Merge pull request #586 from yidongnan/feature/streaming-exception-ha…

…ndling

grpc-server-spring-boot-autoconfigure/src/main/java/net/devh/boot/grpc/server/advice/GrpcAdvice.java

@@ -27,11 +27,12 @@
 
 /**
  * Special {@link Component @Component} to declare global gRPC exception handling.
- * 
+ *
+ * <p>
  * Every class annotated with {@link GrpcAdvice @GrpcAdvice} is marked to be scanned for
  * {@link GrpcExceptionHandler @GrpcExceptionHandler} annotations.
- * <p>
- * 
+ * </p>
+ *
  * @author Andjelko Perisic (andjelko.perisic@gmail.com)
  * @see GrpcExceptionHandler
  */

grpc-server-spring-boot-autoconfigure/src/main/java/net/devh/boot/grpc/server/advice/GrpcAdviceExceptionHandler.java

@@ -17,6 +17,8 @@
 
 package net.devh.boot.grpc.server.advice;
 
+import static java.util.Objects.requireNonNull;
+
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Parameter;
@@ -25,68 +27,128 @@
 
 import org.springframework.lang.Nullable;
 
+import io.grpc.Metadata;
+import io.grpc.ServerCall;
+import io.grpc.Status;
+import io.grpc.StatusException;
+import io.grpc.StatusRuntimeException;
 import lombok.extern.slf4j.Slf4j;
+import net.devh.boot.grpc.server.error.GrpcExceptionInterceptor;
+import net.devh.boot.grpc.server.error.GrpcExceptionResponseHandler;
 
 /**
  * As part of {@link GrpcAdvice @GrpcAdvice}, when a thrown exception is caught during gRPC calls (via global
- * interceptor {@link GrpcAdviceExceptionInterceptor}, then this thrown exception is being handled. By
- * {@link GrpcExceptionHandlerMethodResolver} is a mapping between exception and the in case to be executed method
- * provided. <br>
- * Returned object is declared in {@link GrpcAdvice @GrpcAdvice} classes with annotated methods
- * {@link GrpcExceptionHandler @GrpcExceptionHandler}.
+ * interceptor {@link GrpcExceptionInterceptor}), then this thrown exception is being handled. The
+ * {@link GrpcExceptionHandlerMethodResolver} provides a mapping for exceptions and their respective handler methods.
+ *
  * <p>
+ * The response is derived from methods annotated with {@link GrpcExceptionHandler} inside {@link GrpcAdvice} beans.
+ * </p>
  *
  * @author Andjelko Perisic (andjelko.perisic@gmail.com)
+ * @see GrpcAdvice
+ * @see GrpcExceptionHandler
  * @see GrpcExceptionHandlerMethodResolver
- * @see GrpcAdviceExceptionInterceptor
+ * @see GrpcExceptionInterceptor
  */
 @Slf4j
-public class GrpcAdviceExceptionHandler {
+public class GrpcAdviceExceptionHandler implements GrpcExceptionResponseHandler {
 
     private final GrpcExceptionHandlerMethodResolver grpcExceptionHandlerMethodResolver;
 
+    /**
+     * Creates a new {@link GrpcAdvice} powered {@link GrpcExceptionHandler}.
+     *
+     * @param grpcExceptionHandlerMethodResolver The method resolver to use.
+     */
     public GrpcAdviceExceptionHandler(
             final GrpcExceptionHandlerMethodResolver grpcExceptionHandlerMethodResolver) {
-        this.grpcExceptionHandlerMethodResolver = grpcExceptionHandlerMethodResolver;
+        this.grpcExceptionHandlerMethodResolver =
+                requireNonNull(grpcExceptionHandlerMethodResolver, "grpcExceptionHandlerMethodResolver");
+    }
+
+    @Override
+    public void handleError(final ServerCall<?, ?> serverCall, final Throwable error) {
+        try {
+            final Object mappedReturnType = handleThrownException(error);
+            final Status status = resolveStatus(mappedReturnType);
+            final Metadata metadata = resolveMetadata(mappedReturnType);
+
+            serverCall.close(status, metadata);
+        } catch (final Throwable errorWhileResolving) {
+            if (errorWhileResolving != error) {
+                errorWhileResolving.addSuppressed(error);
+            }
+            handleThrownExceptionByImplementation(serverCall, errorWhileResolving);
+        }
+    }
+
+    protected Status resolveStatus(final Object mappedReturnType) {
+        if (mappedReturnType instanceof Status) {
+            return (Status) mappedReturnType;
+        } else if (mappedReturnType instanceof Throwable) {
+            return Status.fromThrowable((Throwable) mappedReturnType);
+        }
+        throw new IllegalStateException(String.format(
+                "Error for mapped return type [%s] inside @GrpcAdvice, it has to be of type: "
+                        + "[Status, StatusException, StatusRuntimeException, Throwable] ",
+                mappedReturnType));
+    }
+
+    protected Metadata resolveMetadata(final Object mappedReturnType) {
+        Metadata result = null;
+        if (mappedReturnType instanceof StatusException) {
+            final StatusException statusException = (StatusException) mappedReturnType;
+            result = statusException.getTrailers();
+        } else if (mappedReturnType instanceof StatusRuntimeException) {
+            final StatusRuntimeException statusException = (StatusRuntimeException) mappedReturnType;
+            result = statusException.getTrailers();
+        }
+        return (result == null) ? new Metadata() : result;
+    }
+
+    protected void handleThrownExceptionByImplementation(final ServerCall<?, ?> serverCall, final Throwable throwable) {
+        log.error("Exception thrown during invocation of annotated @GrpcExceptionHandler method: ", throwable);
+        serverCall.close(Status.INTERNAL.withCause(throwable)
+                .withDescription("There was a server error trying to handle an exception"), new Metadata());
     }
 
     /**
      * Given an exception, a lookup is performed to retrieve mapped method. <br>
      * In case of successful returned method, and matching exception parameter type for given exception, the exception
      * is handed over to retrieved method. Retrieved method is then being invoked.
-     * 
+     *
      * @param exception exception to search for
-     * @param <E> type of exception
      * @return result of invoked mapped method to given exception
      * @throws Throwable rethrows exception if no mapping existent or exceptions raised by implementation
      */
     @Nullable
-    public <E extends Throwable> Object handleThrownException(E exception) throws Throwable {
+    protected Object handleThrownException(final Throwable exception) throws Throwable {
         log.debug("Exception caught during gRPC execution: ", exception);
 
         final Class<? extends Throwable> exceptionClass = exception.getClass();
-        boolean exceptionIsMapped =
-                grpcExceptionHandlerMethodResolver.isMethodMappedForException(exceptionClass);
+        final boolean exceptionIsMapped =
+                this.grpcExceptionHandlerMethodResolver.isMethodMappedForException(exceptionClass);
         if (!exceptionIsMapped) {
             throw exception;
         }
 
-        Entry<Object, Method> methodWithInstance =
-                grpcExceptionHandlerMethodResolver.resolveMethodWithInstance(exceptionClass);
-        Method mappedMethod = methodWithInstance.getValue();
-        Object instanceOfMappedMethod = methodWithInstance.getKey();
-        Object[] instancedParams = determineInstancedParameters(mappedMethod, exception);
+        final Entry<Object, Method> methodWithInstance =
+                this.grpcExceptionHandlerMethodResolver.resolveMethodWithInstance(exceptionClass);
+        final Method mappedMethod = methodWithInstance.getValue();
+        final Object instanceOfMappedMethod = methodWithInstance.getKey();
+        final Object[] instancedParams = determineInstancedParameters(mappedMethod, exception);
 
         return invokeMappedMethodSafely(mappedMethod, instanceOfMappedMethod, instancedParams);
     }
 
-    private <E extends Throwable> Object[] determineInstancedParameters(Method mappedMethod, E exception) {
+    private Object[] determineInstancedParameters(final Method mappedMethod, final Throwable exception) {
 
-        Parameter[] parameters = mappedMethod.getParameters();
-        Object[] instancedParams = new Object[parameters.length];
+        final Parameter[] parameters = mappedMethod.getParameters();
+        final Object[] instancedParams = new Object[parameters.length];
 
         for (int i = 0; i < parameters.length; i++) {
-            Class<?> parameterClass = convertToClass(parameters[i]);
+            final Class<?> parameterClass = convertToClass(parameters[i]);
             if (parameterClass.isAssignableFrom(exception.getClass())) {
                 instancedParams[i] = exception;
                 break;
@@ -95,18 +157,18 @@ private <E extends Throwable> Object[] determineInstancedParameters(Method mappe
         return instancedParams;
     }
 
-    private Class<?> convertToClass(Parameter parameter) {
-        Type paramType = parameter.getParameterizedType();
+    private Class<?> convertToClass(final Parameter parameter) {
+        final Type paramType = parameter.getParameterizedType();
         if (paramType instanceof Class) {
             return (Class<?>) paramType;
         }
         throw new IllegalStateException("Parameter type of method has to be from Class, it was: " + paramType);
     }
 
     private Object invokeMappedMethodSafely(
-            Method mappedMethod,
-            Object instanceOfMappedMethod,
-            Object[] instancedParams) throws Throwable {
+            final Method mappedMethod,
+            final Object instanceOfMappedMethod,
+            final Object[] instancedParams) throws Throwable {
         try {
             return mappedMethod.invoke(instanceOfMappedMethod, instancedParams);
         } catch (InvocationTargetException | IllegalAccessException e) {

grpc-server-spring-boot-autoconfigure/src/main/java/net/devh/boot/grpc/server/autoconfigure/GrpcAdviceAutoConfiguration.java

@@ -27,10 +27,10 @@
 import net.devh.boot.grpc.server.advice.GrpcAdvice;
 import net.devh.boot.grpc.server.advice.GrpcAdviceDiscoverer;
 import net.devh.boot.grpc.server.advice.GrpcAdviceExceptionHandler;
-import net.devh.boot.grpc.server.advice.GrpcAdviceExceptionInterceptor;
 import net.devh.boot.grpc.server.advice.GrpcAdviceIsPresentCondition;
 import net.devh.boot.grpc.server.advice.GrpcExceptionHandler;
 import net.devh.boot.grpc.server.advice.GrpcExceptionHandlerMethodResolver;
+import net.devh.boot.grpc.server.error.GrpcExceptionInterceptor;
 import net.devh.boot.grpc.server.interceptor.GrpcGlobalServerInterceptor;
 
 /**
@@ -44,7 +44,7 @@
  * @author Andjelko Perisic (andjelko.perisic@gmail.com)
  * @see GrpcAdvice
  * @see GrpcExceptionHandler
- * @see GrpcAdviceExceptionInterceptor
+ * @see GrpcExceptionInterceptor
  */
 @Configuration(proxyBeanMethods = false)
 @Conditional(GrpcAdviceIsPresentCondition.class)
@@ -70,9 +70,9 @@ public GrpcAdviceExceptionHandler grpcAdviceExceptionHandler(
 
     @GrpcGlobalServerInterceptor
     @Order(InterceptorOrder.ORDER_GLOBAL_EXCEPTION_HANDLING)
-    public GrpcAdviceExceptionInterceptor grpcAdviceExceptionInterceptor(
+    public GrpcExceptionInterceptor grpcAdviceExceptionInterceptor(
             GrpcAdviceExceptionHandler grpcAdviceExceptionHandler) {
-        return new GrpcAdviceExceptionInterceptor(grpcAdviceExceptionHandler);
+        return new GrpcExceptionInterceptor(grpcAdviceExceptionHandler);
     }
 
 }