1 /*
2 * Copyright 2016 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.util.concurrent;
17
18 import io.netty.util.concurrent.AutoScalingEventExecutorChooserFactory.AutoScalingUtilizationMetric;
19
20 import java.util.List;
21
22 /**
23 * Factory that creates new {@link EventExecutorChooser}s.
24 */
25 public interface EventExecutorChooserFactory {
26
27 /**
28 * Returns a new {@link EventExecutorChooser}.
29 */
30 EventExecutorChooser newChooser(EventExecutor[] executors);
31
32 /**
33 * Chooses the next {@link EventExecutor} to use.
34 */
35 interface EventExecutorChooser {
36
37 /**
38 * Returns the new {@link EventExecutor} to use.
39 */
40 EventExecutor next();
41 }
42
43 /**
44 * An {@link EventExecutorChooser} that exposes metrics for observation.
45 */
46 interface ObservableEventExecutorChooser extends EventExecutorChooser {
47
48 /**
49 * Returns the current number of active {@link EventExecutor}s.
50 * @return the number of active executors.
51 */
52 int activeExecutorCount();
53
54 /**
55 * Returns a list containing the last calculated utilization for each
56 * {@link EventExecutor} in the group.
57 *
58 * @return an umodifiable view of the executor utilizations.
59 */
60 List<AutoScalingUtilizationMetric> executorUtilizations();
61 }
62 }