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package org.openjdk.jmh.profile;

import joptsimple.OptionException;
import joptsimple.OptionParser;
import joptsimple.OptionSpec;
import org.openjdk.jmh.infra.BenchmarkParams;
import org.openjdk.jmh.results.BenchmarkResult;
import org.openjdk.jmh.results.Result;
import org.openjdk.jmh.util.*;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;

Mac OS X perfasm profiler based on DTrace "profile-n" provider which samples program counter by timer interrupt. Due to DTrace limitations on Mac OS X target JVM cannot be run directly under DTrace control, so DTrace is run separately, all processes are sampled and irrelevant samples are filtered out in readEvents(double, double) stage. Super user privileges are required in order to run DTrace. 

If you see a lot of "[unknown]" regions in profile then you are probably hitting kernel code, kernel sampling is not yet supported.
Author:
Tolstopyatov Vsevolod
Since:
18/10/2017/**
 * Mac OS X perfasm profiler based on DTrace "profile-n" provider which samples program counter by timer interrupt.
 * Due to DTrace limitations on Mac OS X target JVM cannot be run directly under DTrace control, so DTrace is run separately,
 * all processes are sampled and irrelevant samples are filtered out in {@link #readEvents(double, double)} stage.
 * Super user privileges are required in order to run DTrace.
 * <p>
 * If you see a lot of "[unknown]" regions in profile then you are probably hitting kernel code, kernel sampling is not yet supported.
 *
 * @author Tolstopyatov Vsevolod
 * @since 18/10/2017
 */
public class DTraceAsmProfiler extends AbstractPerfAsmProfiler {

    private final long sampleFrequency;
    private volatile String pid;
    private volatile Process dtraceProcess;
    private OptionSpec<Long> optFrequency;

    public DTraceAsmProfiler(String initLine) throws ProfilerException {
        super(initLine, "sampled_pc");

        // Check DTrace availability
        Collection<String> messages = Utils.tryWith("sudo", "dtrace", "-V");
        if (!messages.isEmpty()) {
            throw new ProfilerException(messages.toString());
        }

        try {
            sampleFrequency = set.valueOf(optFrequency);
        } catch (OptionException e) {
            throw new ProfilerException(e.getMessage());
        }
    }

    @Override
    public void beforeTrial(BenchmarkParams params) {
        super.beforeTrial(params);
    }

    @Override
    public Collection<? extends Result> afterTrial(BenchmarkResult br, long pid, File stdOut, File stdErr) {
        if (pid == 0) {
            throw new IllegalStateException("DTrace needs the forked VM PID, but it is not initialized");
        }

        Collection<String> messages = Utils.destroy(dtraceProcess);
        if (!messages.isEmpty()) {
            throw new IllegalStateException(messages.toString());
        }

        this.pid = String.valueOf(pid);
        return super.afterTrial(br, pid, stdOut, stdErr);
    }

    @Override
    public Collection<String> addJVMInvokeOptions(BenchmarkParams params) {
        dtraceProcess = Utils.runAsync("sudo", "dtrace", "-n", "profile-" + sampleFrequency +
                        " /arg1/ { printf(\"%d 0x%lx %d\", pid, arg1, timestamp); ufunc(arg1)}", "-o",
                perfBinData.getAbsolutePath());
        return Collections.emptyList();
    }

    @Override
    public String getDescription() {
        return "DTrace profile provider + PrintAssembly Profiler";
    }

    @Override
    protected void addMyOptions(OptionParser parser) {
        optFrequency = parser.accepts("frequency",
                "Sampling frequency. This is synonymous to profile-#")
                .withRequiredArg().ofType(Long.class).describedAs("freq").defaultsTo(1001L);
    }

    @Override
    protected void parseEvents() {
        // Do nothing because DTrace writes text output anyway
    }

    @Override
    protected PerfEvents readEvents(double skipMs, double lenMs) {
        long start = (long) skipMs;
        long end = (long) (skipMs + lenMs);

        try (FileReader fr = new FileReader(perfBinData.file());
             BufferedReader reader = new BufferedReader(fr)) {

            Deduplicator<MethodDesc> dedup = new Deduplicator<>();
            Multimap<MethodDesc, Long> methods = new HashMultimap<>();
            Multiset<Long> events = new TreeMultiset<>();

            long dtraceTimestampBase = 0L;
            String line;
            while ((line = reader.readLine()) != null) {

                // Filter out DTrace misc
                if (!line.contains(":profile")) {
                    continue;
                }

                line = line.trim();
                line = line.substring(line.indexOf(":profile"));
                String[] splits = line.split(" ", 5);
                String sampledPid = splits[1];

                if (!sampledPid.equals(pid)) {
                    continue;
                }

                // Sometimes DTrace ufunc fails and gives no information about symbols
                if (splits.length < 4) {
                    continue;
                }

                long timestamp = Long.valueOf(splits[3]);
                if (dtraceTimestampBase == 0) {
                    // Use first event timestamp as base for time comparison
                    dtraceTimestampBase = timestamp;
                    continue;
                }

                long elapsed = timestamp - dtraceTimestampBase;
                long elapsedMs = TimeUnit.NANOSECONDS.toMillis(elapsed);

                if (elapsedMs < start || elapsedMs > end) {
                    continue;
                }

                long address = Long.decode(splits[2]);
                events.add(address);

                String methodLine = splits[4];
                // JIT-compiled code has address instead of symbol information
                if (methodLine.startsWith("0x")) {
                    continue;
                }

                String symbol = "[unknown]";
                String[] methodSplit = methodLine.split("`");
                String library = methodSplit[0];
                if ("".equals(library)) {
                    library = "[unknown]";
                }

                if (methodSplit.length == 2) {
                    symbol = methodSplit[1];
                }

                methods.put(dedup.dedup(MethodDesc.nativeMethod(symbol, library)), address);
            }

            IntervalMap<MethodDesc> methodMap = new IntervalMap<>();
            for (MethodDesc md : methods.keys()) {
                Collection<Long> longs = methods.get(md);
                methodMap.add(md, Utils.min(longs), Utils.max(longs));
            }

            Map<String, Multiset<Long>> allEvents = new TreeMap<>();
            assert this.events.size() == 1;
            allEvents.put(this.events.get(0), events);
            return new PerfEvents(this.events, allEvents, methodMap);

        } catch (IOException e) {
            return new PerfEvents(events);
        }

    }

    @Override
    protected String perfBinaryExtension() {
        // DTrace produces human-readable txt
        return ".txt";
    }
}