third_party/WebKit/Source/platform/TraceEvent.h

   1 /*
   2  * Copyright (C) 2011 Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * 1.  Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  16  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  17  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  18  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  19  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  20  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  21  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 // This header file defines implementation details of how the trace macros in
  27 // TraceEventCommon.h collect and store trace events. Anything not
  28 // implementation-specific should go in TraceEventCommon.h instead of here.
  29
  30 #ifndef TraceEvent_h
  31 #define TraceEvent_h
  32
  33 #include "platform/EventTracer.h"
  34 #include "platform/TraceEventCommon.h"
  35
  36 #include "wtf/CurrentTime.h"
  37 #include "wtf/DynamicAnnotations.h"
  38 #include "wtf/PassRefPtr.h"
  39 #include "wtf/text/CString.h"
  40
  41 ////////////////////////////////////////////////////////////////////////////////
  42 // Implementation specific tracing API definitions.
  43
  44 // By default, const char* argument values are assumed to have long-lived scope
  45 // and will not be copied. Use this macro to force a const char* to be copied.
  46 #define TRACE_STR_COPY(str) \
  47     blink::TraceEvent::TraceStringWithCopy(str)
  48
  49 // By default, uint64 ID argument values are not mangled with the Process ID in
  50 // TRACE_EVENT_ASYNC macros. Use this macro to force Process ID mangling.
  51 #define TRACE_ID_MANGLE(id) \
  52     blink::TraceEvent::TraceID::ForceMangle(id)
  53
  54 // By default, pointers are mangled with the Process ID in TRACE_EVENT_ASYNC
  55 // macros. Use this macro to prevent Process ID mangling.
  56 #define TRACE_ID_DONT_MANGLE(id) \
  57     blink::TraceEvent::TraceID::DontMangle(id)
  58
  59
  60 // Creates a scope of a sampling state with the given category and name (both must
  61 // be constant strings). These states are intended for a sampling profiler.
  62 // Implementation note: we store category and name together because we don't
  63 // want the inconsistency/expense of storing two pointers.
  64 // |thread_bucket| is [0..2] and is used to statically isolate samples in one
  65 // thread from others.
  66 //
  67 // {  // The sampling state is set within this scope.
  68 //    TRACE_EVENT_SAMPLING_STATE_SCOPE_FOR_BUCKET(0, "category", "name");
  69 //    ...;
  70 // }
  71 #define TRACE_EVENT_SCOPED_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) \
  72     TraceEvent::SamplingStateScope<bucket_number> traceEventSamplingScope(category "\0" name);
  73
  74 // Returns a current sampling state of the given bucket.
  75 // The format of the returned string is "category\0name".
  76 #define TRACE_EVENT_GET_SAMPLING_STATE_FOR_BUCKET(bucket_number) \
  77     TraceEvent::SamplingStateScope<bucket_number>::current()
  78
  79 // Sets a current sampling state of the given bucket.
  80 // |category| and |name| have to be constant strings.
  81 #define TRACE_EVENT_SET_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) \
  82     TraceEvent::SamplingStateScope<bucket_number>::set(category "\0" name)
  83
  84 // Sets a current sampling state of the given bucket.
  85 // |categoryAndName| doesn't need to be a constant string.
  86 // The format of the string is "category\0name".
  87 #define TRACE_EVENT_SET_NONCONST_SAMPLING_STATE_FOR_BUCKET(bucket_number, categoryAndName) \
  88     TraceEvent::SamplingStateScope<bucket_number>::set(categoryAndName)
  89
  90 // Get a pointer to the enabled state of the given trace category. Only
  91 // long-lived literal strings should be given as the category name. The returned
  92 // pointer can be held permanently in a local static for example. If the
  93 // unsigned char is non-zero, tracing is enabled. If tracing is enabled,
  94 // TRACE_EVENT_API_ADD_TRACE_EVENT can be called. It's OK if tracing is disabled
  95 // between the load of the tracing state and the call to
  96 // TRACE_EVENT_API_ADD_TRACE_EVENT, because this flag only provides an early out
  97 // for best performance when tracing is disabled.
  98 // const unsigned char*
  99 //     TRACE_EVENT_API_GET_CATEGORY_ENABLED(const char* category_name)
 100 #define TRACE_EVENT_API_GET_CATEGORY_ENABLED \
 101     blink::EventTracer::getTraceCategoryEnabledFlag
 102
 103 // Add a trace event to the platform tracing system.
 104 // blink::TraceEvent::TraceEventHandle TRACE_EVENT_API_ADD_TRACE_EVENT(
 105 //                    const char* name,
 106 //                    unsigned long long id,
 107 //                    double timestamp,
 108 //                    int num_args,
 109 //                    const char** arg_names,
 110 //                    const unsigned char* arg_types,
 111 //                    const unsigned long long* arg_values,
 112 //                    PassRefPtr<ConvertableToTraceFormat> convertableValues[],
 113 //                    unsigned char flags)
 114 #define TRACE_EVENT_API_ADD_TRACE_EVENT \
 115     blink::EventTracer::addTraceEvent
 116
 117 // Set the duration field of a COMPLETE trace event.
 118 // void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
 119 //     blink::TraceEvent::TraceEventHandle handle)
 120 #define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION \
 121     blink::EventTracer::updateTraceEventDuration
 122
 123 ////////////////////////////////////////////////////////////////////////////////
 124
 125 // Implementation detail: trace event macros create temporary variables
 126 // to keep instrumentation overhead low. These macros give each temporary
 127 // variable a unique name based on the line number to prevent name collissions.
 128 #define INTERNAL_TRACE_EVENT_UID3(a, b) \
 129     trace_event_unique_##a##b
 130 #define INTERNAL_TRACE_EVENT_UID2(a, b) \
 131     INTERNAL_TRACE_EVENT_UID3(a, b)
 132 #define INTERNALTRACEEVENTUID(name_prefix) \
 133     INTERNAL_TRACE_EVENT_UID2(name_prefix, __LINE__)
 134
 135 // Implementation detail: internal macro to create static category.
 136 // - WTF_ANNOTATE_BENIGN_RACE, see Thread Safety above.
 137
 138 #define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category) \
 139     static const unsigned char* INTERNALTRACEEVENTUID(categoryGroupEnabled) = 0; \
 140     WTF_ANNOTATE_BENIGN_RACE(&INTERNALTRACEEVENTUID(categoryGroupEnabled), \
 141                              "trace_event category"); \
 142     if (!INTERNALTRACEEVENTUID(categoryGroupEnabled)) { \
 143         INTERNALTRACEEVENTUID(categoryGroupEnabled) = \
 144             TRACE_EVENT_API_GET_CATEGORY_ENABLED(category); \
 145     }
 146
 147 // Implementation detail: internal macro to create static category and add
 148 // event if the category is enabled.
 149 #define INTERNAL_TRACE_EVENT_ADD(phase, category, name, flags, ...) \
 150     do { \
 151         INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
 152         if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
 153             blink::TraceEvent::addTraceEvent( \
 154                 phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), name, \
 155                 blink::TraceEvent::noEventId, flags, ##__VA_ARGS__); \
 156         } \
 157     } while (0)
 158
 159 // Implementation detail: internal macro to create static category and add begin
 160 // event if the category is enabled. Also adds the end event when the scope
 161 // ends.
 162 #define INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name, ...) \
 163     INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
 164     blink::TraceEvent::ScopedTracer INTERNALTRACEEVENTUID(scopedTracer); \
 165     if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
 166         blink::TraceEvent::TraceEventHandle h = \
 167             blink::TraceEvent::addTraceEvent( \
 168                 TRACE_EVENT_PHASE_COMPLETE, \
 169                 INTERNALTRACEEVENTUID(categoryGroupEnabled), \
 170                 name, blink::TraceEvent::noEventId, \
 171                 TRACE_EVENT_FLAG_NONE, ##__VA_ARGS__); \
 172         INTERNALTRACEEVENTUID(scopedTracer).initialize( \
 173             INTERNALTRACEEVENTUID(categoryGroupEnabled), name, h); \
 174     }
 175
 176 // Implementation detail: internal macro to create static category and add
 177 // event if the category is enabled.
 178 #define INTERNAL_TRACE_EVENT_ADD_WITH_ID(phase, category, name, id, flags, ...) \
 179     do { \
 180         INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
 181         if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
 182             unsigned char traceEventFlags = flags | TRACE_EVENT_FLAG_HAS_ID; \
 183             blink::TraceEvent::TraceID traceEventTraceID( \
 184                 id, &traceEventFlags); \
 185             blink::TraceEvent::addTraceEvent( \
 186                 phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), \
 187                 name, traceEventTraceID.data(), traceEventFlags, ##__VA_ARGS__); \
 188         } \
 189     } while (0)
 190
 191
 192 // Implementation detail: internal macro to create static category and add event
 193 // if the category is enabled.
 194 #define INTERNAL_TRACE_EVENT_ADD_WITH_ID_AND_TIMESTAMP(phase, category, name, id, timestamp, flags, ...) \
 195     do { \
 196         INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
 197         if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
 198             unsigned char traceEventFlags = flags | TRACE_EVENT_FLAG_HAS_ID; \
 199             blink::TraceEvent::TraceID traceEventTraceID( \
 200                 id, &traceEventFlags); \
 201             blink::TraceEvent::addTraceEvent( \
 202                 phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), \
 203                 name, traceEventTraceID.data(), timestamp, traceEventFlags, ##__VA_ARGS__); \
 204         } \
 205     } while (0)
 206
 207 // Implementation detail: internal macro to create static category and add
 208 // event if the category is enabled.
 209 #define INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(phase, category, name, timestamp, flags, ...) \
 210     do { \
 211         INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
 212         if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
 213             blink::TraceEvent::addTraceEvent( \
 214                 phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), name, \
 215                 blink::TraceEvent::noEventId, timestamp, flags, ##__VA_ARGS__); \
 216         } \
 217     } while (0)
 218
 219
 220 // These values must be in sync with base::debug::TraceLog::CategoryGroupEnabledFlags.
 221 #define ENABLED_FOR_RECORDING (1 << 0)
 222 #define ENABLED_FOR_EVENT_CALLBACK (1 << 2)
 223
 224 #define INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE() \
 225     (*INTERNALTRACEEVENTUID(categoryGroupEnabled) & (ENABLED_FOR_RECORDING | ENABLED_FOR_EVENT_CALLBACK))
 226
 227 #define INTERNAL_TRACE_MEMORY(category, name)
 228
 229 namespace blink {
 230
 231 namespace TraceEvent {
 232
 233 // Specify these values when the corresponding argument of addTraceEvent is not
 234 // used.
 235 const int zeroNumArgs = 0;
 236 const unsigned long long noEventId = 0;
 237
 238 // TraceID encapsulates an ID that can either be an integer or pointer. Pointers
 239 // are mangled with the Process ID so that they are unlikely to collide when the
 240 // same pointer is used on different processes.
 241 class TraceID {
 242 public:
 243     template<bool dummyMangle> class MangleBehavior {
 244     public:
 245         template<typename T> explicit MangleBehavior(T id) : m_data(reinterpret_cast<unsigned long long>(id)) { }
 246         unsigned long long data() const { return m_data; }
 247     private:
 248         unsigned long long m_data;
 249     };
 250     typedef MangleBehavior<false> DontMangle;
 251     typedef MangleBehavior<true> ForceMangle;
 252
 253     TraceID(const void* id, unsigned char* flags) :
 254         m_data(static_cast<unsigned long long>(reinterpret_cast<unsigned long>(id)))
 255     {
 256         *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
 257     }
 258     TraceID(ForceMangle id, unsigned char* flags) : m_data(id.data())
 259     {
 260         *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
 261     }
 262     TraceID(DontMangle id, unsigned char*) : m_data(id.data()) { }
 263     TraceID(unsigned long long id, unsigned char*) : m_data(id) { }
 264     TraceID(unsigned long id, unsigned char*) : m_data(id) { }
 265     TraceID(unsigned id, unsigned char*) : m_data(id) { }
 266     TraceID(unsigned short id, unsigned char*) : m_data(id) { }
 267     TraceID(unsigned char id, unsigned char*) : m_data(id) { }
 268     TraceID(long long id, unsigned char*) :
 269         m_data(static_cast<unsigned long long>(id)) { }
 270     TraceID(long id, unsigned char*) :
 271         m_data(static_cast<unsigned long long>(id)) { }
 272     TraceID(int id, unsigned char*) :
 273         m_data(static_cast<unsigned long long>(id)) { }
 274     TraceID(short id, unsigned char*) :
 275         m_data(static_cast<unsigned long long>(id)) { }
 276     TraceID(signed char id, unsigned char*) :
 277         m_data(static_cast<unsigned long long>(id)) { }
 278
 279     unsigned long long data() const { return m_data; }
 280
 281 private:
 282     unsigned long long m_data;
 283 };
 284
 285 // Simple union to store various types as unsigned long long.
 286 union TraceValueUnion {
 287     bool m_bool;
 288     unsigned long long m_uint;
 289     long long m_int;
 290     double m_double;
 291     const void* m_pointer;
 292     const char* m_string;
 293 };
 294
 295 // Simple container for const char* that should be copied instead of retained.
 296 class TraceStringWithCopy {
 297 public:
 298     explicit TraceStringWithCopy(const char* str) : m_str(str) { }
 299     const char* str() const { return m_str; }
 300 private:
 301     const char* m_str;
 302 };
 303
 304 // Define setTraceValue for each allowed type. It stores the type and
 305 // value in the return arguments. This allows this API to avoid declaring any
 306 // structures so that it is portable to third_party libraries.
 307 #define INTERNAL_DECLARE_SET_TRACE_VALUE(actualType, argExpression, unionMember, valueTypeId) \
 308     static inline void setTraceValue(actualType arg, unsigned char* type, unsigned long long* value) { \
 309         TraceValueUnion typeValue; \
 310         typeValue.unionMember = argExpression; \
 311         *type = valueTypeId; \
 312         *value = typeValue.m_uint; \
 313     }
 314 // Simpler form for int types that can be safely casted.
 315 #define INTERNAL_DECLARE_SET_TRACE_VALUE_INT(actualType, valueTypeId) \
 316     static inline void setTraceValue(actualType arg, \
 317                                      unsigned char* type, \
 318                                      unsigned long long* value) { \
 319         *type = valueTypeId; \
 320         *value = static_cast<unsigned long long>(arg); \
 321     }
 322
 323 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned long long, TRACE_VALUE_TYPE_UINT)
 324 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned, TRACE_VALUE_TYPE_UINT)
 325 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned short, TRACE_VALUE_TYPE_UINT)
 326 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned char, TRACE_VALUE_TYPE_UINT)
 327 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(long long, TRACE_VALUE_TYPE_INT)
 328 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int, TRACE_VALUE_TYPE_INT)
 329 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(short, TRACE_VALUE_TYPE_INT)
 330 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(signed char, TRACE_VALUE_TYPE_INT)
 331 INTERNAL_DECLARE_SET_TRACE_VALUE(bool, arg, m_bool, TRACE_VALUE_TYPE_BOOL)
 332 INTERNAL_DECLARE_SET_TRACE_VALUE(double, arg, m_double, TRACE_VALUE_TYPE_DOUBLE)
 333 INTERNAL_DECLARE_SET_TRACE_VALUE(const void*, arg, m_pointer, TRACE_VALUE_TYPE_POINTER)
 334 INTERNAL_DECLARE_SET_TRACE_VALUE(const char*, arg, m_string, TRACE_VALUE_TYPE_STRING)
 335 INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, arg.str(), m_string, TRACE_VALUE_TYPE_COPY_STRING)
 336
 337 #undef INTERNAL_DECLARE_SET_TRACE_VALUE
 338 #undef INTERNAL_DECLARE_SET_TRACE_VALUE_INT
 339
 340 // WTF::String version of setTraceValue so that trace arguments can be strings.
 341 static inline void setTraceValue(const WTF::CString& arg, unsigned char* type, unsigned long long* value)
 342 {
 343     TraceValueUnion typeValue;
 344     typeValue.m_string = arg.data();
 345     *type = TRACE_VALUE_TYPE_COPY_STRING;
 346     *value = typeValue.m_uint;
 347 }
 348
 349 static inline void setTraceValue(ConvertableToTraceFormat*, unsigned char* type, unsigned long long*)
 350 {
 351     *type = TRACE_VALUE_TYPE_CONVERTABLE;
 352 }
 353
 354 template<typename T> static inline void setTraceValue(const PassRefPtr<T>& ptr, unsigned char* type, unsigned long long* value)
 355 {
 356     setTraceValue(ptr.get(), type, value);
 357 }
 358
 359 template<typename T> struct ConvertableToTraceFormatTraits {
 360     static const bool isConvertable = false;
 361     static PassRefPtr<ConvertableToTraceFormat> moveFromIfConvertable(const T&)
 362     {
 363         return nullptr;
 364     }
 365 };
 366
 367 template<typename T> struct ConvertableToTraceFormatTraits<PassRefPtr<T>> {
 368     static const bool isConvertable = WTF::IsSubclass<T, TraceEvent::ConvertableToTraceFormat>::value;
 369     static PassRefPtr<ConvertableToTraceFormat> moveFromIfConvertable(const PassRefPtr<T>& convertableToTraceFormat)
 370     {
 371         return convertableToTraceFormat;
 372     }
 373 };
 374
 375 template<typename T> bool isConvertableToTraceFormat(const T&)
 376 {
 377     return ConvertableToTraceFormatTraits<T>::isConvertable;
 378 }
 379
 380 template<typename T> PassRefPtr<ConvertableToTraceFormat> moveFromIfConvertableToTraceFormat(const T& value)
 381 {
 382     return ConvertableToTraceFormatTraits<T>::moveFromIfConvertable(value);
 383 }
 384
 385 // These addTraceEvent template functions are defined here instead of in the
 386 // macro, because the arg values could be temporary string objects. In order to
 387 // store pointers to the internal c_str and pass through to the tracing API, the
 388 // arg values must live throughout these procedures.
 389
 390 static inline TraceEventHandle addTraceEvent(
 391     char phase,
 392     const unsigned char* categoryEnabled,
 393     const char* name,
 394     unsigned long long id,
 395     double timestamp,
 396     unsigned char flags)
 397 {
 398     return TRACE_EVENT_API_ADD_TRACE_EVENT(
 399         phase, categoryEnabled, name, id, timestamp,
 400         zeroNumArgs, 0, 0, 0,
 401         flags);
 402 }
 403
 404 template<typename ARG1_TYPE>
 405 static inline TraceEventHandle addTraceEvent(
 406     char phase,
 407     const unsigned char* categoryEnabled,
 408     const char* name,
 409     unsigned long long id,
 410     double timestamp,
 411     unsigned char flags,
 412     const char* arg1Name,
 413     const ARG1_TYPE& arg1Val)
 414 {
 415     const int numArgs = 1;
 416     unsigned char argTypes[1];
 417     unsigned long long argValues[1];
 418     setTraceValue(arg1Val, &argTypes[0], &argValues[0]);
 419     if (isConvertableToTraceFormat(arg1Val)) {
 420         return TRACE_EVENT_API_ADD_TRACE_EVENT(
 421             phase, categoryEnabled, name, id, timestamp,
 422             numArgs, &arg1Name, argTypes, argValues,
 423             moveFromIfConvertableToTraceFormat(arg1Val),
 424             nullptr,
 425             flags);
 426     }
 427     return TRACE_EVENT_API_ADD_TRACE_EVENT(
 428         phase, categoryEnabled, name, id, timestamp,
 429         numArgs, &arg1Name, argTypes, argValues,
 430         flags);
 431 }
 432
 433 template<typename ARG1_TYPE, typename ARG2_TYPE>
 434 static inline TraceEventHandle addTraceEvent(
 435     char phase,
 436     const unsigned char* categoryEnabled,
 437     const char* name,
 438     unsigned long long id,
 439     double timestamp,
 440     unsigned char flags,
 441     const char* arg1Name,
 442     const ARG1_TYPE& arg1Val,
 443     const char* arg2Name,
 444     const ARG2_TYPE& arg2Val)
 445 {
 446     const int numArgs = 2;
 447     const char* argNames[2] = { arg1Name, arg2Name };
 448     unsigned char argTypes[2];
 449     unsigned long long argValues[2];
 450     setTraceValue(arg1Val, &argTypes[0], &argValues[0]);
 451     setTraceValue(arg2Val, &argTypes[1], &argValues[1]);
 452     if (isConvertableToTraceFormat(arg1Val) || isConvertableToTraceFormat(arg2Val)) {
 453         return TRACE_EVENT_API_ADD_TRACE_EVENT(
 454             phase, categoryEnabled, name, id, timestamp,
 455             numArgs, argNames, argTypes, argValues,
 456             moveFromIfConvertableToTraceFormat(arg1Val),
 457             moveFromIfConvertableToTraceFormat(arg2Val),
 458             flags);
 459     }
 460     return TRACE_EVENT_API_ADD_TRACE_EVENT(
 461         phase, categoryEnabled, name, id, timestamp,
 462         numArgs, argNames, argTypes, argValues,
 463         flags);
 464 }
 465
 466 static inline TraceEventHandle addTraceEvent(
 467     char phase,
 468     const unsigned char* categoryEnabled,
 469     const char* name,
 470     unsigned long long id,
 471     unsigned char flags)
 472 {
 473     return addTraceEvent(phase, categoryEnabled, name, id, systemTraceTime(), flags);
 474 }
 475
 476 template<typename ARG1_TYPE>
 477 static inline TraceEventHandle addTraceEvent(
 478     char phase,
 479     const unsigned char* categoryEnabled,
 480     const char* name,
 481     unsigned long long id,
 482     unsigned char flags,
 483     const char* arg1Name,
 484     const ARG1_TYPE& arg1Val)
 485 {
 486     return addTraceEvent(phase, categoryEnabled, name, id, systemTraceTime(), flags, arg1Name, arg1Val);
 487 }
 488
 489
 490 template<typename ARG1_TYPE, typename ARG2_TYPE>
 491 static inline TraceEventHandle addTraceEvent(
 492     char phase,
 493     const unsigned char* categoryEnabled,
 494     const char* name,
 495     unsigned long long id,
 496     unsigned char flags,
 497     const char* arg1Name,
 498     const ARG1_TYPE& arg1Val,
 499     const char* arg2Name,
 500     const ARG2_TYPE& arg2Val)
 501 {
 502     return addTraceEvent(phase, categoryEnabled, name, id, systemTraceTime(), flags, arg1Name, arg1Val, arg2Name, arg2Val);
 503 }
 504
 505 // Used by TRACE_EVENTx macro. Do not use directly.
 506 class ScopedTracer {
 507 public:
 508     // Note: members of m_data intentionally left uninitialized. See initialize.
 509     ScopedTracer() : m_pdata(0) { }
 510     ~ScopedTracer()
 511     {
 512         if (m_pdata && *m_pdata->categoryGroupEnabled)
 513             TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(m_data.categoryGroupEnabled, m_data.name, m_data.eventHandle);
 514     }
 515
 516     void initialize(const unsigned char* categoryGroupEnabled, const char* name, TraceEventHandle eventHandle)
 517     {
 518         m_data.categoryGroupEnabled = categoryGroupEnabled;
 519         m_data.name = name;
 520         m_data.eventHandle = eventHandle;
 521         m_pdata = &m_data;
 522     }
 523
 524 private:
 525     // This Data struct workaround is to avoid initializing all the members
 526     // in Data during construction of this object, since this object is always
 527     // constructed, even when tracing is disabled. If the members of Data were
 528     // members of this class instead, compiler warnings occur about potential
 529     // uninitialized accesses.
 530     struct Data {
 531         const unsigned char* categoryGroupEnabled;
 532         const char* name;
 533         TraceEventHandle eventHandle;
 534     };
 535     Data* m_pdata;
 536     Data m_data;
 537 };
 538
 539 // TraceEventSamplingStateScope records the current sampling state
 540 // and sets a new sampling state. When the scope exists, it restores
 541 // the sampling state having recorded.
 542 template<size_t BucketNumber>
 543 class SamplingStateScope {
 544     WTF_MAKE_FAST_ALLOCATED(SamplingStateScope);
 545 public:
 546     SamplingStateScope(const char* categoryAndName)
 547     {
 548         m_previousState = SamplingStateScope<BucketNumber>::current();
 549         SamplingStateScope<BucketNumber>::set(categoryAndName);
 550     }
 551
 552     ~SamplingStateScope()
 553     {
 554         SamplingStateScope<BucketNumber>::set(m_previousState);
 555     }
 556
 557     // FIXME: Make load/store to traceSamplingState[] thread-safe and atomic.
 558     static const char* current()
 559     {
 560         return reinterpret_cast<const char*>(*blink::traceSamplingState[BucketNumber]);
 561     }
 562     static void set(const char* categoryAndName)
 563     {
 564         *blink::traceSamplingState[BucketNumber] = reinterpret_cast<TraceEventAPIAtomicWord>(categoryAndName);
 565     }
 566
 567 private:
 568     const char* m_previousState;
 569 };
 570
 571 template<typename IDType> class TraceScopedTrackableObject {
 572     WTF_MAKE_NONCOPYABLE(TraceScopedTrackableObject);
 573 public:
 574     TraceScopedTrackableObject(const char* categoryGroup, const char* name, IDType id)
 575         : m_categoryGroup(categoryGroup), m_name(name), m_id(id)
 576     {
 577         TRACE_EVENT_OBJECT_CREATED_WITH_ID(m_categoryGroup, m_name, m_id);
 578     }
 579
 580     ~TraceScopedTrackableObject()
 581     {
 582         TRACE_EVENT_OBJECT_DELETED_WITH_ID(m_categoryGroup, m_name, m_id);
 583     }
 584
 585 private:
 586     const char* m_categoryGroup;
 587     const char* m_name;
 588     IDType m_id;
 589 };
 590
 591 } // namespace TraceEvent
 592
 593 } // namespace blink
 594
 595 #endif