io.perfmark.tracewriter.TraceEventWriter Maven / Gradle / Ivy

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package io.perfmark.tracewriter;

import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonIOException;
import com.google.gson.annotations.SerializedName;
import io.perfmark.impl.Mark;
import io.perfmark.impl.MarkList;
import io.perfmark.impl.Storage;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.lang.management.ManagementFactory;
import java.lang.reflect.Method;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.zip.GZIPOutputStream;
import javax.annotation.Nullable;

/**
 * Writes the PerfMark results to a "Trace Event" JSON file usable by the Chromium Profiler
 * "Catapult". The format is defined at
 * https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview
 */
public final class TraceEventWriter {

  private static final Logger logger = Logger.getLogger(TraceEventWriter.class.getName());

  /**
   * Writes trace events the home directory. By default, it prefers the location in {@code
   * $XDG_DATA_HOME/perfmark} environment variable. If unset, it attempts to use {@code
   * $HOME/.local/share/perfmark}.
   *
   * Authors note: if you are on Windows, or the above defaults aren't right, I'm not really sure
   * where else is a good place to put this data. Please file an issue at https://perfmark.io/ if
   * you have a preference.
   *
   * @throws IOException if there is an error writing to the file.
   */
  public static void writeTraceEvents() throws IOException {
    Path p = pickNextDest(guessDirectory());
    try (OutputStream os = Files.newOutputStream(p)) {
      logger.info("Writing trace to " + p);
      try (OutputStream gzos = new GZIPOutputStream(os)) {
        try (Writer osw = new OutputStreamWriter(gzos, UTF_8)) {
          writeTraceEvents(osw);
        }
      }
    }
  }

  public static void writeTraceEvents(Writer destination) throws IOException {
    writeTraceEvents(
        destination, Storage.read(), Storage.getInitNanoTime(), System.nanoTime(), getPid());
  }

  /**
   * Writes the trace events gathered from {@link Storage#read()}. This method is not API stable. It
   * will be eventually.
   */
  public static void writeTraceEvents(
      Writer destination,
      List markLists,
      long initNanoTime,
      long nowNanoTime,
      long pid)
      throws IOException {
    List traceEvents = new ArrayList<>();
    new TraceEventWalker(traceEvents, pid, initNanoTime).walk(markLists, nowNanoTime);
    Gson gson = new GsonBuilder().setPrettyPrinting().create();
    try {
      gson.toJson(new TraceEventObject(traceEvents), destination);
    } catch (JsonIOException e) {
      throw new IOException(e);
    }
  }

  private static Path pickNextDest(Path dir) throws IOException {
    String fmt = "perfmark-trace-%03d.json.gz";
    int lo;
    int hi = 0;
    while (true) {
      Path candidate = dir.resolve(String.format(fmt, hi));
      if (!Files.exists(candidate)) {
        lo = hi >>> 1;
        break;
      }
      if (hi == 0) {
        hi++;
      } else if (hi >>> 1 >= Integer.MAX_VALUE) {
        throw new IOException("too many files in dir");
      } else {
        hi <<= 1;
      }
    }
    // After this point, hi must always point to a non-existent file.
    while (hi > lo) {
      int mid = (hi + lo) >>> 1; // take THAT, overflow!
      Path candidate = dir.resolve(String.format(fmt, mid));
      if (Files.exists(candidate)) {
        lo = mid + 1;
      } else {
        hi = mid;
      }
    }
    return dir.resolve(String.format(fmt, hi));
  }

  private static Path guessDirectory() throws IOException {
    final String PERFMARK_TRACE_DIR = "perfmark";
    final String sep = File.separator;

    List dataHomeChoices = new ArrayList<>();
    String dataHome = System.getenv("XDG_DATA_HOME");
    if (dataHome != null) {
      dataHomeChoices.add(new File(dataHome + sep + PERFMARK_TRACE_DIR).toPath());
    }
    String home = System.getProperty("user.home");
    if (home != null) {
      dataHomeChoices.add(
          new File(home + sep + ".local" + sep + "share" + sep + PERFMARK_TRACE_DIR).toPath());
    }
    for (Path path : dataHomeChoices) {
      if (!Files.exists(path)) {
        Files.createDirectories(path);
      } else {
        if (!Files.isDirectory(path)) {
          continue;
        }
      }
      return path;
    }
    return new File(".").toPath();
  }

  static final class TraceEventObject {
    @SerializedName("traceEvents")
    @SuppressWarnings("unused")
    final List traceEvents;

    @SerializedName("displayTimeUnit")
    @SuppressWarnings("unused")
    final String displayTimeUnit = "ns";

    @SerializedName("systemTraceEvents")
    @SuppressWarnings("unused")
    final String systemTraceData = "";

    @SerializedName("samples")
    @SuppressWarnings("unused")
    final List