream utilities, and traversal utilities for efficient resource processing