com.cognifide.aet.worker.drivers.AetSocketLock.java Source code

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Here is the source code for com.cognifide.aet.worker.drivers.AetSocketLock.java

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/**
 * Automated Exploratory Tests
 *
 * Copyright (C) 2013 Cognifide Limited
 *
 * 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 com.cognifide.aet.worker.drivers;

/*
 * Copyright 2007-2009 Selenium committers
 *
 * 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.
 */

import org.openqa.selenium.WebDriverException;
import org.openqa.selenium.internal.SocketLock;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketException;

/**
 * Custom implementation of org.openqa.selenium.internal.Lock that has configurable delay between socket
 * checks.
 */
class AetSocketLock extends SocketLock {

    private static final int DELAY_BETWEEN_SOCKET_CHECKS = 600;

    private static final int ADDITIONAL_TIMEOUT_IN_MILLIS = 4000;

    private static final Object syncObject = new Object();

    private static final InetSocketAddress LOCALHOST = new InetSocketAddress("localhost", DEFAULT_PORT - 1);

    private final Socket lockSocket;

    private final InetSocketAddress address;

    AetSocketLock() {
        this.lockSocket = new Socket();
        this.address = LOCALHOST;
    }

    /**
     * @inheritDoc
     */
    @Override
    public void lock(long timeoutInMillis) {
        synchronized (syncObject) {
            // Calculate the 'exit time' for our wait loop.
            long maxWait = System.currentTimeMillis() + timeoutInMillis + ADDITIONAL_TIMEOUT_IN_MILLIS;

            // Attempt to acquire the lock until something goes wrong or we run out of time.
            do {
                try {
                    if (isLockOnInetSocketAddressFree(address)) {
                        return;
                    }
                    // Randomness or retry! Something from my past (Paul H) :
                    // http://www.wattystuff.net/amateur/packet/whatispacket.htm (search for random in page)
                    Thread.sleep((long) (DELAY_BETWEEN_SOCKET_CHECKS * Math.random()));
                } catch (InterruptedException | IOException e) {
                    throw new WebDriverException(e);
                }
            } while (System.currentTimeMillis() < maxWait);

            throw new WebDriverException(String.format("Unable to bind to locking port %d within %d ms",
                    address.getPort(), timeoutInMillis + ADDITIONAL_TIMEOUT_IN_MILLIS));
        }
    }

    @Override
    public void unlock() {
        try {
            if (lockSocket.isBound()) {
                lockSocket.close();
            }
        } catch (IOException e) {
            throw new WebDriverException(e);
        }
    }

    /**
     * Test to see if the lock is free. Returns instantaneously.
     *
     * @param address the address to attempt to bind to
     * @return true if the lock is locked; false if it is not
     * @throws IOException if something goes catastrophically wrong with the socket
     */
    private boolean isLockOnInetSocketAddressFree(InetSocketAddress address) throws IOException {
        try {
            lockSocket.bind(address);
            return true;
        } catch (SocketException e) {
            return false;
        }
    }
}