source: java/main/src/main/java/com/framsticks/util/dispatching/Monitor.java @ 102

package com.framsticks.util.dispatching;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import com.framsticks.util.dispatching.Dispatching;
import java.lang.Thread;
import java.util.concurrent.atomic.AtomicBoolean;

public class Monitor implements JoinableParent {
        private static final Logger log =
                LogManager.getLogger(Monitor.class);

        protected final Joinable joinable;
        protected final Thread shutdownHook;
        protected final AtomicBoolean dropped = new AtomicBoolean(false);
        protected final AtomicBoolean joining = new AtomicBoolean(false);

        /**
         * @param joinable
         */
        public Monitor(Joinable joinable) {
                this.joinable = joinable;

                shutdownHook = new Thread(new Runnable() {
                        @Override
                        public void run() {
                                log.debug("droping and joining");
                                Monitor.this.drop().join();
                                log.debug("droped and joined");
                                AbstractJoinable.report();
                        }
                });
        }

        public Monitor use() {
                Runtime.getRuntime().addShutdownHook(shutdownHook);

                log.debug("{} is using", this);
                Dispatching.use(joinable, this);
                return this;
        }

        public Monitor useFor(double seconds) {
                Dispatching.sleep(seconds);
                return this;
        }

        public Monitor waitFor() {
                log.debug("{} is waiting", this);
                synchronized (this) {
                        while (joinable.getState().ordinal() < JoinableState.FINISHING.ordinal()) {
                                Dispatching.wait(this, 100);
                        }
                }
                log.debug("{} ended waiting", this);
                return this;
        }


        public Monitor drop() {
                if (!dropped.compareAndSet(false, true)) {
                        return this;
                }
                log.debug("{} is droping", this);
                Dispatching.drop(joinable, this);
                return this;
        }

        public Monitor join() {
                if (!joining.compareAndSet(false, true)) {
                        log.debug("not joining");
                        return this;
                }

                log.debug("{} is joining", this);
                Dispatching.joinAbsolutely(joinable);
                log.debug("{} is joined", this);

                try {
                        Runtime.getRuntime().removeShutdownHook(shutdownHook);
                } catch (IllegalStateException e) {
                        /** In case IllegalStateException is caught, it means that JVM is in finalization stage */
                }
                return this;
        }

        @Override
        // @SuppressWarnings("NN_NAKED_NOTIFY")
        public void childChangedState(Joinable joinable, JoinableState state) {
                synchronized (this) {
                        this.notify();
                }
                log.debug("{} received notification about transition to {}", this, state);
        }

        @Override
        public String toString() {
                return "monitor for " + joinable;
        }

        @Override
        public Monitor getMonitor() {
                return this;
        }

        protected ExceptionHandler taskExceptionHandler;

        /**
         * @return the taskExceptionHandler
         */
        public ExceptionHandler getTaskExceptionHandler() {
                return taskExceptionHandler;
        }

        /**
         * @param taskExceptionHandler the taskExceptionHandler to set
         */
        public void setTaskExceptionHandler(ExceptionHandler taskExceptionHandler) {
                this.taskExceptionHandler = taskExceptionHandler;
        }

}