base/trace_event/trace_event_etw_export_win.cc

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/trace_event/trace_event_etw_export_win.h"

#include <stddef.h>

#include "base/at_exit.h"
#include "base/command_line.h"
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "base/strings/string_tokenizer.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/platform_thread.h"
#include "base/trace_event/trace_event.h"
#include "base/trace_event/trace_event_impl.h"

#include <windows.h>

// The GetProcAddress technique is borrowed from
// https://github.com/google/UIforETW/tree/master/ETWProviders
//
// EVNTAPI is used in evntprov.h which is included by chrome_events_win.h.
// We define EVNTAPI without the DECLSPEC_IMPORT specifier so that we can
// implement these functions locally instead of using the import library, and
// can therefore still run on Windows XP.
#define EVNTAPI __stdcall
// Include the event register/write/unregister macros compiled from the manifest
// file. Note that this includes evntprov.h which requires a Vista+ Windows SDK.
//
// In SHARED_INTERMEDIATE_DIR.

// Headers generated by mc.exe have a ';' at the end of extern "C" {} blocks.
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wextra-semi"
#endif

#include "base/trace_event/etw_manifest/chrome_events_win.h"  // NOLINT

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

namespace {

// |kFilteredEventGroupNames| contains the event categories that can be
// exported individually. These categories can be enabled by passing the correct
// keyword when starting the trace. A keyword is a 64-bit flag and we attribute
// one bit per category. We can therefore enable a particular category by
// setting its corresponding bit in the keyword. For events that are not present
// in |kFilteredEventGroupNames|, we have two bits that control their
// behaviour. When bit 61 is enabled, any event that is not disabled by default
// (ie. doesn't start with disabled-by-default-) will be exported. Likewise,
// when bit 62 is enabled, any event that is disabled by default will be
// exported.
//
// Note that bit 63 (MSB) must always be set, otherwise tracing will be disabled
// by ETW. Therefore, the keyword will always be greater than
// 0x8000000000000000.
//
// Examples of passing keywords to the provider using xperf:
// # This exports "benchmark" and "cc" events
// xperf -start chrome -on Chrome:0x8000000000000009
//
// # This exports "gpu", "netlog" and all other events that are not disabled by
// # default
// xperf -start chrome -on Chrome:0xA0000000000000A0
//
// More info about starting a trace and keyword can be obtained by using the
// help section of xperf (xperf -help start). Note that xperf documentation
// refers to keywords as flags and there are two ways to enable them, using
// group names or the hex representation. We only support the latter. Also, we
// ignore the level.
const char* const kFilteredEventGroupNames[] = {
    "benchmark",                             // 0x1
    "blink",                                 // 0x2
    "browser",                               // 0x4
    "cc",                                    // 0x8
    "evdev",                                 // 0x10
    "gpu",                                   // 0x20
    "input",                                 // 0x40
    "netlog",                                // 0x80
    "sequence_manager",                      // 0x100
    "toplevel",                              // 0x200
    "v8",                                    // 0x400
    "disabled-by-default-cc.debug",          // 0x800
    "disabled-by-default-cc.debug.picture",  // 0x1000
    "disabled-by-default-toplevel.flow",     // 0x2000
    "startup",                               // 0x4000
    "latency",                               // 0x8000
    "blink.user_timing",                     // 0x10000
    "media",                                 // 0x20000
    "loading",                               // 0x40000
};
const char kOtherEventsGroupName[] = "__OTHER_EVENTS";  // 0x2000000000000000
const char kDisabledOtherEventsGroupName[] =
    "__DISABLED_OTHER_EVENTS";  // 0x4000000000000000
const uint64_t kOtherEventsKeywordBit = 1ULL << 61;
const uint64_t kDisabledOtherEventsKeywordBit = 1ULL << 62;
const size_t kNumberOfCategories = ARRAYSIZE(kFilteredEventGroupNames) + 2U;

static void __stdcall EtwEnableCallback(LPCGUID SourceId,
                                        ULONG ControlCode,
                                        UCHAR Level,
                                        ULONGLONG MatchAnyKeyword,
                                        ULONGLONG MatchAllKeyword,
                                        PEVENT_FILTER_DESCRIPTOR FilterData,
                                        PVOID CallbackContext) {
  // Invoke the default callback, which updates the information inside
  // CHROME_Context.
  McGenControlCallbackV2(SourceId, ControlCode, Level, MatchAnyKeyword,
                         MatchAllKeyword, FilterData, CallbackContext);

  base::trace_event::TraceEventETWExport::OnETWEnableUpdate();
}

}  // namespace

namespace base {
namespace trace_event {

bool TraceEventETWExport::is_registration_complete_ = false;

TraceEventETWExport::TraceEventETWExport() : etw_match_any_keyword_(0ULL) {
  // Register the ETW provider. If registration fails then the event logging
  // calls will fail. We're essentially doing the same operation as
  // EventRegisterChrome (which was auto generated for our provider by the
  // ETW manifest compiler), but instead we're passing our own callback.
  // This allows us to detect changes to enable/disable/keyword changes.
  // ChromeHandle and the other parameters to EventRegister are all generated
  // globals from chrome_events_win.h
  DCHECK(!ChromeHandle);
  EventRegister(&CHROME, &EtwEnableCallback, &CHROME_Context, &ChromeHandle);
  TraceEventETWExport::is_registration_complete_ = true;

  // Make sure to initialize the map with all the group names. Subsequent
  // modifications will be made by the background thread and only affect the
  // values of the keys (no key addition/deletion). Therefore, the map does not
  // require a lock for access.
  for (size_t i = 0; i < ARRAYSIZE(kFilteredEventGroupNames); i++)
    categories_status_[kFilteredEventGroupNames[i]] = false;
  categories_status_[kOtherEventsGroupName] = false;
  categories_status_[kDisabledOtherEventsGroupName] = false;
  DCHECK_EQ(kNumberOfCategories, categories_status_.size());
}

TraceEventETWExport::~TraceEventETWExport() {
  EventUnregisterChrome();
  is_registration_complete_ = false;
}

// static
void TraceEventETWExport::EnableETWExport() {
  auto* instance = GetInstance();
  if (instance) {
    // Sync the enabled categories with ETW by calling UpdateEnabledCategories()
    // that checks the keyword. We'll stay in sync via the EtwEnableCallback
    // we register in TraceEventETWExport's constructor.
    instance->UpdateEnabledCategories();
  }
}

// static
void TraceEventETWExport::AddEvent(char phase,
                                   const unsigned char* category_group_enabled,
                                   const char* name,
                                   unsigned long long id,
                                   const TraceArguments* args) {
  // We bail early in case exporting is disabled or no consumer is listening.
  auto* instance = GetInstance();
  if (!instance || !EventEnabledChromeEvent())
    return;

  const char* phase_string = nullptr;
  // Space to store the phase identifier and null-terminator, when needed.
  char phase_buffer[2];
  switch (phase) {
    case TRACE_EVENT_PHASE_BEGIN:
      phase_string = "Begin";
      break;
    case TRACE_EVENT_PHASE_END:
      phase_string = "End";
      break;
    case TRACE_EVENT_PHASE_COMPLETE:
      phase_string = "Complete";
      break;
    case TRACE_EVENT_PHASE_INSTANT:
      phase_string = "Instant";
      break;
    case TRACE_EVENT_PHASE_ASYNC_BEGIN:
      phase_string = "Async Begin";
      break;
    case TRACE_EVENT_PHASE_ASYNC_STEP_INTO:
      phase_string = "Async Step Into";
      break;
    case TRACE_EVENT_PHASE_ASYNC_STEP_PAST:
      phase_string = "Async Step Past";
      break;
    case TRACE_EVENT_PHASE_ASYNC_END:
      phase_string = "Async End";
      break;
    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN:
      phase_string = "Nestable Async Begin";
      break;
    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_END:
      phase_string = "Nestable Async End";
      break;
    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT:
      phase_string = "Nestable Async Instant";
      break;
    case TRACE_EVENT_PHASE_FLOW_BEGIN:
      phase_string = "Phase Flow Begin";
      break;
    case TRACE_EVENT_PHASE_FLOW_STEP:
      phase_string = "Phase Flow Step";
      break;
    case TRACE_EVENT_PHASE_FLOW_END:
      phase_string = "Phase Flow End";
      break;
    case TRACE_EVENT_PHASE_METADATA:
      phase_string = "Phase Metadata";
      break;
    case TRACE_EVENT_PHASE_COUNTER:
      phase_string = "Phase Counter";
      break;
    case TRACE_EVENT_PHASE_SAMPLE:
      phase_string = "Phase Sample";
      break;
    case TRACE_EVENT_PHASE_CREATE_OBJECT:
      phase_string = "Phase Create Object";
      break;
    case TRACE_EVENT_PHASE_SNAPSHOT_OBJECT:
      phase_string = "Phase Snapshot Object";
      break;
    case TRACE_EVENT_PHASE_DELETE_OBJECT:
      phase_string = "Phase Delete Object";
      break;
    default:
      phase_buffer[0] = phase;
      phase_buffer[1] = 0;
      phase_string = phase_buffer;
      break;
  }

  std::string arg_values_string[3];
  size_t num_args = args ? args->size() : 0;
  for (size_t i = 0; i < num_args; i++) {
    if (args->types()[i] == TRACE_VALUE_TYPE_CONVERTABLE) {
      // Temporarily do nothing here. This function consumes 1/3 to 1/2 of
      // *total* process CPU time when ETW tracing, and many of the strings
      // created exceed WPA's 4094 byte limit and are shown as:
      // "Unable to parse data". See crbug.com/488257
    } else {
      args->values()[i].AppendAsString(args->types()[i], arg_values_string + i);
    }
  }

  EventWriteChromeEvent(
      name, phase_string, num_args > 0 ? args->names()[0] : "",
      arg_values_string[0].c_str(), num_args > 1 ? args->names()[1] : "",
      arg_values_string[1].c_str(), "", "");
}

// static
void TraceEventETWExport::AddCompleteEndEvent(const char* name) {
  auto* instance = GetInstance();
  if (!instance || !EventEnabledChromeEvent())
    return;

  EventWriteChromeEvent(name, "Complete End", "", "", "", "", "", "");
}

// static
bool TraceEventETWExport::IsCategoryGroupEnabled(
    StringPiece category_group_name) {
  DCHECK(!category_group_name.empty());
  auto* instance = GetInstanceIfExists();
  if (instance == nullptr)
    return false;

  if (!EventEnabledChromeEvent())
    return false;

  CStringTokenizer category_group_tokens(category_group_name.begin(),
                                         category_group_name.end(), ",");
  while (category_group_tokens.GetNext()) {
    StringPiece category_group_token = category_group_tokens.token_piece();
    if (instance->IsCategoryEnabled(category_group_token)) {
      return true;
    }
  }
  return false;
}

bool TraceEventETWExport::UpdateEnabledCategories() {
  if (etw_match_any_keyword_ == CHROME_Context.MatchAnyKeyword)
    return false;

  // If the keyword has changed, update each category.
  // Chrome_Context.MatchAnyKeyword is set by UIforETW (or other ETW trace
  // recording tools) using the ETW infrastructure. This value will be set in
  // all Chrome processes that have registered their ETW provider.
  etw_match_any_keyword_ = CHROME_Context.MatchAnyKeyword;
  for (size_t i = 0; i < ARRAYSIZE(kFilteredEventGroupNames); i++) {
    if (etw_match_any_keyword_ & (1ULL << i)) {
      categories_status_[kFilteredEventGroupNames[i]] = true;
    } else {
      categories_status_[kFilteredEventGroupNames[i]] = false;
    }
  }

  // Also update the two default categories.
  if (etw_match_any_keyword_ & kOtherEventsKeywordBit) {
    categories_status_[kOtherEventsGroupName] = true;
  } else {
    categories_status_[kOtherEventsGroupName] = false;
  }
  if (etw_match_any_keyword_ & kDisabledOtherEventsKeywordBit) {
    categories_status_[kDisabledOtherEventsGroupName] = true;
  } else {
    categories_status_[kDisabledOtherEventsGroupName] = false;
  }

  DCHECK_EQ(kNumberOfCategories, categories_status_.size());

  // Update the categories in TraceLog.
  TraceLog::GetInstance()->UpdateETWCategoryGroupEnabledFlags();

  return true;
}

bool TraceEventETWExport::IsCategoryEnabled(StringPiece category_name) const {
  DCHECK_EQ(kNumberOfCategories, categories_status_.size());
  // Try to find the category and return its status if found
  auto it = categories_status_.find(category_name);
  if (it != categories_status_.end())
    return it->second;

  // Otherwise return the corresponding default status by first checking if the
  // category is disabled by default.
  if (category_name.starts_with("disabled-by-default")) {
    DCHECK(categories_status_.find(kDisabledOtherEventsGroupName) !=
           categories_status_.end());
    return categories_status_.find(kDisabledOtherEventsGroupName)->second;
  } else {
    DCHECK(categories_status_.find(kOtherEventsGroupName) !=
           categories_status_.end());
    return categories_status_.find(kOtherEventsGroupName)->second;
  }
}

// static
void TraceEventETWExport::OnETWEnableUpdate() {
  // During construction, if tracing is already enabled, we'll get
  // a callback synchronously on the same thread. Calling GetInstance
  // in that case will hang since we're in the process of creating the
  // singleton.
  if (is_registration_complete_) {
    auto* instance = GetInstance();
    if (instance)
      instance->UpdateEnabledCategories();
  }
}

// static
TraceEventETWExport* TraceEventETWExport::GetInstance() {
  return Singleton<TraceEventETWExport,
                   StaticMemorySingletonTraits<TraceEventETWExport>>::get();
}

// static
TraceEventETWExport* TraceEventETWExport::GetInstanceIfExists() {
  return Singleton<
      TraceEventETWExport,
      StaticMemorySingletonTraits<TraceEventETWExport>>::GetIfExists();
}

}  // namespace trace_event
}  // namespace base