gecko-dev/tools/profiler/tasktracer/GeckoTaskTracer.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "GeckoTaskTracer.h"
#include "GeckoTaskTracerImpl.h"

#include "platform.h"

#include "mozilla/DebugOnly.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/StaticMutex.h"
#include "mozilla/ThreadLocal.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Unused.h"
#include "nsString.h"
#include "nsThreadUtils.h"
#include "prtime.h"

#include <stdarg.h>

#define MAX_SIZE_LOG (1024 * 128)

// NS_ENSURE_TRUE_VOID() without the warning on the debug build.
#define ENSURE_TRUE_VOID(x)   \
  do {                        \
    if (MOZ_UNLIKELY(!(x))) { \
      return;                 \
    }                         \
  } while (0)

// NS_ENSURE_TRUE() without the warning on the debug build.
#define ENSURE_TRUE(x, ret)   \
  do {                        \
    if (MOZ_UNLIKELY(!(x))) { \
      return ret;             \
    }                         \
  } while (0)

namespace mozilla {
namespace tasktracer {

#define SOURCE_EVENT_NAME(type) \
  const char* CreateSourceEvent##type() { return "SourceEvent" #type; }
#include "SourceEventTypeMap.h"
#undef SOURCE_EVENT_NAME

static MOZ_THREAD_LOCAL(TraceInfo*) sTraceInfoTLS;
static mozilla::StaticMutex sMutex;

// The generation of TraceInfo. It will be > 0 if the Task Tracer is started and
// <= 0 if stopped.
bool gStarted(false);
static nsTArray<UniquePtr<TraceInfo>>* sTraceInfos = nullptr;
static PRTime sStartTime;

static const char sJSLabelPrefix[] = "#tt#";

namespace {

static PRTime GetTimestamp() { return PR_Now() / 1000; }

static TraceInfo* AllocTraceInfo(int aTid) {
  sMutex.AssertCurrentThreadOwns();
  MOZ_ASSERT(sTraceInfos);
  auto* info = sTraceInfos->AppendElement(MakeUnique<TraceInfo>(aTid));

  return info->get();
}

static void CreateSourceEvent(SourceEventType aType) {
  // Create a new unique task id.
  uint64_t newId = GenNewUniqueTaskId();
  {
    TraceInfoHolder info = GetOrCreateTraceInfo();
    ENSURE_TRUE_VOID(info);

    info->mCurTraceSourceId = newId;
    info->mCurTraceSourceType = aType;
    info->mCurTaskId = newId;
  }

  uintptr_t* namePtr;
#define SOURCE_EVENT_NAME(type)                     \
  case SourceEventType::type: {                     \
    namePtr = (uintptr_t*)&CreateSourceEvent##type; \
    break;                                          \
  }

  switch (aType) {
#include "SourceEventTypeMap.h"
    default:
      MOZ_CRASH("Unknown SourceEvent.");
  }
#undef SOURCE_EVENT_NAME

  // Log a fake dispatch and start for this source event.
  LogDispatch(newId, newId, newId, aType);
  LogVirtualTablePtr(newId, newId, namePtr);
  LogBegin(newId, newId);
}

static void DestroySourceEvent() {
  // Log a fake end for this source event.
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  uint64_t curTraceSourceId;
  curTraceSourceId = info->mCurTraceSourceId;
  info.Reset();

  LogEnd(curTraceSourceId, curTraceSourceId);
}

inline static void ObsoleteCurrentTraceInfos() {
  MOZ_ASSERT(sTraceInfos);
  for (uint32_t i = 0; i < sTraceInfos->Length(); ++i) {
    (*sTraceInfos)[i]->mObsolete = true;
  }
}

static void SetLogStarted(bool aIsStartLogging) {
  MOZ_ASSERT(aIsStartLogging != gStarted);
  StaticMutexAutoLock lock(sMutex);

  gStarted = aIsStartLogging;

  if (aIsStartLogging && sTraceInfos == nullptr) {
    sTraceInfos = new nsTArray<UniquePtr<TraceInfo>>();
  }

  if (!aIsStartLogging && sTraceInfos) {
    ObsoleteCurrentTraceInfos();
  }
}

}  // namespace

TraceInfoLogType* TraceInfo::AppendLog() {
  if (mLogsSize >= MAX_SIZE_LOG) {
    return nullptr;
  }
  TraceInfoLogNode* node = new TraceInfoLogNode;
  node->mNext = nullptr;
  if (mLogsTail) {
    mLogsTail->mNext = node;
    mLogsTail = node;
  } else {
    mLogsTail = mLogsHead = node;
  }
  mLogsSize++;
  return &node->mLog;
}

void InitTaskTracer(uint32_t aFlags) {
  StaticMutexAutoLock lock(sMutex);

  if (aFlags & FORKED_AFTER_NUWA) {
    ObsoleteCurrentTraceInfos();
    return;
  }

  MOZ_ASSERT(!sTraceInfos);

  bool success = sTraceInfoTLS.init();
  if (!success) {
    MOZ_CRASH();
  }
}

void ShutdownTaskTracer() {
  if (IsStartLogging()) {
    SetLogStarted(false);

    StaticMutexAutoLock lock(sMutex);
    // Make sure all threads are out of holding mutics.
    // See |GetOrCreateTraceInfo()|
    for (auto& traceinfo : *sTraceInfos) {
      MutexAutoLock lock(traceinfo->mLogsMutex);
    }
    delete sTraceInfos;
    sTraceInfos = nullptr;
  }
}

static void FreeTraceInfo(TraceInfo* aTraceInfo) {
  sMutex.AssertCurrentThreadOwns();
  if (aTraceInfo) {
    UniquePtr<TraceInfo> traceinfo(aTraceInfo);
    mozilla::DebugOnly<bool> removed = sTraceInfos->RemoveElement(traceinfo);
    MOZ_ASSERT(removed);
    Unused << traceinfo.release();  // A dirty hack to prevent double free.
  }
}

void FreeTraceInfo() {
  StaticMutexAutoLock lock(sMutex);
  if (sTraceInfos) {
    FreeTraceInfo(sTraceInfoTLS.get());
  }
}

TraceInfoHolder GetOrCreateTraceInfo() {
  TraceInfo* info = sTraceInfoTLS.get();
  StaticMutexAutoLock lock(sMutex);
  ENSURE_TRUE(IsStartLogging(), TraceInfoHolder{});

  if (info && info->mObsolete) {
    // TraceInfo is obsolete: remove it.
    FreeTraceInfo(info);
    info = nullptr;
  }

  if (!info) {
    info = AllocTraceInfo(profiler_current_thread_id());
    sTraceInfoTLS.set(info);
  }

  return TraceInfoHolder{info};  // |mLogsMutex| will be held, then
                                 // ||sMutex| will be released for
                                 // efficiency reason.
}

uint64_t GenNewUniqueTaskId() {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE(info, 0);

  int tid = profiler_current_thread_id();
  uint64_t taskid = ((uint64_t)tid << 32) | ++info->mLastUniqueTaskId;
  return taskid;
}

AutoSaveCurTraceInfoImpl::AutoSaveCurTraceInfoImpl() {
  GetCurTraceInfo(&mSavedSourceEventId, &mSavedTaskId, &mSavedSourceEventType);
}

AutoSaveCurTraceInfoImpl::~AutoSaveCurTraceInfoImpl() {
  SetCurTraceInfo(mSavedSourceEventId, mSavedTaskId, mSavedSourceEventType);
}

void SetCurTraceInfo(uint64_t aSourceEventId, uint64_t aParentTaskId,
                     SourceEventType aSourceEventType) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  info->mCurTraceSourceId = aSourceEventId;
  info->mCurTaskId = aParentTaskId;
  info->mCurTraceSourceType = aSourceEventType;
}

void GetCurTraceInfo(uint64_t* aOutSourceEventId, uint64_t* aOutParentTaskId,
                     SourceEventType* aOutSourceEventType) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  *aOutSourceEventId = info->mCurTraceSourceId;
  *aOutParentTaskId = info->mCurTaskId;
  *aOutSourceEventType = info->mCurTraceSourceType;
}

void LogDispatch(uint64_t aTaskId, uint64_t aParentTaskId,
                 uint64_t aSourceEventId, SourceEventType aSourceEventType) {
  LogDispatch(aTaskId, aParentTaskId, aSourceEventId, aSourceEventType, 0);
}

void LogDispatch(uint64_t aTaskId, uint64_t aParentTaskId,
                 uint64_t aSourceEventId, SourceEventType aSourceEventType,
                 int aDelayTimeMs) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  // aDelayTimeMs is the expected delay time in milliseconds, thus the dispatch
  // time calculated of it might be slightly off in the real world.
  uint64_t time =
      (aDelayTimeMs <= 0) ? GetTimestamp() : GetTimestamp() + aDelayTimeMs;

  // Log format:
  // [0 taskId dispatchTime sourceEventId sourceEventType parentTaskId]
  TraceInfoLogType* log = info->AppendLog();
  if (log) {
    log->mDispatch.mType = ACTION_DISPATCH;
    log->mDispatch.mTaskId = aTaskId;
    log->mDispatch.mTime = time;
    log->mDispatch.mSourceEventId = aSourceEventId;
    log->mDispatch.mSourceEventType = aSourceEventType;
    log->mDispatch.mParentTaskId = aParentTaskId;
  }
}

void LogBegin(uint64_t aTaskId, uint64_t aSourceEventId) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  // Log format:
  // [1 taskId beginTime processId threadId]
  TraceInfoLogType* log = info->AppendLog();
  if (log) {
    log->mBegin.mType = ACTION_BEGIN;
    log->mBegin.mTaskId = aTaskId;
    log->mBegin.mTime = GetTimestamp();
    log->mBegin.mPid = profiler_current_process_id();
    log->mBegin.mTid = profiler_current_thread_id();

    MOZ_ASSERT(log->mBegin.mPid >= 0,
               "native process ID is < 0 (signed integer overflow)");
    MOZ_ASSERT(log->mBegin.mTid >= 0,
               "native thread ID is < 0  (signed integer overflow)");
  }
}

void LogEnd(uint64_t aTaskId, uint64_t aSourceEventId) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  // Log format:
  // [2 taskId endTime]
  TraceInfoLogType* log = info->AppendLog();
  if (log) {
    log->mEnd.mType = ACTION_END;
    log->mEnd.mTaskId = aTaskId;
    log->mEnd.mTime = GetTimestamp();
  }
}

void LogVirtualTablePtr(uint64_t aTaskId, uint64_t aSourceEventId,
                        uintptr_t* aVptr) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  // Log format:
  // [4 taskId address]
  TraceInfoLogType* log = info->AppendLog();
  if (log) {
    // Since addr2line used by the Gecko Profiler addon can not solve
    // non-function addresses, we use the first entry of vtable as the symbol
    // to solve. We should find a better solution later.
    log->mVPtr.mType = ACTION_GET_VTABLE;
    log->mVPtr.mTaskId = aTaskId;
    log->mVPtr.mVPtr = reinterpret_cast<uintptr_t>(aVptr);
  }
}

void AutoSourceEvent::StartScope(SourceEventType aType) {
  CreateSourceEvent(aType);
}

void AutoSourceEvent::StopScope() { DestroySourceEvent(); }

void AutoScopedLabel::Init(const char* aFormat, va_list& aArgs) {
  nsCString label;
  va_list& args = aArgs;
  label.AppendPrintf(aFormat, args);
  mLabel = strdup(label.get());
  AddLabel("Begin %s", mLabel);
}

void DoAddLabel(const char* aFormat, va_list& aArgs) {
  TraceInfoHolder info = GetOrCreateTraceInfo();
  ENSURE_TRUE_VOID(info);

  // Log format:
  // [3 taskId "label"]
  TraceInfoLogType* log = info->AppendLog();
  if (log) {
    va_list& args = aArgs;
    nsCString& buffer = *info->mStrs.AppendElement();
    buffer.AppendPrintf(aFormat, args);

    log->mLabel.mType = ACTION_ADD_LABEL;
    log->mLabel.mTaskId = info->mCurTaskId;
    log->mLabel.mTime = GetTimestamp();
    log->mLabel.mStrIdx = info->mStrs.Length() - 1;
  }
}

// Functions used by GeckoProfiler.

void StartLogging() {
  sStartTime = GetTimestamp();
  SetLogStarted(true);
}

void StopLogging() { SetLogStarted(false); }

UniquePtr<Vector<nsCString>> GetLoggedData(TimeStamp aTimeStamp) {
  auto result = MakeUnique<Vector<nsCString>>();

  // TODO: This is called from a signal handler. Use semaphore instead.
  StaticMutexAutoLock lock(sMutex);

  if (sTraceInfos == nullptr) {
    return result;
  }

  for (uint32_t i = 0; i < sTraceInfos->Length(); ++i) {
    TraceInfo* info = (*sTraceInfos)[i].get();
    MutexAutoLock lockLogs(info->mLogsMutex);
    if (info->mObsolete) {
      continue;
    }

    nsTArray<nsCString>& strs = info->mStrs;
    for (TraceInfoLogNode* node = info->mLogsHead; node; node = node->mNext) {
      TraceInfoLogType& log = node->mLog;
      MOZ_RELEASE_ASSERT(result->append(nsCString()));
      nsCString& buffer = result->back();

      switch (log.mType) {
        case ACTION_DISPATCH:
          buffer.AppendPrintf("%d %llu %llu %llu %d %llu", ACTION_DISPATCH,
                              (unsigned long long)log.mDispatch.mTaskId,
                              (unsigned long long)log.mDispatch.mTime,
                              (unsigned long long)log.mDispatch.mSourceEventId,
                              log.mDispatch.mSourceEventType,
                              (unsigned long long)log.mDispatch.mParentTaskId);
          break;

        case ACTION_BEGIN:
          buffer.AppendPrintf("%d %llu %llu %d %d", ACTION_BEGIN,
                              (unsigned long long)log.mBegin.mTaskId,
                              (unsigned long long)log.mBegin.mTime,
                              log.mBegin.mPid, log.mBegin.mTid);
          break;

        case ACTION_END:
          buffer.AppendPrintf("%d %llu %llu", ACTION_END,
                              (unsigned long long)log.mEnd.mTaskId,
                              (unsigned long long)log.mEnd.mTime);
          break;

        case ACTION_GET_VTABLE:
          buffer.AppendPrintf("%d %llu %p", ACTION_GET_VTABLE,
                              (unsigned long long)log.mVPtr.mTaskId,
                              (void*)log.mVPtr.mVPtr);
          break;

        case ACTION_ADD_LABEL:
          buffer.AppendPrintf("%d %llu %llu2 \"%s\"", ACTION_ADD_LABEL,
                              (unsigned long long)log.mLabel.mTaskId,
                              (unsigned long long)log.mLabel.mTime,
                              strs[log.mLabel.mStrIdx].get());
          break;

        default:
          MOZ_CRASH("Unknow TaskTracer log type!");
      }
    }
  }

  return result;
}

PRTime GetStartTime() { return sStartTime; }

const char* GetJSLabelPrefix() { return sJSLabelPrefix; }

#undef ENSURE_TRUE_VOID
#undef ENSURE_TRUE

}  // namespace tasktracer
}  // namespace mozilla