if err := target.init(); err != nil {
		return false, err
	}
	return target.isActive()
}

func (target *MySQLTarget) isActive() (bool, error) {
	if err := target.db.Ping(); err != nil {
		if IsConnErr(err) {
			return false, store.ErrNotConnected
		}
		return false, err
	}
	return true, nil
}

 * attempting to add new elements onto the queue and it is full. This queue orders elements FIFO
 * (first-in-first-out). This data structure is logically equivalent to a circular buffer (i.e.,
 * cyclic buffer or ring buffer).
 *
 * <p>An evicting queue must be configured with a maximum size. Each time an element is added to a
 * full queue, the queue automatically removes its head element. This is different from conventional

   * {@code Ping-From}</a> header field name.
   *
   * @since 19.0
   */
  public static final String PING_FROM = "Ping-From";
  /**
   * The HTTP <a href="http://html.spec.whatwg.org/multipage/semantics.html#hyperlink-auditing">
   * {@code Ping-To}</a> header field name.
   *
   * @since 19.0
   */
  public static final String PING_TO = "Ping-To";

  /**
   * The HTTP <a

    writer.write("Hi");
    writer.close();

    assertThrows(IOException.class, () -> writer.write(" Greg"));

    assertThrows(IOException.class, () -> writer.flush());

    // close()ing already closed writer is allowed
    writer.close();
  }

pkg database/sql/driver, type NamedValue struct, Ordinal int
pkg database/sql/driver, type NamedValue struct, Value Value
pkg database/sql/driver, type Pinger interface { Ping }
pkg database/sql/driver, type Pinger interface, Ping(context.Context) error
pkg database/sql/driver, type QueryerContext interface { QueryContext }

	biggerBufMin = 32 << 10

	// This is the maximum size of bigger buffers.
	biggerBufMax = maxBufferSize

	// If there is a queue, merge up to this many messages.
	maxMergeMessages = 30

	// clientPingInterval will ping the remote handler every 15 seconds.
	// Clients disconnect when we exceed 2 intervals.
	clientPingInterval = 15 * time.Second

	// Deadline for single (non-streaming) requests to complete.

{"index":{"_index":"fess_config.scheduled_job","_id":"ping_es"}}

    when pooled connections are evicted).

    If you have a configured ping interval, you should confirm that it is long
    enough for a roundtrip from client to server. If your ping interval is too
    short, slow connections may be misinterpreted as failed connections. A ping
    interval of 30 seconds is reasonable for most use cases.

	if m.outBlock == nil {
		// Closed
		return
	}
	select {
	case m.outBlock <- struct{}{}:
	default:
		gridLogIf(m.ctx, errors.New("output unblocked overflow"))
	}
}

func (m *muxServer) ping(seq uint32) pongMsg {
	if !m.checkSeq(seq) {
		msg := fmt.Sprintf("receive sequence number mismatch. want %d, got %d", m.RecvSeq, seq)
		return pongMsg{Err: &msg}
	}
	select {
	case <-m.ctx.Done():

                                  description: The ring/modulo hash load balancer
                                    implements consistent hashing to backend hosts.
                                  properties:
                                    minimumRingSize:
                                      description: The minimum number of virtual nodes
                                        to use for the hash ring.