src/internal/trace/base.go - go - Git at Google

 // Copyright 2023 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // This file contains data types that all implementations of the trace format
 // parser need to provide to the rest of the package.

 package trace

 import (
 	"fmt"
 	"math"
 	"strings"

 	"internal/trace/event"
 	"internal/trace/event/go122"
 	"internal/trace/version"
 )

 // maxArgs is the maximum number of arguments for "plain" events,
 // i.e. anything that could reasonably be represented as a baseEvent.
 const maxArgs = 5

 // timedEventArgs is an array that is able to hold the arguments for any
 // timed event.
 type timedEventArgs [maxArgs - 1]uint64

 // baseEvent is the basic unprocessed event. This serves as a common
 // fundamental data structure across.
 type baseEvent struct {
 	typ  event.Type
 	time Time
 	args timedEventArgs
 }

 // extra returns a slice representing extra available space in args
 // that the parser can use to pass data up into Event.
 func (e *baseEvent) extra(v version.Version) []uint64 {
 	switch v {
 	case version.Go122:
 		return e.args[len(go122.Specs()[e.typ].Args)-1:]
 	}
 	panic(fmt.Sprintf("unsupported version: go 1.%d", v))
 }

 // evTable contains the per-generation data necessary to
 // interpret an individual event.
 type evTable struct {
 	freq    frequency
 	strings dataTable[stringID, string]
 	stacks  dataTable[stackID, stack]
 	pcs     map[uint64]frame

 	// extraStrings are strings that get generated during
 	// parsing but haven't come directly from the trace, so
 	// they don't appear in strings.
 	extraStrings   []string
 	extraStringIDs map[string]extraStringID
 	nextExtra      extraStringID

 	// expData contains extra unparsed data that is accessible
 	// only to ExperimentEvent via an EventExperimental event.
 	expData map[event.Experiment]*ExperimentalData
 }

 // addExtraString adds an extra string to the evTable and returns
 // a unique ID for the string in the table.
 func (t *evTable) addExtraString(s string) extraStringID {
 	if s == "" {
 		return 0
 	}
 	if t.extraStringIDs == nil {
 		t.extraStringIDs = make(map[string]extraStringID)
 	}
 	if id, ok := t.extraStringIDs[s]; ok {
 		return id
 	}
 	t.nextExtra++
 	id := t.nextExtra
 	t.extraStrings = append(t.extraStrings, s)
 	t.extraStringIDs[s] = id
 	return id
 }

 // getExtraString returns the extra string for the provided ID.
 // The ID must have been produced by addExtraString for this evTable.
 func (t *evTable) getExtraString(id extraStringID) string {
 	if id == 0 {
 		return ""
 	}
 	return t.extraStrings[id-1]
 }

 // dataTable is a mapping from EIs to Es.
 type dataTable[EI ~uint64, E any] struct {
 	present []uint8
 	dense   []E
 	sparse  map[EI]E
 }

 // insert tries to add a mapping from id to s.
 //
 // Returns an error if a mapping for id already exists, regardless
 // of whether or not s is the same in content. This should be used
 // for validation during parsing.
 func (d *dataTable[EI, E]) insert(id EI, data E) error {
 	if d.sparse == nil {
 		d.sparse = make(map[EI]E)
 	}
 	if existing, ok := d.get(id); ok {
 		return fmt.Errorf("multiple %Ts with the same ID: id=%d, new=%v, existing=%v", data, id, data, existing)
 	}
 	d.sparse[id] = data
 	return nil
 }

 // compactify attempts to compact sparse into dense.
 //
 // This is intended to be called only once after insertions are done.
 func (d *dataTable[EI, E]) compactify() {
 	if d.sparse == nil || len(d.dense) != 0 {
 		// Already compactified.
 		return
 	}
 	// Find the range of IDs.
 	maxID := EI(0)
 	minID := ^EI(0)
 	for id := range d.sparse {
 		if id > maxID {
 			maxID = id
 		}
 		if id < minID {
 			minID = id
 		}
 	}
 	if maxID >= math.MaxInt {
 		// We can't create a slice big enough to hold maxID elements
 		return
 	}
 	// We're willing to waste at most 2x memory.
 	if int(maxID-minID) > max(len(d.sparse), 2*len(d.sparse)) {
 		return
 	}
 	if int(minID) > len(d.sparse) {
 		return
 	}
 	size := int(maxID) + 1
 	d.present = make([]uint8, (size+7)/8)
 	d.dense = make([]E, size)
 	for id, data := range d.sparse {
 		d.dense[id] = data
 		d.present[id/8] |= uint8(1) << (id % 8)
 	}
 	d.sparse = nil
 }

 // get returns the E for id or false if it doesn't
 // exist. This should be used for validation during parsing.
 func (d *dataTable[EI, E]) get(id EI) (E, bool) {
 	if id == 0 {
 		return *new(E), true
 	}
 	if uint64(id) < uint64(len(d.dense)) {
 		if d.present[id/8]&(uint8(1)<<(id%8)) != 0 {
 			return d.dense[id], true
 		}
 	} else if d.sparse != nil {
 		if data, ok := d.sparse[id]; ok {
 			return data, true
 		}
 	}
 	return *new(E), false
 }

 // forEach iterates over all ID/value pairs in the data table.
 func (d *dataTable[EI, E]) forEach(yield func(EI, E) bool) bool {
 	for id, value := range d.dense {
 		if d.present[id/8]&(uint8(1)<<(id%8)) == 0 {
 			continue
 		}
 		if !yield(EI(id), value) {
 			return false
 		}
 	}
 	if d.sparse == nil {
 		return true
 	}
 	for id, value := range d.sparse {
 		if !yield(id, value) {
 			return false
 		}
 	}
 	return true
 }

 // mustGet returns the E for id or panics if it fails.
 //
 // This should only be used if id has already been validated.
 func (d *dataTable[EI, E]) mustGet(id EI) E {
 	data, ok := d.get(id)
 	if !ok {
 		panic(fmt.Sprintf("expected id %d in %T table", id, data))
 	}
 	return data
 }

 // frequency is nanoseconds per timestamp unit.
 type frequency float64

 // mul multiplies an unprocessed to produce a time in nanoseconds.
 func (f frequency) mul(t timestamp) Time {
 	return Time(float64(t) * float64(f))
 }

 // stringID is an index into the string table for a generation.
 type stringID uint64

 // extraStringID is an index into the extra string table for a generation.
 type extraStringID uint64

 // stackID is an index into the stack table for a generation.
 type stackID uint64

 // cpuSample represents a CPU profiling sample captured by the trace.
 type cpuSample struct {
 	schedCtx
 	time  Time
 	stack stackID
 }

 // asEvent produces a complete Event from a cpuSample. It needs
 // the evTable from the generation that created it.
 //
 // We don't just store it as an Event in generation to minimize
 // the amount of pointer data floating around.
 func (s cpuSample) asEvent(table *evTable) Event {
 	// TODO(mknyszek): This is go122-specific, but shouldn't be.
 	// Generalize this in the future.
 	e := Event{
 		table: table,
 		ctx:   s.schedCtx,
 		base: baseEvent{
 			typ:  go122.EvCPUSample,
 			time: s.time,
 		},
 	}
 	e.base.args[0] = uint64(s.stack)
 	return e
 }

 // stack represents a goroutine stack sample.
 type stack struct {
 	pcs []uint64
 }

 func (s stack) String() string {
 	var sb strings.Builder
 	for _, frame := range s.pcs {
 		fmt.Fprintf(&sb, "\t%#v\n", frame)
 	}
 	return sb.String()
 }

 // frame represents a single stack frame.
 type frame struct {
 	pc     uint64
 	funcID stringID
 	fileID stringID
 	line   uint64
 }
	// Copyright 2023 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// This file contains data types that all implementations of the trace format
	// parser need to provide to the rest of the package.

	package trace

	import (
	"fmt"
	"math"
	"strings"

	"internal/trace/event"
	"internal/trace/event/go122"
	"internal/trace/version"
	)

	// maxArgs is the maximum number of arguments for "plain" events,
	// i.e. anything that could reasonably be represented as a baseEvent.
	const maxArgs = 5

	// timedEventArgs is an array that is able to hold the arguments for any
	// timed event.
	type timedEventArgs [maxArgs - 1]uint64

	// baseEvent is the basic unprocessed event. This serves as a common
	// fundamental data structure across.
	type baseEvent struct {
	typ event.Type
	time Time
	args timedEventArgs
	}

	// extra returns a slice representing extra available space in args
	// that the parser can use to pass data up into Event.
	func (e *baseEvent) extra(v version.Version) []uint64 {
	switch v {
	case version.Go122:
	return e.args[len(go122.Specs()[e.typ].Args)-1:]
	}
	panic(fmt.Sprintf("unsupported version: go 1.%d", v))
	}

	// evTable contains the per-generation data necessary to
	// interpret an individual event.
	type evTable struct {
	freq frequency
	strings dataTable[stringID, string]
	stacks dataTable[stackID, stack]
	pcs map[uint64]frame

	// extraStrings are strings that get generated during
	// parsing but haven't come directly from the trace, so
	// they don't appear in strings.
	extraStrings []string
	extraStringIDs map[string]extraStringID
	nextExtra extraStringID

	// expData contains extra unparsed data that is accessible
	// only to ExperimentEvent via an EventExperimental event.
	expData map[event.Experiment]*ExperimentalData
	}

	// addExtraString adds an extra string to the evTable and returns
	// a unique ID for the string in the table.
	func (t *evTable) addExtraString(s string) extraStringID {
	if s == "" {
	return 0
	}
	if t.extraStringIDs == nil {
	t.extraStringIDs = make(map[string]extraStringID)
	}
	if id, ok := t.extraStringIDs[s]; ok {
	return id
	}
	t.nextExtra++
	id := t.nextExtra
	t.extraStrings = append(t.extraStrings, s)
	t.extraStringIDs[s] = id
	return id
	}

	// getExtraString returns the extra string for the provided ID.
	// The ID must have been produced by addExtraString for this evTable.
	func (t *evTable) getExtraString(id extraStringID) string {
	if id == 0 {
	return ""
	}
	return t.extraStrings[id-1]
	}

	// dataTable is a mapping from EIs to Es.
	type dataTable[EI ~uint64, E any] struct {
	present []uint8
	dense []E
	sparse map[EI]E
	}

	// insert tries to add a mapping from id to s.
	//
	// Returns an error if a mapping for id already exists, regardless
	// of whether or not s is the same in content. This should be used
	// for validation during parsing.
	func (d *dataTable[EI, E]) insert(id EI, data E) error {
	if d.sparse == nil {
	d.sparse = make(map[EI]E)
	}
	if existing, ok := d.get(id); ok {
	return fmt.Errorf("multiple %Ts with the same ID: id=%d, new=%v, existing=%v", data, id, data, existing)
	}
	d.sparse[id] = data
	return nil
	}

	// compactify attempts to compact sparse into dense.
	//
	// This is intended to be called only once after insertions are done.
	func (d *dataTable[EI, E]) compactify() {
	if d.sparse == nil \|\| len(d.dense) != 0 {
	// Already compactified.
	return
	}
	// Find the range of IDs.
	maxID := EI(0)
	minID := ^EI(0)
	for id := range d.sparse {
	if id > maxID {
	maxID = id
	}
	if id < minID {
	minID = id
	}
	}
	if maxID >= math.MaxInt {
	// We can't create a slice big enough to hold maxID elements
	return
	}
	// We're willing to waste at most 2x memory.
	if int(maxID-minID) > max(len(d.sparse), 2*len(d.sparse)) {
	return
	}
	if int(minID) > len(d.sparse) {
	return
	}
	size := int(maxID) + 1
	d.present = make([]uint8, (size+7)/8)
	d.dense = make([]E, size)
	for id, data := range d.sparse {
	d.dense[id] = data
	d.present[id/8] \|= uint8(1) << (id % 8)
	}
	d.sparse = nil
	}

	// get returns the E for id or false if it doesn't
	// exist. This should be used for validation during parsing.
	func (d *dataTable[EI, E]) get(id EI) (E, bool) {
	if id == 0 {
	return *new(E), true
	}
	if uint64(id) < uint64(len(d.dense)) {
	if d.present[id/8]&(uint8(1)<<(id%8)) != 0 {
	return d.dense[id], true
	}
	} else if d.sparse != nil {
	if data, ok := d.sparse[id]; ok {
	return data, true
	}
	}
	return *new(E), false
	}

	// forEach iterates over all ID/value pairs in the data table.
	func (d *dataTable[EI, E]) forEach(yield func(EI, E) bool) bool {
	for id, value := range d.dense {
	if d.present[id/8]&(uint8(1)<<(id%8)) == 0 {
	continue
	}
	if !yield(EI(id), value) {
	return false
	}
	}
	if d.sparse == nil {
	return true
	}
	for id, value := range d.sparse {
	if !yield(id, value) {
	return false
	}
	}
	return true
	}

	// mustGet returns the E for id or panics if it fails.
	//
	// This should only be used if id has already been validated.
	func (d *dataTable[EI, E]) mustGet(id EI) E {
	data, ok := d.get(id)
	if !ok {
	panic(fmt.Sprintf("expected id %d in %T table", id, data))
	}
	return data
	}

	// frequency is nanoseconds per timestamp unit.
	type frequency float64

	// mul multiplies an unprocessed to produce a time in nanoseconds.
	func (f frequency) mul(t timestamp) Time {
	return Time(float64(t) * float64(f))
	}

	// stringID is an index into the string table for a generation.
	type stringID uint64

	// extraStringID is an index into the extra string table for a generation.
	type extraStringID uint64

	// stackID is an index into the stack table for a generation.
	type stackID uint64

	// cpuSample represents a CPU profiling sample captured by the trace.
	type cpuSample struct {
	schedCtx
	time Time
	stack stackID
	}

	// asEvent produces a complete Event from a cpuSample. It needs
	// the evTable from the generation that created it.
	//
	// We don't just store it as an Event in generation to minimize
	// the amount of pointer data floating around.
	func (s cpuSample) asEvent(table *evTable) Event {
	// TODO(mknyszek): This is go122-specific, but shouldn't be.
	// Generalize this in the future.
	e := Event{
	table: table,
	ctx: s.schedCtx,
	base: baseEvent{
	typ: go122.EvCPUSample,
	time: s.time,
	},
	}
	e.base.args[0] = uint64(s.stack)
	return e
	}

	// stack represents a goroutine stack sample.
	type stack struct {
	pcs []uint64
	}

	func (s stack) String() string {
	var sb strings.Builder
	for _, frame := range s.pcs {
	fmt.Fprintf(&sb, "\t%#v\n", frame)
	}
	return sb.String()
	}

	// frame represents a single stack frame.
	type frame struct {
	pc uint64
	funcID stringID
	fileID stringID
	line uint64
	}