event.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package trace
     6  
     7  import (
     8  	"fmt"
     9  	"iter"
    10  	"math"
    11  	"strings"
    12  	"time"
    13  
    14  	"internal/trace/event"
    15  	"internal/trace/event/go122"
    16  	"internal/trace/version"
    17  )
    18  
    19  // EventKind indicates the kind of event this is.
    20  //
    21  // Use this information to obtain a more specific event that
    22  // allows access to more detailed information.
    23  type EventKind uint16
    24  
    25  const (
    26  	EventBad EventKind = iota
    27  
    28  	// EventKindSync is an event that indicates a global synchronization
    29  	// point in the trace. At the point of a sync event, the
    30  	// trace reader can be certain that all resources (e.g. threads,
    31  	// goroutines) that have existed until that point have been enumerated.
    32  	EventSync
    33  
    34  	// EventMetric is an event that represents the value of a metric at
    35  	// a particular point in time.
    36  	EventMetric
    37  
    38  	// EventLabel attaches a label to a resource.
    39  	EventLabel
    40  
    41  	// EventStackSample represents an execution sample, indicating what a
    42  	// thread/proc/goroutine was doing at a particular point in time via
    43  	// its backtrace.
    44  	//
    45  	// Note: Samples should be considered a close approximation of
    46  	// what a thread/proc/goroutine was executing at a given point in time.
    47  	// These events may slightly contradict the situation StateTransitions
    48  	// describe, so they should only be treated as a best-effort annotation.
    49  	EventStackSample
    50  
    51  	// EventRangeBegin and EventRangeEnd are a pair of generic events representing
    52  	// a special range of time. Ranges are named and scoped to some resource
    53  	// (identified via ResourceKind). A range that has begun but has not ended
    54  	// is considered active.
    55  	//
    56  	// EvRangeBegin and EvRangeEnd will share the same name, and an End will always
    57  	// follow a Begin on the same instance of the resource. The associated
    58  	// resource ID can be obtained from the Event. ResourceNone indicates the
    59  	// range is globally scoped. That is, any goroutine/proc/thread can start or
    60  	// stop, but only one such range may be active at any given time.
    61  	//
    62  	// EventRangeActive is like EventRangeBegin, but indicates that the range was
    63  	// already active. In this case, the resource referenced may not be in the current
    64  	// context.
    65  	EventRangeBegin
    66  	EventRangeActive
    67  	EventRangeEnd
    68  
    69  	// EvTaskBegin and EvTaskEnd are a pair of events representing a runtime/trace.Task.
    70  	EventTaskBegin
    71  	EventTaskEnd
    72  
    73  	// EventRegionBegin and EventRegionEnd are a pair of events represent a runtime/trace.Region.
    74  	EventRegionBegin
    75  	EventRegionEnd
    76  
    77  	// EventLog represents a runtime/trace.Log call.
    78  	EventLog
    79  
    80  	// EventStateTransition represents a state change for some resource.
    81  	EventStateTransition
    82  
    83  	// EventExperimental is an experimental event that is unvalidated and exposed in a raw form.
    84  	// Users are expected to understand the format and perform their own validation. These events
    85  	// may always be safely ignored.
    86  	EventExperimental
    87  )
    88  
    89  // String returns a string form of the EventKind.
    90  func (e EventKind) String() string {
    91  	if int(e) >= len(eventKindStrings) {
    92  		return eventKindStrings[0]
    93  	}
    94  	return eventKindStrings[e]
    95  }
    96  
    97  var eventKindStrings = [...]string{
    98  	EventBad:             "Bad",
    99  	EventSync:            "Sync",
   100  	EventMetric:          "Metric",
   101  	EventLabel:           "Label",
   102  	EventStackSample:     "StackSample",
   103  	EventRangeBegin:      "RangeBegin",
   104  	EventRangeActive:     "RangeActive",
   105  	EventRangeEnd:        "RangeEnd",
   106  	EventTaskBegin:       "TaskBegin",
   107  	EventTaskEnd:         "TaskEnd",
   108  	EventRegionBegin:     "RegionBegin",
   109  	EventRegionEnd:       "RegionEnd",
   110  	EventLog:             "Log",
   111  	EventStateTransition: "StateTransition",
   112  	EventExperimental:    "Experimental",
   113  }
   114  
   115  const maxTime = Time(math.MaxInt64)
   116  
   117  // Time is a timestamp in nanoseconds.
   118  //
   119  // It corresponds to the monotonic clock on the platform that the
   120  // trace was taken, and so is possible to correlate with timestamps
   121  // for other traces taken on the same machine using the same clock
   122  // (i.e. no reboots in between).
   123  //
   124  // The actual absolute value of the timestamp is only meaningful in
   125  // relation to other timestamps from the same clock.
   126  //
   127  // BUG: Timestamps coming from traces on Windows platforms are
   128  // only comparable with timestamps from the same trace. Timestamps
   129  // across traces cannot be compared, because the system clock is
   130  // not used as of Go 1.22.
   131  //
   132  // BUG: Traces produced by Go versions 1.21 and earlier cannot be
   133  // compared with timestamps from other traces taken on the same
   134  // machine. This is because the system clock was not used at all
   135  // to collect those timestamps.
   136  type Time int64
   137  
   138  // Sub subtracts t0 from t, returning the duration in nanoseconds.
   139  func (t Time) Sub(t0 Time) time.Duration {
   140  	return time.Duration(int64(t) - int64(t0))
   141  }
   142  
   143  // Metric provides details about a Metric event.
   144  type Metric struct {
   145  	// Name is the name of the sampled metric.
   146  	//
   147  	// Names follow the same convention as metric names in the
   148  	// runtime/metrics package, meaning they include the unit.
   149  	// Names that match with the runtime/metrics package represent
   150  	// the same quantity. Note that this corresponds to the
   151  	// runtime/metrics package for the Go version this trace was
   152  	// collected for.
   153  	Name string
   154  
   155  	// Value is the sampled value of the metric.
   156  	//
   157  	// The Value's Kind is tied to the name of the metric, and so is
   158  	// guaranteed to be the same for metric samples for the same metric.
   159  	Value Value
   160  }
   161  
   162  // Label provides details about a Label event.
   163  type Label struct {
   164  	// Label is the label applied to some resource.
   165  	Label string
   166  
   167  	// Resource is the resource to which this label should be applied.
   168  	Resource ResourceID
   169  }
   170  
   171  // Range provides details about a Range event.
   172  type Range struct {
   173  	// Name is a human-readable name for the range.
   174  	//
   175  	// This name can be used to identify the end of the range for the resource
   176  	// its scoped to, because only one of each type of range may be active on
   177  	// a particular resource. The relevant resource should be obtained from the
   178  	// Event that produced these details. The corresponding RangeEnd will have
   179  	// an identical name.
   180  	Name string
   181  
   182  	// Scope is the resource that the range is scoped to.
   183  	//
   184  	// For example, a ResourceGoroutine scope means that the same goroutine
   185  	// must have a start and end for the range, and that goroutine can only
   186  	// have one range of a particular name active at any given time. The
   187  	// ID that this range is scoped to may be obtained via Event.Goroutine.
   188  	//
   189  	// The ResourceNone scope means that the range is globally scoped. As a
   190  	// result, any goroutine/proc/thread may start or end the range, and only
   191  	// one such named range may be active globally at any given time.
   192  	//
   193  	// For RangeBegin and RangeEnd events, this will always reference some
   194  	// resource ID in the current execution context. For RangeActive events,
   195  	// this may reference a resource not in the current context. Prefer Scope
   196  	// over the current execution context.
   197  	Scope ResourceID
   198  }
   199  
   200  // RangeAttributes provides attributes about a completed Range.
   201  type RangeAttribute struct {
   202  	// Name is the human-readable name for the range.
   203  	Name string
   204  
   205  	// Value is the value of the attribute.
   206  	Value Value
   207  }
   208  
   209  // TaskID is the internal ID of a task used to disambiguate tasks (even if they
   210  // are of the same type).
   211  type TaskID uint64
   212  
   213  const (
   214  	// NoTask indicates the lack of a task.
   215  	NoTask = TaskID(^uint64(0))
   216  
   217  	// BackgroundTask is the global task that events are attached to if there was
   218  	// no other task in the context at the point the event was emitted.
   219  	BackgroundTask = TaskID(0)
   220  )
   221  
   222  // Task provides details about a Task event.
   223  type Task struct {
   224  	// ID is a unique identifier for the task.
   225  	//
   226  	// This can be used to associate the beginning of a task with its end.
   227  	ID TaskID
   228  
   229  	// ParentID is the ID of the parent task.
   230  	Parent TaskID
   231  
   232  	// Type is the taskType that was passed to runtime/trace.NewTask.
   233  	//
   234  	// May be "" if a task's TaskBegin event isn't present in the trace.
   235  	Type string
   236  }
   237  
   238  // Region provides details about a Region event.
   239  type Region struct {
   240  	// Task is the ID of the task this region is associated with.
   241  	Task TaskID
   242  
   243  	// Type is the regionType that was passed to runtime/trace.StartRegion or runtime/trace.WithRegion.
   244  	Type string
   245  }
   246  
   247  // Log provides details about a Log event.
   248  type Log struct {
   249  	// Task is the ID of the task this region is associated with.
   250  	Task TaskID
   251  
   252  	// Category is the category that was passed to runtime/trace.Log or runtime/trace.Logf.
   253  	Category string
   254  
   255  	// Message is the message that was passed to runtime/trace.Log or runtime/trace.Logf.
   256  	Message string
   257  }
   258  
   259  // Stack represents a stack. It's really a handle to a stack and it's trivially comparable.
   260  //
   261  // If two Stacks are equal then their Frames are guaranteed to be identical. If they are not
   262  // equal, however, their Frames may still be equal.
   263  type Stack struct {
   264  	table *evTable
   265  	id    stackID
   266  }
   267  
   268  // Frames is an iterator over the frames in a Stack.
   269  func (s Stack) Frames() iter.Seq[StackFrame] {
   270  	return func(yield func(StackFrame) bool) {
   271  		if s.id == 0 {
   272  			return
   273  		}
   274  		stk := s.table.stacks.mustGet(s.id)
   275  		for _, pc := range stk.pcs {
   276  			f := s.table.pcs[pc]
   277  			sf := StackFrame{
   278  				PC:   f.pc,
   279  				Func: s.table.strings.mustGet(f.funcID),
   280  				File: s.table.strings.mustGet(f.fileID),
   281  				Line: f.line,
   282  			}
   283  			if !yield(sf) {
   284  				return
   285  			}
   286  		}
   287  	}
   288  }
   289  
   290  // NoStack is a sentinel value that can be compared against any Stack value, indicating
   291  // a lack of a stack trace.
   292  var NoStack = Stack{}
   293  
   294  // StackFrame represents a single frame of a stack.
   295  type StackFrame struct {
   296  	// PC is the program counter of the function call if this
   297  	// is not a leaf frame. If it's a leaf frame, it's the point
   298  	// at which the stack trace was taken.
   299  	PC uint64
   300  
   301  	// Func is the name of the function this frame maps to.
   302  	Func string
   303  
   304  	// File is the file which contains the source code of Func.
   305  	File string
   306  
   307  	// Line is the line number within File which maps to PC.
   308  	Line uint64
   309  }
   310  
   311  // ExperimentalEvent presents a raw view of an experimental event's arguments and their names.
   312  type ExperimentalEvent struct {
   313  	// Name is the name of the event.
   314  	Name string
   315  
   316  	// ArgNames is the names of the event's arguments in order.
   317  	// This may refer to a globally shared slice. Copy before mutating.
   318  	ArgNames []string
   319  
   320  	// Args contains the event's arguments.
   321  	Args []uint64
   322  
   323  	// Data is additional unparsed data that is associated with the experimental event.
   324  	// Data is likely to be shared across many ExperimentalEvents, so callers that parse
   325  	// Data are encouraged to cache the parse result and look it up by the value of Data.
   326  	Data *ExperimentalData
   327  }
   328  
   329  // ExperimentalData represents some raw and unparsed sidecar data present in the trace that is
   330  // associated with certain kinds of experimental events. For example, this data may contain
   331  // tables needed to interpret ExperimentalEvent arguments, or the ExperimentEvent could just be
   332  // a placeholder for a differently encoded event that's actually present in the experimental data.
   333  type ExperimentalData struct {
   334  	// Batches contain the actual experimental data, along with metadata about each batch.
   335  	Batches []ExperimentalBatch
   336  }
   337  
   338  // ExperimentalBatch represents a packet of unparsed data along with metadata about that packet.
   339  type ExperimentalBatch struct {
   340  	// Thread is the ID of the thread that produced a packet of data.
   341  	Thread ThreadID
   342  
   343  	// Data is a packet of unparsed data all produced by one thread.
   344  	Data []byte
   345  }
   346  
   347  // Event represents a single event in the trace.
   348  type Event struct {
   349  	table *evTable
   350  	ctx   schedCtx
   351  	base  baseEvent
   352  }
   353  
   354  // Kind returns the kind of event that this is.
   355  func (e Event) Kind() EventKind {
   356  	return go122Type2Kind[e.base.typ]
   357  }
   358  
   359  // Time returns the timestamp of the event.
   360  func (e Event) Time() Time {
   361  	return e.base.time
   362  }
   363  
   364  // Goroutine returns the ID of the goroutine that was executing when
   365  // this event happened. It describes part of the execution context
   366  // for this event.
   367  //
   368  // Note that for goroutine state transitions this always refers to the
   369  // state before the transition. For example, if a goroutine is just
   370  // starting to run on this thread and/or proc, then this will return
   371  // NoGoroutine. In this case, the goroutine starting to run will be
   372  // can be found at Event.StateTransition().Resource.
   373  func (e Event) Goroutine() GoID {
   374  	return e.ctx.G
   375  }
   376  
   377  // Proc returns the ID of the proc this event event pertains to.
   378  //
   379  // Note that for proc state transitions this always refers to the
   380  // state before the transition. For example, if a proc is just
   381  // starting to run on this thread, then this will return NoProc.
   382  func (e Event) Proc() ProcID {
   383  	return e.ctx.P
   384  }
   385  
   386  // Thread returns the ID of the thread this event pertains to.
   387  //
   388  // Note that for thread state transitions this always refers to the
   389  // state before the transition. For example, if a thread is just
   390  // starting to run, then this will return NoThread.
   391  //
   392  // Note: tracking thread state is not currently supported, so this
   393  // will always return a valid thread ID. However thread state transitions
   394  // may be tracked in the future, and callers must be robust to this
   395  // possibility.
   396  func (e Event) Thread() ThreadID {
   397  	return e.ctx.M
   398  }
   399  
   400  // Stack returns a handle to a stack associated with the event.
   401  //
   402  // This represents a stack trace at the current moment in time for
   403  // the current execution context.
   404  func (e Event) Stack() Stack {
   405  	if e.base.typ == evSync {
   406  		return NoStack
   407  	}
   408  	if e.base.typ == go122.EvCPUSample {
   409  		return Stack{table: e.table, id: stackID(e.base.args[0])}
   410  	}
   411  	spec := go122.Specs()[e.base.typ]
   412  	if len(spec.StackIDs) == 0 {
   413  		return NoStack
   414  	}
   415  	// The stack for the main execution context is always the
   416  	// first stack listed in StackIDs. Subtract one from this
   417  	// because we've peeled away the timestamp argument.
   418  	id := stackID(e.base.args[spec.StackIDs[0]-1])
   419  	if id == 0 {
   420  		return NoStack
   421  	}
   422  	return Stack{table: e.table, id: id}
   423  }
   424  
   425  // Metric returns details about a Metric event.
   426  //
   427  // Panics if Kind != EventMetric.
   428  func (e Event) Metric() Metric {
   429  	if e.Kind() != EventMetric {
   430  		panic("Metric called on non-Metric event")
   431  	}
   432  	var m Metric
   433  	switch e.base.typ {
   434  	case go122.EvProcsChange:
   435  		m.Name = "/sched/gomaxprocs:threads"
   436  		m.Value = Value{kind: ValueUint64, scalar: e.base.args[0]}
   437  	case go122.EvHeapAlloc:
   438  		m.Name = "/memory/classes/heap/objects:bytes"
   439  		m.Value = Value{kind: ValueUint64, scalar: e.base.args[0]}
   440  	case go122.EvHeapGoal:
   441  		m.Name = "/gc/heap/goal:bytes"
   442  		m.Value = Value{kind: ValueUint64, scalar: e.base.args[0]}
   443  	default:
   444  		panic(fmt.Sprintf("internal error: unexpected event type for Metric kind: %s", go122.EventString(e.base.typ)))
   445  	}
   446  	return m
   447  }
   448  
   449  // Label returns details about a Label event.
   450  //
   451  // Panics if Kind != EventLabel.
   452  func (e Event) Label() Label {
   453  	if e.Kind() != EventLabel {
   454  		panic("Label called on non-Label event")
   455  	}
   456  	if e.base.typ != go122.EvGoLabel {
   457  		panic(fmt.Sprintf("internal error: unexpected event type for Label kind: %s", go122.EventString(e.base.typ)))
   458  	}
   459  	return Label{
   460  		Label:    e.table.strings.mustGet(stringID(e.base.args[0])),
   461  		Resource: ResourceID{Kind: ResourceGoroutine, id: int64(e.ctx.G)},
   462  	}
   463  }
   464  
   465  // Range returns details about an EventRangeBegin, EventRangeActive, or EventRangeEnd event.
   466  //
   467  // Panics if Kind != EventRangeBegin, Kind != EventRangeActive, and Kind != EventRangeEnd.
   468  func (e Event) Range() Range {
   469  	if kind := e.Kind(); kind != EventRangeBegin && kind != EventRangeActive && kind != EventRangeEnd {
   470  		panic("Range called on non-Range event")
   471  	}
   472  	var r Range
   473  	switch e.base.typ {
   474  	case go122.EvSTWBegin, go122.EvSTWEnd:
   475  		// N.B. ordering.advance smuggles in the STW reason as e.base.args[0]
   476  		// for go122.EvSTWEnd (it's already there for Begin).
   477  		r.Name = "stop-the-world (" + e.table.strings.mustGet(stringID(e.base.args[0])) + ")"
   478  		r.Scope = ResourceID{Kind: ResourceGoroutine, id: int64(e.Goroutine())}
   479  	case go122.EvGCBegin, go122.EvGCActive, go122.EvGCEnd:
   480  		r.Name = "GC concurrent mark phase"
   481  		r.Scope = ResourceID{Kind: ResourceNone}
   482  	case go122.EvGCSweepBegin, go122.EvGCSweepActive, go122.EvGCSweepEnd:
   483  		r.Name = "GC incremental sweep"
   484  		r.Scope = ResourceID{Kind: ResourceProc}
   485  		if e.base.typ == go122.EvGCSweepActive {
   486  			r.Scope.id = int64(e.base.args[0])
   487  		} else {
   488  			r.Scope.id = int64(e.Proc())
   489  		}
   490  		r.Scope.id = int64(e.Proc())
   491  	case go122.EvGCMarkAssistBegin, go122.EvGCMarkAssistActive, go122.EvGCMarkAssistEnd:
   492  		r.Name = "GC mark assist"
   493  		r.Scope = ResourceID{Kind: ResourceGoroutine}
   494  		if e.base.typ == go122.EvGCMarkAssistActive {
   495  			r.Scope.id = int64(e.base.args[0])
   496  		} else {
   497  			r.Scope.id = int64(e.Goroutine())
   498  		}
   499  	default:
   500  		panic(fmt.Sprintf("internal error: unexpected event type for Range kind: %s", go122.EventString(e.base.typ)))
   501  	}
   502  	return r
   503  }
   504  
   505  // RangeAttributes returns attributes for a completed range.
   506  //
   507  // Panics if Kind != EventRangeEnd.
   508  func (e Event) RangeAttributes() []RangeAttribute {
   509  	if e.Kind() != EventRangeEnd {
   510  		panic("Range called on non-Range event")
   511  	}
   512  	if e.base.typ != go122.EvGCSweepEnd {
   513  		return nil
   514  	}
   515  	return []RangeAttribute{
   516  		{
   517  			Name:  "bytes swept",
   518  			Value: Value{kind: ValueUint64, scalar: e.base.args[0]},
   519  		},
   520  		{
   521  			Name:  "bytes reclaimed",
   522  			Value: Value{kind: ValueUint64, scalar: e.base.args[1]},
   523  		},
   524  	}
   525  }
   526  
   527  // Task returns details about a TaskBegin or TaskEnd event.
   528  //
   529  // Panics if Kind != EventTaskBegin and Kind != EventTaskEnd.
   530  func (e Event) Task() Task {
   531  	if kind := e.Kind(); kind != EventTaskBegin && kind != EventTaskEnd {
   532  		panic("Task called on non-Task event")
   533  	}
   534  	parentID := NoTask
   535  	var typ string
   536  	switch e.base.typ {
   537  	case go122.EvUserTaskBegin:
   538  		parentID = TaskID(e.base.args[1])
   539  		typ = e.table.strings.mustGet(stringID(e.base.args[2]))
   540  	case go122.EvUserTaskEnd:
   541  		parentID = TaskID(e.base.extra(version.Go122)[0])
   542  		typ = e.table.getExtraString(extraStringID(e.base.extra(version.Go122)[1]))
   543  	default:
   544  		panic(fmt.Sprintf("internal error: unexpected event type for Task kind: %s", go122.EventString(e.base.typ)))
   545  	}
   546  	return Task{
   547  		ID:     TaskID(e.base.args[0]),
   548  		Parent: parentID,
   549  		Type:   typ,
   550  	}
   551  }
   552  
   553  // Region returns details about a RegionBegin or RegionEnd event.
   554  //
   555  // Panics if Kind != EventRegionBegin and Kind != EventRegionEnd.
   556  func (e Event) Region() Region {
   557  	if kind := e.Kind(); kind != EventRegionBegin && kind != EventRegionEnd {
   558  		panic("Region called on non-Region event")
   559  	}
   560  	if e.base.typ != go122.EvUserRegionBegin && e.base.typ != go122.EvUserRegionEnd {
   561  		panic(fmt.Sprintf("internal error: unexpected event type for Region kind: %s", go122.EventString(e.base.typ)))
   562  	}
   563  	return Region{
   564  		Task: TaskID(e.base.args[0]),
   565  		Type: e.table.strings.mustGet(stringID(e.base.args[1])),
   566  	}
   567  }
   568  
   569  // Log returns details about a Log event.
   570  //
   571  // Panics if Kind != EventLog.
   572  func (e Event) Log() Log {
   573  	if e.Kind() != EventLog {
   574  		panic("Log called on non-Log event")
   575  	}
   576  	if e.base.typ != go122.EvUserLog {
   577  		panic(fmt.Sprintf("internal error: unexpected event type for Log kind: %s", go122.EventString(e.base.typ)))
   578  	}
   579  	return Log{
   580  		Task:     TaskID(e.base.args[0]),
   581  		Category: e.table.strings.mustGet(stringID(e.base.args[1])),
   582  		Message:  e.table.strings.mustGet(stringID(e.base.args[2])),
   583  	}
   584  }
   585  
   586  // StateTransition returns details about a StateTransition event.
   587  //
   588  // Panics if Kind != EventStateTransition.
   589  func (e Event) StateTransition() StateTransition {
   590  	if e.Kind() != EventStateTransition {
   591  		panic("StateTransition called on non-StateTransition event")
   592  	}
   593  	var s StateTransition
   594  	switch e.base.typ {
   595  	case go122.EvProcStart:
   596  		s = procStateTransition(ProcID(e.base.args[0]), ProcIdle, ProcRunning)
   597  	case go122.EvProcStop:
   598  		s = procStateTransition(e.ctx.P, ProcRunning, ProcIdle)
   599  	case go122.EvProcSteal:
   600  		// N.B. ordering.advance populates e.base.extra.
   601  		beforeState := ProcRunning
   602  		if go122.ProcStatus(e.base.extra(version.Go122)[0]) == go122.ProcSyscallAbandoned {
   603  			// We've lost information because this ProcSteal advanced on a
   604  			// SyscallAbandoned state. Treat the P as idle because ProcStatus
   605  			// treats SyscallAbandoned as Idle. Otherwise we'll have an invalid
   606  			// transition.
   607  			beforeState = ProcIdle
   608  		}
   609  		s = procStateTransition(ProcID(e.base.args[0]), beforeState, ProcIdle)
   610  	case go122.EvProcStatus:
   611  		// N.B. ordering.advance populates e.base.extra.
   612  		s = procStateTransition(ProcID(e.base.args[0]), ProcState(e.base.extra(version.Go122)[0]), go122ProcStatus2ProcState[e.base.args[1]])
   613  	case go122.EvGoCreate, go122.EvGoCreateBlocked:
   614  		status := GoRunnable
   615  		if e.base.typ == go122.EvGoCreateBlocked {
   616  			status = GoWaiting
   617  		}
   618  		s = goStateTransition(GoID(e.base.args[0]), GoNotExist, status)
   619  		s.Stack = Stack{table: e.table, id: stackID(e.base.args[1])}
   620  	case go122.EvGoCreateSyscall:
   621  		s = goStateTransition(GoID(e.base.args[0]), GoNotExist, GoSyscall)
   622  	case go122.EvGoStart:
   623  		s = goStateTransition(GoID(e.base.args[0]), GoRunnable, GoRunning)
   624  	case go122.EvGoDestroy:
   625  		s = goStateTransition(e.ctx.G, GoRunning, GoNotExist)
   626  		s.Stack = e.Stack() // This event references the resource the event happened on.
   627  	case go122.EvGoDestroySyscall:
   628  		s = goStateTransition(e.ctx.G, GoSyscall, GoNotExist)
   629  	case go122.EvGoStop:
   630  		s = goStateTransition(e.ctx.G, GoRunning, GoRunnable)
   631  		s.Reason = e.table.strings.mustGet(stringID(e.base.args[0]))
   632  		s.Stack = e.Stack() // This event references the resource the event happened on.
   633  	case go122.EvGoBlock:
   634  		s = goStateTransition(e.ctx.G, GoRunning, GoWaiting)
   635  		s.Reason = e.table.strings.mustGet(stringID(e.base.args[0]))
   636  		s.Stack = e.Stack() // This event references the resource the event happened on.
   637  	case go122.EvGoUnblock, go122.EvGoSwitch, go122.EvGoSwitchDestroy:
   638  		// N.B. GoSwitch and GoSwitchDestroy both emit additional events, but
   639  		// the first thing they both do is unblock the goroutine they name,
   640  		// identically to an unblock event (even their arguments match).
   641  		s = goStateTransition(GoID(e.base.args[0]), GoWaiting, GoRunnable)
   642  	case go122.EvGoSyscallBegin:
   643  		s = goStateTransition(e.ctx.G, GoRunning, GoSyscall)
   644  		s.Stack = e.Stack() // This event references the resource the event happened on.
   645  	case go122.EvGoSyscallEnd:
   646  		s = goStateTransition(e.ctx.G, GoSyscall, GoRunning)
   647  		s.Stack = e.Stack() // This event references the resource the event happened on.
   648  	case go122.EvGoSyscallEndBlocked:
   649  		s = goStateTransition(e.ctx.G, GoSyscall, GoRunnable)
   650  		s.Stack = e.Stack() // This event references the resource the event happened on.
   651  	case go122.EvGoStatus, go122.EvGoStatusStack:
   652  		packedStatus := e.base.args[2]
   653  		from, to := packedStatus>>32, packedStatus&((1<<32)-1)
   654  		s = goStateTransition(GoID(e.base.args[0]), GoState(from), go122GoStatus2GoState[to])
   655  	default:
   656  		panic(fmt.Sprintf("internal error: unexpected event type for StateTransition kind: %s", go122.EventString(e.base.typ)))
   657  	}
   658  	return s
   659  }
   660  
   661  // Experimental returns a view of the raw event for an experimental event.
   662  //
   663  // Panics if Kind != EventExperimental.
   664  func (e Event) Experimental() ExperimentalEvent {
   665  	if e.Kind() != EventExperimental {
   666  		panic("Experimental called on non-Experimental event")
   667  	}
   668  	spec := go122.Specs()[e.base.typ]
   669  	argNames := spec.Args[1:] // Skip timestamp; already handled.
   670  	return ExperimentalEvent{
   671  		Name:     spec.Name,
   672  		ArgNames: argNames,
   673  		Args:     e.base.args[:len(argNames)],
   674  		Data:     e.table.expData[spec.Experiment],
   675  	}
   676  }
   677  
   678  const evSync = ^event.Type(0)
   679  
   680  var go122Type2Kind = [...]EventKind{
   681  	go122.EvCPUSample:           EventStackSample,
   682  	go122.EvProcsChange:         EventMetric,
   683  	go122.EvProcStart:           EventStateTransition,
   684  	go122.EvProcStop:            EventStateTransition,
   685  	go122.EvProcSteal:           EventStateTransition,
   686  	go122.EvProcStatus:          EventStateTransition,
   687  	go122.EvGoCreate:            EventStateTransition,
   688  	go122.EvGoCreateSyscall:     EventStateTransition,
   689  	go122.EvGoStart:             EventStateTransition,
   690  	go122.EvGoDestroy:           EventStateTransition,
   691  	go122.EvGoDestroySyscall:    EventStateTransition,
   692  	go122.EvGoStop:              EventStateTransition,
   693  	go122.EvGoBlock:             EventStateTransition,
   694  	go122.EvGoUnblock:           EventStateTransition,
   695  	go122.EvGoSyscallBegin:      EventStateTransition,
   696  	go122.EvGoSyscallEnd:        EventStateTransition,
   697  	go122.EvGoSyscallEndBlocked: EventStateTransition,
   698  	go122.EvGoStatus:            EventStateTransition,
   699  	go122.EvSTWBegin:            EventRangeBegin,
   700  	go122.EvSTWEnd:              EventRangeEnd,
   701  	go122.EvGCActive:            EventRangeActive,
   702  	go122.EvGCBegin:             EventRangeBegin,
   703  	go122.EvGCEnd:               EventRangeEnd,
   704  	go122.EvGCSweepActive:       EventRangeActive,
   705  	go122.EvGCSweepBegin:        EventRangeBegin,
   706  	go122.EvGCSweepEnd:          EventRangeEnd,
   707  	go122.EvGCMarkAssistActive:  EventRangeActive,
   708  	go122.EvGCMarkAssistBegin:   EventRangeBegin,
   709  	go122.EvGCMarkAssistEnd:     EventRangeEnd,
   710  	go122.EvHeapAlloc:           EventMetric,
   711  	go122.EvHeapGoal:            EventMetric,
   712  	go122.EvGoLabel:             EventLabel,
   713  	go122.EvUserTaskBegin:       EventTaskBegin,
   714  	go122.EvUserTaskEnd:         EventTaskEnd,
   715  	go122.EvUserRegionBegin:     EventRegionBegin,
   716  	go122.EvUserRegionEnd:       EventRegionEnd,
   717  	go122.EvUserLog:             EventLog,
   718  	go122.EvGoSwitch:            EventStateTransition,
   719  	go122.EvGoSwitchDestroy:     EventStateTransition,
   720  	go122.EvGoCreateBlocked:     EventStateTransition,
   721  	go122.EvGoStatusStack:       EventStateTransition,
   722  	go122.EvSpan:                EventExperimental,
   723  	go122.EvSpanAlloc:           EventExperimental,
   724  	go122.EvSpanFree:            EventExperimental,
   725  	go122.EvHeapObject:          EventExperimental,
   726  	go122.EvHeapObjectAlloc:     EventExperimental,
   727  	go122.EvHeapObjectFree:      EventExperimental,
   728  	go122.EvGoroutineStack:      EventExperimental,
   729  	go122.EvGoroutineStackAlloc: EventExperimental,
   730  	go122.EvGoroutineStackFree:  EventExperimental,
   731  	evSync:                      EventSync,
   732  }
   733  
   734  var go122GoStatus2GoState = [...]GoState{
   735  	go122.GoRunnable: GoRunnable,
   736  	go122.GoRunning:  GoRunning,
   737  	go122.GoWaiting:  GoWaiting,
   738  	go122.GoSyscall:  GoSyscall,
   739  }
   740  
   741  var go122ProcStatus2ProcState = [...]ProcState{
   742  	go122.ProcRunning:          ProcRunning,
   743  	go122.ProcIdle:             ProcIdle,
   744  	go122.ProcSyscall:          ProcRunning,
   745  	go122.ProcSyscallAbandoned: ProcIdle,
   746  }
   747  
   748  // String returns the event as a human-readable string.
   749  //
   750  // The format of the string is intended for debugging and is subject to change.
   751  func (e Event) String() string {
   752  	var sb strings.Builder
   753  	fmt.Fprintf(&sb, "M=%d P=%d G=%d", e.Thread(), e.Proc(), e.Goroutine())
   754  	fmt.Fprintf(&sb, " %s Time=%d", e.Kind(), e.Time())
   755  	// Kind-specific fields.
   756  	switch kind := e.Kind(); kind {
   757  	case EventMetric:
   758  		m := e.Metric()
   759  		fmt.Fprintf(&sb, " Name=%q Value=%s", m.Name, valueAsString(m.Value))
   760  	case EventLabel:
   761  		l := e.Label()
   762  		fmt.Fprintf(&sb, " Label=%q Resource=%s", l.Label, l.Resource)
   763  	case EventRangeBegin, EventRangeActive, EventRangeEnd:
   764  		r := e.Range()
   765  		fmt.Fprintf(&sb, " Name=%q Scope=%s", r.Name, r.Scope)
   766  		if kind == EventRangeEnd {
   767  			fmt.Fprintf(&sb, " Attributes=[")
   768  			for i, attr := range e.RangeAttributes() {
   769  				if i != 0 {
   770  					fmt.Fprintf(&sb, " ")
   771  				}
   772  				fmt.Fprintf(&sb, "%q=%s", attr.Name, valueAsString(attr.Value))
   773  			}
   774  			fmt.Fprintf(&sb, "]")
   775  		}
   776  	case EventTaskBegin, EventTaskEnd:
   777  		t := e.Task()
   778  		fmt.Fprintf(&sb, " ID=%d Parent=%d Type=%q", t.ID, t.Parent, t.Type)
   779  	case EventRegionBegin, EventRegionEnd:
   780  		r := e.Region()
   781  		fmt.Fprintf(&sb, " Task=%d Type=%q", r.Task, r.Type)
   782  	case EventLog:
   783  		l := e.Log()
   784  		fmt.Fprintf(&sb, " Task=%d Category=%q Message=%q", l.Task, l.Category, l.Message)
   785  	case EventStateTransition:
   786  		s := e.StateTransition()
   787  		fmt.Fprintf(&sb, " Resource=%s Reason=%q", s.Resource, s.Reason)
   788  		switch s.Resource.Kind {
   789  		case ResourceGoroutine:
   790  			id := s.Resource.Goroutine()
   791  			old, new := s.Goroutine()
   792  			fmt.Fprintf(&sb, " GoID=%d %s->%s", id, old, new)
   793  		case ResourceProc:
   794  			id := s.Resource.Proc()
   795  			old, new := s.Proc()
   796  			fmt.Fprintf(&sb, " ProcID=%d %s->%s", id, old, new)
   797  		}
   798  		if s.Stack != NoStack {
   799  			fmt.Fprintln(&sb)
   800  			fmt.Fprintln(&sb, "TransitionStack=")
   801  			for f := range s.Stack.Frames() {
   802  				fmt.Fprintf(&sb, "\t%s @ 0x%x\n", f.Func, f.PC)
   803  				fmt.Fprintf(&sb, "\t\t%s:%d\n", f.File, f.Line)
   804  			}
   805  		}
   806  	case EventExperimental:
   807  		r := e.Experimental()
   808  		fmt.Fprintf(&sb, " Name=%s ArgNames=%v Args=%v", r.Name, r.ArgNames, r.Args)
   809  	}
   810  	if stk := e.Stack(); stk != NoStack {
   811  		fmt.Fprintln(&sb)
   812  		fmt.Fprintln(&sb, "Stack=")
   813  		for f := range stk.Frames() {
   814  			fmt.Fprintf(&sb, "\t%s @ 0x%x\n", f.Func, f.PC)
   815  			fmt.Fprintf(&sb, "\t\t%s:%d\n", f.File, f.Line)
   816  		}
   817  	}
   818  	return sb.String()
   819  }
   820  
   821  // validateTableIDs checks to make sure lookups in e.table
   822  // will work.
   823  func (e Event) validateTableIDs() error {
   824  	if e.base.typ == evSync {
   825  		return nil
   826  	}
   827  	spec := go122.Specs()[e.base.typ]
   828  
   829  	// Check stacks.
   830  	for _, i := range spec.StackIDs {
   831  		id := stackID(e.base.args[i-1])
   832  		_, ok := e.table.stacks.get(id)
   833  		if !ok {
   834  			return fmt.Errorf("found invalid stack ID %d for event %s", id, spec.Name)
   835  		}
   836  	}
   837  	// N.B. Strings referenced by stack frames are validated
   838  	// early on, when reading the stacks in to begin with.
   839  
   840  	// Check strings.
   841  	for _, i := range spec.StringIDs {
   842  		id := stringID(e.base.args[i-1])
   843  		_, ok := e.table.strings.get(id)
   844  		if !ok {
   845  			return fmt.Errorf("found invalid string ID %d for event %s", id, spec.Name)
   846  		}
   847  	}
   848  	return nil
   849  }
   850  
   851  func syncEvent(table *evTable, ts Time) Event {
   852  	return Event{
   853  		table: table,
   854  		ctx: schedCtx{
   855  			G: NoGoroutine,
   856  			P: NoProc,
   857  			M: NoThread,
   858  		},
   859  		base: baseEvent{
   860  			typ:  evSync,
   861  			time: ts,
   862  		},
   863  	}
   864  }
   865
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