* application. The tuning parameters in this pool are subject to change in future OkHttp releases.
 * Currently this pool holds up to 5 idle connections which will be evicted after 5 minutes of
 * inactivity.
 */
class ConnectionPool internal constructor(
  internal val delegate: RealConnectionPool,
) {
  internal constructor(
    maxIdleConnections: Int = 5,

   * CacheBuilder#expireAfterWrite} or {@link CacheBuilder#expireAfterAccess}.
   */
  EXPIRED {
    @Override
    boolean wasEvicted() {
      return true;
    }
  },

  /**
   * The entry was evicted due to size constraints. This can occur when using {@link
   * CacheBuilder#maximumSize} or {@link CacheBuilder#maximumWeight}.
   */
  SIZE {
    @Override
    boolean wasEvicted() {
      return true;
    }
  };

      }

      else -> {
        toEvict = null
        toEvictIdleAtNs = -1L
      }
    }

    when {
      toEvict != null -> {
        // We've chosen a connection to evict. Confirm it's still okay to be evicted, then close it.
        toEvict.withLock {
          if (toEvict.calls.isNotEmpty()) return 0L // No longer idle.
          if (toEvict.idleAtNs != toEvictIdleAtNs) return 0L // No longer oldest.

 *             for loading to complete (whether successful or not) and then increment {@code
 *             missCount}.
 *       </ul>
 *   <li>When an entry is evicted from the cache, {@code evictionCount} is incremented.
 *   <li>No stats are modified when a cache entry is invalidated or manually removed.

            // key3 should definitely exist (just created)
            assertNotNull(limitedManager.getLease(key3));

            // key1 should have been evicted (oldest)
            assertNull(limitedManager.getLease(key1));

            // key2 should still exist (not the oldest)
            assertNotNull(limitedManager.getLease(key2));
        } finally {

Once the response has been received, the connection will be returned to the pool so it can be reused for a future request. Connections are evicted from the pool after a period of inactivity.

### [Fast Fallback](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/fast-fallback/)

/**
 * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
 * #get(Object, Callable)} or {@link #put(Object, Object)}, and are stored in the cache until either
 * evicted or manually invalidated. The common way to build instances is using {@link CacheBuilder}.
 *
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 *

    assertThat(removalListener.getCount()).isEqualTo(2);

    // caches 1, evicts nothing
    assertThat(cache.getUnchecked(1)).isEqualTo(1);
    assertThat(cache.asMap().keySet()).containsExactly(3, 1);

    CacheTesting.processPendingNotifications(cache);
    assertThat(removalListener.getCount()).isEqualTo(2);

    // caches 4, evicts 1 and 3
    assertThat(cache.getUnchecked(4)).isEqualTo(4);

/**
 * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
 * #get(Object, Callable)} or {@link #put(Object, Object)}, and are stored in the cache until either
 * evicted or manually invalidated. The common way to build instances is using {@link CacheBuilder}.
 *
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 *

        assertEquals(10000, urlSet.size());
        assertTrue(urlSet.contains("http://overflow.com/robots.txt"));
        assertFalse(urlSet.contains("http://example0.com/robots.txt")); // First one should be evicted
    }

    /**
     * Test activeThreadCountLock getter
     */
    public void test_activeThreadCountLock() {
        Object lock = crawlerContext.getActiveThreadCountLock();
        assertNotNull(lock);