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Part of the Alchemy Collection. Makes it Simple to work with Thrift in Java. Saves you from writing boiler-plate code, such as management of Clients, and serialization of Thrift Objects. This library also demonstrates how to incorporate thrift with maven, for incorporation into your continuous delivery and distribution of your thrift schemas.

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/*
 * Copyright © 2018. Sir Wellington.
 * 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 tech.sirwellington.alchemy.thrift.clients;

import org.apache.thrift.TException;
import org.apache.thrift.TServiceClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import tech.sirwellington.alchemy.annotations.access.NonInstantiable;

/**
 * Common operations performed on Thrift Clients.
 *
 * @author SirWellington
 */
@NonInstantiable
public class Clients
{

    private static final Logger LOG = LoggerFactory.getLogger(Clients.class);

    Clients() throws IllegalAccessException
    {
        throw new IllegalAccessException("cannot instantiate");
    }

    /**
     * This function attempts to close Thrift Client, similar to {@link #close(org.apache.thrift.TServiceClient) }.
     * 
     * This function differs in that it accepts a generic Object type.
     * ß
     * This is necessary because Thrift {@code Iface}'s don't contain protocol information, and hence cannot
     * be closed. This prevents programming to the interface while retaining the ability to close the client.
     * This operation closes the client if it's a {@link TServiceClient}, and ignores it otherwise.
     *
     * @param client Expected to be of type {@link TServiceClient}, ignored otherwise.
     * @throws TException
     */
    public static void attemptClose(Object client) throws TException
    {
        if (client == null)
        {
            return;
        }

        if (!(client instanceof TServiceClient))
        {
            return;
        }

        TServiceClient thriftClient = (TServiceClient) client;
        close(thriftClient);
    }

    /**
     * Like {@link #attemptClose(java.lang.Object) }, but swallows any exceptions that occurs
     * in the attempt to close the Client.
     *
     * @param client
     */
    public static void attemptCloseSilently(Object client)
    {
        try
        {
            attemptClose(client);
        }
        catch (TException ex)
        {
            LOG.info("Could not silently close client: {}", client, ex);
        }
    }


    /**
     * Closes a Thrift Client, both the Input and Output Transports.
     *
     * @param client The client to close. Will be ignored if null.
     * @throws TException If the Client cannot be closed
     */
    public static void close(TServiceClient client) throws TException
    {
        if (client != null)
        {
            try
            {
                if (client.getInputProtocol() != null && client.getInputProtocol().getTransport() != null)
                {
                    client.getInputProtocol().getTransport().close();
                }
                if (client.getOutputProtocol() != null && client.getOutputProtocol().getTransport() != null)
                {
                    client.getOutputProtocol().getTransport().close();
                }
            }
            catch (Exception ex)
            {
                throw new TException(ex);
            }
        }
    }

    /**
     * Attempts to close a Thrift Client silently. Any Exceptions will be logged and swallowed.
     *
     * @param client The Client to close. If null will be ignored.
     */
    public static void closeSilently(TServiceClient client)
    {
        try
        {
            close(client);
        }
        catch (TException ex)
        {
            LOG.error("Failed to close Thrift Client {}", client, ex);
        }
    }

}