private static LambdaRequestHandler wrapRequestStreamHandler()

in aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/EventHandlerLoader.java [528:606]
59 lines of code
9 McCabe index (conditional complexity)

    private static LambdaRequestHandler wrapRequestStreamHandler(final RequestStreamHandler handler) {
        return new LambdaRequestHandler() {
            private final ByteArrayOutputStream output = new ByteArrayOutputStream(1024);
            private Functions.V2<String, String> log4jContextPutMethod = null;

            private void safeAddRequestIdToLog4j(String log4jContextClassName,
                                                 InvocationRequest request, Class contextMapValueClass) {
                try {
                    Class<?> log4jContextClass = ReflectUtil.loadClass(AWSLambda.customerClassLoader, log4jContextClassName);
                    log4jContextPutMethod = ReflectUtil.loadStaticV2(log4jContextClass, "put", false, String.class, contextMapValueClass);
                    log4jContextPutMethod.call("AWSRequestId", request.getId());
                } catch (Exception e) {
                    // nothing to do here
                }
            }

            /**
             * Passes the LambdaContext to the logger so that the JSON formatter can include the requestId.
             *
             * We do casting here because both the LambdaRuntime and the LambdaLogger is in the core package,
             * and the setLambdaContext(context) is a method we don't want to publish for customers. That method is
             * only implemented on the internal LambdaContextLogger, so we check and cast to be able to call it.
             * @param context the LambdaContext
             */
            private void safeAddContextToLambdaLogger(LambdaContext context) {
                LambdaLogger logger = com.amazonaws.services.lambda.runtime.LambdaRuntime.getLogger();
                if (logger instanceof LambdaContextLogger) {
                    LambdaContextLogger contextLogger = (LambdaContextLogger) logger;
                    contextLogger.setLambdaContext(context);
                }
            }

            public ByteArrayOutputStream call(InvocationRequest request) throws Error, Exception {
                output.reset();

                LambdaCognitoIdentity cognitoIdentity = null;
                if (request.getCognitoIdentity() != null && !request.getCognitoIdentity().isEmpty()) {
                    cognitoIdentity = getCognitoSerializer().fromJson(request.getCognitoIdentity());
                }

                LambdaClientContext clientContext = null;
                if (request.getClientContext() != null && !request.getClientContext().isEmpty()) {
                    //Use GSON here because it handles immutable types without requiring annotations
                    clientContext = getContextSerializer().fromJson(request.getClientContext());
                }

                LambdaContext context = new LambdaContext(
                        LambdaEnvironment.MEMORY_LIMIT,
                        request.getDeadlineTimeInMs(),
                        request.getId(),
                        LambdaEnvironment.LOG_GROUP_NAME,
                        LambdaEnvironment.LOG_STREAM_NAME,
                        LambdaEnvironment.FUNCTION_NAME,
                        cognitoIdentity,
                        LambdaEnvironment.FUNCTION_VERSION,
                        request.getInvokedFunctionArn(),
                        request.getTenantId(),
                        clientContext
                );

                safeAddContextToLambdaLogger(context);

                if (LambdaRuntimeInternal.getUseLog4jAppender()) {
                    safeAddRequestIdToLog4j("org.apache.log4j.MDC", request, Object.class);
                    safeAddRequestIdToLog4j("org.apache.logging.log4j.ThreadContext", request, String.class);
                    // if put method not assigned in either call to safeAddRequestIdtoLog4j then log4jContextPutMethod = null
                    if (log4jContextPutMethod == null) {
                        System.err.println("Customer using log4j appender but unable to load either " 
                            + "org.apache.log4j.MDC or org.apache.logging.log4j.ThreadContext. " 
                            + "Customer cannot see RequestId in log4j log lines.");
                    }
                }

                ByteArrayInputStream bais = new ByteArrayInputStream(request.getContent());
                handler.handleRequest(bais, output, context);
                return output;
            }
        };
    }