src/jdk.jfr/share/classes/jdk/jfr/internal/consumer/Dispatcher.java

/*
 * Copyright (c) 2019, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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
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package jdk.jfr.internal.consumer;

import java.time.Instant;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

import jdk.jfr.EventType;
import jdk.jfr.consumer.RecordedEvent;
import jdk.jfr.internal.LongMap;
import jdk.jfr.internal.consumer.ChunkParser.ParserConfiguration;

final class Dispatcher {

    final static class EventDispatcher {
        private final static EventDispatcher[] NO_DISPATCHERS = new EventDispatcher[0];

        private final String eventName;
        private final Consumer<RecordedEvent> action;

        public EventDispatcher(String eventName, Consumer<RecordedEvent> action) {
            this.eventName = eventName;
            this.action = action;
        }

        private void offer(RecordedEvent event) {
            action.accept(event);
        }

        private boolean accepts(EventType eventType) {
            return (eventName == null || eventType.getName().equals(eventName));
        }

        public Consumer<RecordedEvent> getAction() {
            return action;
        }
    }

    private final Consumer<Throwable>[] errorActions;
    private final Runnable[] flushActions;
    private final Runnable[] closeActions;
    private final EventDispatcher[] dispatchers;
    private final LongMap<EventDispatcher[]> dispatcherLookup = new LongMap<>();
    final ParserConfiguration parserConfiguration;
    final Instant startTime;
    final Instant endTime;
    final long startNanos;
    final long endNanos;

    // Cache
    private EventType cacheEventType;
    private EventDispatcher[] cacheDispatchers;

    @SuppressWarnings({"rawtypes", "unchecked"})
    public Dispatcher(StreamConfiguration c) {
        this.flushActions = c.flushActions.toArray(new Runnable[0]);
        this.closeActions = c.closeActions.toArray(new Runnable[0]);
        this.errorActions = c.errorActions.toArray(new Consumer[0]);
        this.dispatchers = c.eventActions.toArray(new EventDispatcher[0]);
        this.parserConfiguration = new ParserConfiguration(0, Long.MAX_VALUE, c.reuse, c.ordered, buildFilter(dispatchers));
        this.startTime = c.startTime;
        this.endTime = c.endTime;
        this.startNanos = c.startNanos;
        this.endNanos = c.endNanos;
    }

    public void runFlushActions() {
        Runnable[] flushActions = this.flushActions;
        for (int i = 0; i < flushActions.length; i++) {
            try {
                flushActions[i].run();
            } catch (Exception e) {
                handleError(e);
            }
        }
    }

    public void runCloseActions() {
        Runnable[] closeActions = this.closeActions;
        for (int i = 0; i < closeActions.length; i++) {
            try {
                closeActions[i].run();
            } catch (Exception e) {
                handleError(e);
            }
        }
    }

    private static ParserFilter buildFilter(EventDispatcher[] dispatchers) {
        ParserFilter ef = new ParserFilter();
        for (EventDispatcher ed : dispatchers) {
            String name = ed.eventName;
            if (name == null) {
                return ParserFilter.ACCEPT_ALL;
            }
            ef.setThreshold(name, 0);
        }
        return ef;
    }

    void dispatch(RecordedEvent event) {
        EventType type = event.getEventType();
        EventDispatcher[] dispatchers = null;
        if (type == cacheEventType) {
            dispatchers = cacheDispatchers;
        } else {
            dispatchers = dispatcherLookup.get(type.getId());
            if (dispatchers == null) {
                List<EventDispatcher> list = new ArrayList<>();
                for (EventDispatcher e : this.dispatchers) {
                    if (e.accepts(type)) {
                        list.add(e);
                    }
                }
                dispatchers = list.isEmpty() ? EventDispatcher.NO_DISPATCHERS : list.toArray(new EventDispatcher[0]);
                dispatcherLookup.put(type.getId(), dispatchers);
            }
            cacheDispatchers = dispatchers;
        }
        // Expected behavior if exception occurs in onEvent:
        //
        // Synchronous:
        //  - User has added onError action:
        //     Catch exception, call onError and continue with next event
        //     Let Errors propagate to caller of EventStream::start
        //  - Default action
        //     Catch exception, e.printStackTrace() and continue with next event
        //     Let Errors propagate to caller of EventStream::start
        //
        // Asynchronous
        //  - User has added onError action
        //     Catch exception, call onError and continue with next event
        //     Let Errors propagate, shutdown thread and stream
        //  - Default action
        //    Catch exception, e.printStackTrace() and continue with next event
        //    Let Errors propagate and shutdown thread and stream
        //
        for (int i = 0; i < dispatchers.length; i++) {
            try {
                dispatchers[i].offer(event);
            } catch (Exception e) {
                handleError(e);
            }
        }
    }

    private void handleError(Throwable e) {
        Consumer<?>[] consumers = this.errorActions;
        if (consumers.length == 0) {
            defaultErrorHandler(e);
            return;
        }
        for (int i = 0; i < consumers.length; i++) {
            @SuppressWarnings("unchecked")
            Consumer<Throwable> consumer = (Consumer<Throwable>) consumers[i];
            consumer.accept(e);
        }
    }

    private void defaultErrorHandler(Throwable e) {
        e.printStackTrace();
    }
}