001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.messaging.simp.user; 018 019import java.util.concurrent.ScheduledFuture; 020import java.util.concurrent.TimeUnit; 021 022import org.springframework.context.ApplicationListener; 023import org.springframework.lang.Nullable; 024import org.springframework.messaging.Message; 025import org.springframework.messaging.MessageHandler; 026import org.springframework.messaging.MessagingException; 027import org.springframework.messaging.converter.MessageConverter; 028import org.springframework.messaging.simp.SimpMessageHeaderAccessor; 029import org.springframework.messaging.simp.SimpMessageType; 030import org.springframework.messaging.simp.SimpMessagingTemplate; 031import org.springframework.messaging.simp.broker.BrokerAvailabilityEvent; 032import org.springframework.scheduling.TaskScheduler; 033import org.springframework.util.Assert; 034 035/** 036 * {@code MessageHandler} that handles user registry broadcasts from other 037 * application servers and periodically broadcasts the content of the local 038 * user registry. 039 * 040 * <p>The aggregated information is maintained in a {@link MultiServerUserRegistry}. 041 * 042 * @author Rossen Stoyanchev 043 * @since 4.2 044 */ 045public class UserRegistryMessageHandler implements MessageHandler, ApplicationListener<BrokerAvailabilityEvent> { 046 047 private final MultiServerUserRegistry userRegistry; 048 049 private final SimpMessagingTemplate brokerTemplate; 050 051 private final String broadcastDestination; 052 053 private final TaskScheduler scheduler; 054 055 private final UserRegistryTask schedulerTask = new UserRegistryTask(); 056 057 @Nullable 058 private volatile ScheduledFuture<?> scheduledFuture; 059 060 private long registryExpirationPeriod = TimeUnit.SECONDS.toMillis(20); 061 062 063 /** 064 * Constructor. 065 * @param userRegistry the registry with local and remote user registry information 066 * @param brokerTemplate template for broadcasting local registry information 067 * @param broadcastDestination the destination to broadcast to 068 * @param scheduler the task scheduler to use 069 */ 070 public UserRegistryMessageHandler(MultiServerUserRegistry userRegistry, 071 SimpMessagingTemplate brokerTemplate, String broadcastDestination, TaskScheduler scheduler) { 072 073 Assert.notNull(userRegistry, "'userRegistry' is required"); 074 Assert.notNull(brokerTemplate, "'brokerTemplate' is required"); 075 Assert.hasText(broadcastDestination, "'broadcastDestination' is required"); 076 Assert.notNull(scheduler, "'scheduler' is required"); 077 078 this.userRegistry = userRegistry; 079 this.brokerTemplate = brokerTemplate; 080 this.broadcastDestination = broadcastDestination; 081 this.scheduler = scheduler; 082 } 083 084 085 /** 086 * Return the configured destination for broadcasting UserRegistry information. 087 */ 088 public String getBroadcastDestination() { 089 return this.broadcastDestination; 090 } 091 092 /** 093 * Configure the amount of time (in milliseconds) before a remote user 094 * registry snapshot is considered expired. 095 * <p>By default this is set to 20 seconds (value of 20000). 096 * @param milliseconds the expiration period in milliseconds 097 */ 098 @SuppressWarnings("unused") 099 public void setRegistryExpirationPeriod(long milliseconds) { 100 this.registryExpirationPeriod = milliseconds; 101 } 102 103 /** 104 * Return the configured registry expiration period. 105 */ 106 public long getRegistryExpirationPeriod() { 107 return this.registryExpirationPeriod; 108 } 109 110 111 @Override 112 public void onApplicationEvent(BrokerAvailabilityEvent event) { 113 if (event.isBrokerAvailable()) { 114 long delay = getRegistryExpirationPeriod() / 2; 115 this.scheduledFuture = this.scheduler.scheduleWithFixedDelay(this.schedulerTask, delay); 116 } 117 else { 118 ScheduledFuture<?> future = this.scheduledFuture; 119 if (future != null ){ 120 future.cancel(true); 121 this.scheduledFuture = null; 122 } 123 } 124 } 125 126 @Override 127 public void handleMessage(Message<?> message) throws MessagingException { 128 MessageConverter converter = this.brokerTemplate.getMessageConverter(); 129 this.userRegistry.addRemoteRegistryDto(message, converter, getRegistryExpirationPeriod()); 130 } 131 132 133 private class UserRegistryTask implements Runnable { 134 135 @Override 136 public void run() { 137 try { 138 SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE); 139 accessor.setHeader(SimpMessageHeaderAccessor.IGNORE_ERROR, true); 140 accessor.setLeaveMutable(true); 141 Object payload = userRegistry.getLocalRegistryDto(); 142 brokerTemplate.convertAndSend(getBroadcastDestination(), payload, accessor.getMessageHeaders()); 143 } 144 finally { 145 userRegistry.purgeExpiredRegistries(); 146 } 147 } 148 } 149 150}