![Events Diagram](../assets/images/******@****.***)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java
class PrintingEventListener extends EventListener {
  private long callStartNanos;

  private void printEvent(String name) {
    long nowNanos = System.nanoTime();

	// additional labels for +Inf for all histogram metrics
	if expPoints := len(labels) * (len(histBuckets) + 1); expPoints != len(metrics) {
		t.Fatalf("Expected %v data points but got %v", expPoints, len(metrics))
	}

// limitations under the License.

package compare

import (
	"bytes"
	"fmt"
	"time"

	"github.com/pmezard/go-difflib/difflib"

	"istio.io/istio/pkg/util/protomarshal"
)

// RouteDiff prints a diff between Istiod and Envoy routes to the passed writer
func (c *Comparator) RouteDiff() error {
	envoyBytes, istiodBytes := &bytes.Buffer{}, &bytes.Buffer{}
	envoyRouteDump, err := c.envoy.GetDynamicRouteDump(true)

 * It's currently implemented by two use cases:
 * 1. Collect cache misses for compilation tasks and publish a `CACHE_MISS` tag for build scan.
 * 2. Collect failed task paths and display a link which points to the corresponding task in the build scan, like `https://ge.gradle.org/s/xxx/console-log?task=yyy`.
 */

import (
	"bytes"
	"fmt"

	"github.com/pmezard/go-difflib/difflib"

	// Force import protos
	_ "istio.io/istio/pilot/pkg/xds/filters"
	"istio.io/istio/pkg/util/protomarshal"
)

// ListenerDiff prints a diff between Istiod and Envoy listeners to the passed writer
func (c *Comparator) ListenerDiff() error {
	envoyBytes, istiodBytes := &bytes.Buffer{}, &bytes.Buffer{}
	envoyListenerDump, err := c.envoy.GetDynamicListenerDump(true)

    list.add("cool");
    assertTrue(all(list, predicate));
    list.add("pants");
    assertFalse(all(list, predicate));
  }

  public void testFind() {
    Iterable<String> list = newArrayList("cool", "pants");
    assertEquals("cool", find(list, equalTo("cool")));
    assertEquals("pants", find(list, equalTo("pants")));
    assertThrows(NoSuchElementException.class, () -> find(list, Predicates.alwaysFalse()));

  optional string nodeName = 6;

  // zone is the name of the Zone this endpoint exists in.
  // +optional
  optional string zone = 7;

  // hints contains information associated with how an endpoint should be
  // consumed.
  // +optional
  optional EndpointHints hints = 8;
}

// EndpointConditions represents the current condition of an endpoint.
message EndpointConditions {

    val index =
      mappings.binarySearch {
        when {
          it.sourceCodePoint1 < codePoint -> -1
          it.sourceCodePoint0 > codePoint -> 1
          else -> 0
        }
      }

    // Code points must be in 0..0x10ffff.
    require(index in mappings.indices) { "unexpected code point: $codePoint" }

    val mapping = mappings[index]
    var result = true

    when (mapping.type) {
      TYPE_IGNORED -> Unit

	if err != nil {
		return nil, err
	}
	c.envoy = envoyDump
	c.w = w
	c.context = 7
	c.location = "Local" // the time.Location for formatting time.Time instances
	return c, nil
}

// Diff prints a diff between Istiod and Envoy to the passed writer
func (c *Comparator) Diff() error {
	if err := c.ClusterDiff(); err != nil {
		return err
	}
	if err := c.ListenerDiff(); err != nil {
		return err
	}

	we, ok := w.(*multierror.Error)
	if ok {
		we.ErrorFormat = func(i []error) string {
			points := make([]string, len(i))
			for i, err := range i {
				points[i] = fmt.Sprintf("* %s", err)
			}

			return fmt.Sprintf(
				"\n\t%s\n",
				strings.Join(points, "\n\t"))
		}
	}
	return w.Error()
}

func servicePortPrefixed(n string) bool {
	i := strings.IndexByte(n, '-')