汕头快速建站模板,做网站基本步骤,循环视频做网站背景,应用市场本文只是分析Letture类型的Redis 池化连接出现的连接超时异常、读超时异常问题。
1.RedisConnectionException
默认是10秒。 通过如下可以配置#xff1a;
public class MyLettuceClientConfigurationBuilderCustomizer implements LettuceClientConfigurationBuilderCusto…本文只是分析Letture类型的Redis 池化连接出现的连接超时异常、读超时异常问题。
1.RedisConnectionException
默认是10秒。 通过如下可以配置
public class MyLettuceClientConfigurationBuilderCustomizer implements LettuceClientConfigurationBuilderCustomizer {Overridepublic void customize(LettuceClientConfiguration.LettuceClientConfigurationBuilder clientConfigurationBuilder) {
// spring.redis.timeout等价clientConfigurationBuilder.commandTimeout(Duration.ofSeconds(100));
// 控制连接超时时间默认是10秒ClientOptions.Builder builder ClientOptions.builder().socketOptions(SocketOptions.builder().connectTimeout(Duration.ofMillis(10)).build());clientConfigurationBuilder.clientOptions(builder.build());}
}2.RedisCommandTimeoutException
结论抛出RedisCommandTimeoutException异常并非数据的写一定失败。只不过Redis内部超时逻辑跟写逻辑是异步处理所以存在写成功后仍然抛出异常的情况。但是只要出现该异常必须得处理。 io.lettuce.core.RedisCommandTimeoutException: Command timed out after 2 second(s) 2.1.CommandHandler限制
CommandHandler是Netty中的handler。只不过其同时充当入栈、出栈handler。通俗点讲是Redis Write Flush 数据到通道NioSocketChannel的必经之路。
AsyncCommand存在两大核心功能。其一是包裹用户数据其二是实现了CompletableFuture接口方便实现异步相关操作。
public class CommandHandler extends ChannelDuplexHandler implements HasQueuedCommands {private void writeSingleCommand(ChannelHandlerContext ctx, RedisCommand?, ?, ? command, ChannelPromise promise){if (!isWriteable(command)) {// 此处的就是判断是否存在超时的核心之处借用CompletableFuture异步操作功能promise.trySuccess();// 此时说明数据写过程中超过用户设定的超时时间return;}...ctx.write(command, promise);// 数据正常写入最终归宿是服务端}private static boolean isWriteable(RedisCommand?, ?, ? command) {return !command.isDone();}
}public class CompletableFutureT implements FutureT, CompletionStageT {public boolean isDone() {return result ! null;}
}通过上述得知只要CompletableFuture内部的变量result不为空则就会按TimeoutException处理。所以result值何时赋值呢
如下所示CommandHandler处理完数据之后会通过如下方式设置result的值。
public class AsyncCommandK, V, T extends CompletableFutureT implements RedisCommandK, V, T, RedisFutureT,CompleteableCommandT, DecoratedCommandK, V, T {protected void completeResult() {if (command.getOutput() null) {complete(null);} else if (command.getOutput().hasError()) {doCompleteExceptionally(ExceptionFactory.createExecutionException(command.getOutput().getError()));} else {// 成功发送则Output为字符串类型的“ok”complete(command.getOutput().get());}}
}3.超时处理时机
3.1.阻塞等待超时
class FutureSyncInvocationHandler extends AbstractInvocationHandler {protected Object handleInvocation(Object proxy, Method method, Object[] args) throws Throwable {try {Method targetMethod this.translator.get(method);// CommandExpiryWriter#writerObject result targetMethod.invoke(asyncApi, args);if (result instanceof RedisFuture?) {...long timeout getTimeoutNs(command);//用户自定义的超时时间//command:AsyncCommand 利用CompletableFuture异步特性return LettuceFutures.awaitOrCancel(command, timeout, TimeUnit.NANOSECONDS);}return result;} catch (InvocationTargetException e) {throw e.getTargetException();}}
}public class LettuceFutures {public static T T awaitOrCancel(RedisFutureT cmd, long timeout, TimeUnit unit) {try {//阻塞 其实内存调用的CompletableFuture#get阻塞方法。如果返回TimeoutExeception则说明AsyncCommand没有执行完毕超时处理if (!cmd.await(timeout, unit)) {cmd.cancel(true);throw ExceptionFactory.createTimeoutException(Duration.ofNanos(unit.toNanos(timeout)));}return cmd.get();//这个方法还是调用CompletableFuture#get阻塞方法但是该方法是根据内部属性result进行判断} catch (RuntimeException e) {throw e;} catch (ExecutionException e) {if (e.getCause() instanceof RedisCommandExecutionException) {throw ExceptionFactory.createExecutionException(e.getCause().getMessage(), e.getCause());}if (e.getCause() instanceof RedisCommandTimeoutException) {throw new RedisCommandTimeoutException(e.getCause());}throw new RedisException(e.getCause());} catch (InterruptedException e) {Thread.currentThread().interrupt();throw new RedisCommandInterruptedException(e);} catch (Exception e) {throw ExceptionFactory.createExecutionException(null, e);}}
}如下伪代码所示如果result不为null则根据result类型抛出相关异常。否则通过timedGet在规定时间内阻塞等待超时则抛出TimeoutException。
public class CompletableFutureT implements FutureT, CompletionStageT {public T get(long timeout, TimeUnit unit)throws InterruptedException, ExecutionException, TimeoutException {Object r;long nanos unit.toNanos(timeout);return reportGet((r result) null ? timedGet(nanos) : r);}
}3.2.定时任务超时处理
public class CommandExpiryWriter implements RedisChannelWriter {public K, V, T RedisCommandK, V, T write(RedisCommandK, V, T command) {potentiallyExpire(command, getExecutorService());//开启定时任务return writer.write(command);//DefaultEndPoint#write}private void potentiallyExpire(RedisCommand?, ?, ? command, ScheduledExecutorService executors) {long timeout applyConnectionTimeout ? this.timeout : source.getTimeout(command);//用户自定义的超时时间if (timeout 0) {return;}// 从 timeout 时间之后开始执行定时任务。此时result值如果存在值则说明超时ScheduledFuture? schedule executors.schedule(() - {if (!command.isDone()) {command.completeExceptionally(ExceptionFactory.createTimeoutException(Duration.ofNanos(timeUnit.toNanos(timeout))));}}, timeout, timeUnit);if (command instanceof CompleteableCommand) {((CompleteableCommand) command).onComplete((o, o2) - {if (!schedule.isDone()) {schedule.cancel(false);}});}}
}重点定时任务判断成功与否的唯一条件就是result是否存在值。情况1如果此时result ok表明数据已经在服务端落盘成功但是同样会抛出RedisCommandTimeoutException。情况2发送之前出现异常则result值为Throwable类型的异常值。
