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/*
 * Copyright (C) 2003-2007 Jost Boekemeier
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

package io.soluble.pjb.bridge;

/**
 * A specialized thread pool which automatically terminates all group threads at the end of the request.
 * When this thread pool is used, users cannot create long-running threads from PHP scripts
 *
 * @author jostb
 */
public final class AppThreadPool extends ThreadPool {

    /**
     * Every Delegate has its own locked ThreadGroup.
     */
    static final class Group extends ThreadGroup {
        boolean isLocked = false;

        void lock() {
            isLocked = true;
        }

        void unlock() {
            isLocked = false;
        }

        private void init() {
            setDaemon(true);
        }

        public Group(String name) {
            super(name);
            init();
        }

        public Group(ThreadGroup group, String name) {
            super(group, name);
            init();
        }
    }

    /**
     * Application threads belong to this group
     */
    static final class AppGroup extends ThreadGroup {
        private void init() {
            setDaemon(true);
        }

        public AppGroup(String name) {
            super(name);
            init();
        }

        public AppGroup(ThreadGroup group, String name) {
            super(group, name);
            init();
        }
    }

    /**
     * A specialized delegate which can handle persistent connections
     * and interrupts application threads when end() or terminate()
     * is called.
     */
    final class Delegate extends ThreadPool.Delegate {
        protected ThreadGroup appGroup = null;

        /**
         * Create a new delegate. The thread runs until
         * terminatePersistent() is called.
         *
         * @param name The name of the delegate.
         */
        protected Delegate(String name) {
            super(new Group(name), name);
            ((Group) getThreadGroup()).lock();
        }

        /**
         * Return the app group for this delegate. All user-created
         * threads live in this group and receive an interrupt (which
         * should terminate them), when the request is done.
         *
         * @return The application group
         */
        public ThreadGroup getAppGroup() {
            if (appGroup != null) return appGroup;
            Group group = (Group) getThreadGroup();
            group.unlock();
            appGroup = new AppGroup("JavaBridgeThreadPoolAppGroup");
            group.lock();
            return appGroup;
        }

        /**
         * Make this thread a daemon thread. A daemon is not visible
         * but still managed by the thread pool.
         */
        public void setPersistent() {
            if (!checkReserve() && !terminate) {
                // pool is nearly full, store new long-running clients outside
                terminate = true;
                String name = getName();
                setName(name + ",isDaemon=true");
                if (Util.logLevel > 5) name += "+";
                createThread(name);
            }
            end();
        }

        protected void createThread(String name) {
            Group group = (Group) getThreadGroup();
            group.unlock();
            super.createThread(name);
            group.lock();
        }

        protected void terminate() {
            if (Util.logLevel > 4) Util.logDebug("term (thread removed from pool): " + this);
            ThreadGroup group = appGroup;
            if (group != null) {
                try {
                    group.interrupt();
                } catch (SecurityException e) {
                    return;
                }
                try {
                    group.destroy();
                } catch (SecurityException e) {/*ignore*/
                } catch (IllegalThreadStateException e1) {
                    Util.printStackTrace(e1);
                } catch (Exception e2) {
                    Util.printStackTrace(e2);
                } finally {
                    appGroup = null;
                }
            }
        }

        protected void end() {
            super.end();
            if (Util.logLevel > 4) Util.logDebug("end (thread returned to pool): " + this);
            ThreadGroup group = appGroup;
            if (group != null)
                try {
                    group.interrupt();
                } catch (SecurityException e) {/*ignore*/
                } catch (Exception e2) {
                    Util.printStackTrace(e2);
                } finally {
                    appGroup = null;
                }
        }

    }

    protected ThreadPool.Delegate createDelegate(String name) {
        return new Delegate(name);
    }

    /**
     * Creates a new thread pool.
     *
     * @param name        - The name of the pool threads.
     * @param poolMaxSize - The max. number of threads, must be >= 1.
     */
    public AppThreadPool(String name, int poolMaxSize) {
        super(name, poolMaxSize);
    }
}