/*

 * 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.io.IOException;

import java.nio.file.Path;

import java.security.AccessControlContext;

import java.time.Instant;

import java.util.Arrays;

import java.util.Comparator;

import java.util.Objects;

import jdk.jfr.consumer.RecordedEvent;

import jdk.jfr.internal.JVM;

import jdk.jfr.internal.PlatformRecording;

import jdk.jfr.internal.Utils;

import jdk.jfr.internal.consumer.ChunkParser.ParserConfiguration;

/**

 * Implementation of an {@code EventStream}} that operates against a directory

 * with chunk files.

 *

 */

public class EventDirectoryStream extends AbstractEventStream {

    private final static Comparator<? super RecordedEvent> EVENT_COMPARATOR = JdkJfrConsumer.instance().eventComparator();

    private final RepositoryFiles repositoryFiles;

    private final PlatformRecording recording;

    private final FileAccess fileAccess;

    private ChunkParser currentParser;

    private long currentChunkStartNanos;

    private RecordedEvent[] sortedCache;

    private int threadExclusionLevel = 0;

    public EventDirectoryStream(AccessControlContext acc, Path p, FileAccess fileAccess, PlatformRecording recording) throws IOException {

        super(acc, recording);

        this.fileAccess = Objects.requireNonNull(fileAccess);

        this.recording = recording;

        this.repositoryFiles = new RepositoryFiles(fileAccess, p);

    }

    @Override

    public void close() {

        setClosed(true);

        dispatcher().runCloseActions();

        repositoryFiles.close();

    }

    @Override

    public void start() {

        start(Utils.timeToNanos(Instant.now()));

    }

    @Override

    public void startAsync() {

        startAsync(Utils.timeToNanos(Instant.now()));

    }

    @Override

    protected void process() throws IOException {

        JVM jvm = JVM.getJVM();

        Thread t = Thread.currentThread();

        try {

            if (jvm.isExcluded(t)) {

                threadExclusionLevel++;

            } else {

                jvm.exclude(t);

            }

            processRecursionSafe();

        } finally {

            if (threadExclusionLevel > 0) {

                threadExclusionLevel--;

            } else {

                jvm.include(t);

            }

        }

    }

    protected void processRecursionSafe() throws IOException {

        Dispatcher disp = dispatcher();

        Path path;

        boolean validStartTime = recording != null || disp.startTime != null;

        if (validStartTime) {

            path = repositoryFiles.firstPath(disp.startNanos);

        } else {

            path = repositoryFiles.lastPath();

        }

        if (path == null) { // closed

            return;

        }

        currentChunkStartNanos = repositoryFiles.getTimestamp(path);

        try (RecordingInput input = new RecordingInput(path.toFile(), fileAccess)) {

            currentParser = new ChunkParser(input, disp.parserConfiguration);

            long segmentStart = currentParser.getStartNanos() + currentParser.getChunkDuration();

            long filterStart = validStartTime ? disp.startNanos : segmentStart;

            long filterEnd = disp.endTime != null ? disp.endNanos: Long.MAX_VALUE;

            while (!isClosed()) {

                boolean awaitnewEvent = false;

                while (!isClosed() && !currentParser.isChunkFinished()) {

                    disp = dispatcher();

                    ParserConfiguration pc = disp.parserConfiguration;

                    pc.filterStart = filterStart;

                    pc.filterEnd = filterEnd;

                    currentParser.updateConfiguration(pc, true);

                    currentParser.setFlushOperation(getFlushOperation());

                    if (pc.isOrdered()) {

                        awaitnewEvent = processOrdered(disp, awaitnewEvent);

                    } else {

                        awaitnewEvent = processUnordered(disp, awaitnewEvent);

                    }

                    if (currentParser.getStartNanos() + currentParser.getChunkDuration() > filterEnd) {

                        close();

                        return;

                    }

                }

                if (isLastChunk()) {

                    // Recording was stopped/closed externally, and no more data to process.

                    return;

                }

                if (repositoryFiles.hasFixedPath() && currentParser.isFinalChunk()) {

                    // JVM process exited/crashed, or repository migrated to an unknown location

                    return;

                }

                if (isClosed()) {

                    // Stream was closed

                    return;

                }

                long durationNanos = currentParser.getChunkDuration();

                if (durationNanos == 0) {

                    // Avoid reading the same chunk again and again if

                    // duration is 0 ns

                    durationNanos++;

                }

                path = repositoryFiles.nextPath(currentChunkStartNanos + durationNanos);

                if (path == null) {

                    return; // stream closed

                }

                currentChunkStartNanos = repositoryFiles.getTimestamp(path);

                input.setFile(path);

                currentParser = currentParser.newChunkParser();

                // TODO: Optimization. No need filter when we reach new chunk

                // Could set start = 0;

            }

        }

    }

    private boolean isLastChunk() {

        if (recording == null) {

            return false;

        }

        return recording.getFinalChunkStartNanos() >= currentParser.getStartNanos();

    }

    private boolean processOrdered(Dispatcher c, boolean awaitNewEvents) throws IOException {

        if (sortedCache == null) {

            sortedCache = new RecordedEvent[100_000];

        }

        int index = 0;

        while (true) {

            RecordedEvent e = currentParser.readStreamingEvent(awaitNewEvents);

            if (e == null) {

                // wait for new event with next call to

                // readStreamingEvent()

                awaitNewEvents = true;

                break;

            }

            awaitNewEvents = false;

            if (index == sortedCache.length) {

                sortedCache = Arrays.copyOf(sortedCache, sortedCache.length * 2);

            }

            sortedCache[index++] = e;

        }

        // no events found

        if (index == 0 && currentParser.isChunkFinished()) {

            return awaitNewEvents;

        }

        // at least 2 events, sort them

        if (index > 1) {

            Arrays.sort(sortedCache, 0, index, EVENT_COMPARATOR);

        }

        for (int i = 0; i < index; i++) {

            c.dispatch(sortedCache[i]);

        }

        return awaitNewEvents;

    }

    private boolean processUnordered(Dispatcher c, boolean awaitNewEvents) throws IOException {

        while (true) {

            RecordedEvent e = currentParser.readStreamingEvent(awaitNewEvents);

            if (e == null) {

                return true;

            } else {

                c.dispatch(e);

            }

        }

    }

}