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/*
* Copyright 2015-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.services.lambda.invoke;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.nio.ByteBuffer;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.services.lambda.AWSLambda;
import com.amazonaws.services.lambda.model.InvocationType;
import com.amazonaws.services.lambda.model.InvokeRequest;
import com.amazonaws.services.lambda.model.InvokeResult;
import com.amazonaws.services.lambda.model.LogType;
import com.amazonaws.util.Base64;
import com.amazonaws.util.BinaryUtils;
import com.amazonaws.util.StringUtils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
/**
* A factory for objects that implement a user-supplied interface by invoking a remote Lambda
* function.
*
*
* public class Request {
* // Standard POJO stuff here modeling the input your Lambda function
* // expects.
* }
*
* public class Result {
* // More standard POJO stuff here modeling the output your Lambda
* // function produces.
* }
*
* public interface LambdaFunctions {
*
* @LambdaFunction Result doSomeStuff(Request request); } LambdaFunctions functions =
* LambdaInvokerFactory.build( LambdaFunctions.class, new AWSLambdaClient());
* Request request = new Request(...); Result result =
* functions.doSomeStuff(request);
*/
public final class LambdaInvokerFactory {
private static final ObjectMapper MAPPER = new ObjectMapper();
/**
* Creates a new Lambda invoker implementing the given interface and wrapping the given
* {@code AWSLambda} client.
*
* @param interfaceClass
* the interface to implement
* @param awsLambda
* the lambda client to use for making remote calls
*/
public static T build(Class interfaceClass, AWSLambda awsLambda) {
return build(interfaceClass, awsLambda, new LambdaInvokerFactoryConfig());
}
/**
* Creates a new Lambda invoker implementing the given interface and wrapping the given
* {@code AWSLambda} client.
*
* @param interfaceClass
* the interface to implement
* @param awsLambda
* the lambda client to use for making remote calls
* @param config
* configuration for the LambdaInvokerFactory
*/
public static T build(Class interfaceClass, AWSLambda awsLambda, LambdaInvokerFactoryConfig config) {
Object proxy = Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class[] { interfaceClass },
new LambdaInvocationHandler(interfaceClass, awsLambda, config));
return interfaceClass.cast(proxy);
}
private LambdaInvokerFactory() {
}
private static class LambdaInvocationHandler implements InvocationHandler {
private final AWSLambda awsLambda;
private final Log log;
private final LambdaInvokerFactoryConfig config;
public LambdaInvocationHandler(Class interfaceClass, AWSLambda awsLambda, LambdaInvokerFactoryConfig config) {
this.awsLambda = awsLambda;
this.log = LogFactory.getLog(interfaceClass);
this.config = config;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
LambdaFunction annotation = validateInterfaceMethod(method, args);
InvokeRequest invokeRequest = buildInvokeRequest(method, annotation, args == null ? null : args[0]);
InvokeResult invokeResult = awsLambda.invoke(invokeRequest);
return processInvokeResult(method, invokeResult);
}
/**
* Verifies that the given method is annotated appropriately.
*/
private LambdaFunction validateInterfaceMethod(Method method, Object[] args) {
LambdaFunction annotation = method.getAnnotation(LambdaFunction.class);
if (annotation == null) {
throw new LambdaSerializationException("No LambdaFunction annotation for method " + method.getName());
}
if (annotation.invocationType() != InvocationType.RequestResponse && annotation.logType() != LogType.None) {
throw new LambdaSerializationException("InvocationType must be RequestResponse if LogType " + "is set");
}
if (args != null && args.length > 1) {
throw new LambdaSerializationException("LambdaFunctions take either 0 or 1 arguments");
}
return annotation;
}
/**
* Builds an InvokeRequest from the given method, its {@code LambdaFunction} annotation, and
* the input parameter (if any).
*/
private InvokeRequest buildInvokeRequest(Method method, LambdaFunction annotation, Object input) {
InvokeRequest invokeRequest = new InvokeRequest();
String functionName = config.getLambdaFunctionNameResolver().getFunctionName(method, annotation, config);
invokeRequest.setFunctionName(functionName);
invokeRequest.setInvocationType(annotation.invocationType());
invokeRequest.setLogType(annotation.logType());
if (input != null) {
try {
String payload = MAPPER.writer().writeValueAsString(input);
if (log.isDebugEnabled()) {
log.debug("Serialized request object to '" + payload + "'");
}
invokeRequest.setPayload(payload);
} catch (JsonProcessingException ex) {
throw new LambdaSerializationException("Failed to serialize request object to JSON", ex);
}
}
return invokeRequest;
}
/**
* Process the result of invoking a remote function. If the response includes server-side
* logs, dump them into our logs; if it includes a server-side error indication, parse it
* into a corresponding {@code Exception} type, otherwise parse the result payload into a
* Java object suitable for returning from this method.
*/
private Object processInvokeResult(Method method, InvokeResult invokeResult) throws Throwable {
if (invokeResult.getLogResult() != null && log.isInfoEnabled()) {
try {
String decoded = new String(Base64.decode(invokeResult.getLogResult()), StringUtils.UTF8);
log.info(method.getName() + " log:\n\t" + decoded.replaceAll("\n", "\n\t"));
} catch (Exception ex) {
log.warn("Error decoding log result '" + invokeResult.getLogResult() + "'", ex);
}
}
String functionError = invokeResult.getFunctionError();
if (functionError == null) {
// Success.
return getObjectFromPayload(method, invokeResult);
} else {
throw getExceptionFromPayload(method, invokeResult);
}
}
/**
* Reads a Java object suitable for returning from the given method from the payload of the
* given {@code InvokeResult} (or returns {@code null} if the method has no return value or
* the response contains no payload).
*
* @throws LambdaSerializationException
* on error deserializing
*/
private Object getObjectFromPayload(Method method, InvokeResult invokeResult) {
try {
return getObjectFromPayload(method.getGenericReturnType(), invokeResult.getPayload());
} catch (IOException ex) {
throw new LambdaSerializationException("Failed to parse Lambda function result", ex);
}
}
private Throwable getExceptionFromPayload(Method method, InvokeResult invokeResult) {
Throwable throwable = null;
String message = "Unexpected error executing Lambda function";
String type = null;
List stackTrace = null;
try {
LambdaFunctionError error = getObjectFromPayload(LambdaFunctionError.class, invokeResult.getPayload());
if (error != null) {
message = error.getErrorMessage();
type = error.getErrorType();
stackTrace = error.getStackTrace();
throwable = getCustomException(method, error);
}
} catch (Exception ex) {
log.warn("Error parsing exception information from response " + "payload", ex);
}
if (throwable == null) {
throwable = new LambdaFunctionException(message, "Handled".equals(invokeResult.getFunctionError()),
type);
}
if (stackTrace != null) {
fillStackTrace(throwable, stackTrace, method.getDeclaringClass());
}
return throwable;
}
private Throwable getCustomException(Method method, LambdaFunctionError error) {
String type = error.getErrorType();
Constructor constructor = null;
if (type != null) {
for (Class exceptionType : method.getExceptionTypes()) {
if (exceptionType.getSimpleName().startsWith(type)) {
constructor = findConstructor(exceptionType);
if (constructor != null) {
break;
}
}
}
}
if (constructor != null) {
try {
return (Throwable) constructor.newInstance(error.getErrorMessage());
} catch (Exception ex) {
log.warn("Error constructing custom exception", ex);
}
}
return null;
}
private Constructor findConstructor(Class type) {
for (Constructor constructor : type.getConstructors()) {
Class[] params = constructor.getParameterTypes();
if (params != null && params.length == 1 && String.class.equals(params[0])) {
return constructor;
}
}
return null;
}
private void fillStackTrace(Throwable throwable, List stackTrace, Class interfaceClass) {
StackTraceElement[] elements = new StackTraceElement[stackTrace.size()];
for (int i = 0; i < stackTrace.size(); ++i) {
elements[i] = new StackTraceElement(interfaceClass.getName(), stackTrace.get(i).trim(), null, 0);
}
throwable.setStackTrace(elements);
}
private T getObjectFromPayload(Class type, ByteBuffer payload) throws IOException {
return type.cast(getObjectFromPayload((Type) type, payload));
}
private Object getObjectFromPayload(Type type, ByteBuffer payload) throws IOException {
if (type == void.class || payload.remaining() == 0) {
return null;
}
JavaType javaType = MAPPER.getTypeFactory().constructType(type);
return MAPPER.reader(javaType).readValue(BinaryUtils.copyAllBytesFrom(payload));
}
}
}