/*

 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package nsk.share.jdi;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.TimeUnit;

import nsk.share.Failure;

/**

 * Functions to set and wait for states in threads.

 * Used to sync main thread and debuggee thread.

 */

public class ThreadState {

    private final Lock lock = new ReentrantLock();

    private final Condition cond = lock.newCondition();

    private volatile String currentState;

    private long timeoutMs;

    public ThreadState(String startState, long timeoutMs) {

        currentState = startState;

        this.timeoutMs = timeoutMs;

    }

    /**

     * Set new state.

     */

    public void setState(String newState) {

        lock.lock();

        try {

            log(MSG_SET_STATE, newState);

            currentState = newState;

            cond.signalAll();

        } finally {

            lock.unlock();

        }

    }

    /**

     * Wait for the specified state.

     * Throws Failure if timeout.

     */

    public void waitForState(String waitState) {

        lock.lock();

        try {

            log(MSG_WAIT_STATE, waitState);

            while (!currentState.equals(waitState)) {

                if (!cond.await(timeoutMs, TimeUnit.MILLISECONDS)) {

                    throw new Failure(format(MSG_TIMEOUT, waitState));

                }

            }

            log(MSG_GOT_STATE, waitState);

        } catch (InterruptedException e) {

            e.printStackTrace();

            throw new Failure(e);

        } finally {

            lock.unlock();

        }

    }

    /**

     * Simple helper that sets a new state and then wait for another state.

     */

    public void setAndWait(String newState, String waitState) {

        setState(newState);

        waitForState(waitState);

    }

    private static final String MSG_TIMEOUT = "ThreadState(thread='%s', state='%s') timeout waiting for %s";

    private static final String MSG_SET_STATE = "ThreadState(thread='%s', state='%s') set state to %s";

    private static final String MSG_WAIT_STATE = "ThreadState(thread='%s', state='%s') waiting for state %s";

    private static final String MSG_GOT_STATE = "ThreadState(thread='%s', state='%s') got state %s";

    private String format(String pattern, String state) {

        final String threadName = Thread.currentThread().getName();

        return String.format(pattern, threadName, currentState, state);

    }

    private void log(String pattern, String state) {

        System.out.println(format(pattern, state));

    }

}