Package io.servicetalk.grpc.netty

Class GrpcLifecycleObserverServiceFilter

java.lang.Object

io.servicetalk.http.netty.HttpLifecycleObserverServiceFilter

io.servicetalk.grpc.netty.GrpcLifecycleObserverServiceFilter

All Implemented Interfaces:

HttpExecutionStrategyInfluencer, StreamingHttpServiceFilterFactory, ExecutionStrategyInfluencer<HttpExecutionStrategy>

public final class GrpcLifecycleObserverServiceFilter
extends HttpLifecycleObserverServiceFilter

An HTTP service filter that tracks events during gRPC request/response lifecycle.

The result of the observed behavior will depend on the position of this filter in the execution chain. This filter is recommended to be appended as one of the first filters using HttpServerBuilder.appendNonOffloadingServiceFilter(StreamingHttpServiceFilterFactory) method via GrpcServerBuilder.initializeHttp(GrpcServerBuilder.HttpInitializer) to account for all work done by other filters and offloading of the requests processing. It can be appended at another position, considering the following:

• After a tracing filter or any other filter that populates request context, AsyncContext, MDC, or alters HttpRequestMetaData if that information has to be available for GrpcLifecycleObserver.GrpcExchangeObserver.
• After TimeoutHttpRequesterFilter if the timeout event should be observed as cancellation instead of an error.
• After any filter that can reject requests, like BasicAuthHttpServiceFilter, if only allowed requests should be observed.
• Before any filter that can reject requests, like BasicAuthHttpServiceFilter, if all incoming requests have to be observed.
• Before any filter that populates response context or alters HttpResponseMetaData if that information has to be available for GrpcLifecycleObserver.GrpcExchangeObserver.
• Before any filter that maps/translates HttpResponseMetaData into an exception or throws an exception during response payload body transformation if that exception has to be observed by GrpcLifecycleObserver.GrpcExchangeObserver.
• Before any exception mapping filter that maps an exception into a valid response, like GrpcExceptionMapperServiceFilter, if the GrpcLifecycleObserver.GrpcExchangeObserver should see what GrpcStatus is returned to the client.
• Using HttpServerBuilder.appendServiceFilter(StreamingHttpServiceFilterFactory) if an exchange should be observed after it's offloaded from an IoExecutor (if offloading is enabled).
• Using HttpServerBuilder.appendNonOffloadingServiceFilter(Predicate, StreamingHttpServiceFilterFactory) or HttpServerBuilder.appendServiceFilter(Predicate, StreamingHttpServiceFilterFactory) if the observer should be applied conditionally.
• As the last HttpServerBuilder.appendServiceFilter(StreamingHttpServiceFilterFactory) if only service business logic should be observed without accounting for work of any other filters.

An alternative way to install an GrpcLifecycleObserver is to use GrpcServerBuilder.lifecycleObserver(GrpcLifecycleObserver).

See Also:

• GrpcServerBuilder.lifecycleObserver(GrpcLifecycleObserver)

Constructor Summary

Constructors

Constructor	Description
GrpcLifecycleObserverServiceFilter(GrpcLifecycleObserver observer)	Create a new instance.

Method Summary

Modifier and Type	Method	Description
final HttpExecutionStrategy	requiredOffloads()	Return an ExecutionStrategy that describes the offloads required by the influencer.

Methods inherited from class io.servicetalk.http.netty.HttpLifecycleObserverServiceFilter

create

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.servicetalk.http.api.HttpExecutionStrategyInfluencer

influenceStrategy, requiredOffloads

Constructor Details

GrpcLifecycleObserverServiceFilter

public GrpcLifecycleObserverServiceFilter(GrpcLifecycleObserver observer)

Create a new instance.

Parameters:

observer - The observer implementation that consumes gRPC lifecycle events.

Method Details

requiredOffloads

public final HttpExecutionStrategy requiredOffloads()

Description copied from interface: HttpExecutionStrategyInfluencer

Return an ExecutionStrategy that describes the offloads required by the influencer.

The provided default implementation requests offloading of all operations. Implementations that require no offloading should be careful to return HttpExecutionStrategies.offloadNone() rather than HttpExecutionStrategies.offloadNever(). Implementations should avoid returning HttpExecutionStrategies.defaultStrategy(), instead returning the strategy they require or HttpExecutionStrategies.offloadAll() if offloading for all paths is required (safe default).

Specified by:

requiredOffloads in interface ExecutionStrategyInfluencer<HttpExecutionStrategy>

Specified by:

requiredOffloads in interface HttpExecutionStrategyInfluencer

Returns:

the ExecutionStrategy required by the influencer.