src/vm/TraceLoggingGraph.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "vm/TraceLoggingGraph.h"

#ifdef XP_WIN
#  include <process.h>
#  define getpid _getpid
#else
#  include <unistd.h>
#endif

#include "mozilla/EndianUtils.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/ScopeExit.h"

#include "js/Printf.h"
#include "js/UniquePtr.h"
#include "threading/LockGuard.h"
#include "threading/Thread.h"
#include "util/Text.h"
#include "vm/TraceLogging.h"

#ifndef DEFAULT_TRACE_LOG_DIR
#  if defined(_WIN32)
#    define DEFAULT_TRACE_LOG_DIR "."
#  else
#    define DEFAULT_TRACE_LOG_DIR "/tmp/"
#  endif
#endif

using mozilla::MakeScopeExit;
using mozilla::NativeEndian;

TraceLoggerGraphState* traceLoggerGraphState = nullptr;

// gcc and clang have these in symcat.h, but MSVC does not.
#ifndef STRINGX
#  define STRINGX(x) #  x
#endif
#ifndef XSTRING
#  define XSTRING(macro) STRINGX(macro)
#endif

#define MAX_LOGGERS 999

// Return a filename relative to the output directory. %u and %d substitutions
// are allowed, with %u standing for a full 32-bit number and %d standing for
// an up to 3-digit number.
static js::UniqueChars MOZ_FORMAT_PRINTF(1, 2)
    AllocTraceLogFilename(const char* pattern, ...) {
  va_list ap;

  const char* outdir =
      getenv("TLDIR") ? getenv("TLDIR") : DEFAULT_TRACE_LOG_DIR;
  size_t len = strlen(outdir) + 1;  // "+ 1" is for the '/'

  for (const char* p = pattern; *p; p++) {
    if (*p == '%') {
      p++;
      if (*p == 'u') {
        len += sizeof("4294967295") - 1;
      } else if (*p == 'd') {
        len += sizeof(XSTRING(MAX_LOGGERS)) - 1;
      } else {
        MOZ_CRASH("Invalid format");
      }
    } else {
      len++;
    }
  }

  len++;  // For the terminating NUL.

  js::UniqueChars filename(js_pod_malloc<char>(len));
  if (!filename) {
    return nullptr;
  }
  char* rest = filename.get() + sprintf(filename.get(), "%s/", outdir);

  va_start(ap, pattern);
  int ret = vsnprintf(rest, len, pattern, ap);
  va_end(ap);
  if (ret < 0) {
    return nullptr;
  }

  MOZ_ASSERT(size_t(ret) <= len - (strlen(outdir) + 1),
             "overran TL filename buffer; %d given too large a value?");

  return filename;
}

bool TraceLoggerGraphState::init() {
  pid_ = (uint32_t)getpid();

  js::UniqueChars filename = AllocTraceLogFilename("tl-data.%u.json", pid_);
  out = fopen(filename.get(), "w");
  if (!out) {
    fprintf(stderr, "warning: failed to create TraceLogger output file %s\n",
            filename.get());
    return false;
  }

  fprintf(out, "[");

  // Write the latest tl-data.*.json file to tl-data.json.
  // In most cases that is the wanted file.
  js::UniqueChars masterFilename = AllocTraceLogFilename("tl-data.json");
  if (FILE* last = fopen(masterFilename.get(), "w")) {
    char* basename = strrchr(filename.get(), '/');
    basename = basename ? basename + 1 : filename.get();
    fprintf(last, "\"%s\"", basename);
    fclose(last);
  }

#ifdef DEBUG
  initialized = true;
#endif
  return true;
}

TraceLoggerGraphState::~TraceLoggerGraphState() {
  if (out) {
    fprintf(out, "]");
    fclose(out);
    out = nullptr;
  }

#ifdef DEBUG
  initialized = false;
#endif
}

uint32_t TraceLoggerGraphState::nextLoggerId() {
  js::LockGuard<js::Mutex> guard(lock);

  MOZ_ASSERT(initialized);

  if (numLoggers > MAX_LOGGERS) {
    fputs("TraceLogging: Can't create more than " XSTRING(
              MAX_LOGGERS) " different loggers.",
          stderr);
    return uint32_t(-1);
  }

  if (numLoggers > 0) {
    int written = fprintf(out, ",\n");
    if (written < 0) {
      fprintf(stderr, "TraceLogging: Error while writing.\n");
      return uint32_t(-1);
    }
  }

  int written = fprintf(
      out,
      "{\"tree\":\"tl-tree.%u.%u.tl\", \"events\":\"tl-event.%u.%u.tl\", "
      "\"dict\":\"tl-dict.%u.%u.json\", \"treeFormat\":\"64,64,31,1,32\"",
      pid_, numLoggers, pid_, numLoggers, pid_, numLoggers);

  if (written > 0) {
    char threadName[16];
    js::ThisThread::GetName(threadName, sizeof(threadName));
    if (threadName[0]) {
      written = fprintf(out, R"(, "threadName":"%s")", threadName);
    }
  }

  if (written > 0) {
    written = fprintf(out, "}");
  }

  if (written < 0) {
    fprintf(stderr, "TraceLogging: Error while writing.\n");
    return uint32_t(-1);
  }

  return numLoggers++;
}

size_t TraceLoggerGraphState::sizeOfExcludingThis(
    mozilla::MallocSizeOf mallocSizeOf) const {
  return 0;
}

static bool EnsureTraceLoggerGraphState() {
  if (MOZ_LIKELY(traceLoggerGraphState)) {
    return true;
  }

  traceLoggerGraphState = js_new<TraceLoggerGraphState>();
  if (!traceLoggerGraphState) {
    return false;
  }

  if (!traceLoggerGraphState->init()) {
    js::DestroyTraceLoggerGraphState();
    return false;
  }

  return true;
}

size_t js::SizeOfTraceLogGraphState(mozilla::MallocSizeOf mallocSizeOf) {
  return traceLoggerGraphState
             ? traceLoggerGraphState->sizeOfIncludingThis(mallocSizeOf)
             : 0;
}

void js::DestroyTraceLoggerGraphState() {
  if (traceLoggerGraphState) {
    js_delete(traceLoggerGraphState);
    traceLoggerGraphState = nullptr;
  }
}

bool TraceLoggerGraph::init(uint64_t startTimestamp, bool graphFileEnabled) {
  auto fail = MakeScopeExit([&] { failed = true; });

  if (graphFileEnabled) {
    if (!EnsureTraceLoggerGraphState()) {
      return false;
    }

    uint32_t loggerId = traceLoggerGraphState->nextLoggerId();
    if (loggerId == uint32_t(-1)) {
      return false;
    }

    uint32_t pid = traceLoggerGraphState->pid();

    js::UniqueChars dictFilename =
        AllocTraceLogFilename("tl-dict.%u.%u.json", pid, loggerId);
    dictFile = fopen(dictFilename.get(), "w");
    if (!dictFile) {
      return false;
    }
    auto cleanupDict = MakeScopeExit([&] {
      fclose(dictFile);
      dictFile = nullptr;
    });

    js::UniqueChars treeFilename =
        AllocTraceLogFilename("tl-tree.%u.%u.tl", pid, loggerId);
    treeFile = fopen(treeFilename.get(), "w+b");
    if (!treeFile) {
      return false;
    }
    auto cleanupTree = MakeScopeExit([&] {
      fclose(treeFile);
      treeFile = nullptr;
    });

    js::UniqueChars eventFilename =
        AllocTraceLogFilename("tl-event.%u.%u.tl", pid, loggerId);
    eventFile = fopen(eventFilename.get(), "wb");
    if (!eventFile) {
      return false;
    }
    auto cleanupEvent = MakeScopeExit([&] {
      fclose(eventFile);
      eventFile = nullptr;
    });

    if (fprintf(dictFile, "[") < 0) {
      fprintf(stderr, "TraceLogging: Error while writing.\n");
      return false;
    }

    cleanupDict.release();
    cleanupTree.release();
    cleanupEvent.release();
  }

  if (!tree.init()) {
    return false;
  }
  if (!stack.init()) {
    return false;
  }

  // Create the top tree node and corresponding first stack item.
  TreeEntry& treeEntry = tree.pushUninitialized();
  treeEntry.setStart(startTimestamp);
  treeEntry.setStop(0);
  treeEntry.setTextId(0);
  treeEntry.setHasChildren(false);
  treeEntry.setNextId(0);

  StackEntry& stackEntry = stack.pushUninitialized();
  stackEntry.setTreeId(0);
  stackEntry.setLastChildId(0);
  stackEntry.setActive(true);

  fail.release();

  return true;
}

TraceLoggerGraph::~TraceLoggerGraph() {
  // Write dictionary to disk
  if (dictFile) {
    int written = fprintf(dictFile, "]");
    if (written < 0) {
      fprintf(stderr, "TraceLogging: Error while writing.\n");
    }
    fclose(dictFile);

    dictFile = nullptr;
  }

  if (!failed && treeFile) {
    // Make sure every start entry has a corresponding stop value.
    // We temporarily enable logging for this. Stop doesn't need any extra data,
    // so is safe to do even when we have encountered OOM.
    enabled = true;
    while (stack.size() > 1) {
      stopEvent(0);
    }
    enabled = false;
  }

  if (!failed && !flush()) {
    fprintf(stderr, "TraceLogging: Couldn't write the data to disk.\n");
    enabled = false;
    failed = true;
  }

  if (treeFile) {
    fclose(treeFile);
    treeFile = nullptr;
  }

  if (eventFile) {
    fclose(eventFile);
    eventFile = nullptr;
  }
}

bool TraceLoggerGraph::flush() {
  MOZ_ASSERT(!failed);

  if (treeFile) {
    // Format data in big endian.
    for (size_t i = 0; i < tree.size(); i++) {
      entryToBigEndian(&tree[i]);
    }

    int success = fseek(treeFile, 0, SEEK_END);
    if (success != 0) {
      return false;
    }

    size_t bytesWritten =
        fwrite(tree.data(), sizeof(TreeEntry), tree.size(), treeFile);
    if (bytesWritten < tree.size()) {
      return false;
    }

    treeOffset += tree.size();
    tree.clear();
  }

  return true;
}

void TraceLoggerGraph::entryToBigEndian(TreeEntry* entry) {
  entry->start_ = NativeEndian::swapToBigEndian(entry->start_);
  entry->stop_ = NativeEndian::swapToBigEndian(entry->stop_);
  uint32_t data = (entry->u.s.textId_ << 1) + entry->u.s.hasChildren_;
  entry->u.value_ = NativeEndian::swapToBigEndian(data);
  entry->nextId_ = NativeEndian::swapToBigEndian(entry->nextId_);
}

void TraceLoggerGraph::entryToSystemEndian(TreeEntry* entry) {
  entry->start_ = NativeEndian::swapFromBigEndian(entry->start_);
  entry->stop_ = NativeEndian::swapFromBigEndian(entry->stop_);

  uint32_t data = NativeEndian::swapFromBigEndian(entry->u.value_);
  entry->u.s.textId_ = data >> 1;
  entry->u.s.hasChildren_ = data & 0x1;

  entry->nextId_ = NativeEndian::swapFromBigEndian(entry->nextId_);
}

void TraceLoggerGraph::startEvent(uint32_t id, uint64_t timestamp) {
  if (failed || enabled == 0) {
    return;
  }

  if (!tree.hasSpaceForAdd()) {
    if (tree.size() >= treeSizeFlushLimit() || !tree.ensureSpaceBeforeAdd()) {
      if (!treeFile) {
        disable(timestamp);
        return;
      }

      if (!flush()) {
        fprintf(stderr, "TraceLogging: Couldn't write the data to disk.\n");
        enabled = false;
        failed = true;
        return;
      }
    }
  }

  if (!startEventInternal(id, timestamp)) {
    fprintf(stderr, "TraceLogging: Failed to start an event.\n");
    enabled = false;
    failed = true;
    return;
  }
}

TraceLoggerGraph::StackEntry& TraceLoggerGraph::getActiveAncestor() {
  uint32_t parentId = stack.lastEntryId();
  while (!stack[parentId].active()) {
    parentId--;
  }
  return stack[parentId];
}

bool TraceLoggerGraph::startEventInternal(uint32_t id, uint64_t timestamp) {
  if (!stack.ensureSpaceBeforeAdd()) {
    return false;
  }

  // Patch up the tree to be correct. There are two scenarios:
  // 1) Parent has no children yet. So update parent to include children.
  // 2) Parent has already children. Update last child to link to the new
  //    child.
  StackEntry& parent = getActiveAncestor();
#ifdef DEBUG
  TreeEntry entry;
  if (!getTreeEntry(parent.treeId(), &entry)) {
    return false;
  }
#endif

  if (parent.lastChildId() == 0) {
    MOZ_ASSERT(!entry.hasChildren());
    MOZ_ASSERT(parent.treeId() == treeOffset + tree.size() - 1);

    if (!updateHasChildren(parent.treeId())) {
      return false;
    }
  } else {
    MOZ_ASSERT(entry.hasChildren());

    if (!updateNextId(parent.lastChildId(), tree.size() + treeOffset)) {
      return false;
    }
  }

  // Add a new tree entry.
  TreeEntry& treeEntry = tree.pushUninitialized();
  treeEntry.setStart(timestamp);
  treeEntry.setStop(0);
  treeEntry.setTextId(id);
  treeEntry.setHasChildren(false);
  treeEntry.setNextId(0);

  // Add a new stack entry.
  StackEntry& stackEntry = stack.pushUninitialized();
  stackEntry.setTreeId(tree.lastEntryId() + treeOffset);
  stackEntry.setLastChildId(0);
  stackEntry.setActive(true);

  // Set the last child of the parent to this newly added entry.
  parent.setLastChildId(tree.lastEntryId() + treeOffset);

  return true;
}

void TraceLoggerGraph::stopEvent(uint32_t id, uint64_t timestamp) {
#ifdef DEBUG
  if (id != TraceLogger_Scripts && id != TraceLogger_Engine &&
      stack.size() > 1 && stack.lastEntry().active()) {
    TreeEntry entry;
    MOZ_ASSERT(getTreeEntry(stack.lastEntry().treeId(), &entry));
    MOZ_ASSERT(entry.textId() == id);
  }
#endif

  stopEvent(timestamp);
}

void TraceLoggerGraph::stopEvent(uint64_t timestamp) {
  if (enabled && stack.lastEntry().active()) {
    if (!updateStop(stack.lastEntry().treeId(), timestamp)) {
      fprintf(stderr, "TraceLogging: Failed to stop an event.\n");
      enabled = false;
      failed = true;
      return;
    }
  }
  if (stack.size() == 1) {
    if (!enabled) {
      return;
    }

    // Forcefully disable logging. We have no stack information anymore.
    logTimestamp(TraceLogger_Disable, timestamp);
    return;
  }
  stack.pop();
}

void TraceLoggerGraph::logTimestamp(uint32_t id, uint64_t timestamp) {
  if (failed) {
    return;
  }

  if (id == TraceLogger_Enable) {
    enabled = true;
  }

  if (!enabled) {
    return;
  }

  if (id == TraceLogger_Disable) {
    disable(timestamp);
  }

  if (!eventFile) {
    return;
  }

  // Format data in big endian
  timestamp = NativeEndian::swapToBigEndian(timestamp);
  id = NativeEndian::swapToBigEndian(id);

  // The layout of the event log in the log file is:
  // [timestamp, textId]
  size_t itemsWritten = 0;
  itemsWritten += fwrite(&timestamp, sizeof(uint64_t), 1, eventFile);
  itemsWritten += fwrite(&id, sizeof(uint32_t), 1, eventFile);
  if (itemsWritten < 2) {
    failed = true;
    enabled = false;
  }
}

bool TraceLoggerGraph::getTreeEntry(uint32_t treeId, TreeEntry* entry) {
  // Entry is still in memory
  if (treeId >= treeOffset) {
    *entry = tree[treeId - treeOffset];
    return true;
  }

  // If treeFile is null and treeOffset is non-zero then something is wrong
  if (!treeFile) {
    return false;
  }

  // Entry has been flushed to disk. Look it up.
  int success = fseek(treeFile, treeId * sizeof(TreeEntry), SEEK_SET);
  if (success != 0) {
    return false;
  }

  size_t itemsRead = fread((void*)entry, sizeof(TreeEntry), 1, treeFile);
  if (itemsRead < 1) {
    return false;
  }

  entryToSystemEndian(entry);
  return true;
}

bool TraceLoggerGraph::saveTreeEntry(uint32_t treeId, TreeEntry* entry) {
  MOZ_ASSERT(treeFile != nullptr);
  int success = fseek(treeFile, treeId * sizeof(TreeEntry), SEEK_SET);
  if (success != 0) {
    return false;
  }

  entryToBigEndian(entry);

  size_t itemsWritten = fwrite(entry, sizeof(TreeEntry), 1, treeFile);
  if (itemsWritten < 1) {
    return false;
  }

  return true;
}

bool TraceLoggerGraph::updateHasChildren(uint32_t treeId, bool hasChildren) {
  if (treeId < treeOffset) {
    TreeEntry entry;
    if (!getTreeEntry(treeId, &entry)) {
      return false;
    }
    entry.setHasChildren(hasChildren);
    if (treeFile && !saveTreeEntry(treeId, &entry)) {
      return false;
    }
    return true;
  }

  tree[treeId - treeOffset].setHasChildren(hasChildren);
  return true;
}

bool TraceLoggerGraph::updateNextId(uint32_t treeId, uint32_t nextId) {
  if (treeId < treeOffset) {
    TreeEntry entry;
    if (!getTreeEntry(treeId, &entry)) {
      return false;
    }
    entry.setNextId(nextId);
    if (treeFile && !saveTreeEntry(treeId, &entry)) {
      return false;
    }
    return true;
  }

  tree[treeId - treeOffset].setNextId(nextId);
  return true;
}

bool TraceLoggerGraph::updateStop(uint32_t treeId, uint64_t timestamp) {
  if (treeId < treeOffset) {
    TreeEntry entry;
    if (!getTreeEntry(treeId, &entry)) {
      return false;
    }
    entry.setStop(timestamp);
    if (treeFile && !saveTreeEntry(treeId, &entry)) {
      return false;
    }
    return true;
  }

  tree[treeId - treeOffset].setStop(timestamp);
  return true;
}

void TraceLoggerGraph::disable(uint64_t timestamp) {
  MOZ_ASSERT(enabled);
  while (stack.size() > 1) {
    stopEvent(timestamp);
  }

  enabled = false;
}

void TraceLoggerGraph::log(ContinuousSpace<EventEntry>& events,
                           mozilla::TimeStamp startTime) {
  for (uint32_t i = 0; i < events.size(); i++) {
    mozilla::TimeDuration delta = events[i].time - startTime;
    uint64_t timeOffset = static_cast<uint64_t>(delta.ToMicroseconds());

    if (events[i].textId == TraceLogger_Stop) {
      stopEvent(timeOffset);
    } else if (TLTextIdIsTreeEvent(events[i].textId)) {
      startEvent(events[i].textId, timeOffset);
    } else {
      logTimestamp(events[i].textId, timeOffset);
    }
  }
}

void TraceLoggerGraph::addTextId(uint32_t id, const char* text) {
  mozilla::Maybe<uint32_t> line = mozilla::Nothing();
  mozilla::Maybe<uint32_t> column = mozilla::Nothing();
  addTextId(id, text, line, column);
}

void TraceLoggerGraph::addTextId(uint32_t id, const char* text,
                                 mozilla::Maybe<uint32_t>& line,
                                 mozilla::Maybe<uint32_t>& column) {
  if (failed) {
    return;
  }

  // Assume ids are given in order. Which is currently true.
  MOZ_ASSERT(id == nextTextId_);
  nextTextId_++;

  if (id > 0) {
    int written = fprintf(dictFile, ",\n");
    if (written < 0) {
      failed = true;
      return;
    }
  }

  js::UniqueChars str;
  if (line && column) {
    str = JS_smprintf("script %s:%u:%u", text, *line, *column);
  } else if (line) {
    str = JS_smprintf("script %s:%u", text, *line);
  } else {
    str = JS_smprintf("%s", text);
  }

  if (!js::FileEscapedString(dictFile, str.get(), strlen(str.get()), '"')) {
    failed = true;
  }
  str.reset();
}

size_t TraceLoggerGraph::sizeOfExcludingThis(
    mozilla::MallocSizeOf mallocSizeOf) const {
  size_t size = 0;
  size += tree.sizeOfExcludingThis(mallocSizeOf);
  size += stack.sizeOfExcludingThis(mallocSizeOf);
  return size;
}

size_t TraceLoggerGraph::sizeOfIncludingThis(
    mozilla::MallocSizeOf mallocSizeOf) const {
  return mallocSizeOf(this) + sizeOfExcludingThis(mallocSizeOf);
}

#undef getpid