前言

上一节我们总结了服务器模块的硬盘管理,将交换机,队列,绑定存书到Sqlite数据库中,将消息按照队进行创建文件存储在本地硬盘中.并且封装了对于数据库和文件的各种操作.实现了持久化的效果,但是实际的消息存储/转发,主要靠内存的结构.对于消息队列来说,内存部分是更关键的,内存速度更快,可以达到更高的并发.本节就对内存管理进行封装.本项目全部代码已上传Gitee,链接放在文章末尾,欢迎大家访问!

1. 创建MemoryDataCenter

路径:mqserver.datacenter.MemoryDataCenter

考虑到多线程的原因,我们将HashMap替换成ConcurrentHashMap (对每个哈希桶进行加锁,相对来说是线程安全的)

@Data
public class MemoryDataCenter {// 1. 交换机  多线程环境下使用,使用ConcurrentHashMap会相对线程安全//         key:ExchangeName,value:Exchange对象private ConcurrentHashMap<String, Exchange> exchangeMap = new ConcurrentHashMap<>();// 2. 队列  key:QueueName,value:MSQueue对象private ConcurrentHashMap<String, MSQueue> queueMap = new ConcurrentHashMap<>();// 3. 绑定  key:ExchangeName,value:HashMap(key:QueueName,value:MSQueue对象)private ConcurrentHashMap<String,ConcurrentHashMap<String, Binding>> bindingsMap = new ConcurrentHashMap<>();// 4. 消息  key:MessageID,value:Message对象private ConcurrentHashMap<String, Message> messageMap = new ConcurrentHashMap<>();// 5. 消息和队列的映射关系 HashMap: key:QueueName,value:LinkedList(Message对象)private ConcurrentHashMap<String, LinkedList<Message>> queueMessageMap = new ConcurrentHashMap<>();// 6. 未确认的消息  HashMap: key:QueueName,value:HashMap(key:MessageID,value:Message对象)private ConcurrentHashMap<String,ConcurrentHashMap<String, Message>> queueMessageWaitAckMap = new ConcurrentHashMap<>();
}

2. 封装Exchange 和 Queue方法

主要就是插入和获取数据以及删除

   /*** 1. 针对内存中的交换机,队列设置操作*/public void insertExchange(Exchange exchange) {exchangeMap.put(exchange.getName(), exchange);System.out.println("[MemoryDataCenter] 新交换机添加成功! exchangeName=" + exchange.getName());}public Exchange getExchange(String exchangeName) {return exchangeMap.get(exchangeName);}public void deleteExchange(String exchangeName) {exchangeMap.remove(exchangeName);System.out.println("[MemoryDataCenter] 交换机删除成功! exchangeName=" + exchangeName);}public void insertQueue(MSQueue queue) {queueMap.put(queue.getName(), queue);System.out.println("[MemoryDataCenter] 新队列添加成功! queueName=" + queue.getName());}public MSQueue getQueue(String queueName) {return queueMap.get(queueName);}public void deleteQueue(String queueName) {queueMap.remove(queueName);System.out.println("[MemoryDataCenter] 队列删除成功! queueName=" + queueName);}

3. 封装Binding操作

这里呢之所以将绑定的操作单独列举出来,是因为存储绑定信息的数据结构是相对比较复杂的,是嵌套的HashMap.

对于插入绑定信息:

1, 首先按照交换机的名字进行查找,如果查找不到就进行创建一个HashMap的数据结构存储到含有绑定信息的HashMap中,如果存在的话在按照队列名字进行查找绑定信息,如果查找到了,说明改绑定信息已经插入过就不要进行插入了,如果没找到就进行插入操作.

2. 在上述查找和插入的操作比并不是原子的,所以我们要给是上述操作,按照bindingMap进行加锁.以保证我们的线程操作是安全的.

下述是相关对于绑定的操作的代码:

    /*** 2. 针对绑定进行操作*//*** 2.1插入绑定信息* @param binding* @throws MqException*/public void insertBinding(Binding binding) throws MqException {
//        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(binding.getExchangeName());
//        if (bindingMap == null) {
//            bindingMap = new ConcurrentHashMap<>();
//            bindingsMap.put(binding.getExchangeName(), bindingMap);
//        }// 先使用 exchangeName 查一下, 对应的哈希表是否存在. 不存在就创建一个.ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(),k -> new ConcurrentHashMap<>());synchronized (bindingMap) {// 再根据 queueName 查一下目前的绑定的交换机绑定的是否是当前传入的队列. 如果已经存在(存在相同的绑定关系了,就不需要进行传入), 就抛出异常. 不存在才能插入.if (bindingMap.get(binding.getQueueName()) != null) {throw new MqException("[MemoryDataCenter] 绑定已经存在! exchangeName=" + binding.getExchangeName() +", queueName=" + binding.getQueueName());}// 最后将绑定关系传入到bingMap中bindingMap.put(binding.getQueueName(), binding);}System.out.println("[MemoryDataCenter] 新绑定添加成功! exchangeName=" + binding.getExchangeName()+ ", queueName=" + binding.getQueueName());}/*** 2.2 获取绑定1: 根据exchangeName, queueName 获取唯一的绑定* @param exchangeName* @param queueName*/public Binding getBinding(String exchangeName, String queueName){ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(exchangeName);if (bindingMap == null){return null;}synchronized (bindingMap){// 防止当别的操作删除了这个队列的绑定信息,而导致的线程错误return bindingMap.get(queueName);}}/*** 2.3 获取绑定2: 根据exchangeName 查询所有绑定* @param exchangeName* @return*/public ConcurrentHashMap<String, Binding> getBindings(String exchangeName) throws MqException {if (bindingsMap.get(exchangeName) == null){return null;}return bindingsMap.get(exchangeName);}/*** 2.4 删除绑定关系(单个) 一个交换机对应的单个队列的绑定关系* @param binding* @throws MqException*/public void deleteBinding(Binding binding) throws MqException {ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(binding.getExchangeName());if (bindingMap == null) {// 该交换机没有绑定任何队列. 报错.throw new MqException("[MemoryDataCenter] 绑定不存在! exchangeName=" + binding.getExchangeName()+ ", queueName=" + binding.getQueueName());}bindingMap.remove(binding.getQueueName());System.out.println("[MemoryDataCenter] 绑定删除成功! exchangeName=" + binding.getExchangeName()+ ", queueName=" + binding.getQueueName());}/*** 2.5 删除绑定关系(多个) 1个交换机对应的多个队列的绑定关系.*/public void deleteBinding(String exchangeName){bindingsMap.remove(exchangeName);}

4. 封装Message操作

4.1 封装消息中心集合messageMap

1. 添加消息到消息中心
2. 根据消息ID查询消息
3. 根据消息ID删除消息

 /*** 3. 针对消息进行操作*//*** 3.1 添加消息* @param message*/public void addMessage(Message message) {messageMap.put(message.getMessageID(), message);System.out.println("[MemoryDataCenter] 新消息添加成功! messageId=" + message.getMessageID());}/*** 3.2 根据 id 查询消息* @param messageId* @return*/public Message getMessage(String messageId) {return messageMap.get(messageId);}/*** 3.3 根据 id 删除消息* @param messageId*/public void removeMessage(String messageId) {messageMap.remove(messageId);System.out.println("[MemoryDataCenter] 消息被移除! messageId=" + messageId);}

4.2 封装消息与队列的关系集合queueMessageMap的操作

1. 发送消息到指定队列名字的队列
2. 从指定队列中获取消息集合
3. 获取指定队列名字队列中消息的个数

 /*** 4 针对消息和队列的关系进行操作*//*** 4.1 发送消息到指定队列* @param queue* @param message*/public void sendMessage(MSQueue queue, Message message) {// 先根据队列的名字, 找到该队列对应的消息链表.// 先根据队列的名字进行查询,查不到就进行创建该队列对应的链表  // computeIfAbsent线程安全的LinkedList<Message> messages = queueMessageMap.computeIfAbsent(queue.getName(),k-> new LinkedList<>());// 再把数据加到 messages 里面synchronized (messages) {// 对该队列进行添加的时候需要进行加锁messages.add(message);}// 在这里把该消息也往消息中心中插入一下. 假设如果 message 已经在消息中心存在, 重复插入也没关系.// 主要就是相同 messageId, 对应的 message 的内容一定是一样的. (服务器代码不会对 Message 内容做修改 basicProperties 和 body)addMessage(message);System.out.println("[MemoryDataCenter] 消息被添加到队列中! messageId=" + message.getMessageID());}/*** 4.2 从指定队列名字中进行提取信息* @param queueName* @return*/public Message pollMessage(String queueName){LinkedList<Message> messages = queueMessageMap.get(queueName);// 队列中没有信息if (messages == null){System.out.println("[MemoryDataCenter] 该队列中没有信息! queueName=" + queueName);return null;}// 将队列进行头删除(提取信息)synchronized (messages){if (messages.size() == 0){System.out.println("[MemoryDataCenter] 该队列中没有信息! queueName=" + queueName);return null;}Message currentMessage = messages.remove(0); System.out.println("[MemoryDataCenter] 消息已经从队列中取出! queueName=" + queueName + ", MessageID=" + currentMessage.getMessageID() );return currentMessage;}}/*** 4.3 获取指定队列名字中消息的个数* @param queueName* @return*/public int getMessageCount(String queueName){LinkedList<Message> messages = queueMessageMap.get(queueName);// 队列中没有信息if (messages == null){System.out.println("[MemoryDataCenter] 该队列中没有信息! queueName=" + queueName);return 0;}// 将队列进行头删除(提取信息)synchronized (messages){if (messages.size() == 0){System.out.println("[MemoryDataCenter] 该队列中没有信息! queueName=" + queueName);return 0;}return messages.size();}}

5. 封装未确认消息集合waitMessage的操作

1. 添加消息到等待确认队列
2. 从指定未确认队列中删除消息
3. 根据指定的消息ID与未确认队列名字获取消息内容

/*** 5. 未确认消息Map的操作*//*** 5.1 添加消息到指定等待确认队列* @param queueName* @param message*/public void addMessageWaitAck(String queueName, Message message){ConcurrentHashMap<String,Message> waitMessage = queueMessageWaitAckMap.computeIfAbsent(queueName, k-> new ConcurrentHashMap<>());waitMessage.put(message.getMessageID(),message);System.out.println("[MemoryDataCenter] 消息进入等待确认队列! messageID=" + message.getMessageID());}/*** 5.2 从指定的未确认消息队列中进行删除消息* @param queueName* @param messageId*/public void removeMessageWaitAck(String queueName, String messageId){ConcurrentHashMap<String,Message> waitMessage = queueMessageWaitAckMap.get(queueName);if (waitMessage == null){System.out.println("[MemoryDataCenter] 该队列为空! queueName=" + queueName);return;}waitMessage.remove(messageId);System.out.println("[MemoryDataCenter] 消息已经从等待确认队列中移除! messageId=" + messageId);}/*** 5.3 根据指定消息ID从队列中进行获取信息* @param queueName* @param messageId* @return*/public Message geMessageWaitAck(String queueName, String messageId){ConcurrentHashMap<String,Message> waitMessage = queueMessageWaitAckMap.get(queueName);if (waitMessage == null){System.out.println("[MemoryDataCenter] 该队列为空! queueName=" + queueName);return null;}return waitMessage.get(messageId);}

6. 从硬盘中恢复数据到内存中

使用之前封装过的diskDataCenter进行恢复数据.

1. 清空当前内存数据结构中的数据

2. 恢复所有的交换机,队列,绑定,消息数据,恢复消息数据的时候,要将消息中心和消息与队列的映射进行恢复.

/*** 6. 从硬盘中恢复数据到内存中 (使用之前封装好的管理硬盘的类进行实现)*/public void recovery(DiskDataCenter diskDataCenter) throws IOException, MqException, ClassNotFoundException {// 1. 清空内存中各种数据信息queueMap.clear();exchangeMap.clear();bindingsMap.clear();messageMap.clear();queueMessageMap.clear();// 2. 恢复所有的交换机信息List<Exchange> exchanges = diskDataCenter.selectAllExchange();for (Exchange exchange :exchanges) {exchangeMap.put(exchange.getName(),exchange);}// 3. 恢复所有的队列信息List<MSQueue> queues = diskDataCenter.selectAllMSQueue();for (MSQueue msQueue :queues) {queueMap.put(msQueue.getName(),msQueue);}// 4. 恢复所有的绑定数据List<Binding> bindings = diskDataCenter.selectAllBinding();for (Binding binding: bindings){ConcurrentHashMap<String,Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(), k-> new ConcurrentHashMap<>());bindingMap.put(binding.getQueueName(),binding);}// 4. 恢复所有的消息数据// 4.1 遍历所有的队列// List<MSQueue> queues = diskDataCenter.selectAllMSQueue();for (MSQueue msQueue:queues) {LinkedList<Message> messages = diskDataCenter.loadAllMessageFromQueue(msQueue.getName());// 4.2 将获取的消息进行进行加入到队列queueMessageMap.put(msQueue.getName(),messages);// 4.3 将消息添加上到消息中心for (Message message : messages) {messageMap.put(message.getMessageID(),message);}}

7. MemoryDataCenter单元测试

package com.example.demo.mqserver.datacenter;import com.example.demo.DemoApplication;
import com.example.demo.common.MqException;
import com.example.demo.mqserver.core.*;
import org.apache.tomcat.util.http.fileupload.FileUtils;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.test.context.SpringBootTest;import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;import static org.junit.jupiter.api.Assertions.*;/*** Created with IntelliJ IDEA.* Description:* User: YAO* Date: 2023-07-31* Time: 10:30*/
@SpringBootTest
class MemoryDataCenterTest {MemoryDataCenter memoryDataCenter = null;@BeforeEachvoid setUp() {memoryDataCenter = new MemoryDataCenter();}@AfterEachvoid tearDown() {memoryDataCenter = null;}// 创建一个测试交换机private Exchange createTestExchange(String exchangeName) {Exchange exchange = new Exchange();exchange.setName(exchangeName);exchange.setType(ExchangeType.DIRECT);exchange.setAutoDelete(false);exchange.setDurable(true);return exchange;}// 创建一个测试队列private MSQueue createTestQueue(String queueName) {MSQueue queue = new MSQueue();queue.setName(queueName);queue.setDurable(true);queue.setExclusive(false);queue.setAutoDelete(false);return queue;}/*** 1. 针对交换机进行操作*/@Testpublic void testExchange(){// 1. 创建交换机进行插入Exchange expectExchange = createTestExchange("testExchange");memoryDataCenter.insertExchange(expectExchange);// 2. 查询交换机Exchange actualExchange = memoryDataCenter.getExchange("testExchange");// 比较内存中的引用是否是同一个引用Assertions.assertEquals(expectExchange,actualExchange);// 3. 删除交换机memoryDataCenter.deleteExchange("testExchange");// 4. 查询交换机,比较结果actualExchange = memoryDataCenter.getExchange("testExchange");Assertions.assertNull(actualExchange);}/*** 2. 针对队列进行操作*/@Testpublic void testQueue(){// 1. 创建交换机进行插入MSQueue expectQueue = createTestQueue("testQueue");memoryDataCenter.insertQueue(expectQueue);// 2. 查询交换机MSQueue actualQueue = memoryDataCenter.getQueue("testQueue");// 比较内存中的引用是否是同一个引用Assertions.assertEquals(expectQueue,actualQueue);// 3. 删除交换机memoryDataCenter.deleteQueue("testQueue");// 4. 查询交换机,比较结果actualQueue = memoryDataCenter.getQueue("testQueue");Assertions.assertNull(actualQueue);}/*** 3. 针对绑定进行测试*/@Testpublic void testBinding() throws MqException {// 1.创建绑定并加入到集合中Binding expectedBinding = new Binding();expectedBinding.setExchangeName("testExchange");expectedBinding.setQueueName("testQueue");memoryDataCenter.insertBinding(expectedBinding);// 2. 查询绑定(单个)Binding actualBinding = memoryDataCenter.getBinding("testExchange","testQueue");Assertions.assertEquals(expectedBinding,actualBinding);// 2.1 查询所有的绑定ConcurrentHashMap<String, Binding> bindingMap = memoryDataCenter.getBindings("testExchange");Assertions.assertEquals(1, bindingMap.size());Assertions.assertEquals(expectedBinding, bindingMap.get("testQueue"));// 3. 删除绑定memoryDataCenter.deleteBinding("testExchange");actualBinding = memoryDataCenter.getBinding("testExchange","testQueue");Assertions.assertNull(actualBinding);bindingMap = memoryDataCenter.getBindings("testExchange");Assertions.assertNull(bindingMap);}private Message createTestMessage(String content) {Message message = Message.createMessageWithId("testRoutingKey", null, content.getBytes());return message;}/*** 4. 针对消息进行测试*/@Testpublic void testMessage(){// 1. 创建消息并插入Message expectedMessage = createTestMessage("testMessage");memoryDataCenter.addMessage(expectedMessage);// 2. 查询消息并比较Message actualMessage = memoryDataCenter.getMessage(expectedMessage.getMessageID());Assertions.assertEquals(expectedMessage, actualMessage);// 4. 删除消息memoryDataCenter.removeMessage(expectedMessage.getMessageID());// 5. 查询消息并比较actualMessage = memoryDataCenter.getMessage(expectedMessage.getMessageID());Assertions.assertNull(actualMessage);}/*** 5. 测试将消息发送到对列中*/@Testpublic void sendMessage(){// 1. 创建一个队列. 创建10条消息,进行插入到队列MSQueue expectQueue = createTestQueue("testQueue");List<Message> expectMessage = new ArrayList<>();for (int i = 0; i < 10; i++) {Message message = createTestMessage("testMessage" + i);memoryDataCenter.sendMessage(expectQueue,message);expectMessage.add(message);}// 2.从队列进行取出消息List<Message> actualMessage = new ArrayList<>();while (true){Message message = memoryDataCenter.pollMessage("testQueue");if (message == null){break;}actualMessage.add(message);}// 3. 比较消息前后是否一致Assertions.assertEquals(expectMessage.size(),actualMessage.size());for (int i = 0; i < expectMessage.size(); i++) {Assertions.assertEquals(expectMessage.get(i),actualMessage.get(i));}}/*** 6. 测试未被确认的消息*/@Testpublic void testMessageWaitAck(){// 1. 创建消息,插入到未被确认的队列中Message expectedMessage = createTestMessage("expectedMessage");memoryDataCenter.addMessageWaitAck("testQueue", expectedMessage);// 2. 获取消息从未被确认的队列中Message actualMessage = memoryDataCenter.geMessageWaitAck("testQueue", expectedMessage.getMessageID());Assertions.assertEquals(expectedMessage, actualMessage);// 3. 从未被确认的队列中进行删除消息memoryDataCenter.removeMessageWaitAck("testQueue", expectedMessage.getMessageID());// 4. 比较删除之后的队列是否还有消息actualMessage = memoryDataCenter.geMessageWaitAck("testQueue", expectedMessage.getMessageID());Assertions.assertNull(actualMessage);}/*** 7. 测试从硬盘中恢复数据到内存*/@Testpublic void testRecovery() throws IOException, MqException, ClassNotFoundException {// 由于后续需要进行数据库操作, 依赖 MyBatis. 就需要先启动 SpringApplication, 这样才能进行后续的数据库操作.DemoApplication.context = SpringApplication.run(DemoApplication.class);// 1. 在硬盘上构造好数据DiskDataCenter diskDataCenter = new DiskDataCenter();diskDataCenter.init();// 构造交换机Exchange expectedExchange = createTestExchange("testExchange");diskDataCenter.insertExchange(expectedExchange);// 构造队列MSQueue expectedQueue = createTestQueue("testQueue");diskDataCenter.insertQueue(expectedQueue);// 构造绑定Binding expectedBinding = new Binding();expectedBinding.setExchangeName("testExchange");expectedBinding.setQueueName("testQueue");expectedBinding.setBindingKey("testBindingKey");diskDataCenter.insertBinding(expectedBinding);// 构造消息Message expectedMessage = createTestMessage("testContent");diskDataCenter.sendMessage(expectedQueue, expectedMessage);// 2. 执行恢复操作memoryDataCenter.recovery(diskDataCenter);// 3. 对比结果Exchange actualExchange = memoryDataCenter.getExchange("testExchange");Assertions.assertEquals(expectedExchange.getName(), actualExchange.getName());Assertions.assertEquals(expectedExchange.getType(), actualExchange.getType());Assertions.assertEquals(expectedExchange.isDurable(), actualExchange.isDurable());Assertions.assertEquals(expectedExchange.isAutoDelete(), actualExchange.isAutoDelete());MSQueue actualQueue = memoryDataCenter.getQueue("testQueue");Assertions.assertEquals(expectedQueue.getName(), actualQueue.getName());Assertions.assertEquals(expectedQueue.isDurable(), actualQueue.isDurable());Assertions.assertEquals(expectedQueue.isAutoDelete(), actualQueue.isAutoDelete());Assertions.assertEquals(expectedQueue.isExclusive(), actualQueue.isExclusive());Binding actualBinding = memoryDataCenter.getBinding("testExchange", "testQueue");Assertions.assertEquals(expectedBinding.getExchangeName(), actualBinding.getExchangeName());Assertions.assertEquals(expectedBinding.getQueueName(), actualBinding.getQueueName());Assertions.assertEquals(expectedBinding.getBindingKey(), actualBinding.getBindingKey());Message actualMessage = memoryDataCenter.pollMessage("testQueue");Assertions.assertEquals(expectedMessage.getMessageID(), actualMessage.getMessageID());Assertions.assertEquals(expectedMessage.getRoutingKey(), actualMessage.getRoutingKey());Assertions.assertEquals(expectedMessage.getDeliverMode(), actualMessage.getDeliverMode());Assertions.assertArrayEquals(expectedMessage.getBody(), actualMessage.getBody());// 4. 清理硬盘的数据, 把整个 data 目录里的内容都删掉(包含了 meta.db 和 队列的目录).DemoApplication.context.close();File dataDir = new File("./data");FileUtils.deleteDirectory(dataDir);}
}

结语

以上内容就是针对内存管理的封装,主要是设计了6中数据机构进行存储交换机队列绑定消息消息和队列的映射未确认信息.后续对数据进行操作的时候会更加具有效率.这样我们虚拟主机中两大核心部分:硬盘管理和内存管理都总结完成,下一节会对上述两种操作进一步封装到(VirtualHost)中,然后正式的提出消息队列服务器BrokerServer这个概念,对其进行完善和功能封装.请持续关注,谢谢!!!

完整的项目代码已上传Gitee,欢迎大家访问.👇👇👇

模拟实现消息队列https://gitee.com/yao-fa/advanced-java-ee/tree/master/My-mq