序

本文次要钻研一下dubbo-go的gracefulShutdownFilter

gracefulShutdownFilter

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

type gracefulShutdownFilter struct {    activeCount    int32    shutdownConfig *config.ShutdownConfig}
  • gracefulShutdownFilter定义了activeCount、shutdownConfig属性

init

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

func init() {    var consumerFiler = &gracefulShutdownFilter{        shutdownConfig: config.GetConsumerConfig().ShutdownConfig,    }    var providerFilter = &gracefulShutdownFilter{        shutdownConfig: config.GetProviderConfig().ShutdownConfig,    }    extension.SetFilter(constant.CONSUMER_SHUTDOWN_FILTER, func() filter.Filter {        return consumerFiler    })    extension.SetFilter(constant.PROVIDER_SHUTDOWN_FILTER, func() filter.Filter {        return providerFilter    })}
  • init办法别离创立并设置了CONSUMER_SHUTDOWN_FILTER、PROVIDER_SHUTDOWN_FILTER

Invoke

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

func (gf *gracefulShutdownFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {    if gf.rejectNewRequest() {        logger.Info("The application is closing, new request will be rejected.")        return gf.getRejectHandler().RejectedExecution(invoker.GetUrl(), invocation)    }    atomic.AddInt32(&gf.activeCount, 1)    return invoker.Invoke(ctx, invocation)}
  • Invoke办法先判断gracefulShutdownFilter的rejectNewRequest是否为true，若为true则执行getRejectHandler().RejectedExecution，否则执行atomic.AddInt32及invoker.Invoke(ctx, invocation)

OnResponse

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

func (gf *gracefulShutdownFilter) OnResponse(ctx context.Context, result protocol.Result, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {    atomic.AddInt32(&gf.activeCount, -1)    // although this isn't thread safe, it won't be a problem if the gf.rejectNewRequest() is true.    if gf.shutdownConfig != nil && gf.activeCount <= 0 {        gf.shutdownConfig.RequestsFinished = true    }    return result}
  • OnResponse办法先执行atomic.AddInt32(&gf.activeCount, -1)，之后判断gf.activeCount是否小于等于0，是的话则标记gf.shutdownConfig.RequestsFinished为true

rejectNewRequest

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

func (gf *gracefulShutdownFilter) rejectNewRequest() bool {    if gf.shutdownConfig == nil {        return false    }    return gf.shutdownConfig.RejectRequest}
  • rejectNewRequest办法在shutdownConfig为nil是返回false，否则返回gf.shutdownConfig.RejectRequest的值

getRejectHandler

dubbo-go-v1.4.2/filter/filter_impl/graceful_shutdown_filter.go

func (gf *gracefulShutdownFilter) getRejectHandler() filter.RejectedExecutionHandler {    handler := constant.DEFAULT_KEY    if gf.shutdownConfig != nil && len(gf.shutdownConfig.RejectRequestHandler) > 0 {        handler = gf.shutdownConfig.RejectRequestHandler    }    return extension.GetRejectedExecutionHandler(handler)}
  • getRejectHandler办法在gf.shutdownConfig不为nil且gf.shutdownConfig.RejectRequestHandler长度大于0时设置handler值为gf.shutdownConfig.RejectRequestHandler，之后依据该值执行extension.GetRejectedExecutionHandler

小结

gracefulShutdownFilter定义了activeCount、shutdownConfig属性；其Invoke办法先判断gracefulShutdownFilter的rejectNewRequest是否为true，若为true则执行getRejectHandler().RejectedExecution，否则执行atomic.AddInt32及invoker.Invoke(ctx, invocation)；其OnResponse办法先执行atomic.AddInt32(&gf.activeCount, -1)，之后判断gf.activeCount是否小于等于0，是的话则标记gf.shutdownConfig.RequestsFinished为true

doc

  • graceful_shutdown_filter