base/test/trace_event_analyzer.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // Use trace_analyzer::Query and trace_analyzer::TraceAnalyzer to search for
   6 // specific trace events that were generated by the trace_event.h API.
   7 //
   8 // Basic procedure:
   9 // - Get trace events JSON string from base::debug::TraceLog.
  10 // - Create TraceAnalyzer with JSON string.
  11 // - Call TraceAnalyzer::AssociateBeginEndEvents (optional).
  12 // - Call TraceAnalyzer::AssociateEvents (zero or more times).
  13 // - Call TraceAnalyzer::FindEvents with queries to find specific events.
  14 //
  15 // A Query is a boolean expression tree that evaluates to true or false for a
  16 // given trace event. Queries can be combined into a tree using boolean,
  17 // arithmetic and comparison operators that refer to data of an individual trace
  18 // event.
  19 //
  20 // The events are returned as trace_analyzer::TraceEvent objects.
  21 // TraceEvent contains a single trace event's data, as well as a pointer to
  22 // a related trace event. The related trace event is typically the matching end
  23 // of a begin event or the matching begin of an end event.
  24 //
  25 // The following examples use this basic setup code to construct TraceAnalyzer
  26 // with the json trace string retrieved from TraceLog and construct an event
  27 // vector for retrieving events:
  28 //
  29 // TraceAnalyzer analyzer(json_events);
  30 // TraceEventVector events;
  31 //
  32 // EXAMPLE 1: Find events named "my_event".
  33 //
  34 // analyzer.FindEvents(Query(EVENT_NAME) == "my_event", &events);
  35 //
  36 // EXAMPLE 2: Find begin events named "my_event" with duration > 1 second.
  37 //
  38 // Query q = (Query(EVENT_NAME) == Query::String("my_event") &&
  39 //            Query(EVENT_PHASE) == Query::Phase(TRACE_EVENT_PHASE_BEGIN) &&
  40 //            Query(EVENT_DURATION) > Query::Double(1000000.0));
  41 // analyzer.FindEvents(q, &events);
  42 //
  43 // EXAMPLE 3: Associating event pairs across threads.
  44 //
  45 // If the test needs to analyze something that starts and ends on different
  46 // threads, the test needs to use INSTANT events. The typical procedure is to
  47 // specify the same unique ID as a TRACE_EVENT argument on both the start and
  48 // finish INSTANT events. Then use the following procedure to associate those
  49 // events.
  50 //
  51 // Step 1: instrument code with custom begin/end trace events.
  52 //   [Thread 1 tracing code]
  53 //   TRACE_EVENT_INSTANT1("test_latency", "timing1_begin", "id", 3);
  54 //   [Thread 2 tracing code]
  55 //   TRACE_EVENT_INSTANT1("test_latency", "timing1_end", "id", 3);
  56 //
  57 // Step 2: associate these custom begin/end pairs.
  58 //   Query begin(Query(EVENT_NAME) == Query::String("timing1_begin"));
  59 //   Query end(Query(EVENT_NAME) == Query::String("timing1_end"));
  60 //   Query match(Query(EVENT_ARG, "id") == Query(OTHER_ARG, "id"));
  61 //   analyzer.AssociateEvents(begin, end, match);
  62 //
  63 // Step 3: search for "timing1_begin" events with existing other event.
  64 //   Query q = (Query(EVENT_NAME) == Query::String("timing1_begin") &&
  65 //              Query(EVENT_HAS_OTHER));
  66 //   analyzer.FindEvents(q, &events);
  67 //
  68 // Step 4: analyze events, such as checking durations.
  69 //   for (size_t i = 0; i < events.size(); ++i) {
  70 //     double duration;
  71 //     EXPECT_TRUE(events[i].GetAbsTimeToOtherEvent(&duration));
  72 //     EXPECT_LT(duration, 1000000.0/60.0); // expect less than 1/60 second.
  73 //   }
  74
  75
  76 #ifndef BASE_TEST_TRACE_EVENT_ANALYZER_H_
  77 #define BASE_TEST_TRACE_EVENT_ANALYZER_H_
  78
  79 #include <map>
  80
  81 #include "base/debug/trace_event.h"
  82 #include "base/memory/ref_counted.h"
  83
  84 namespace base {
  85 class Value;
  86 }
  87
  88 namespace trace_analyzer {
  89 class QueryNode;
  90
  91 // trace_analyzer::TraceEvent is a more convenient form of the
  92 // base::debug::TraceEvent class to make tracing-based tests easier to write.
  93 struct TraceEvent {
  94   // ProcessThreadID contains a Process ID and Thread ID.
  95   struct ProcessThreadID {
  96     ProcessThreadID() : process_id(0), thread_id(0) {}
  97     ProcessThreadID(int process_id, int thread_id)
  98         : process_id(process_id), thread_id(thread_id) {}
  99     bool operator< (const ProcessThreadID& rhs) const {
 100       if (process_id != rhs.process_id)
 101         return process_id < rhs.process_id;
 102       return thread_id < rhs.thread_id;
 103     }
 104     int process_id;
 105     int thread_id;
 106   };
 107
 108   TraceEvent();
 109   ~TraceEvent();
 110
 111   bool SetFromJSON(const base::Value* event_value) WARN_UNUSED_RESULT;
 112
 113   bool operator< (const TraceEvent& rhs) const {
 114     return timestamp < rhs.timestamp;
 115   }
 116
 117   bool has_other_event() const { return other_event; }
 118
 119   // Returns absolute duration in microseconds between this event and other
 120   // event. Must have already verified that other_event exists by
 121   // Query(EVENT_HAS_OTHER) or by calling has_other_event().
 122   double GetAbsTimeToOtherEvent() const;
 123
 124   // Return the argument value if it exists and it is a string.
 125   bool GetArgAsString(const std::string& name, std::string* arg) const;
 126   // Return the argument value if it exists and it is a number.
 127   bool GetArgAsNumber(const std::string& name, double* arg) const;
 128
 129   // Check if argument exists and is string.
 130   bool HasStringArg(const std::string& name) const;
 131   // Check if argument exists and is number (double, int or bool).
 132   bool HasNumberArg(const std::string& name) const;
 133
 134   // Get known existing arguments as specific types.
 135   // Useful when you have already queried the argument with
 136   // Query(HAS_NUMBER_ARG) or Query(HAS_STRING_ARG).
 137   std::string GetKnownArgAsString(const std::string& name) const;
 138   double GetKnownArgAsDouble(const std::string& name) const;
 139   int GetKnownArgAsInt(const std::string& name) const;
 140   bool GetKnownArgAsBool(const std::string& name) const;
 141
 142   // Process ID and Thread ID.
 143   ProcessThreadID thread;
 144
 145   // Time since epoch in microseconds.
 146   // Stored as double to match its JSON representation.
 147   double timestamp;
 148
 149   double duration;
 150
 151   char phase;
 152
 153   std::string category;
 154
 155   std::string name;
 156
 157   std::string id;
 158
 159   // All numbers and bool values from TraceEvent args are cast to double.
 160   // bool becomes 1.0 (true) or 0.0 (false).
 161   std::map<std::string, double> arg_numbers;
 162
 163   std::map<std::string, std::string> arg_strings;
 164
 165   // The other event associated with this event (or NULL).
 166   const TraceEvent* other_event;
 167 };
 168
 169 typedef std::vector<const TraceEvent*> TraceEventVector;
 170
 171 class Query {
 172  public:
 173   Query(const Query& query);
 174
 175   ~Query();
 176
 177   ////////////////////////////////////////////////////////////////
 178   // Query literal values
 179
 180   // Compare with the given string.
 181   static Query String(const std::string& str);
 182
 183   // Compare with the given number.
 184   static Query Double(double num);
 185   static Query Int(int32 num);
 186   static Query Uint(uint32 num);
 187
 188   // Compare with the given bool.
 189   static Query Bool(bool boolean);
 190
 191   // Compare with the given phase.
 192   static Query Phase(char phase);
 193
 194   // Compare with the given string pattern. Only works with == and != operators.
 195   // Example: Query(EVENT_NAME) == Query::Pattern("MyEvent*")
 196   static Query Pattern(const std::string& pattern);
 197
 198   ////////////////////////////////////////////////////////////////
 199   // Query event members
 200
 201   static Query EventPid() { return Query(EVENT_PID); }
 202
 203   static Query EventTid() { return Query(EVENT_TID); }
 204
 205   // Return the timestamp of the event in microseconds since epoch.
 206   static Query EventTime() { return Query(EVENT_TIME); }
 207
 208   // Return the absolute time between event and other event in microseconds.
 209   // Only works if Query::EventHasOther() == true.
 210   static Query EventDuration() { return Query(EVENT_DURATION); }
 211
 212   // Return the duration of a COMPLETE event.
 213   static Query EventCompleteDuration() {
 214     return Query(EVENT_COMPLETE_DURATION);
 215   }
 216
 217   static Query EventPhase() { return Query(EVENT_PHASE); }
 218
 219   static Query EventCategory() { return Query(EVENT_CATEGORY); }
 220
 221   static Query EventName() { return Query(EVENT_NAME); }
 222
 223   static Query EventId() { return Query(EVENT_ID); }
 224
 225   static Query EventPidIs(int process_id) {
 226     return Query(EVENT_PID) == Query::Int(process_id);
 227   }
 228
 229   static Query EventTidIs(int thread_id) {
 230     return Query(EVENT_TID) == Query::Int(thread_id);
 231   }
 232
 233   static Query EventThreadIs(const TraceEvent::ProcessThreadID& thread) {
 234     return EventPidIs(thread.process_id) && EventTidIs(thread.thread_id);
 235   }
 236
 237   static Query EventTimeIs(double timestamp) {
 238     return Query(EVENT_TIME) == Query::Double(timestamp);
 239   }
 240
 241   static Query EventDurationIs(double duration) {
 242     return Query(EVENT_DURATION) == Query::Double(duration);
 243   }
 244
 245   static Query EventPhaseIs(char phase) {
 246     return Query(EVENT_PHASE) == Query::Phase(phase);
 247   }
 248
 249   static Query EventCategoryIs(const std::string& category) {
 250     return Query(EVENT_CATEGORY) == Query::String(category);
 251   }
 252
 253   static Query EventNameIs(const std::string& name) {
 254     return Query(EVENT_NAME) == Query::String(name);
 255   }
 256
 257   static Query EventIdIs(const std::string& id) {
 258     return Query(EVENT_ID) == Query::String(id);
 259   }
 260
 261   // Evaluates to true if arg exists and is a string.
 262   static Query EventHasStringArg(const std::string& arg_name) {
 263     return Query(EVENT_HAS_STRING_ARG, arg_name);
 264   }
 265
 266   // Evaluates to true if arg exists and is a number.
 267   // Number arguments include types double, int and bool.
 268   static Query EventHasNumberArg(const std::string& arg_name) {
 269     return Query(EVENT_HAS_NUMBER_ARG, arg_name);
 270   }
 271
 272   // Evaluates to arg value (string or number).
 273   static Query EventArg(const std::string& arg_name) {
 274     return Query(EVENT_ARG, arg_name);
 275   }
 276
 277   // Return true if associated event exists.
 278   static Query EventHasOther() { return Query(EVENT_HAS_OTHER); }
 279
 280   // Access the associated other_event's members:
 281
 282   static Query OtherPid() { return Query(OTHER_PID); }
 283
 284   static Query OtherTid() { return Query(OTHER_TID); }
 285
 286   static Query OtherTime() { return Query(OTHER_TIME); }
 287
 288   static Query OtherPhase() { return Query(OTHER_PHASE); }
 289
 290   static Query OtherCategory() { return Query(OTHER_CATEGORY); }
 291
 292   static Query OtherName() { return Query(OTHER_NAME); }
 293
 294   static Query OtherId() { return Query(OTHER_ID); }
 295
 296   static Query OtherPidIs(int process_id) {
 297     return Query(OTHER_PID) == Query::Int(process_id);
 298   }
 299
 300   static Query OtherTidIs(int thread_id) {
 301     return Query(OTHER_TID) == Query::Int(thread_id);
 302   }
 303
 304   static Query OtherThreadIs(const TraceEvent::ProcessThreadID& thread) {
 305     return OtherPidIs(thread.process_id) && OtherTidIs(thread.thread_id);
 306   }
 307
 308   static Query OtherTimeIs(double timestamp) {
 309     return Query(OTHER_TIME) == Query::Double(timestamp);
 310   }
 311
 312   static Query OtherPhaseIs(char phase) {
 313     return Query(OTHER_PHASE) == Query::Phase(phase);
 314   }
 315
 316   static Query OtherCategoryIs(const std::string& category) {
 317     return Query(OTHER_CATEGORY) == Query::String(category);
 318   }
 319
 320   static Query OtherNameIs(const std::string& name) {
 321     return Query(OTHER_NAME) == Query::String(name);
 322   }
 323
 324   static Query OtherIdIs(const std::string& id) {
 325     return Query(OTHER_ID) == Query::String(id);
 326   }
 327
 328   // Evaluates to true if arg exists and is a string.
 329   static Query OtherHasStringArg(const std::string& arg_name) {
 330     return Query(OTHER_HAS_STRING_ARG, arg_name);
 331   }
 332
 333   // Evaluates to true if arg exists and is a number.
 334   // Number arguments include types double, int and bool.
 335   static Query OtherHasNumberArg(const std::string& arg_name) {
 336     return Query(OTHER_HAS_NUMBER_ARG, arg_name);
 337   }
 338
 339   // Evaluates to arg value (string or number).
 340   static Query OtherArg(const std::string& arg_name) {
 341     return Query(OTHER_ARG, arg_name);
 342   }
 343
 344   ////////////////////////////////////////////////////////////////
 345   // Common queries:
 346
 347   // Find BEGIN events that have a corresponding END event.
 348   static Query MatchBeginWithEnd() {
 349     return (Query(EVENT_PHASE) == Query::Phase(TRACE_EVENT_PHASE_BEGIN)) &&
 350            Query(EVENT_HAS_OTHER);
 351   }
 352
 353   // Find COMPLETE events.
 354   static Query MatchComplete() {
 355     return (Query(EVENT_PHASE) == Query::Phase(TRACE_EVENT_PHASE_COMPLETE));
 356   }
 357
 358   // Find ASYNC_BEGIN events that have a corresponding ASYNC_END event.
 359   static Query MatchAsyncBeginWithNext() {
 360     return (Query(EVENT_PHASE) ==
 361             Query::Phase(TRACE_EVENT_PHASE_ASYNC_BEGIN)) &&
 362            Query(EVENT_HAS_OTHER);
 363   }
 364
 365   // Find BEGIN events of given |name| which also have associated END events.
 366   static Query MatchBeginName(const std::string& name) {
 367     return (Query(EVENT_NAME) == Query(name)) && MatchBeginWithEnd();
 368   }
 369
 370   // Find COMPLETE events of given |name|.
 371   static Query MatchCompleteName(const std::string& name) {
 372     return (Query(EVENT_NAME) == Query(name)) && MatchComplete();
 373   }
 374
 375   // Match given Process ID and Thread ID.
 376   static Query MatchThread(const TraceEvent::ProcessThreadID& thread) {
 377     return (Query(EVENT_PID) == Query::Int(thread.process_id)) &&
 378            (Query(EVENT_TID) == Query::Int(thread.thread_id));
 379   }
 380
 381   // Match event pair that spans multiple threads.
 382   static Query MatchCrossThread() {
 383     return (Query(EVENT_PID) != Query(OTHER_PID)) ||
 384            (Query(EVENT_TID) != Query(OTHER_TID));
 385   }
 386
 387   ////////////////////////////////////////////////////////////////
 388   // Operators:
 389
 390   // Boolean operators:
 391   Query operator==(const Query& rhs) const;
 392   Query operator!=(const Query& rhs) const;
 393   Query operator< (const Query& rhs) const;
 394   Query operator<=(const Query& rhs) const;
 395   Query operator> (const Query& rhs) const;
 396   Query operator>=(const Query& rhs) const;
 397   Query operator&&(const Query& rhs) const;
 398   Query operator||(const Query& rhs) const;
 399   Query operator!() const;
 400
 401   // Arithmetic operators:
 402   // Following operators are applied to double arguments:
 403   Query operator+(const Query& rhs) const;
 404   Query operator-(const Query& rhs) const;
 405   Query operator*(const Query& rhs) const;
 406   Query operator/(const Query& rhs) const;
 407   Query operator-() const;
 408   // Mod operates on int64 args (doubles are casted to int64 beforehand):
 409   Query operator%(const Query& rhs) const;
 410
 411   // Return true if the given event matches this query tree.
 412   // This is a recursive method that walks the query tree.
 413   bool Evaluate(const TraceEvent& event) const;
 414
 415  private:
 416   enum TraceEventMember {
 417     EVENT_INVALID,
 418     EVENT_PID,
 419     EVENT_TID,
 420     EVENT_TIME,
 421     EVENT_DURATION,
 422     EVENT_COMPLETE_DURATION,
 423     EVENT_PHASE,
 424     EVENT_CATEGORY,
 425     EVENT_NAME,
 426     EVENT_ID,
 427     EVENT_HAS_STRING_ARG,
 428     EVENT_HAS_NUMBER_ARG,
 429     EVENT_ARG,
 430     EVENT_HAS_OTHER,
 431     OTHER_PID,
 432     OTHER_TID,
 433     OTHER_TIME,
 434     OTHER_PHASE,
 435     OTHER_CATEGORY,
 436     OTHER_NAME,
 437     OTHER_ID,
 438     OTHER_HAS_STRING_ARG,
 439     OTHER_HAS_NUMBER_ARG,
 440     OTHER_ARG,
 441   };
 442
 443   enum Operator {
 444     OP_INVALID,
 445     // Boolean operators:
 446     OP_EQ,
 447     OP_NE,
 448     OP_LT,
 449     OP_LE,
 450     OP_GT,
 451     OP_GE,
 452     OP_AND,
 453     OP_OR,
 454     OP_NOT,
 455     // Arithmetic operators:
 456     OP_ADD,
 457     OP_SUB,
 458     OP_MUL,
 459     OP_DIV,
 460     OP_MOD,
 461     OP_NEGATE
 462   };
 463
 464   enum QueryType {
 465     QUERY_BOOLEAN_OPERATOR,
 466     QUERY_ARITHMETIC_OPERATOR,
 467     QUERY_EVENT_MEMBER,
 468     QUERY_NUMBER,
 469     QUERY_STRING
 470   };
 471
 472   // Compare with the given member.
 473   explicit Query(TraceEventMember member);
 474
 475   // Compare with the given member argument value.
 476   Query(TraceEventMember member, const std::string& arg_name);
 477
 478   // Compare with the given string.
 479   explicit Query(const std::string& str);
 480
 481   // Compare with the given number.
 482   explicit Query(double num);
 483
 484   // Construct a boolean Query that returns (left <binary_op> right).
 485   Query(const Query& left, const Query& right, Operator binary_op);
 486
 487   // Construct a boolean Query that returns (<binary_op> left).
 488   Query(const Query& left, Operator unary_op);
 489
 490   // Try to compare left_ against right_ based on operator_.
 491   // If either left or right does not convert to double, false is returned.
 492   // Otherwise, true is returned and |result| is set to the comparison result.
 493   bool CompareAsDouble(const TraceEvent& event, bool* result) const;
 494
 495   // Try to compare left_ against right_ based on operator_.
 496   // If either left or right does not convert to string, false is returned.
 497   // Otherwise, true is returned and |result| is set to the comparison result.
 498   bool CompareAsString(const TraceEvent& event, bool* result) const;
 499
 500   // Attempt to convert this Query to a double. On success, true is returned
 501   // and the double value is stored in |num|.
 502   bool GetAsDouble(const TraceEvent& event, double* num) const;
 503
 504   // Attempt to convert this Query to a string. On success, true is returned
 505   // and the string value is stored in |str|.
 506   bool GetAsString(const TraceEvent& event, std::string* str) const;
 507
 508   // Evaluate this Query as an arithmetic operator on left_ and right_.
 509   bool EvaluateArithmeticOperator(const TraceEvent& event,
 510                                   double* num) const;
 511
 512   // For QUERY_EVENT_MEMBER Query: attempt to get the double value of the Query.
 513   bool GetMemberValueAsDouble(const TraceEvent& event, double* num) const;
 514
 515   // For QUERY_EVENT_MEMBER Query: attempt to get the string value of the Query.
 516   bool GetMemberValueAsString(const TraceEvent& event, std::string* num) const;
 517
 518   // Does this Query represent a value?
 519   bool is_value() const { return type_ != QUERY_BOOLEAN_OPERATOR; }
 520
 521   bool is_unary_operator() const {
 522     return operator_ == OP_NOT || operator_ == OP_NEGATE;
 523   }
 524
 525   bool is_comparison_operator() const {
 526     return operator_ != OP_INVALID && operator_ < OP_AND;
 527   }
 528
 529   const Query& left() const;
 530   const Query& right() const;
 531
 532   QueryType type_;
 533   Operator operator_;
 534   scoped_refptr<QueryNode> left_;
 535   scoped_refptr<QueryNode> right_;
 536   TraceEventMember member_;
 537   double number_;
 538   std::string string_;
 539   bool is_pattern_;
 540 };
 541
 542 // Implementation detail:
 543 // QueryNode allows Query to store a ref-counted query tree.
 544 class QueryNode : public base::RefCounted<QueryNode> {
 545  public:
 546   explicit QueryNode(const Query& query);
 547   const Query& query() const { return query_; }
 548
 549  private:
 550   friend class base::RefCounted<QueryNode>;
 551   ~QueryNode();
 552
 553   Query query_;
 554 };
 555
 556 // TraceAnalyzer helps tests search for trace events.
 557 class TraceAnalyzer {
 558  public:
 559   ~TraceAnalyzer();
 560
 561   // Use trace events from JSON string generated by tracing API.
 562   // Returns non-NULL if the JSON is successfully parsed.
 563   static TraceAnalyzer* Create(const std::string& json_events)
 564                                WARN_UNUSED_RESULT;
 565
 566   // Associate BEGIN and END events with each other. This allows Query(OTHER_*)
 567   // to access the associated event and enables Query(EVENT_DURATION).
 568   // An end event will match the most recent begin event with the same name,
 569   // category, process ID and thread ID. This matches what is shown in
 570   // about:tracing. After association, the BEGIN event will point to the
 571   // matching END event, but the END event will not point to the BEGIN event.
 572   void AssociateBeginEndEvents();
 573
 574   // Associate ASYNC_BEGIN, ASYNC_STEP and ASYNC_END events with each other.
 575   // An ASYNC_END event will match the most recent ASYNC_BEGIN or ASYNC_STEP
 576   // event with the same name, category, and ID. This creates a singly linked
 577   // list of ASYNC_BEGIN->ASYNC_STEP...->ASYNC_END.
 578   void AssociateAsyncBeginEndEvents();
 579
 580   // AssociateEvents can be used to customize event associations by setting the
 581   // other_event member of TraceEvent. This should be used to associate two
 582   // INSTANT events.
 583   //
 584   // The assumptions are:
 585   // - |first| events occur before |second| events.
 586   // - the closest matching |second| event is the correct match.
 587   //
 588   // |first|  - Eligible |first| events match this query.
 589   // |second| - Eligible |second| events match this query.
 590   // |match|  - This query is run on the |first| event. The OTHER_* EventMember
 591   //            queries will point to an eligible |second| event. The query
 592   //            should evaluate to true if the |first|/|second| pair is a match.
 593   //
 594   // When a match is found, the pair will be associated by having the first
 595   // event's other_event member point to the other. AssociateEvents does not
 596   // clear previous associations, so it is possible to associate multiple pairs
 597   // of events by calling AssociateEvents more than once with different queries.
 598   //
 599   // NOTE: AssociateEvents will overwrite existing other_event associations if
 600   // the queries pass for events that already had a previous association.
 601   //
 602   // After calling any Find* method, it is not allowed to call AssociateEvents
 603   // again.
 604   void AssociateEvents(const Query& first,
 605                        const Query& second,
 606                        const Query& match);
 607
 608   // For each event, copy its arguments to the other_event argument map. If
 609   // argument name already exists, it will not be overwritten.
 610   void MergeAssociatedEventArgs();
 611
 612   // Find all events that match query and replace output vector.
 613   size_t FindEvents(const Query& query, TraceEventVector* output);
 614
 615   // Find first event that matches query or NULL if not found.
 616   const TraceEvent* FindFirstOf(const Query& query);
 617
 618   // Find last event that matches query or NULL if not found.
 619   const TraceEvent* FindLastOf(const Query& query);
 620
 621   const std::string& GetThreadName(const TraceEvent::ProcessThreadID& thread);
 622
 623  private:
 624   TraceAnalyzer();
 625
 626   bool SetEvents(const std::string& json_events) WARN_UNUSED_RESULT;
 627
 628   // Read metadata (thread names, etc) from events.
 629   void ParseMetadata();
 630
 631   std::map<TraceEvent::ProcessThreadID, std::string> thread_names_;
 632   std::vector<TraceEvent> raw_events_;
 633   bool allow_assocation_changes_;
 634
 635   DISALLOW_COPY_AND_ASSIGN(TraceAnalyzer);
 636 };
 637
 638 // Utility functions for TraceEventVector.
 639
 640 struct RateStats {
 641   double min_us;
 642   double max_us;
 643   double mean_us;
 644   double standard_deviation_us;
 645 };
 646
 647 struct RateStatsOptions {
 648   RateStatsOptions() : trim_min(0u), trim_max(0u) {}
 649   // After the times between events are sorted, the number of specified elements
 650   // will be trimmed before calculating the RateStats. This is useful in cases
 651   // where extreme outliers are tolerable and should not skew the overall
 652   // average.
 653   size_t trim_min;  // Trim this many minimum times.
 654   size_t trim_max;  // Trim this many maximum times.
 655 };
 656
 657 // Calculate min/max/mean and standard deviation from the times between
 658 // adjacent events.
 659 bool GetRateStats(const TraceEventVector& events,
 660                   RateStats* stats,
 661                   const RateStatsOptions* options);
 662
 663 // Starting from |position|, find the first event that matches |query|.
 664 // Returns true if found, false otherwise.
 665 bool FindFirstOf(const TraceEventVector& events,
 666                  const Query& query,
 667                  size_t position,
 668                  size_t* return_index);
 669
 670 // Starting from |position|, find the last event that matches |query|.
 671 // Returns true if found, false otherwise.
 672 bool FindLastOf(const TraceEventVector& events,
 673                 const Query& query,
 674                 size_t position,
 675                 size_t* return_index);
 676
 677 // Find the closest events to |position| in time that match |query|.
 678 // return_second_closest may be NULL. Closeness is determined by comparing
 679 // with the event timestamp.
 680 // Returns true if found, false otherwise. If both return parameters are
 681 // requested, both must be found for a successful result.
 682 bool FindClosest(const TraceEventVector& events,
 683                  const Query& query,
 684                  size_t position,
 685                  size_t* return_closest,
 686                  size_t* return_second_closest);
 687
 688 // Count matches, inclusive of |begin_position|, exclusive of |end_position|.
 689 size_t CountMatches(const TraceEventVector& events,
 690                     const Query& query,
 691                     size_t begin_position,
 692                     size_t end_position);
 693
 694 // Count all matches.
 695 static inline size_t CountMatches(const TraceEventVector& events,
 696                                   const Query& query) {
 697   return CountMatches(events, query, 0u, events.size());
 698 }
 699
 700 }  // namespace trace_analyzer
 701
 702 #endif  // BASE_TEST_TRACE_EVENT_ANALYZER_H_