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/*
* Copyright 2014 The gRPC Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc;
import com.google.common.base.Preconditions;
import java.io.BufferedInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* Utility methods for working with {@link ServerInterceptor}s.
*/
public final class ServerInterceptors {
// Prevent instantiation
private ServerInterceptors() {}
/**
* Create a new {@code ServerServiceDefinition} whose {@link ServerCallHandler}s will call
* {@code interceptors} before calling the pre-existing {@code ServerCallHandler}. The first
* interceptor will have its {@link ServerInterceptor#interceptCall} called first.
*
* @param serviceDef the service definition for which to intercept all its methods.
* @param interceptors array of interceptors to apply to the service.
* @return a wrapped version of {@code serviceDef} with the interceptors applied.
*/
public static ServerServiceDefinition interceptForward(ServerServiceDefinition serviceDef,
ServerInterceptor... interceptors) {
return interceptForward(serviceDef, Arrays.asList(interceptors));
}
public static ServerServiceDefinition interceptForward(BindableService bindableService,
ServerInterceptor... interceptors) {
return interceptForward(bindableService.bindService(), Arrays.asList(interceptors));
}
/**
* Create a new {@code ServerServiceDefinition} whose {@link ServerCallHandler}s will call
* {@code interceptors} before calling the pre-existing {@code ServerCallHandler}. The first
* interceptor will have its {@link ServerInterceptor#interceptCall} called first.
*
* @param serviceDef the service definition for which to intercept all its methods.
* @param interceptors list of interceptors to apply to the service.
* @return a wrapped version of {@code serviceDef} with the interceptors applied.
*/
public static ServerServiceDefinition interceptForward(
ServerServiceDefinition serviceDef,
List interceptors) {
List copy = new ArrayList<>(interceptors);
Collections.reverse(copy);
return intercept(serviceDef, copy);
}
public static ServerServiceDefinition interceptForward(
BindableService bindableService,
List interceptors) {
return interceptForward(bindableService.bindService(), interceptors);
}
/**
* Create a new {@code ServerServiceDefinition} whose {@link ServerCallHandler}s will call
* {@code interceptors} before calling the pre-existing {@code ServerCallHandler}. The last
* interceptor will have its {@link ServerInterceptor#interceptCall} called first.
*
* @param serviceDef the service definition for which to intercept all its methods.
* @param interceptors array of interceptors to apply to the service.
* @return a wrapped version of {@code serviceDef} with the interceptors applied.
*/
public static ServerServiceDefinition intercept(ServerServiceDefinition serviceDef,
ServerInterceptor... interceptors) {
return intercept(serviceDef, Arrays.asList(interceptors));
}
public static ServerServiceDefinition intercept(BindableService bindableService,
ServerInterceptor... interceptors) {
Preconditions.checkNotNull(bindableService, "bindableService");
return intercept(bindableService.bindService(), Arrays.asList(interceptors));
}
/**
* Create a new {@code ServerServiceDefinition} whose {@link ServerCallHandler}s will call
* {@code interceptors} before calling the pre-existing {@code ServerCallHandler}. The last
* interceptor will have its {@link ServerInterceptor#interceptCall} called first.
*
* @param serviceDef the service definition for which to intercept all its methods.
* @param interceptors list of interceptors to apply to the service.
* @return a wrapped version of {@code serviceDef} with the interceptors applied.
*/
public static ServerServiceDefinition intercept(ServerServiceDefinition serviceDef,
List interceptors) {
Preconditions.checkNotNull(serviceDef, "serviceDef");
if (interceptors.isEmpty()) {
return serviceDef;
}
ServerServiceDefinition.Builder serviceDefBuilder
= ServerServiceDefinition.builder(serviceDef.getServiceDescriptor());
for (ServerMethodDefinition method : serviceDef.getMethods()) {
wrapAndAddMethod(serviceDefBuilder, method, interceptors);
}
return serviceDefBuilder.build();
}
public static ServerServiceDefinition intercept(BindableService bindableService,
List interceptors) {
Preconditions.checkNotNull(bindableService, "bindableService");
return intercept(bindableService.bindService(), interceptors);
}
/**
* Create a new {@code ServerServiceDefinition} whose {@link MethodDescriptor} serializes to
* and from InputStream for all methods. The InputStream is guaranteed return true for
* markSupported(). The {@code ServerCallHandler} created will automatically
* convert back to the original types for request and response before calling the existing
* {@code ServerCallHandler}. Calling this method combined with the intercept methods will
* allow the developer to choose whether to intercept messages of InputStream, or the modeled
* types of their application.
*
* @param serviceDef the service definition to convert messages to InputStream
* @return a wrapped version of {@code serviceDef} with the InputStream conversion applied.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1712")
public static ServerServiceDefinition useInputStreamMessages(
final ServerServiceDefinition serviceDef) {
final MethodDescriptor.Marshaller marshaller =
new MethodDescriptor.Marshaller() {
@Override
public InputStream stream(final InputStream value) {
return value;
}
@Override
public InputStream parse(final InputStream stream) {
if (stream.markSupported()) {
return stream;
} else if (stream instanceof KnownLength) {
return new KnownLengthBufferedInputStream(stream);
} else {
return new BufferedInputStream(stream);
}
}
};
return useMarshalledMessages(serviceDef, marshaller);
}
/** {@link BufferedInputStream} that also implements {@link KnownLength}. */
private static final class KnownLengthBufferedInputStream extends BufferedInputStream
implements KnownLength {
KnownLengthBufferedInputStream(InputStream in) {
super(in);
}
}
/**
* Create a new {@code ServerServiceDefinition} whose {@link MethodDescriptor} serializes to
* and from T for all methods. The {@code ServerCallHandler} created will automatically
* convert back to the original types for request and response before calling the existing
* {@code ServerCallHandler}. Calling this method combined with the intercept methods will
* allow the developer to choose whether to intercept messages of T, or the modeled types
* of their application. This can also be chained to allow for interceptors to handle messages
* as multiple different T types within the chain if the added cost of serialization is not
* a concern.
*
* @param serviceDef the service definition to convert messages to T
* @return a wrapped version of {@code serviceDef} with the T conversion applied.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1712")
public static ServerServiceDefinition useMarshalledMessages(
final ServerServiceDefinition serviceDef,
final MethodDescriptor.Marshaller marshaller) {
return useMarshalledMessages(serviceDef, marshaller, marshaller);
}
/**
* Create a new {@code ServerServiceDefinition} with {@link MethodDescriptor} for deserializing
* requests and separate {@link MethodDescriptor} for serializing responses. The {@code
* ServerCallHandler} created will automatically convert back to the original types for request
* and response before calling the existing {@code ServerCallHandler}. Calling this method
* combined with the intercept methods will allow the developer to choose whether to intercept
* messages of ReqT/RespT, or the modeled types of their application. This can also be chained
* to allow for interceptors to handle messages as multiple different ReqT/RespT types within
* the chain if the added cost of serialization is not a concern.
*
* @param serviceDef the service definition to add request and response marshallers to.
* @param requestMarshaller request marshaller
* @param responseMarshaller response marshaller
* @param the request payload type
* @param the response payload type.
* @return a wrapped version of {@code serviceDef} with the ReqT and RespT conversion applied.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/9870")
public static ServerServiceDefinition useMarshalledMessages(
final ServerServiceDefinition serviceDef,
final MethodDescriptor.Marshaller requestMarshaller,
final MethodDescriptor.Marshaller responseMarshaller) {
List> wrappedMethods =
new ArrayList<>();
List> wrappedDescriptors =
new ArrayList<>();
// Wrap the descriptors
for (final ServerMethodDefinition definition : serviceDef.getMethods()) {
final MethodDescriptor originalMethodDescriptor = definition.getMethodDescriptor();
final MethodDescriptor wrappedMethodDescriptor =
originalMethodDescriptor.toBuilder(requestMarshaller, responseMarshaller).build();
wrappedDescriptors.add(wrappedMethodDescriptor);
wrappedMethods.add(wrapMethod(definition, wrappedMethodDescriptor));
}
// Build the new service descriptor
final ServiceDescriptor.Builder serviceDescriptorBuilder =
ServiceDescriptor.newBuilder(serviceDef.getServiceDescriptor().getName())
.setSchemaDescriptor(serviceDef.getServiceDescriptor().getSchemaDescriptor());
for (MethodDescriptor wrappedDescriptor : wrappedDescriptors) {
serviceDescriptorBuilder.addMethod(wrappedDescriptor);
}
// Create the new service definition.
final ServerServiceDefinition.Builder serviceBuilder =
ServerServiceDefinition.builder(serviceDescriptorBuilder.build());
for (ServerMethodDefinition definition : wrappedMethods) {
serviceBuilder.addMethod(definition);
}
return serviceBuilder.build();
}
private static void wrapAndAddMethod(
ServerServiceDefinition.Builder serviceDefBuilder, ServerMethodDefinition method,
List interceptors) {
ServerCallHandler callHandler = method.getServerCallHandler();
for (ServerInterceptor interceptor : interceptors) {
callHandler = InterceptCallHandler.create(interceptor, callHandler);
}
serviceDefBuilder.addMethod(method.withServerCallHandler(callHandler));
}
static final class InterceptCallHandler implements ServerCallHandler {
public static InterceptCallHandler create(
ServerInterceptor interceptor, ServerCallHandler callHandler) {
return new InterceptCallHandler<>(interceptor, callHandler);
}
private final ServerInterceptor interceptor;
private final ServerCallHandler callHandler;
private InterceptCallHandler(
ServerInterceptor interceptor, ServerCallHandler callHandler) {
this.interceptor = Preconditions.checkNotNull(interceptor, "interceptor");
this.callHandler = callHandler;
}
@Override
public ServerCall.Listener startCall(
ServerCall call,
Metadata headers) {
return interceptor.interceptCall(call, headers, callHandler);
}
}
static ServerMethodDefinition wrapMethod(
final ServerMethodDefinition definition,
final MethodDescriptor wrappedMethod) {
final ServerCallHandler wrappedHandler = wrapHandler(
definition.getServerCallHandler(),
definition.getMethodDescriptor(),
wrappedMethod);
return ServerMethodDefinition.create(wrappedMethod, wrappedHandler);
}
private static ServerCallHandler wrapHandler(
final ServerCallHandler originalHandler,
final MethodDescriptor originalMethod,
final MethodDescriptor wrappedMethod) {
return new ServerCallHandler() {
@Override
public ServerCall.Listener startCall(
final ServerCall call,
final Metadata headers) {
final ServerCall unwrappedCall =
new PartialForwardingServerCall() {
@Override
protected ServerCall delegate() {
return call;
}
@Override
public void sendMessage(ORespT message) {
final InputStream is = originalMethod.streamResponse(message);
final WRespT wrappedMessage = wrappedMethod.parseResponse(is);
delegate().sendMessage(wrappedMessage);
}
@Override
public MethodDescriptor getMethodDescriptor() {
return originalMethod;
}
};
final ServerCall.Listener originalListener = originalHandler
.startCall(unwrappedCall, headers);
return new PartialForwardingServerCallListener() {
@Override
protected ServerCall.Listener delegate() {
return originalListener;
}
@Override
public void onMessage(WReqT message) {
final InputStream is = wrappedMethod.streamRequest(message);
final OReqT originalMessage = originalMethod.parseRequest(is);
delegate().onMessage(originalMessage);
}
};
}
};
}
}
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