* 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,
    keepAliveDuration: Long = 5,
    timeUnit: TimeUnit = TimeUnit.MINUTES,

This logs task enqueues, starts, and finishes.

```
[2020-01-01 00:00:00] Q10000 scheduled after   0 µs: OkHttp ConnectionPool
[2020-01-01 00:00:00] Q10000 starting              : OkHttp ConnectionPool
[2020-01-01 00:00:00] Q10000 run again after 300 s : OkHttp ConnectionPool
[2020-01-01 00:00:00] Q10000 finished run in   1 ms: OkHttp ConnectionPool
[2020-01-01 00:00:00] Q10001 scheduled after   0 µs: OkHttp squareup.com applyAndAckSettings

  private var client: OkHttpClient =
    OkHttpClient
      .Builder()
      .sslSocketFactory(
        handshakeCertificates.sslSocketFactory(),
        handshakeCertificates.trustManager,
      ).connectionPool(ConnectionPool(0, 1, TimeUnit.SECONDS))
      .build()

  private val server =
    MockWebServer()

  @Test
  fun testHttpsRequest() {
    server.useHttps(handshakeCertificates.sslSocketFactory())

    val request = Request(server.url("/"))

    client.newCall(request).execute().use { response ->
      assertEquals(200, response.code)
    }

    client.connectionPool.evictAll()
    assertEquals(0, client.connectionPool.connectionCount())

    // Force reuse. This appears flaky (30% of the time) even though sessions are reused.
    // javax.net.ssl.SSLHandshakeException: No new session is allowed and no existing

  private var client: OkHttpClient =
    clientTestRule
      .newClientBuilder()
      .connectionPool(ConnectionPool(connectionListener = listener))
      .fastFallback(fastFallback)
      .build()

  @BeforeEach
  fun setUp() {
    platform.assumeNotOpenJSSE()
    platform.assumeNotBouncyCastle()
    listener.forbidLock(get(client.connectionPool))
    listener.forbidLock(client.dispatcher)
  }

  @Test

  }

  @Test fun inUseConnectionsNotEvicted() {
    val pool = factory.newConnectionPool()
    val poolApi = ConnectionPool(pool)
    val c1 = factory.newConnection(pool, routeA1, 50L)
    val client =
      OkHttpClient
        .Builder()
        .connectionPool(poolApi)
        .build()
    val call = client.newCall(Request(addressA.url)) as RealCall

      assertThat(it.protocol).isEqualTo(Protocol.HTTP_2)
      assertThat(it.handshake!!.tlsVersion).isEqualTo(TlsVersion.TLS_1_3)
    }

    client.connectionPool.evictAll()
    assertEquals(0, client.connectionPool.connectionCount())

    client.newCall(request).execute().use {
      assertThat(it.protocol).isEqualTo(Protocol.HTTP_2)

          .source()
          .readUtf8Line()
          .also { line = it } != null
      ) {
        println(line)
      }
    } finally {
      response.body.close()
    }
    client.connectionPool.evictAll()
  }

internal fun OkHttpClient.Builder.taskRunnerInternal(taskRunner: TaskRunner) = this.taskRunner(taskRunner)

internal fun buildConnectionPool(
  connectionListener: ConnectionListener,
  taskRunner: TaskRunner,
): ConnectionPool =
  ConnectionPool(
    connectionListener = connectionListener,
    taskRunner = taskRunner,

  ): RealRoutePlanner {
    val call = RealCall(client, Request(address.url), forWebSocket = false)
    val chain = newChain(call)
    return RealRoutePlanner(
      taskRunner = client.taskRunner,
      connectionPool = client.connectionPool.delegate,
      readTimeoutMillis = client.readTimeoutMillis,
      writeTimeoutMillis = client.writeTimeoutMillis,
      socketConnectTimeoutMillis = chain.connectTimeoutMillis,