source: java/main/src/main/java/com/framsticks/util/dispatching/AbstractJoinable.java @ 88

package com.framsticks.util.dispatching;

import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import javax.annotation.Nonnull;

import org.apache.commons.collections.CollectionUtils;
import org.apache.log4j.Logger;

import com.framsticks.util.FramsticksException;



public abstract class AbstractJoinable implements Joinable {
        private static final Logger log = Logger.getLogger(AbstractJoinable.class);


        protected final Set<JoinableParent> owners = new HashSet<JoinableParent>();
        protected final Set<JoinableParent> joinableListeners = new HashSet<JoinableParent>();

        protected static final Set<AbstractJoinable> joinablesRegistry = Collections.synchronizedSet(new HashSet<AbstractJoinable>());

        JoinableState state = JoinableState.INITILIAZED;

        /**
         *
         */
        public AbstractJoinable() {
                joinablesRegistry.add(this);
        }

        public static void report() {
                StringBuilder b = new StringBuilder();
                synchronized (joinablesRegistry) {
                        for (AbstractJoinable j : joinablesRegistry) {
                                b.append("\n").append(j.getState()).append(" : ").append(j);
                        }
                }
                log.debug("state: " + b);
        }

        private synchronized boolean changeState(JoinableState state) {
                if (this.state.ordinal() >= state.ordinal()) {
                        return false;
                }
                if (this.state.ordinal() + 1 != state.ordinal()) {
                        throw new FramsticksException().msg("failed to change state").arg("from", this.state).arg("to", state).arg("joinable", this);
                }
                this.state = state;

                synchronized (this) {
                        log.debug(this + " is notifying " + joinableListeners.size() + " parents");

                        List<JoinableParent> parents = new LinkedList<>();
                        CollectionUtils.addAll(parents, joinableListeners.iterator());

                        for (JoinableParent p : parents) {
                                if (p != null) {
                                        Dispatching.childChangedState(p, this, state);
                                }
                        }
                }
                report();

                return true;
        }



        public final boolean start() {
                if (changeState(JoinableState.RUNNING)) {
                        joinableStart();
                        return true;
                }
                return false;
        }

        public final boolean interrupt() {
                if (changeState(JoinableState.FINISHING)) {
                        joinableInterrupt();
                        return true;
                }
                return false;
        }

        protected final boolean finish() {
                if (changeState(JoinableState.JOINABLE)) {
                        joinableFinish();
                        return true;
                }
                return false;
        }



        @Override
        public final void join() throws InterruptedException {
                synchronized (this) {
                        if (this.state.equals(JoinableState.JOINED)) {
                                return;
                        }
                        if (!this.state.equals(JoinableState.JOINABLE)) {
                                throw new InterruptedException();
                        }
                }
                joinableJoin();
                synchronized (this) {
                        this.state = JoinableState.JOINED;
                }
        }

        protected final boolean proceedToState(JoinableState state) {
                switch (state) {
                        case RUNNING:
                                return start();
                        case FINISHING:
                                return interrupt();
                        case JOINABLE:
                                return finish();
                        default: return false;
                }
        }

        protected abstract void joinableStart();

        protected abstract void joinableInterrupt();

        protected abstract void joinableFinish();

        protected abstract void joinableJoin() throws InterruptedException;

        public final boolean use(@Nonnull JoinableParent owner) {
                boolean start = false;
                synchronized (this) {
                        assert !owners.contains(owner);
                        start = owners.isEmpty();
                        log.debug(owner + " is using " + this);
                        owners.add(owner);
                        joinableListeners.add(owner);
                }
                if (start) {
                        return this.start();
                }
                return false;
        }

        public final boolean drop(@Nonnull JoinableParent owner) {
                boolean stop = false;
                synchronized (this) {
                        if (!owners.contains(owner)) {
                                return false;
                                // throw new FramsticksException().msg("object is not owning that joinable").arg("joinable", this).arg("object", owner);
                        }
                        // assert owners.containsKey(owner);
                        log.debug(owner + " is droping " + this);
                        owners.remove(owner);
                        stop = owners.isEmpty();
                }
                if (stop) {
                        Dispatching.dispatcherGuardedInvoke(this, new RunAt<Object>() {
                                @Override
                                public void run() {
                                        interrupt();
                                }
                        });
                        return true;
                }
                return stop;
        }

        /**
         * @return the state
         */
        public JoinableState getState() {
                return state;
        }

        protected boolean isInState(JoinableState state) {
                return this.state.equals(state);
        }


}