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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * accompanied this code).

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package jdk.jfr.api.consumer.streaming;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.time.Duration;

import java.time.Instant;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicInteger;

import com.sun.tools.attach.VirtualMachine;

import jdk.jfr.Event;

import jdk.jfr.Recording;

import jdk.jfr.consumer.EventStream;

import jdk.test.lib.Asserts;

import jdk.test.lib.process.ProcessTools;

/**

 * @test

 * @summary Test scenario where JFR event producer is in a different process

 *          with respect to the JFR event stream consumer.

 * @key jfr

 * @requires vm.hasJFR

 * @library /test/lib /test/jdk

 * @modules jdk.attach

 *          jdk.jfr

 * @run main jdk.jfr.api.consumer.streaming.TestCrossProcessStreaming

 */

public class TestCrossProcessStreaming {

    static String MAIN_STARTED_TOKEN = "MAIN_STARTED";

    public static class TestEvent extends Event {

    }

    public static class ResultEvent extends Event {

        int nrOfEventsProduced;

    }

    public static class EventProducer {

        public static void main(String... args) throws Exception {

            CrossProcessSynchronizer sync = new CrossProcessSynchronizer();

            log(MAIN_STARTED_TOKEN);

            long pid = ProcessHandle.current().pid();

            int nrOfEvents = 0;

            boolean exitRequested = false;

            while (!exitRequested) {

                TestEvent e = new TestEvent();

                e.commit();

                nrOfEvents++;

                if (nrOfEvents % 1000 == 0) {

                    Thread.sleep(100);

                    exitRequested = CrossProcessSynchronizer.exitRequested(pid);

                }

            }

            ResultEvent re = new ResultEvent();

            re.nrOfEventsProduced = nrOfEvents;

            re.commit();

            log("Number of TestEvents generated: " + nrOfEvents);

        }

    }

    static class CrossProcessSynchronizer {

        static void requestExit(long pid) throws Exception {

            Files.createFile(file(pid));

       }

        static boolean exitRequested(long pid) throws Exception {

            return Files.exists(file(pid));

        }

        static Path file(long pid) {

            return Paths.get(".", "exit-requested-" + pid);

        }

    }

    static class ConsumedEvents {

        AtomicInteger total = new AtomicInteger(0);

        AtomicInteger whileProducerAlive = new AtomicInteger(0);

        AtomicInteger produced = new AtomicInteger(-1);

    }

    public static void main(String... args) throws Exception {

        Process p = startProducerProcess("normal");

        String repo = getJfrRepository(p);

        ConsumedEvents ce = consumeEvents(p, repo);

        p.waitFor();

        Asserts.assertEquals(p.exitValue(), 0,

                             "Process exited abnormally, exitValue = " + p.exitValue());

        Asserts.assertEquals(ce.total.get(), ce.produced.get(), "Some events were lost");

        // Expected that some portion of events emitted by the producer are delivered

        // to the consumer while producer is still alive, at least one event for certain.

        Asserts.assertLTE(1, ce.whileProducerAlive.get(),

                           "Too few events are delivered while producer is alive");

    }

    static Process startProducerProcess(String extraParam) throws Exception {

        ProcessBuilder pb =

            ProcessTools.createJavaProcessBuilder(false,

                                                  "-XX:StartFlightRecording",

                                                  EventProducer.class.getName(),

                                                  extraParam);

        Process p = ProcessTools.startProcess("Event-Producer", pb,

                                              line -> line.equals(MAIN_STARTED_TOKEN),

                                              0, TimeUnit.SECONDS);

        return p;

    }

    static String getJfrRepository(Process p) throws Exception {

        String repo = null;

        // It may take little bit of time for the observed process to set the property after

        // the process starts, therefore read the property in a loop.

        while (repo == null) {

            VirtualMachine vm = VirtualMachine.attach(String.valueOf(p.pid()));

            repo = vm.getSystemProperties().getProperty("jdk.jfr.repository");

            vm.detach();

        }

        log("JFR repository = " + repo);

        return repo;

    }

    static ConsumedEvents consumeEvents(Process p, String repo) throws Exception {

        ConsumedEvents result = new ConsumedEvents();

        // wait for couple of JFR stream flushes before concluding the test

        CountDownLatch flushed = new CountDownLatch(2);

        // consume events produced by another process via event stream

        try (EventStream es = EventStream.openRepository(Paths.get(repo))) {

                es.onEvent(TestEvent.class.getName(),

                           e -> {

                               result.total.incrementAndGet();

                               if (p.isAlive()) {

                                   result.whileProducerAlive.incrementAndGet();

                               }

                           });

                es.onEvent(ResultEvent.class.getName(),

                           e -> result.produced.set(e.getInt("nrOfEventsProduced")));

                es.onFlush( () -> flushed.countDown() );

                // Setting start time to the beginning of the Epoch is a good way to start

                // reading the stream from the very beginning.

                es.setStartTime(Instant.EPOCH);

                es.startAsync();

                // await for certain number of flush events before concluding the test case

                flushed.await();

                CrossProcessSynchronizer.requestExit(p.pid());

                es.awaitTermination();

            }

        return result;

    }

    private static final void log(String msg) {

        System.out.println(msg);

    }

}