com.github.raduciumag.shapeshift.server.BaseServer Maven / Gradle / Ivy

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package com.github.raduciumag.shapeshift.server;

import com.github.raduciumag.shapeshift.config.ServerConfig;
import com.github.raduciumag.shapeshift.model.server.ServerStatus;
import com.google.common.base.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.locks.ReentrantLock;

public abstract class BaseServer implements Server {
    private static final Logger LOG = LoggerFactory.getLogger(BaseServer.class);

    protected final T config;
    protected final Thread startThread;
    protected final Thread stopThread;

    protected ServerStatus status = ServerStatus.STOPPED;
    protected ReentrantLock statusLock = new ReentrantLock();

    public BaseServer(final T config) {
        this.config = config;
        this.startThread = new Thread(this::startInternal);
        this.stopThread = new Thread(() -> {
            try {
                stopInternal();
            } catch (final InterruptedException exc) {
                LOG.error("Server stop interrupted", exc);
            }
        });
    }

    @Override
    public void start() {
        Preconditions.checkArgument(config != null, "The server configuration is required");

        statusLock.lock();
        try {
            Preconditions.checkState(status == ServerStatus.STOPPED, "The server status " + status + " does not allow " +
                    "a start command");
            Preconditions.checkState(!startThread.isAlive(), "The server is already started");

            LOG.info("Starting \"{}\" server", config.getName());

            startThread.start();
        } finally {
            statusLock.unlock();
        }
    }

    protected abstract void startInternal();

    @Override
    public void stop() {
        Preconditions.checkArgument(config != null, "The server configuration is required");

        statusLock.lock();
        try {
            Preconditions.checkState(status == ServerStatus.STARTED, "The server status " + status + " does not allow " +
                    "a stop command");
            Preconditions.checkState(!stopThread.isAlive(), "The server is already stopping");

            LOG.info("Stopping \"{}\" server", config.getName());

            stopThread.start();
        } finally {
            statusLock.unlock();
        }
    }

    protected abstract void stopInternal() throws InterruptedException;

    @Override
    public T getConfig() {
        return config;
    }

    @Override
    public ServerStatus getStatus() {
        return status;
    }
}