org.embulk.util.retryhelper.jaxrs.JAXRSSingleRequester Maven / Gradle / Ivy

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/*
 * Copyright 2020 The Embulk project
 *
 * 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.embulk.util.retryhelper.jaxrs;

/**
 * JAXRSSingleRequester is to define a single request to the target REST service to be ready for retries.
 *
 * It is expected to use with {@link JAXRSRetryHelper} as follows.
 *
 * {@code
 * javax.ws.rs.core.Response response = jaxrsRetryHelper.requestWithRetry(
 *     new StringJAXRSResponseEntityReader(),
 *     new JAXRSSingleRequester() {
 *         @Override
 *         public Response requestOnce(javax.ws.rs.client.Client client)
 *         {
 *             return client.target("https://example.com/api/resource").request().get;
 *         }
 *
 *         @Override
 *         public boolean isResponseStatusToRetry(javax.ws.rs.core.Response response)
 *         {
 *             return (response.getStatus() / 100) == 4;
 *         }
 *     });
 * }
 *
 * @see JAXRSResponseReadable
 * @see StringJAXRSResponseEntityReader
 */
public abstract class JAXRSSingleRequester
{
    /**
     * Requests to the target service with the given {@code javax.ws.rs.client.Client}.
     *
     * The method is {@code abstract} that must be overridden.
     */
    public abstract javax.ws.rs.core.Response requestOnce(javax.ws.rs.client.Client client);

    /**
     * Returns {@code true} if the given {@code Exception} from {@link JAXRSRetryHelper} is to retry.
     *
     * This method cannot be overridden. Override {@code isResponseStatusRetryable} and {@code isExceptionRetryable}
     * instead. {@code isResponseStatusRetryable} is called for {@code javax.ws.rs.WebApplicationException}.
     * {@code isExceptionRetryable} is called for other exceptions.
     */
    public final boolean toRetry(Exception exception) {
        // Expects |javax.ws.rs.WebApplicationException| is throws in case of HTTP error status
        // such as implemented in |JAXRSRetryHelper|.
        if (exception instanceof javax.ws.rs.WebApplicationException) {
            return isResponseStatusToRetry(((javax.ws.rs.WebApplicationException) exception).getResponse());
        }
        else {
            return isExceptionToRetry(exception);
        }
    }

    /**
     * Returns {@code true} if the given {@code javax.ws.rs.core.Response} is to retry.
     *
     * This method is {@code abstract} to be overridden, and {@code protected} to be called from {@code isRetryable}.
     */
    protected abstract boolean isResponseStatusToRetry(javax.ws.rs.core.Response response);

    /**
     * Returns true if the given {@code Exception} is to retry.
     *
     * This method available to override, and {@code protected} to be called from {@code isRetryable}.
     */
    protected boolean isExceptionToRetry(Exception exception) {
        return false;
    }
}