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/*
* Copyright 2017 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.util;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.SettableFuture;
import io.grpc.Attributes;
import io.grpc.ExperimentalApi;
import io.grpc.ForwardingServerCall;
import io.grpc.ForwardingServerCallListener;
import io.grpc.Metadata;
import io.grpc.ServerCall;
import io.grpc.ServerCallHandler;
import io.grpc.ServerInterceptor;
import io.grpc.Status;
import io.grpc.StatusRuntimeException;
import io.grpc.internal.SerializingExecutor;
import java.util.concurrent.ExecutionException;
import javax.annotation.Nullable;
/**
* A class that intercepts uncaught exceptions of type {@link StatusRuntimeException} and handles
* them by closing the {@link ServerCall}, and transmitting the exception's status and metadata
* to the client.
*
* Without this interceptor, gRPC will strip all details and close the {@link ServerCall} with
* a generic {@link Status#UNKNOWN} code.
*
*
Security warning: the {@link Status} and {@link Metadata} may contain sensitive server-side
* state information, and generally should not be sent to clients. Only install this interceptor
* if all clients are trusted.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/2189")
public final class TransmitStatusRuntimeExceptionInterceptor implements ServerInterceptor {
private TransmitStatusRuntimeExceptionInterceptor() {
}
public static ServerInterceptor instance() {
return new TransmitStatusRuntimeExceptionInterceptor();
}
@Override
public ServerCall.Listener interceptCall(
ServerCall call, Metadata headers, ServerCallHandler next) {
final ServerCall serverCall = new SerializingServerCall<>(call);
ServerCall.Listener listener = next.startCall(serverCall, headers);
return new ForwardingServerCallListener.SimpleForwardingServerCallListener(listener) {
@Override
public void onMessage(ReqT message) {
try {
super.onMessage(message);
} catch (StatusRuntimeException e) {
closeWithException(e);
}
}
@Override
public void onHalfClose() {
try {
super.onHalfClose();
} catch (StatusRuntimeException e) {
closeWithException(e);
}
}
@Override
public void onCancel() {
try {
super.onCancel();
} catch (StatusRuntimeException e) {
closeWithException(e);
}
}
@Override
public void onComplete() {
try {
super.onComplete();
} catch (StatusRuntimeException e) {
closeWithException(e);
}
}
@Override
public void onReady() {
try {
super.onReady();
} catch (StatusRuntimeException e) {
closeWithException(e);
}
}
private void closeWithException(StatusRuntimeException t) {
Metadata metadata = t.getTrailers();
if (metadata == null) {
metadata = new Metadata();
}
serverCall.close(t.getStatus(), metadata);
}
};
}
/**
* A {@link ServerCall} that wraps around a non thread safe delegate and provides thread safe
* access by serializing everything on an executor.
*/
private static class SerializingServerCall extends
ForwardingServerCall.SimpleForwardingServerCall {
private static final String ERROR_MSG = "Encountered error during serialized access";
private final SerializingExecutor serializingExecutor =
new SerializingExecutor(MoreExecutors.directExecutor());
private boolean closeCalled = false;
SerializingServerCall(ServerCall delegate) {
super(delegate);
}
@Override
public void sendMessage(final RespT message) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
SerializingServerCall.super.sendMessage(message);
}
});
}
@Override
public void request(final int numMessages) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
SerializingServerCall.super.request(numMessages);
}
});
}
@Override
public void sendHeaders(final Metadata headers) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
SerializingServerCall.super.sendHeaders(headers);
}
});
}
@Override
public void close(final Status status, final Metadata trailers) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
if (!closeCalled) {
closeCalled = true;
SerializingServerCall.super.close(status, trailers);
}
}
});
}
@Override
public boolean isReady() {
final SettableFuture retVal = SettableFuture.create();
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
retVal.set(SerializingServerCall.super.isReady());
}
});
try {
return retVal.get();
} catch (InterruptedException e) {
throw new RuntimeException(ERROR_MSG, e);
} catch (ExecutionException e) {
throw new RuntimeException(ERROR_MSG, e);
}
}
@Override
public boolean isCancelled() {
final SettableFuture retVal = SettableFuture.create();
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
retVal.set(SerializingServerCall.super.isCancelled());
}
});
try {
return retVal.get();
} catch (InterruptedException e) {
throw new RuntimeException(ERROR_MSG, e);
} catch (ExecutionException e) {
throw new RuntimeException(ERROR_MSG, e);
}
}
@Override
public void setMessageCompression(final boolean enabled) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
SerializingServerCall.super.setMessageCompression(enabled);
}
});
}
@Override
public void setCompression(final String compressor) {
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
SerializingServerCall.super.setCompression(compressor);
}
});
}
@Override
public Attributes getAttributes() {
final SettableFuture retVal = SettableFuture.create();
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
retVal.set(SerializingServerCall.super.getAttributes());
}
});
try {
return retVal.get();
} catch (InterruptedException e) {
throw new RuntimeException(ERROR_MSG, e);
} catch (ExecutionException e) {
throw new RuntimeException(ERROR_MSG, e);
}
}
@Nullable
@Override
public String getAuthority() {
final SettableFuture retVal = SettableFuture.create();
serializingExecutor.execute(new Runnable() {
@Override
public void run() {
retVal.set(SerializingServerCall.super.getAuthority());
}
});
try {
return retVal.get();
} catch (InterruptedException e) {
throw new RuntimeException(ERROR_MSG, e);
} catch (ExecutionException e) {
throw new RuntimeException(ERROR_MSG, e);
}
}
}
}