序
本文主要研究一下dubbo的ConnectionOrderedDispatcher
ConnectionOrderedDispatcher
dubbo-2.7.3/dubbo-remoting/dubbo-remoting-api/src/main/java/org/apache/dubbo/remoting/transport/dispatcher/connection/ConnectionOrderedDispatcher.java
代码语言：javascript复制public class ConnectionOrderedDispatcher implements Dispatcher {
public static final String NAME = "connection";
@Override
public ChannelHandler dispatch(ChannelHandler handler, URL url) {
return new ConnectionOrderedChannelHandler(handler, url);
}
}- ConnectionOrderedDispatcher实现了Dispatcher接口，其dispatch方法返回的是ConnectionOrderedChannelHandler
ConnectionOrderedChannelHandler
dubbo-2.7.3/dubbo-remoting/dubbo-remoting-api/src/main/java/org/apache/dubbo/remoting/transport/dispatcher/connection/ConnectionOrderedChannelHandler.java
代码语言：javascript复制public class ConnectionOrderedChannelHandler extends WrappedChannelHandler {
protected final ThreadPoolExecutor connectionExecutor;
private final int queuewarninglimit;
public ConnectionOrderedChannelHandler(ChannelHandler handler, URL url) {
super(handler, url);
String threadName = url.getParameter(THREAD_NAME_KEY, DEFAULT_THREAD_NAME);
connectionExecutor = new ThreadPoolExecutor(1, 1,
0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>(url.getPositiveParameter(CONNECT_QUEUE_CAPACITY, Integer.MAX_VALUE)),
new NamedThreadFactory(threadName, true),
new AbortPolicyWithReport(threadName, url)
); // FIXME There's no place to release connectionExecutor!
queuewarninglimit = url.getParameter(CONNECT_QUEUE_WARNING_SIZE, DEFAULT_CONNECT_QUEUE_WARNING_SIZE);
}
@Override
public void connected(Channel channel) throws RemotingException {
try {
checkQueueLength();
connectionExecutor.execute(new ChannelEventRunnable(channel, handler, ChannelState.CONNECTED));
} catch (Throwable t) {
throw new ExecutionException("connect event", channel, getClass() " error when process connected event .", t);
}
}
@Override
public void disconnected(Channel channel) throws RemotingException {
try {
checkQueueLength();
connectionExecutor.execute(new ChannelEventRunnable(channel, handler, ChannelState.DISCONNECTED));
} catch (Throwable t) {
throw new ExecutionException("disconnected event", channel, getClass() " error when process disconnected event .", t);
}
}
@Override
public void received(Channel channel, Object message) throws RemotingException {
ExecutorService executor = getExecutorService();
try {
executor.execute(new ChannelEventRunnable(channel, handler, ChannelState.RECEIVED, message));
} catch (Throwable t) {
//fix, reject exception can not be sent to consumer because thread pool is full, resulting in consumers waiting till timeout.
if (message instanceof Request && t instanceof RejectedExecutionException) {
Request request = (Request) message;
if (request.isTwoWay()) {
String msg = "Server side(" url.getIp() "," url.getPort() ") threadpool is exhausted ,detail msg:" t.getMessage();
Response response = new Response(request.getId(), request.getVersion());
response.setStatus(Response.SERVER_THREADPOOL_EXHAUSTED_ERROR);
response.setErrorMessage(msg);
channel.send(response);
return;
}
}
throw new ExecutionException(message, channel, getClass() " error when process received event .", t);
}
}
@Override
public void caught(Channel channel, Throwable exception) throws RemotingException {
ExecutorService executor = getExecutorService();
try {
executor.execute(new ChannelEventRunnable(channel, handler, ChannelState.CAUGHT, exception));
} catch (Throwable t) {
throw new ExecutionException("caught event", channel, getClass() " error when process caught event .", t);
}
}
private void checkQueueLength() {
if (connectionExecutor.getQueue().size() > queuewarninglimit) {
logger.warn(new IllegalThreadStateException("connectionordered channel handler `queue size: " connectionExecutor.getQueue().size() " exceed the warning limit number :" queuewarninglimit));
}
}
}- ConnectionOrderedChannelHandler继承了WrappedChannelHandler，其构造器创建了corePoolSize及maximumPoolSize均为1，queue为LinkedBlockingQueue的connectionExecutor
- 其connected、disconnected方法均是使用connectionExecutor来执行新创建的ChannelEventRunnable；这两个方法均会先执行checkQueueLength来判断queue大小是否大于queuewarninglimit，大于的话则打印warn日志
- 其received、caught均是通过父类的getExecutorService获取线程池，然后执行创建的ChannelEventRunnable；received方法在捕获到异常时RejectedExecutionException且message是Request，而且request是twoWay的时候会返回SERVER_THREADPOOL_EXHAUSTED_ERROR
ConnectChannelHandlerTest
dubbo-2.7.3/dubbo-remoting/dubbo-remoting-api/src/test/java/org/apache/dubbo/remoting/handler/ConnectChannelHandlerTest.java
代码语言：javascript复制public class ConnectChannelHandlerTest extends WrappedChannelHandlerTest {
@BeforeEach
public void setUp() throws Exception {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(true), url);
}
@Test
public void test_Connect_Blocked() throws RemotingException {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(false), url);
ThreadPoolExecutor executor = (ThreadPoolExecutor) getField(handler, "connectionExecutor", 1);
Assertions.assertEquals(1, executor.getMaximumPoolSize());
int runs = 20;
int taskCount = runs * 2;
for (int i = 0; i < runs; i ) {
handler.connected(new MockedChannel());
handler.disconnected(new MockedChannel());
Assertions.assertTrue(executor.getActiveCount() <= 1, executor.getActiveCount() " must <=1");
}
//queue.size
Assertions.assertEquals(taskCount - 1, executor.getQueue().size());
for (int i = 0; i < taskCount; i ) {
if (executor.getCompletedTaskCount() < taskCount) {
sleep(100);
}
}
Assertions.assertEquals(taskCount, executor.getCompletedTaskCount());
}
@Test //biz error should not throw and affect biz thread.
public void test_Connect_Biz_Error() throws RemotingException {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(true), url);
handler.connected(new MockedChannel());
}
@Test //biz error should not throw and affect biz thread.
public void test_Disconnect_Biz_Error() throws RemotingException {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(true), url);
handler.disconnected(new MockedChannel());
}
@Test
public void test_Connect_Execute_Error() throws RemotingException {
Assertions.assertThrows(ExecutionException.class, () -> {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(false), url);
ThreadPoolExecutor executor = (ThreadPoolExecutor) getField(handler, "connectionExecutor", 1);
executor.shutdown();
handler.connected(new MockedChannel());
});
}
@Test
public void test_Disconnect_Execute_Error() throws RemotingException {
Assertions.assertThrows(ExecutionException.class, () -> {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(false), url);
ThreadPoolExecutor executor = (ThreadPoolExecutor) getField(handler, "connectionExecutor", 1);
executor.shutdown();
handler.disconnected(new MockedChannel());
});
}
//throw ChannelEventRunnable.runtimeExeception(int logger) not in execute exception
@Test//(expected = RemotingException.class)
public void test_MessageReceived_Biz_Error() throws RemotingException {
handler.received(new MockedChannel(), "");
}
//throw ChannelEventRunnable.runtimeExeception(int logger) not in execute exception
@Test
public void test_Caught_Biz_Error() throws RemotingException {
handler.caught(new MockedChannel(), new BizException());
}
@Test
public void test_Received_InvokeInExecuter() throws RemotingException {
Assertions.assertThrows(ExecutionException.class, () -> {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(false), url);
ThreadPoolExecutor executor = (ThreadPoolExecutor) getField(handler, "SHARED_EXECUTOR", 1);
executor.shutdown();
executor = (ThreadPoolExecutor) getField(handler, "executor", 1);
executor.shutdown();
handler.received(new MockedChannel(), "");
});
}
/**
* Events do not pass through the thread pool and execute directly on the IO
*/
@SuppressWarnings("deprecation")
@Disabled("Heartbeat is processed in HeartbeatHandler not WrappedChannelHandler.")
@Test
public void test_Received_Event_invoke_direct() throws RemotingException {
handler = new ConnectionOrderedChannelHandler(new BizChannelHander(false), url);
ThreadPoolExecutor executor = (ThreadPoolExecutor) getField(handler, "SHARED_EXECUTOR", 1);
executor.shutdown();
executor = (ThreadPoolExecutor) getField(handler, "executor", 1);
executor.shutdown();
Request req = new Request();
req.setHeartbeat(true);
final AtomicInteger count = new AtomicInteger(0);
handler.received(new MockedChannel() {
@Override
public void send(Object message) throws RemotingException {
Assertions.assertTrue(((Response) message).isHeartbeat(), "response.heartbeat");
count.incrementAndGet();
}
}, req);
Assertions.assertEquals(1, count.get(), "channel.send must be invoke");
}
}- ConnectChannelHandlerTest在setup时创建的是ConnectionOrderedChannelHandler，然后进行了test_Connect_Blocked、test_Connect_Biz_Error、test_Disconnect_Biz_Error、test_Connect_Execute_Error、test_Disconnect_Execute_Error、test_MessageReceived_Biz_Error、test_Caught_Biz_Error、test_Received_InvokeInExecuter、test_Received_Event_invoke_direct
小结
- ConnectionOrderedDispatcher实现了Dispatcher接口，其dispatch方法返回的是ConnectionOrderedChannelHandler；ConnectionOrderedChannelHandler继承了WrappedChannelHandler，其构造器创建了corePoolSize及maximumPoolSize均为1，queue为LinkedBlockingQueue的connectionExecutor
- ConnectionOrderedChannelHandler的connected、disconnected方法均是使用connectionExecutor来执行新创建的ChannelEventRunnable；这两个方法均会先执行checkQueueLength来判断queue大小是否大于queuewarninglimit，大于的话则打印warn日志
- ConnectionOrderedChannelHandler的received、caught均是通过父类的getExecutorService获取线程池，然后执行创建的ChannelEventRunnable；received方法在捕获到异常时RejectedExecutionException且message是Request，而且request是twoWay的时候会返回SERVER_THREADPOOL_EXHAUSTED_ERROR
doc
- ConnectionOrderedDispatcher
