introduction
In the above we have identified a series of preparatory work to be done before the message is sent. This paper continues this part of the source code reading, mainly related to delayed access to information as well as policy-based routing assistant fault Broker.
- The basic flow
- to sum up
First, the basic process
Need to obtain routing information when sending messages, in the previous article we know that is from the following methods will tryToFindTopicPublishInfo()get. The message to be sent contains a Topic- variable from the local cache client information attempts topicPublishInfoTableto find the. If there is no routing information is updated Topic from NameServer.
In MQClientInstanceinstances of updateTopicRouteInfoFromNameServerupdating and maintaining routing information for the message producer cache method function.
public boolean updateTopicRouteInfoFromNameServer(final String topic, boolean isDefault,
DefaultMQProducer defaultMQProducer) {
try {
if (this.lockNamesrv.tryLock(LOCK_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) {
try {
TopicRouteData topicRouteData;
//
if (isDefault && defaultMQProducer != null) {
topicRouteData = this.mQClientAPIImpl.getDefaultTopicRouteInfoFromNameServer(defaultMQProducer.getCreateTopicKey(),
1000 * 3);
if (topicRouteData != null) {
for (QueueData data : topicRouteData.getQueueDatas()) {
int queueNums = Math.min(defaultMQProducer.getDefaultTopicQueueNums(), data.getReadQueueNums());
data.setReadQueueNums(queueNums);
data.setWriteQueueNums(queueNums);
}
}
} else {
topicRouteData = this.mQClientAPIImpl.getTopicRouteInfoFromNameServer(topic, 1000 * 3);
}
if (topicRouteData != null) {
TopicRouteData old = this.topicRouteTable.get(topic);
boolean changed = topicRouteDataIsChange(old, topicRouteData);
if (!changed) {
changed = this.isNeedUpdateTopicRouteInfo(topic);
} else {
log.info("the topic[{}] route info changed, old[{}] ,new[{}]", topic, old, topicRouteData);
}
if (changed) {
TopicRouteData cloneTopicRouteData = topicRouteData.cloneTopicRouteData();
for (BrokerData bd : topicRouteData.getBrokerDatas()) {
this.brokerAddrTable.put(bd.getBrokerName(), bd.getBrokerAddrs());
}
// Update Pub info
{
TopicPublishInfo publishInfo = topicRouteData2TopicPublishInfo(topic, topicRouteData);
publishInfo.setHaveTopicRouterInfo(true);
Iterator<Entry<String, MQProducerInner>> it = this.producerTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, MQProducerInner> entry = it.next();
MQProducerInner impl = entry.getValue();
if (impl != null) {
impl.updateTopicPublishInfo(topic, publishInfo);
}
}
}
// Update sub info
{
Set<MessageQueue> subscribeInfo = topicRouteData2TopicSubscribeInfo(topic, topicRouteData);
Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, MQConsumerInner> entry = it.next();
MQConsumerInner impl = entry.getValue();
if (impl != null) {
impl.updateTopicSubscribeInfo(topic, subscribeInfo);
}
}
}
log.info("topicRouteTable.put. Topic = {}, TopicRouteData[{}]", topic, cloneTopicRouteData);
this.topicRouteTable.put(topic, cloneTopicRouteData);
return true;
}
} else {
log.warn("updateTopicRouteInfoFromNameServer, getTopicRouteInfoFromNameServer return null, Topic: {}", topic);
}
} catch (Exception e) {
if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX) && !topic.equals(MixAll.AUTO_CREATE_TOPIC_KEY_TOPIC)) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);
}
} finally {
this.lockNamesrv.unlock();
}
} else {
log.warn("updateTopicRouteInfoFromNameServer tryLock timeout {}ms", LOCK_TIMEOUT_MILLIS);
}
} catch (InterruptedException e) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);
}
return false;
}
public MessageQueue selectOneMessageQueue(final String lastBrokerName) {
if (lastBrokerName == null) {
return selectOneMessageQueue();
} else {
int index = this.sendWhichQueue.getAndIncrement();
for (int i = 0; i < this.messageQueueList.size(); i++) {
int pos = Math.abs(index++) % this.messageQueueList.size();
if (pos < 0)
pos = 0;
MessageQueue mq = this.messageQueueList.get(pos);
if (!mq.getBrokerName().equals(lastBrokerName)) {
return mq;
}
}
return selectOneMessageQueue();
}
}
Broker delay fault policy mechanism MQFaultStrategyis defined in the main method is selectOneMessageQueuesubstantially the following processing flow:
the specific source code analysis is as follows:
public class MQFaultStrategy {
private final static InternalLogger log = ClientLogger.getLog();
//维护每个Broker发送消息的延迟
private final LatencyFaultTolerance<String> latencyFaultTolerance = new LatencyFaultToleranceImpl();
//发送消息延迟容错开关
private boolean sendLatencyFaultEnable = false;
//延迟级别数组
private long[] latencyMax = {50L, 100L, 550L, 1000L, 2000L, 3000L, 15000L};
//不可用时长数组
private long[] notAvailableDuration = {0L, 0L, 30000L, 60000L, 120000L, 180000L, 600000L};
public long[] getNotAvailableDuration() {
return notAvailableDuration;
}
public void setNotAvailableDuration(final long[] notAvailableDuration) {
this.notAvailableDuration = notAvailableDuration;
}
public long[] getLatencyMax() {
return latencyMax;
}
public void setLatencyMax(final long[] latencyMax) {
this.latencyMax = latencyMax;
}
public boolean isSendLatencyFaultEnable() {
return sendLatencyFaultEnable;
}
public void setSendLatencyFaultEnable(final boolean sendLatencyFaultEnable) {
this.sendLatencyFaultEnable = sendLatencyFaultEnable;
}
public MessageQueue selectOneMessageQueue(final TopicPublishInfo tpInfo, final String lastBrokerName) {
if (this.sendLatencyFaultEnable) {
try {
//1.在随机递增取模的基础上，再过滤掉not available的Broker代理;对之前失败的，按一定的时间做退避
int index = tpInfo.getSendWhichQueue().getAndIncrement();
//队列轮询
for (int i = 0; i < tpInfo.getMessageQueueList().size(); i++) {
int pos = Math.abs(index++) % tpInfo.getMessageQueueList().size();
if (pos < 0)
pos = 0;
//获取一个消息队列
MessageQueue mq = tpInfo.getMessageQueueList().get(pos);
//验证消息队列是否可用
if (latencyFaultTolerance.isAvailable(mq.getBrokerName())) {
if (null == lastBrokerName || mq.getBrokerName().equals(lastBrokerName))
return mq;
}
}
final String notBestBroker = latencyFaultTolerance.pickOneAtLeast();
int writeQueueNums = tpInfo.getQueueIdByBroker(notBestBroker);
if (writeQueueNums > 0) {
final MessageQueue mq = tpInfo.selectOneMessageQueue();
if (notBestBroker != null) {
mq.setBrokerName(notBestBroker);
mq.setQueueId(tpInfo.getSendWhichQueue().getAndIncrement() % writeQueueNums);
}
return mq;
} else {
latencyFaultTolerance.remove(notBestBroker);
}
} catch (Exception e) {
log.error("Error occurred when selecting message queue", e);
}
return tpInfo.selectOneMessageQueue();
}
//2.采用随机递增取模的方式选择一个队列（MessageQueue）来发送消息
return tpInfo.selectOneMessageQueue(lastBrokerName);
}
public void updateFaultItem(final String brokerName, final long currentLatency, boolean isolation) {
if (this.sendLatencyFaultEnable) {
long duration = computeNotAvailableDuration(isolation ? 30000 : currentLatency);
this.latencyFaultTolerance.updateFaultItem(brokerName, currentLatency, duration);
}
}
private long computeNotAvailableDuration(final long currentLatency) {
for (int i = latencyMax.length - 1; i >= 0; i--) {
if (currentLatency >= latencyMax[i])
return this.notAvailableDuration[i];
}
return 0;
}
}
Second, summary
This paper describes, before the message is sent RocketMQundertaken Brokerfault delay selection strategy. It is a failure for Brokera method of scheduling strategy can be circumvented for failure Brokerto use. In the following, we will conduct a formal analysis of the source code and read the message sent.
