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   char phase;
 150
 151   std::string category;
 152
 153   std::string name;
 154
 155   std::string id;
 156
 157   // All numbers and bool values from TraceEvent args are cast to double.
 158   // bool becomes 1.0 (true) or 0.0 (false).
 159   std::map<std::string, double> arg_numbers;
 160
 161   std::map<std::string, std::string> arg_strings;
 162
 163   // The other event associated with this event (or NULL).
 164   const TraceEvent* other_event;
 165 };
 166
 167 typedef std::vector<const TraceEvent*> TraceEventVector;
 168
 169 class Query {
 170  public:
 171   Query(const Query& query);
 172
 173   ~Query();
 174
 175   ////////////////////////////////////////////////////////////////
 176   // Query literal values
 177
 178   // Compare with the given string.
 179   static Query String(const std::string& str);
 180
 181   // Compare with the given number.
 182   static Query Double(double num);
 183   static Query Int(int32 num);
 184   static Query Uint(uint32 num);
 185
 186   // Compare with the given bool.
 187   static Query Bool(bool boolean);
 188
 189   // Compare with the given phase.
 190   static Query Phase(char phase);
 191
 192   // Compare with the given string pattern. Only works with == and != operators.
 193   // Example: Query(EVENT_NAME) == Query::Pattern("MyEvent*")
 194   static Query Pattern(const std::string& pattern);
 195
 196   ////////////////////////////////////////////////////////////////
 197   // Query event members
 198
 199   static Query EventPid() { return Query(EVENT_PID); }
 200
 201   static Query EventTid() { return Query(EVENT_TID); }
 202
 203   // Return the timestamp of the event in microseconds since epoch.
 204   static Query EventTime() { return Query(EVENT_TIME); }
 205
 206   // Return the absolute time between event and other event in microseconds.
 207   // Only works if Query::EventHasOther() == true.
 208   static Query EventDuration() { return Query(EVENT_DURATION); }
 209
 210   static Query EventPhase() { return Query(EVENT_PHASE); }
 211
 212   static Query EventCategory() { return Query(EVENT_CATEGORY); }
 213
 214   static Query EventName() { return Query(EVENT_NAME); }
 215
 216   static Query EventId() { return Query(EVENT_ID); }
 217
 218   static Query EventPidIs(int process_id) {
 219     return Query(EVENT_PID) == Query::Int(process_id);
 220   }
 221
 222   static Query EventTidIs(int thread_id) {
 223     return Query(EVENT_TID) == Query::Int(thread_id);
 224   }
 225
 226   static Query EventThreadIs(const TraceEvent::ProcessThreadID& thread) {
 227     return EventPidIs(thread.process_id) && EventTidIs(thread.thread_id);
 228   }
 229
 230   static Query EventTimeIs(double timestamp) {
 231     return Query(EVENT_TIME) == Query::Double(timestamp);
 232   }
 233
 234   static Query EventDurationIs(double duration) {
 235     return Query(EVENT_DURATION) == Query::Double(duration);
 236   }
 237
 238   static Query EventPhaseIs(char phase) {
 239     return Query(EVENT_PHASE) == Query::Phase(phase);
 240   }
 241
 242   static Query EventCategoryIs(const std::string& category) {
 243     return Query(EVENT_CATEGORY) == Query::String(category);
 244   }
 245
 246   static Query EventNameIs(const std::string& name) {
 247     return Query(EVENT_NAME) == Query::String(name);
 248   }
 249
 250   static Query EventIdIs(const std::string& id) {
 251     return Query(EVENT_ID) == Query::String(id);
 252   }
 253
 254   // Evaluates to true if arg exists and is a string.
 255   static Query EventHasStringArg(const std::string& arg_name) {
 256     return Query(EVENT_HAS_STRING_ARG, arg_name);
 257   }
 258
 259   // Evaluates to true if arg exists and is a number.
 260   // Number arguments include types double, int and bool.
 261   static Query EventHasNumberArg(const std::string& arg_name) {
 262     return Query(EVENT_HAS_NUMBER_ARG, arg_name);
 263   }
 264
 265   // Evaluates to arg value (string or number).
 266   static Query EventArg(const std::string& arg_name) {
 267     return Query(EVENT_ARG, arg_name);
 268   }
 269
 270   // Return true if associated event exists.
 271   static Query EventHasOther() { return Query(EVENT_HAS_OTHER); }
 272
 273   // Access the associated other_event's members:
 274
 275   static Query OtherPid() { return Query(OTHER_PID); }
 276
 277   static Query OtherTid() { return Query(OTHER_TID); }
 278
 279   static Query OtherTime() { return Query(OTHER_TIME); }
 280
 281   static Query OtherPhase() { return Query(OTHER_PHASE); }
 282
 283   static Query OtherCategory() { return Query(OTHER_CATEGORY); }
 284
 285   static Query OtherName() { return Query(OTHER_NAME); }
 286
 287   static Query OtherId() { return Query(OTHER_ID); }
 288
 289   static Query OtherPidIs(int process_id) {
 290     return Query(OTHER_PID) == Query::Int(process_id);
 291   }
 292
 293   static Query OtherTidIs(int thread_id) {
 294     return Query(OTHER_TID) == Query::Int(thread_id);
 295   }
 296
 297   static Query OtherThreadIs(const TraceEvent::ProcessThreadID& thread) {
 298     return OtherPidIs(thread.process_id) && OtherTidIs(thread.thread_id);
 299   }
 300
 301   static Query OtherTimeIs(double timestamp) {
 302     return Query(OTHER_TIME) == Query::Double(timestamp);
 303   }
 304
 305   static Query OtherPhaseIs(char phase) {
 306     return Query(OTHER_PHASE) == Query::Phase(phase);
 307   }
 308
 309   static Query OtherCategoryIs(const std::string& category) {
 310     return Query(OTHER_CATEGORY) == Query::String(category);
 311   }
 312
 313   static Query OtherNameIs(const std::string& name) {
 314     return Query(OTHER_NAME) == Query::String(name);
 315   }
 316
 317   static Query OtherIdIs(const std::string& id) {
 318     return Query(OTHER_ID) == Query::String(id);
 319   }
 320
 321   // Evaluates to true if arg exists and is a string.
 322   static Query OtherHasStringArg(const std::string& arg_name) {
 323     return Query(OTHER_HAS_STRING_ARG, arg_name);
 324   }
 325
 326   // Evaluates to true if arg exists and is a number.
 327   // Number arguments include types double, int and bool.
 328   static Query OtherHasNumberArg(const std::string& arg_name) {
 329     return Query(OTHER_HAS_NUMBER_ARG, arg_name);
 330   }
 331
 332   // Evaluates to arg value (string or number).
 333   static Query OtherArg(const std::string& arg_name) {
 334     return Query(OTHER_ARG, arg_name);
 335   }
 336
 337   ////////////////////////////////////////////////////////////////
 338   // Common queries:
 339
 340   // Find BEGIN events that have a corresponding END event.
 341   static Query MatchBeginWithEnd() {
 342     return (Query(EVENT_PHASE) == Query::Phase(TRACE_EVENT_PHASE_BEGIN)) &&
 343            Query(EVENT_HAS_OTHER);
 344   }
 345
 346   // Find ASYNC_BEGIN events that have a corresponding ASYNC_END event.
 347   static Query MatchAsyncBeginWithNext() {
 348     return (Query(EVENT_PHASE) ==
 349             Query::Phase(TRACE_EVENT_PHASE_ASYNC_BEGIN)) &&
 350            Query(EVENT_HAS_OTHER);
 351   }
 352
 353   // Find BEGIN events of given |name| which also have associated END events.
 354   static Query MatchBeginName(const std::string& name) {
 355     return (Query(EVENT_NAME) == Query(name)) && MatchBeginWithEnd();
 356   }
 357
 358   // Match given Process ID and Thread ID.
 359   static Query MatchThread(const TraceEvent::ProcessThreadID& thread) {
 360     return (Query(EVENT_PID) == Query::Int(thread.process_id)) &&
 361            (Query(EVENT_TID) == Query::Int(thread.thread_id));
 362   }
 363
 364   // Match event pair that spans multiple threads.
 365   static Query MatchCrossThread() {
 366     return (Query(EVENT_PID) != Query(OTHER_PID)) ||
 367            (Query(EVENT_TID) != Query(OTHER_TID));
 368   }
 369
 370   ////////////////////////////////////////////////////////////////
 371   // Operators:
 372
 373   // Boolean operators:
 374   Query operator==(const Query& rhs) const;
 375   Query operator!=(const Query& rhs) const;
 376   Query operator< (const Query& rhs) const;
 377   Query operator<=(const Query& rhs) const;
 378   Query operator> (const Query& rhs) const;
 379   Query operator>=(const Query& rhs) const;
 380   Query operator&&(const Query& rhs) const;
 381   Query operator||(const Query& rhs) const;
 382   Query operator!() const;
 383
 384   // Arithmetic operators:
 385   // Following operators are applied to double arguments:
 386   Query operator+(const Query& rhs) const;
 387   Query operator-(const Query& rhs) const;
 388   Query operator*(const Query& rhs) const;
 389   Query operator/(const Query& rhs) const;
 390   Query operator-() const;
 391   // Mod operates on int64 args (doubles are casted to int64 beforehand):
 392   Query operator%(const Query& rhs) const;
 393
 394   // Return true if the given event matches this query tree.
 395   // This is a recursive method that walks the query tree.
 396   bool Evaluate(const TraceEvent& event) const;
 397
 398  private:
 399   enum TraceEventMember {
 400     EVENT_INVALID,
 401     EVENT_PID,
 402     EVENT_TID,
 403     EVENT_TIME,
 404     EVENT_DURATION,
 405     EVENT_PHASE,
 406     EVENT_CATEGORY,
 407     EVENT_NAME,
 408     EVENT_ID,
 409     EVENT_HAS_STRING_ARG,
 410     EVENT_HAS_NUMBER_ARG,
 411     EVENT_ARG,
 412     EVENT_HAS_OTHER,
 413     OTHER_PID,
 414     OTHER_TID,
 415     OTHER_TIME,
 416     OTHER_PHASE,
 417     OTHER_CATEGORY,
 418     OTHER_NAME,
 419     OTHER_ID,
 420     OTHER_HAS_STRING_ARG,
 421     OTHER_HAS_NUMBER_ARG,
 422     OTHER_ARG,
 423   };
 424
 425   enum Operator {
 426     OP_INVALID,
 427     // Boolean operators:
 428     OP_EQ,
 429     OP_NE,
 430     OP_LT,
 431     OP_LE,
 432     OP_GT,
 433     OP_GE,
 434     OP_AND,
 435     OP_OR,
 436     OP_NOT,
 437     // Arithmetic operators:
 438     OP_ADD,
 439     OP_SUB,
 440     OP_MUL,
 441     OP_DIV,
 442     OP_MOD,
 443     OP_NEGATE
 444   };
 445
 446   enum QueryType {
 447     QUERY_BOOLEAN_OPERATOR,
 448     QUERY_ARITHMETIC_OPERATOR,
 449     QUERY_EVENT_MEMBER,
 450     QUERY_NUMBER,
 451     QUERY_STRING
 452   };
 453
 454   // Compare with the given member.
 455   explicit Query(TraceEventMember member);
 456
 457   // Compare with the given member argument value.
 458   Query(TraceEventMember member, const std::string& arg_name);
 459
 460   // Compare with the given string.
 461   explicit Query(const std::string& str);
 462
 463   // Compare with the given number.
 464   explicit Query(double num);
 465
 466   // Construct a boolean Query that returns (left <binary_op> right).
 467   Query(const Query& left, const Query& right, Operator binary_op);
 468
 469   // Construct a boolean Query that returns (<binary_op> left).
 470   Query(const Query& left, Operator unary_op);
 471
 472   // Try to compare left_ against right_ based on operator_.
 473   // If either left or right does not convert to double, false is returned.
 474   // Otherwise, true is returned and |result| is set to the comparison result.
 475   bool CompareAsDouble(const TraceEvent& event, bool* result) const;
 476
 477   // Try to compare left_ against right_ based on operator_.
 478   // If either left or right does not convert to string, false is returned.
 479   // Otherwise, true is returned and |result| is set to the comparison result.
 480   bool CompareAsString(const TraceEvent& event, bool* result) const;
 481
 482   // Attempt to convert this Query to a double. On success, true is returned
 483   // and the double value is stored in |num|.
 484   bool GetAsDouble(const TraceEvent& event, double* num) const;
 485
 486   // Attempt to convert this Query to a string. On success, true is returned
 487   // and the string value is stored in |str|.
 488   bool GetAsString(const TraceEvent& event, std::string* str) const;
 489
 490   // Evaluate this Query as an arithmetic operator on left_ and right_.
 491   bool EvaluateArithmeticOperator(const TraceEvent& event,
 492                                   double* num) const;
 493
 494   // For QUERY_EVENT_MEMBER Query: attempt to get the double value of the Query.
 495   bool GetMemberValueAsDouble(const TraceEvent& event, double* num) const;
 496
 497   // For QUERY_EVENT_MEMBER Query: attempt to get the string value of the Query.
 498   bool GetMemberValueAsString(const TraceEvent& event, std::string* num) const;
 499
 500   // Does this Query represent a value?
 501   bool is_value() const { return type_ != QUERY_BOOLEAN_OPERATOR; }
 502
 503   bool is_unary_operator() const {
 504     return operator_ == OP_NOT || operator_ == OP_NEGATE;
 505   }
 506
 507   bool is_comparison_operator() const {
 508     return operator_ != OP_INVALID && operator_ < OP_AND;
 509   }
 510
 511   const Query& left() const;
 512   const Query& right() const;
 513
 514   QueryType type_;
 515   Operator operator_;
 516   scoped_refptr<QueryNode> left_;
 517   scoped_refptr<QueryNode> right_;
 518   TraceEventMember member_;
 519   double number_;
 520   std::string string_;
 521   bool is_pattern_;
 522 };
 523
 524 // Implementation detail:
 525 // QueryNode allows Query to store a ref-counted query tree.
 526 class QueryNode : public base::RefCounted<QueryNode> {
 527  public:
 528   explicit QueryNode(const Query& query);
 529   const Query& query() const { return query_; }
 530
 531  private:
 532   friend class base::RefCounted<QueryNode>;
 533   ~QueryNode();
 534
 535   Query query_;
 536 };
 537
 538 // TraceAnalyzer helps tests search for trace events.
 539 class TraceAnalyzer {
 540  public:
 541   ~TraceAnalyzer();
 542
 543   // Use trace events from JSON string generated by tracing API.
 544   // Returns non-NULL if the JSON is successfully parsed.
 545   static TraceAnalyzer* Create(const std::string& json_events)
 546                                WARN_UNUSED_RESULT;
 547
 548   // Associate BEGIN and END events with each other. This allows Query(OTHER_*)
 549   // to access the associated event and enables Query(EVENT_DURATION).
 550   // An end event will match the most recent begin event with the same name,
 551   // category, process ID and thread ID. This matches what is shown in
 552   // about:tracing. After association, the BEGIN event will point to the
 553   // matching END event, but the END event will not point to the BEGIN event.
 554   void AssociateBeginEndEvents();
 555
 556   // Associate ASYNC_BEGIN, ASYNC_STEP and ASYNC_END events with each other.
 557   // An ASYNC_END event will match the most recent ASYNC_BEGIN or ASYNC_STEP
 558   // event with the same name, category, and ID. This creates a singly linked
 559   // list of ASYNC_BEGIN->ASYNC_STEP...->ASYNC_END.
 560   void AssociateAsyncBeginEndEvents();
 561
 562   // AssociateEvents can be used to customize event associations by setting the
 563   // other_event member of TraceEvent. This should be used to associate two
 564   // INSTANT events.
 565   //
 566   // The assumptions are:
 567   // - |first| events occur before |second| events.
 568   // - the closest matching |second| event is the correct match.
 569   //
 570   // |first|  - Eligible |first| events match this query.
 571   // |second| - Eligible |second| events match this query.
 572   // |match|  - This query is run on the |first| event. The OTHER_* EventMember
 573   //            queries will point to an eligible |second| event. The query
 574   //            should evaluate to true if the |first|/|second| pair is a match.
 575   //
 576   // When a match is found, the pair will be associated by having the first
 577   // event's other_event member point to the other. AssociateEvents does not
 578   // clear previous associations, so it is possible to associate multiple pairs
 579   // of events by calling AssociateEvents more than once with different queries.
 580   //
 581   // NOTE: AssociateEvents will overwrite existing other_event associations if
 582   // the queries pass for events that already had a previous association.
 583   //
 584   // After calling any Find* method, it is not allowed to call AssociateEvents
 585   // again.
 586   void AssociateEvents(const Query& first,
 587                        const Query& second,
 588                        const Query& match);
 589
 590   // For each event, copy its arguments to the other_event argument map. If
 591   // argument name already exists, it will not be overwritten.
 592   void MergeAssociatedEventArgs();
 593
 594   // Find all events that match query and replace output vector.
 595   size_t FindEvents(const Query& query, TraceEventVector* output);
 596
 597   // Find first event that matches query or NULL if not found.
 598   const TraceEvent* FindFirstOf(const Query& query);
 599
 600   // Find last event that matches query or NULL if not found.
 601   const TraceEvent* FindLastOf(const Query& query);
 602
 603   const std::string& GetThreadName(const TraceEvent::ProcessThreadID& thread);
 604
 605  private:
 606   TraceAnalyzer();
 607
 608   bool SetEvents(const std::string& json_events) WARN_UNUSED_RESULT;
 609
 610   // Read metadata (thread names, etc) from events.
 611   void ParseMetadata();
 612
 613   std::map<TraceEvent::ProcessThreadID, std::string> thread_names_;
 614   std::vector<TraceEvent> raw_events_;
 615   bool allow_assocation_changes_;
 616
 617   DISALLOW_COPY_AND_ASSIGN(TraceAnalyzer);
 618 };
 619
 620 // Utility functions for TraceEventVector.
 621
 622 struct RateStats {
 623   double min_us;
 624   double max_us;
 625   double mean_us;
 626   double standard_deviation_us;
 627 };
 628
 629 struct RateStatsOptions {
 630   RateStatsOptions() : trim_min(0u), trim_max(0u) {}
 631   // After the times between events are sorted, the number of specified elements
 632   // will be trimmed before calculating the RateStats. This is useful in cases
 633   // where extreme outliers are tolerable and should not skew the overall
 634   // average.
 635   size_t trim_min;  // Trim this many minimum times.
 636   size_t trim_max;  // Trim this many maximum times.
 637 };
 638
 639 // Calculate min/max/mean and standard deviation from the times between
 640 // adjacent events.
 641 bool GetRateStats(const TraceEventVector& events,
 642                   RateStats* stats,
 643                   const RateStatsOptions* options);
 644
 645 // Starting from |position|, find the first event that matches |query|.
 646 // Returns true if found, false otherwise.
 647 bool FindFirstOf(const TraceEventVector& events,
 648                  const Query& query,
 649                  size_t position,
 650                  size_t* return_index);
 651
 652 // Starting from |position|, find the last event that matches |query|.
 653 // Returns true if found, false otherwise.
 654 bool FindLastOf(const TraceEventVector& events,
 655                 const Query& query,
 656                 size_t position,
 657                 size_t* return_index);
 658
 659 // Find the closest events to |position| in time that match |query|.
 660 // return_second_closest may be NULL. Closeness is determined by comparing
 661 // with the event timestamp.
 662 // Returns true if found, false otherwise. If both return parameters are
 663 // requested, both must be found for a successful result.
 664 bool FindClosest(const TraceEventVector& events,
 665                  const Query& query,
 666                  size_t position,
 667                  size_t* return_closest,
 668                  size_t* return_second_closest);
 669
 670 // Count matches, inclusive of |begin_position|, exclusive of |end_position|.
 671 size_t CountMatches(const TraceEventVector& events,
 672                     const Query& query,
 673                     size_t begin_position,
 674                     size_t end_position);
 675
 676 // Count all matches.
 677 static inline size_t CountMatches(const TraceEventVector& events,
 678                                   const Query& query) {
 679   return CountMatches(events, query, 0u, events.size());
 680 }
 681
 682 }  // namespace trace_analyzer
 683
 684 #endif  // BASE_TEST_TRACE_EVENT_ANALYZER_H_