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本文主要研究一下canal的CanalAdapterWorker
CanalAdapterWorker
canal-1.1.4/client-adapter/launcher/src/main/java/com/alibaba/otter/canal/adapter/launcher/loader/CanalAdapterWorker.java
public class CanalAdapterWorker extends AbstractCanalAdapterWorker {
private static final int BATCH_SIZE = 50;
private static final int SO_TIMEOUT = 0;
private CanalConnector connector;
/**
* 单台client适配器worker的构造方法
*
* @param canalDestination canal实例名
* @param address canal-server地址
* @param canalOuterAdapters 外部适配器组
*/
public CanalAdapterWorker(CanalClientConfig canalClientConfig, String canalDestination, SocketAddress address,
List<List<OuterAdapter>> canalOuterAdapters){
super(canalOuterAdapters);
this.canalClientConfig = canalClientConfig;
this.canalDestination = canalDestination;
connector = CanalConnectors.newSingleConnector(address, canalDestination, "", "");
}
/**
* HA模式下client适配器worker的构造方法
*
* @param canalDestination canal实例名
* @param zookeeperHosts zookeeper地址
* @param canalOuterAdapters 外部适配器组
*/
public CanalAdapterWorker(CanalClientConfig canalClientConfig, String canalDestination, String zookeeperHosts,
List<List<OuterAdapter>> canalOuterAdapters){
super(canalOuterAdapters);
this.canalDestination = canalDestination;
this.canalClientConfig = canalClientConfig;
connector = CanalConnectors.newClusterConnector(zookeeperHosts, canalDestination, "", "");
((ClusterCanalConnector) connector).setSoTimeout(SO_TIMEOUT);
}
@Override
protected void process() {
while (!running) { // waiting until running == true
while (!running) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
}
}
int retry = canalClientConfig.getRetries() == null || canalClientConfig.getRetries() == 0 ? 1 : canalClientConfig.getRetries();
if (retry == -1) {
// 重试次数-1代表异常时一直阻塞重试
retry = Integer.MAX_VALUE;
}
// long timeout = canalClientConfig.getTimeout() == null ? 300000 :
// canalClientConfig.getTimeout(); // 默认超时5分钟
Integer batchSize = canalClientConfig.getBatchSize();
if (batchSize == null) {
batchSize = BATCH_SIZE;
}
while (running) {
try {
syncSwitch.get(canalDestination);
logger.info("=============> Start to connect destination: {} <=============", this.canalDestination);
connector.connect();
logger.info("=============> Start to subscribe destination: {} <=============", this.canalDestination);
connector.subscribe();
logger.info("=============> Subscribe destination: {} succeed <=============", this.canalDestination);
while (running) {
try {
syncSwitch.get(canalDestination, 1L, TimeUnit.MINUTES);
} catch (TimeoutException e) {
break;
}
if (!running) {
break;
}
for (int i = 0; i < retry; i++) {
if (!running) {
break;
}
Message message = connector.getWithoutAck(batchSize); // 获取指定数量的数据
long batchId = message.getId();
try {
int size = message.getEntries().size();
if (batchId == -1 || size == 0) {
Thread.sleep(500);
} else {
if (logger.isDebugEnabled()) {
logger.debug("destination: {} batchId: {} batchSize: {} ",
canalDestination,
batchId,
size);
}
long begin = System.currentTimeMillis();
writeOut(message);
if (logger.isDebugEnabled()) {
logger.debug("destination: {} batchId: {} elapsed time: {} ms",
canalDestination,
batchId,
System.currentTimeMillis() - begin);
}
}
connector.ack(batchId); // 提交确认
break;
} catch (Exception e) {
if (i != retry - 1) {
connector.rollback(batchId); // 处理失败, 回滚数据
logger.error(e.getMessage() + " Error sync and rollback, execute times: " + (i + 1));
} else {
connector.ack(batchId);
logger.error(e.getMessage() + " Error sync but ACK!");
}
Thread.sleep(500);
}
}
}
} catch (Throwable e) {
logger.error("process error!", e);
} finally {
connector.disconnect();
logger.info("=============> Disconnect destination: {} <=============", this.canalDestination);
}
if (running) { // is reconnect
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// ignore
}
}
}
}
@Override
public void stop() {
try {
if (!running) {
return;
}
if (connector instanceof ClusterCanalConnector) {
((ClusterCanalConnector) connector).stopRunning();
} else if (connector instanceof SimpleCanalConnector) {
((SimpleCanalConnector) connector).stopRunning();
}
running = false;
syncSwitch.release(canalDestination);
logger.info("destination {} is waiting for adapters' worker thread die!", canalDestination);
if (thread != null) {
try {
thread.join();
} catch (InterruptedException e) {
// ignore
}
}
groupInnerExecutorService.shutdown();
logger.info("destination {} adapters worker thread dead!", canalDestination);
canalOuterAdapters.forEach(outerAdapters -> outerAdapters.forEach(OuterAdapter::destroy));
logger.info("destination {} all adapters destroyed!", canalDestination);
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
}
- CanalAdapterWorker的process方法使用了两层while循环，第一层先执行syncSwitch.get(canalDestination)，若出现异常则在finally里头执行connector.disconnect()；第二层先执行syncSwitch.get(canalDestination, 1L, TimeUnit.MINUTES)，若出现TimeoutException则继续循环，之后使用retry次数的循环来执行connector.getWithoutAck(batchSize)，然后调用writeOut(message)，最后执行connector.ack(batchId)，然后跳出循环；若出现异常，在不超出retry次数时执行connector.rollback(batchId)，超出retry次数则直接ack；其stop方法执行connector.stopRunning，然后执行syncSwitch.release(canalDestination)、groupInnerExecutorService.shutdown()、outerAdapter的destroy方法
AbstractCanalAdapterWorker
canal-1.1.4/client-adapter/launcher/src/main/java/com/alibaba/otter/canal/adapter/launcher/loader/AbstractCanalAdapterWorker.java
public abstract class AbstractCanalAdapterWorker {
protected final Logger logger = LoggerFactory.getLogger(this.getClass());
protected String canalDestination; // canal实例
protected String groupId = null; // groupId
protected List<List<OuterAdapter>> canalOuterAdapters; // 外部适配器
protected CanalClientConfig canalClientConfig; // 配置
protected ExecutorService groupInnerExecutorService; // 组内工作线程池
protected volatile boolean running = false; // 是否运行中
protected Thread thread = null;
protected Thread.UncaughtExceptionHandler handler = (t, e) -> logger.error("parse events has an error", e);
protected SyncSwitch syncSwitch;
public AbstractCanalAdapterWorker(List<List<OuterAdapter>> canalOuterAdapters){
this.canalOuterAdapters = canalOuterAdapters;
this.groupInnerExecutorService = Util.newFixedThreadPool(canalOuterAdapters.size(), 5000L);
syncSwitch = (SyncSwitch) SpringContext.getBean(SyncSwitch.class);
}
protected void writeOut(final Message message) {
List<Future<Boolean>> futures = new ArrayList<>();
// 组间适配器并行运行
canalOuterAdapters.forEach(outerAdapters -> {
final List<OuterAdapter> adapters = outerAdapters;
futures.add(groupInnerExecutorService.submit(() -> {
try {
// 组内适配器穿行运行，尽量不要配置组内适配器
adapters.forEach(adapter -> {
long begin = System.currentTimeMillis();
List<Dml> dmls = MessageUtil.parse4Dml(canalDestination, groupId, message);
if (dmls != null) {
batchSync(dmls, adapter);
if (logger.isDebugEnabled()) {
logger.debug("{} elapsed time: {}",
adapter.getClass().getName(),
(System.currentTimeMillis() - begin));
}
}
});
return true;
} catch (Exception e) {
logger.error(e.getMessage(), e);
return false;
}
}));
// 等待所有适配器写入完成
// 由于是组间并发操作，所以将阻塞直到耗时最久的工作组操作完成
RuntimeException exception = null;
for (Future<Boolean> future : futures) {
try {
if (!future.get()) {
exception = new RuntimeException("Outer adapter sync failed! ");
}
} catch (Exception e) {
exception = new RuntimeException(e);
}
}
if (exception != null) {
throw exception;
}
});
}
private void batchSync(List<Dml> dmls, OuterAdapter adapter) {
// 分批同步
if (dmls.size() <= canalClientConfig.getSyncBatchSize()) {
adapter.sync(dmls);
} else {
int len = 0;
List<Dml> dmlsBatch = new ArrayList<>();
for (Dml dml : dmls) {
dmlsBatch.add(dml);
if (dml.getData() == null || dml.getData().isEmpty()) {
len += 1;
} else {
len += dml.getData().size();
}
if (len >= canalClientConfig.getSyncBatchSize()) {
adapter.sync(dmlsBatch);
dmlsBatch.clear();
len = 0;
}
}
if (!dmlsBatch.isEmpty()) {
adapter.sync(dmlsBatch);
}
}
}
//......
}
- AbstractCanalAdapterWorker的writeOut方法遍历canalOuterAdapters，挨个往groupInnerExecutorService提交batchSync任务；batchSync方法按canalClientConfig.getSyncBatchSize()配置分批执行adapter.sync(dmls)
SyncSwitch
canal-1.1.4/client-adapter/launcher/src/main/java/com/alibaba/otter/canal/adapter/launcher/common/SyncSwitch.java
@Component
public class SyncSwitch {
private static final String SYN_SWITCH_ZK_NODE = "/sync-switch/";
private static final Map<String, BooleanMutex> LOCAL_LOCK = new ConcurrentHashMap<>();
private static final Map<String, BooleanMutex> DISTRIBUTED_LOCK = new ConcurrentHashMap<>();
private Mode mode = Mode.LOCAL;
@Resource
private AdapterCanalConfig adapterCanalConfig;
@Resource
private CuratorClient curatorClient;
@PostConstruct
public void init() {
CuratorFramework curator = curatorClient.getCurator();
if (curator != null) {
mode = Mode.DISTRIBUTED;
DISTRIBUTED_LOCK.clear();
for (String destination : adapterCanalConfig.DESTINATIONS) {
// 对应每个destination注册锁
BooleanMutex mutex = new BooleanMutex(true);
initMutex(curator, destination, mutex);
DISTRIBUTED_LOCK.put(destination, mutex);
startListen(destination, mutex);
}
} else {
mode = Mode.LOCAL;
LOCAL_LOCK.clear();
for (String destination : adapterCanalConfig.DESTINATIONS) {
// 对应每个destination注册锁
LOCAL_LOCK.put(destination, new BooleanMutex(true));
}
}
}
public void get(String destination) throws InterruptedException {
if (mode == Mode.LOCAL) {
BooleanMutex mutex = LOCAL_LOCK.get(destination);
if (mutex != null) {
mutex.get();
}
} else {
BooleanMutex mutex = DISTRIBUTED_LOCK.get(destination);
if (mutex != null) {
mutex.get();
}
}
}
public void get(String destination, long timeout, TimeUnit unit) throws InterruptedException, TimeoutException {
if (mode == Mode.LOCAL) {
BooleanMutex mutex = LOCAL_LOCK.get(destination);
if (mutex != null) {
mutex.get(timeout, unit);
}
} else {
BooleanMutex mutex = DISTRIBUTED_LOCK.get(destination);
if (mutex != null) {
mutex.get(timeout, unit);
}
}
}
public synchronized void release(String destination) {
if (mode == Mode.LOCAL) {
BooleanMutex mutex = LOCAL_LOCK.get(destination);
if (mutex != null && !mutex.state()) {
mutex.set(true);
}
}
if (mode == Mode.DISTRIBUTED) {
BooleanMutex mutex = DISTRIBUTED_LOCK.get(destination);
if (mutex != null && !mutex.state()) {
mutex.set(true);
}
}
}
//......
}
- SyncSwitch支持LOCAL、DISTRIBUTED模式，其get方法执行mutex.get()或者mutex.get(timeout, unit)方法；其release方法执行mutex.set(true)
小结
CanalAdapterWorker的process方法使用了两层while循环，第一层先执行syncSwitch.get(canalDestination)，若出现异常则在finally里头执行connector.disconnect()；第二层先执行syncSwitch.get(canalDestination, 1L, TimeUnit.MINUTES)，若出现TimeoutException则继续循环，之后使用retry次数的循环来执行connector.getWithoutAck(batchSize)，然后调用writeOut(message)，最后执行connector.ack(batchId)，然后跳出循环；若出现异常，在不超出retry次数时执行connector.rollback(batchId)，超出retry次数则直接ack；其stop方法执行connector.stopRunning，然后执行syncSwitch.release(canalDestination)、groupInnerExecutorService.shutdown()、outerAdapter的destroy方法
doc
来源：oschina
链接：https://my.oschina.net/go4it/blog/3220290