AmazonRdsRetryInterceptorBeanDefinitionParser.java

/*
 * Copyright 2013-2014 the original author or 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 org.springframework.cloud.aws.jdbc.config.xml;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.ManagedList;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.cloud.aws.context.config.xml.GlobalBeanDefinitionUtils;
import org.springframework.cloud.aws.jdbc.retry.DatabaseInstanceStatusRetryPolicy;
import org.springframework.cloud.aws.jdbc.retry.RdbmsRetryOperationsInterceptor;
import org.springframework.cloud.aws.jdbc.retry.SqlRetryPolicy;
import org.springframework.core.Conventions;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

import static org.springframework.cloud.aws.core.config.xml.XmlWebserviceConfigurationUtils.getCustomClientOrDefaultClientBeanName;

/**
 * {@link org.springframework.beans.factory.xml.BeanDefinitionParser} implementation for the
 * <code>retry-interceptor</code> element. This parser produces a {@link org.aopalliance.intercept.MethodInterceptor}
 * which can be used by advice to intercept method calls and retry their particular operation.
 *
 * @author Agim Emruli
 * @since 1.0
 */
class AmazonRdsRetryInterceptorBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {

    /**
     * Class name for the RetryTemplate. String because retry support is optional
     */
    private static final String RETRY_OPERATIONS_CLASS_NAME = "org.springframework.retry.support.RetryTemplate";

    /**
     * Class name used for the policy, which is a composition of two policies (database instance status and SQL error code)
     */
    private static final String COMPOSITE_RETRY_POLICY_CLASS_NAME = "org.springframework.retry.policy.CompositeRetryPolicy";

    /**
     * Attribute name for the number of retries that should be done
     */
    private static final String MAX_NUMBER_OF_RETRIES = "max-number-of-retries";

    /**
     * Attribute name to a custom back off policy
     */
    private static final String BACK_OFF_POLICY = "back-off-policy";
    private static final String AMAZON_RDS_CLIENT_CLASS_NAME = "com.amazonaws.services.rds.AmazonRDSClient";

    @Override
    protected Class<?> getBeanClass(Element element) {
        return RdbmsRetryOperationsInterceptor.class;
    }

    @Override
    protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
        builder.addPropertyValue("retryOperations", buildRetryOperationDefinition(element, parserContext));
    }

    /**
     * Builds the RetryOperation {@link BeanDefinition} with its collaborators
     *
     * @param element
     *         - <code>retry-interceptor Element</code>
     * @param parserContext
     *         - ParserContext used to query the {@link org.springframework.beans.factory.support.BeanDefinitionRegistry}
     * @return Configured but non registered bean definition
     */
    private static BeanDefinition buildRetryOperationDefinition(Element element, ParserContext parserContext) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(RETRY_OPERATIONS_CLASS_NAME);
        builder.addPropertyValue("retryPolicy", buildRetryPolicyDefinition(element, parserContext));

        if (StringUtils.hasText(element.getAttribute(BACK_OFF_POLICY))) {
            String backOffPolicyBeanName = element.getAttribute(BACK_OFF_POLICY);
            builder.addPropertyReference(Conventions.attributeNameToPropertyName(BACK_OFF_POLICY), backOffPolicyBeanName);
        }

        return builder.getBeanDefinition();
    }

    private static BeanDefinition buildRetryPolicyDefinition(Element element, ParserContext parserContext) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(COMPOSITE_RETRY_POLICY_CLASS_NAME);

        ManagedList<BeanDefinition> policies = new ManagedList<>(2);
        policies.add(buildDatabaseInstancePolicy(element, parserContext));
        policies.add(buildSQLRetryPolicy(element));

        builder.addPropertyValue("policies", policies);

        return builder.getBeanDefinition();
    }

    private static BeanDefinition buildDatabaseInstancePolicy(Element element, ParserContext parserContext) {
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(DatabaseInstanceStatusRetryPolicy.class);

        String amazonRdsClientBeanName = getCustomClientOrDefaultClientBeanName(element, parserContext, "amazon-rds", AMAZON_RDS_CLIENT_CLASS_NAME);

        beanDefinitionBuilder.addConstructorArgReference(amazonRdsClientBeanName);
        beanDefinitionBuilder.addConstructorArgValue(element.getAttribute(AmazonRdsDataSourceBeanDefinitionParser.DB_INSTANCE_IDENTIFIER));

        String resourceIdResolverBeanName = GlobalBeanDefinitionUtils.retrieveResourceIdResolverBeanName(parserContext.getRegistry());
        beanDefinitionBuilder.addPropertyReference("resourceIdResolver", resourceIdResolverBeanName);

        return beanDefinitionBuilder.getBeanDefinition();
    }

    private static BeanDefinition buildSQLRetryPolicy(Element element) {
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(SqlRetryPolicy.class);
        if (StringUtils.hasText(element.getAttribute(MAX_NUMBER_OF_RETRIES))) {
            beanDefinitionBuilder.addPropertyValue(Conventions.attributeNameToPropertyName(MAX_NUMBER_OF_RETRIES), element.getAttribute(MAX_NUMBER_OF_RETRIES));
        }
        return beanDefinitionBuilder.getBeanDefinition();
    }
}