Copyright 2012 Netflix, Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
/**
 * Copyright 2012 Netflix, Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.netflix.hystrix.strategy.eventnotifier;

import java.util.List;

import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixCommandProperties.ExecutionIsolationStrategy;
import com.netflix.hystrix.HystrixEventType;
import com.netflix.hystrix.strategy.HystrixPlugins;

Abstract EventNotifier that allows receiving notifications for different events with default implementations.
 See HystrixPlugins or the Hystrix GitHub Wiki for information on configuring plugins: https://github.com/Netflix/Hystrix/wiki/Plugins.

Note on thread-safety and performance

A single implementation of this class will be used globally so methods on this class will be invoked concurrently from multiple threads so all functionality must be thread-safe.

Methods are also invoked synchronously and will add to execution time of the commands so all behavior should be fast. If anything time-consuming is to be done it should be spawned asynchronously
onto separate worker threads.
/**
 * Abstract EventNotifier that allows receiving notifications for different events with default implementations.
 * <p>
 * See {@link HystrixPlugins} or the Hystrix GitHub Wiki for information on configuring plugins: <a
 * href="https://github.com/Netflix/Hystrix/wiki/Plugins">https://github.com/Netflix/Hystrix/wiki/Plugins</a>.
 * <p>
 * <b>Note on thread-safety and performance</b>
 * <p>
 * A single implementation of this class will be used globally so methods on this class will be invoked concurrently from multiple threads so all functionality must be thread-safe.
 * <p>
 * Methods are also invoked synchronously and will add to execution time of the commands so all behavior should be fast. If anything time-consuming is to be done it should be spawned asynchronously
 * onto separate worker threads.
 */
public abstract class HystrixEventNotifier {

    
Called for every event fired.

Default Implementation:  Does nothing
Params:
eventType – event type
key – event key/**
     * Called for every event fired.
     * <p>
     * <b>Default Implementation: </b> Does nothing
     * 
     * @param eventType event type
     * @param key event key
     */
    public void markEvent(HystrixEventType eventType, HystrixCommandKey key) {
        // do nothing
    }

    
Called after a command is executed using thread isolation.

Will not get called if a command is rejected, short-circuited etc.

Default Implementation:  Does nothing
Params:
key –  HystrixCommandKey of command instance.
isolationStrategy –  ExecutionIsolationStrategy the isolation strategy used by the command when executed
duration – 
           time in milliseconds of executing run() method
eventsDuringExecution –  List<HystrixEventType> of events occurred during execution./**
     * Called after a command is executed using thread isolation.
     * <p>
     * Will not get called if a command is rejected, short-circuited etc.
     * <p>
     * <b>Default Implementation: </b> Does nothing
     * 
     * @param key
     *            {@link HystrixCommandKey} of command instance.
     * @param isolationStrategy
     *            {@link ExecutionIsolationStrategy} the isolation strategy used by the command when executed
     * @param duration
     *            time in milliseconds of executing <code>run()</code> method
     * @param eventsDuringExecution
     *            {@code List<HystrixEventType>} of events occurred during execution.
     */
    public void markCommandExecution(HystrixCommandKey key, ExecutionIsolationStrategy isolationStrategy, int duration, List<HystrixEventType> eventsDuringExecution) {
        // do nothing
    }

}