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本文主要研究一下rocketmq的RemotingException

RemotingException

org/apache/rocketmq/remoting/exception/RemotingException.java

public class RemotingException extends Exception {
    private static final long serialVersionUID = -5690687334570505110L;

    public RemotingException(String message) {
        super(message);
    }

    public RemotingException(String message, Throwable cause) {
        super(message, cause);
    }
}

• 继承自checked exception，底下有RemotingCommandException、RemotingConnectException、RemotingSendRequestException、RemotingTimeoutException、RemotingTooMuchRequestException

RemotingCommandException

org/apache/rocketmq/remoting/exception/RemotingCommandException.java

public class RemotingCommandException extends RemotingException {
    private static final long serialVersionUID = -6061365915274953096L;

    public RemotingCommandException(String message) {
        super(message, null);
    }

    public RemotingCommandException(String message, Throwable cause) {
        super(message, cause);
    }
}

• RemotingCommand解码decodeCommandCustomHeader时可能抛出的异常

RemotingConnectException

org/apache/rocketmq/remoting/exception/RemotingConnectException.java

public class RemotingConnectException extends RemotingException {
    private static final long serialVersionUID = -5565366231695911316L;

    public RemotingConnectException(String addr) {
        this(addr, null);
    }

    public RemotingConnectException(String addr, Throwable cause) {
        super("connect to <" + addr + "> failed", cause);
    }
}

• NettyRemotingClient在channel出现问题的时候会抛出RemotingConnectException

RemotingSendRequestException

org/apache/rocketmq/remoting/exception/RemotingSendRequestException.java

public class RemotingSendRequestException extends RemotingException {
    private static final long serialVersionUID = 5391285827332471674L;

    public RemotingSendRequestException(String addr) {
        this(addr, null);
    }

    public RemotingSendRequestException(String addr, Throwable cause) {
        super("send request to <" + addr + "> failed", cause);
    }
}

• NettyRemotingClient在发送请求失败的时候，会抛出RemotingSendRequestException

RemotingTimeoutException

org/apache/rocketmq/remoting/exception/RemotingTimeoutException.java

public class RemotingTimeoutException extends RemotingException {

    private static final long serialVersionUID = 4106899185095245979L;

    public RemotingTimeoutException(String message) {
        super(message);
    }

    public RemotingTimeoutException(String addr, long timeoutMillis) {
        this(addr, timeoutMillis, null);
    }

    public RemotingTimeoutException(String addr, long timeoutMillis, Throwable cause) {
        super("wait response on the channel <" + addr + "> timeout, " + timeoutMillis + "(ms)", cause);
    }
}

• NettyRemotingClient在发送请求时，如果返回回来的RemotingCommand为null，但是发送请求成功，则抛出RemotingTimeoutException

RemotingTooMuchRequestException

org/apache/rocketmq/remoting/exception/RemotingTooMuchRequestException.java

public class RemotingTooMuchRequestException extends RemotingException {
    private static final long serialVersionUID = 4326919581254519654L;

    public RemotingTooMuchRequestException(String message) {
        super(message);
    }
}

• NettyRemotingAbstract在执行请求之前要进行流控，如果获取不到信号量，则区分是否是超时，如果是无timeout获取信号量也没获取到，则表示RemotingTooMuchRequestException

小结

rocketmq的remoting模块的异常采用的是checked exception，定义了根异常RemotingException，底下有几个异常分别为RemotingCommandException、RemotingConnectException、RemotingSendRequestException、RemotingTimeoutException、RemotingTooMuchRequestException。

doc

• RemotingException