// Copyright 2014 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package profile
import (
"encoding/binary"
"fmt"
"sort"
"strconv"
"strings"
)
// Compact performs garbage collection on a profile to remove any
// unreferenced fields. This is useful to reduce the size of a profile
// after samples or locations have been removed.
func (p *Profile) Compact() *Profile {
p, _ = Merge([]*Profile{p})
return p
}
// Merge merges all the profiles in profs into a single Profile.
// Returns a new profile independent of the input profiles. The merged
// profile is compacted to eliminate unused samples, locations,
// functions and mappings. Profiles must have identical profile sample
// and period types or the merge will fail. profile.Period of the
// resulting profile will be the maximum of all profiles, and
// profile.TimeNanos will be the earliest nonzero one. Merges are
// associative with the caveat of the first profile having some
// specialization in how headers are combined. There may be other
// subtleties now or in the future regarding associativity.
func Merge(srcs []*Profile) (*Profile, error) {
if len(srcs) == 0 {
return nil, fmt.Errorf("no profiles to merge")
}
p, err := combineHeaders(srcs)
if err != nil {
return nil, err
}
pm := &profileMerger{
p: p,
samples: make(map[sampleKey]*Sample, len(srcs[0].Sample)),
locations: make(map[locationKey]*Location, len(srcs[0].Location)),
functions: make(map[functionKey]*Function, len(srcs[0].Function)),
mappings: make(map[mappingKey]*Mapping, len(srcs[0].Mapping)),
}
for _, src := range srcs {
// Clear the profile-specific hash tables
pm.locationsByID = makeLocationIDMap(len(src.Location))
pm.functionsByID = make(map[uint64]*Function, len(src.Function))
pm.mappingsByID = make(map[uint64]mapInfo, len(src.Mapping))
if len(pm.mappings) == 0 && len(src.Mapping) > 0 {
// The Mapping list has the property that the first mapping
// represents the main binary. Take the first Mapping we see,
// otherwise the operations below will add mappings in an
// arbitrary order.
pm.mapMapping(src.Mapping[0])
}
for _, s := range src.Sample {
if !isZeroSample(s) {
pm.mapSample(s)
}
}
}
for _, s := range p.Sample {
if isZeroSample(s) {
// If there are any zero samples, re-merge the profile to GC
// them.
return Merge([]*Profile{p})
}
}
return p, nil
}
// Normalize normalizes the source profile by multiplying each value in profile by the
// ratio of the sum of the base profile's values of that sample type to the sum of the
// source profile's value of that sample type.
func (p *Profile) Normalize(pb *Profile) error {
if err := p.compatible(pb); err != nil {
return err
}
baseVals := make([]int64, len(p.SampleType))
for _, s := range pb.Sample {
for i, v := range s.Value {
baseVals[i] += v
}
}
srcVals := make([]int64, len(p.SampleType))
for _, s := range p.Sample {
for i, v := range s.Value {
srcVals[i] += v
}
}
normScale := make([]float64, len(baseVals))
for i := range baseVals {
if srcVals[i] == 0 {
normScale[i] = 0.0
} else {
normScale[i] = float64(baseVals[i]) / float64(srcVals[i])
}
}
p.ScaleN(normScale)
return nil
}
func isZeroSample(s *Sample) bool {
for _, v := range s.Value {
if v != 0 {
return false
}
}
return true
}
type profileMerger struct {
p *Profile
// Memoization tables within a profile.
locationsByID locationIDMap
functionsByID map[uint64]*Function
mappingsByID map[uint64]mapInfo
// Memoization tables for profile entities.
samples map[sampleKey]*Sample
locations map[locationKey]*Location
functions map[functionKey]*Function
mappings map[mappingKey]*Mapping
}
type mapInfo struct {
m *Mapping
offset int64
}
func (pm *profileMerger) mapSample(src *Sample) *Sample {
// Check memoization table
k := pm.sampleKey(src)
if ss, ok := pm.samples[k]; ok {
for i, v := range src.Value {
ss.Value[i] += v
}
return ss
}
// Make new sample.
s := &Sample{
Location: make([]*Location, len(src.Location)),
Value: make([]int64, len(src.Value)),
Label: make(map[string][]string, len(src.Label)),
NumLabel: make(map[string][]int64, len(src.NumLabel)),
NumUnit: make(map[string][]string, len(src.NumLabel)),
}
for i, l := range src.Location {
s.Location[i] = pm.mapLocation(l)
}
for k, v := range src.Label {
vv := make([]string, len(v))
copy(vv, v)
s.Label[k] = vv
}
for k, v := range src.NumLabel {
u := src.NumUnit[k]
vv := make([]int64, len(v))
uu := make([]string, len(u))
copy(vv, v)
copy(uu, u)
s.NumLabel[k] = vv
s.NumUnit[k] = uu
}
copy(s.Value, src.Value)
pm.samples[k] = s
pm.p.Sample = append(pm.p.Sample, s)
return s
}
func (pm *profileMerger) sampleKey(sample *Sample) sampleKey {
// Accumulate contents into a string.
var buf strings.Builder
buf.Grow(64) // Heuristic to avoid extra allocs
// encode a number
putNumber := func(v uint64) {
var num [binary.MaxVarintLen64]byte
n := binary.PutUvarint(num[:], v)
buf.Write(num[:n])
}
// encode a string prefixed with its length.
putDelimitedString := func(s string) {
putNumber(uint64(len(s)))
buf.WriteString(s)
}
for _, l := range sample.Location {
// Get the location in the merged profile, which may have a different ID.
if loc := pm.mapLocation(l); loc != nil {
putNumber(loc.ID)
}
}
putNumber(0) // Delimiter
for _, l := range sortedKeys1(sample.Label) {
putDelimitedString(l)
values := sample.Label[l]
putNumber(uint64(len(values)))
for _, v := range values {
putDelimitedString(v)
}
}
for _, l := range sortedKeys2(sample.NumLabel) {
putDelimitedString(l)
values := sample.NumLabel[l]
putNumber(uint64(len(values)))
for _, v := range values {
putNumber(uint64(v))
}
units := sample.NumUnit[l]
putNumber(uint64(len(units)))
for _, v := range units {
putDelimitedString(v)
}
}
return sampleKey(buf.String())
}
type sampleKey string
// sortedKeys1 returns the sorted keys found in a string->[]string map.
//
// Note: this is currently non-generic since github pprof runs golint,
// which does not support generics. When that issue is fixed, it can
// be merged with sortedKeys2 and made into a generic function.
func sortedKeys1(m map[string][]string) []string {
if len(m) == 0 {
return nil
}
keys := make([]string, 0, len(m))
for k := range m {
keys = append(keys, k)
}
sort.Strings(keys)
return keys
}
// sortedKeys2 returns the sorted keys found in a string->[]int64 map.
//
// Note: this is currently non-generic since github pprof runs golint,
// which does not support generics. When that issue is fixed, it can
// be merged with sortedKeys1 and made into a generic function.
func sortedKeys2(m map[string][]int64) []string {
if len(m) == 0 {
return nil
}
keys := make([]string, 0, len(m))
for k := range m {
keys = append(keys, k)
}
sort.Strings(keys)
return keys
}
func (pm *profileMerger) mapLocation(src *Location) *Location {
if src == nil {
return nil
}
if l := pm.locationsByID.get(src.ID); l != nil {
return l
}
mi := pm.mapMapping(src.Mapping)
l := &Location{
ID: uint64(len(pm.p.Location) + 1),
Mapping: mi.m,
Address: uint64(int64(src.Address) + mi.offset),
Line: make([]Line, len(src.Line)),
IsFolded: src.IsFolded,
}
for i, ln := range src.Line {
l.Line[i] = pm.mapLine(ln)
}
// Check memoization table. Must be done on the remapped location to
// account for the remapped mapping ID.
k := l.key()
if ll, ok := pm.locations[k]; ok {
pm.locationsByID.set(src.ID, ll)
return ll
}
pm.locationsByID.set(src.ID, l)
pm.locations[k] = l
pm.p.Location = append(pm.p.Location, l)
return l
}
// key generates locationKey to be used as a key for maps.
func (l *Location) key() locationKey {
key := locationKey{
addr: l.Address,
isFolded: l.IsFolded,
}
if l.Mapping != nil {
// Normalizes address to handle address space randomization.
key.addr -= l.Mapping.Start
key.mappingID = l.Mapping.ID
}
lines := make([]string, len(l.Line)*3)
for i, line := range l.Line {
if line.Function != nil {
lines[i*2] = strconv.FormatUint(line.Function.ID, 16)
}
lines[i*2+1] = strconv.FormatInt(line.Line, 16)
lines[i*2+2] = strconv.FormatInt(line.Column, 16)
}
key.lines = strings.Join(lines, "|")
return key
}
type locationKey struct {
addr, mappingID uint64
lines string
isFolded bool
}
func (pm *profileMerger) mapMapping(src *Mapping) mapInfo {
if src == nil {
return mapInfo{}
}
if mi, ok := pm.mappingsByID[src.ID]; ok {
return mi
}
// Check memoization tables.
mk := src.key()
if m, ok := pm.mappings[mk]; ok {
mi := mapInfo{m, int64(m.Start) - int64(src.Start)}
pm.mappingsByID[src.ID] = mi
return mi
}
m := &Mapping{
ID: uint64(len(pm.p.Mapping) + 1),
Start: src.Start,
Limit: src.Limit,
Offset: src.Offset,
File: src.File,
KernelRelocationSymbol: src.KernelRelocationSymbol,
BuildID: src.BuildID,
HasFunctions: src.HasFunctions,
HasFilenames: src.HasFilenames,
HasLineNumbers: src.HasLineNumbers,
HasInlineFrames: src.HasInlineFrames,
}
pm.p.Mapping = append(pm.p.Mapping, m)
// Update memoization tables.
pm.mappings[mk] = m
mi := mapInfo{m, 0}
pm.mappingsByID[src.ID] = mi
return mi
}
// key generates encoded strings of Mapping to be used as a key for
// maps.
func (m *Mapping) key() mappingKey {
// Normalize addresses to handle address space randomization.
// Round up to next 4K boundary to avoid minor discrepancies.
const mapsizeRounding = 0x1000
size := m.Limit - m.Start
size = size + mapsizeRounding - 1
size = size - (size % mapsizeRounding)
key := mappingKey{
size: size,
offset: m.Offset,
}
switch {
case m.BuildID != "":
key.buildIDOrFile = m.BuildID
case m.File != "":
key.buildIDOrFile = m.File
default:
// A mapping containing neither build ID nor file name is a fake mapping. A
// key with empty buildIDOrFile is used for fake mappings so that they are
// treated as the same mapping during merging.
}
return key
}
type mappingKey struct {
size, offset uint64
buildIDOrFile string
}
func (pm *profileMerger) mapLine(src Line) Line {
ln := Line{
Function: pm.mapFunction(src.Function),
Line: src.Line,
Column: src.Column,
}
return ln
}
func (pm *profileMerger) mapFunction(src *Function) *Function {
if src == nil {
return nil
}
if f, ok := pm.functionsByID[src.ID]; ok {
return f
}
k := src.key()
if f, ok := pm.functions[k]; ok {
pm.functionsByID[src.ID] = f
return f
}
f := &Function{
ID: uint64(len(pm.p.Function) + 1),
Name: src.Name,
SystemName: src.SystemName,
Filename: src.Filename,
StartLine: src.StartLine,
}
pm.functions[k] = f
pm.functionsByID[src.ID] = f
pm.p.Function = append(pm.p.Function, f)
return f
}
// key generates a struct to be used as a key for maps.
func (f *Function) key() functionKey {
return functionKey{
f.StartLine,
f.Name,
f.SystemName,
f.Filename,
}
}
type functionKey struct {
startLine int64
name, systemName, fileName string
}
// combineHeaders checks that all profiles can be merged and returns
// their combined profile.
func combineHeaders(srcs []*Profile) (*Profile, error) {
for _, s := range srcs[1:] {
if err := srcs[0].compatible(s); err != nil {
return nil, err
}
}
var timeNanos, durationNanos, period int64
var comments []string
seenComments := map[string]bool{}
var docURL string
var defaultSampleType string
for _, s := range srcs {
if timeNanos == 0 || s.TimeNanos < timeNanos {
timeNanos = s.TimeNanos
}
durationNanos += s.DurationNanos
if period == 0 || period < s.Period {
period = s.Period
}
for _, c := range s.Comments {
if seen := seenComments[c]; !seen {
comments = append(comments, c)
seenComments[c] = true
}
}
if defaultSampleType == "" {
defaultSampleType = s.DefaultSampleType
}
if docURL == "" {
docURL = s.DocURL
}
}
p := &Profile{
SampleType: make([]*ValueType, len(srcs[0].SampleType)),
DropFrames: srcs[0].DropFrames,
KeepFrames: srcs[0].KeepFrames,
TimeNanos: timeNanos,
DurationNanos: durationNanos,
PeriodType: srcs[0].PeriodType,
Period: period,
Comments: comments,
DefaultSampleType: defaultSampleType,
DocURL: docURL,
}
copy(p.SampleType, srcs[0].SampleType)
return p, nil
}
// compatible determines if two profiles can be compared/merged.
// returns nil if the profiles are compatible; otherwise an error with
// details on the incompatibility.
func (p *Profile) compatible(pb *Profile) error {
if !equalValueType(p.PeriodType, pb.PeriodType) {
return fmt.Errorf("incompatible period types %v and %v", p.PeriodType, pb.PeriodType)
}
if len(p.SampleType) != len(pb.SampleType) {
return fmt.Errorf("incompatible sample types %v and %v", p.SampleType, pb.SampleType)
}
for i := range p.SampleType {
if !equalValueType(p.SampleType[i], pb.SampleType[i]) {
return fmt.Errorf("incompatible sample types %v and %v", p.SampleType, pb.SampleType)
}
}
return nil
}
// equalValueType returns true if the two value types are semantically
// equal. It ignores the internal fields used during encode/decode.
func equalValueType(st1, st2 *ValueType) bool {
return st1.Type == st2.Type && st1.Unit == st2.Unit
}
// locationIDMap is like a map[uint64]*Location, but provides efficiency for
// ids that are densely numbered, which is often the case.
type locationIDMap struct {
dense []*Location // indexed by id for id < len(dense)
sparse map[uint64]*Location // indexed by id for id >= len(dense)
}
func makeLocationIDMap(n int) locationIDMap {
return locationIDMap{
dense: make([]*Location, n),
sparse: map[uint64]*Location{},
}
}
func (lm locationIDMap) get(id uint64) *Location {
if id < uint64(len(lm.dense)) {
return lm.dense[int(id)]
}
return lm.sparse[id]
}
func (lm locationIDMap) set(id uint64, loc *Location) {
if id < uint64(len(lm.dense)) {
lm.dense[id] = loc
return
}
lm.sparse[id] = loc
}
// CompatibilizeSampleTypes makes profiles compatible to be compared/merged. It
// keeps sample types that appear in all profiles only and drops/reorders the
// sample types as necessary.
//
// In the case of sample types order is not the same for given profiles the
// order is derived from the first profile.
//
// Profiles are modified in-place.
//
// It returns an error if the sample type's intersection is empty.
func CompatibilizeSampleTypes(ps []*Profile) error {
sTypes := commonSampleTypes(ps)
if len(sTypes) == 0 {
return fmt.Errorf("profiles have empty common sample type list")
}
for _, p := range ps {
if err := compatibilizeSampleTypes(p, sTypes); err != nil {
return err
}
}
return nil
}
// commonSampleTypes returns sample types that appear in all profiles in the
// order how they ordered in the first profile.
func commonSampleTypes(ps []*Profile) []string {
if len(ps) == 0 {
return nil
}
sTypes := map[string]int{}
for _, p := range ps {
for _, st := range p.SampleType {
sTypes[st.Type]++
}
}
var res []string
for _, st := range ps[0].SampleType {
if sTypes[st.Type] == len(ps) {
res = append(res, st.Type)
}
}
return res
}
// compatibilizeSampleTypes drops sample types that are not present in sTypes
// list and reorder them if needed.
//
// It sets DefaultSampleType to sType[0] if it is not in sType list.
//
// It assumes that all sample types from the sTypes list are present in the
// given profile otherwise it returns an error.
func compatibilizeSampleTypes(p *Profile, sTypes []string) error {
if len(sTypes) == 0 {
return fmt.Errorf("sample type list is empty")
}
defaultSampleType := sTypes[0]
reMap, needToModify := make([]int, len(sTypes)), false
for i, st := range sTypes {
if st == p.DefaultSampleType {
defaultSampleType = p.DefaultSampleType
}
idx := searchValueType(p.SampleType, st)
if idx < 0 {
return fmt.Errorf("%q sample type is not found in profile", st)
}
reMap[i] = idx
if idx != i {
needToModify = true
}
}
if !needToModify && len(sTypes) == len(p.SampleType) {
return nil
}
p.DefaultSampleType = defaultSampleType
oldSampleTypes := p.SampleType
p.SampleType = make([]*ValueType, len(sTypes))
for i, idx := range reMap {
p.SampleType[i] = oldSampleTypes[idx]
}
values := make([]int64, len(sTypes))
for _, s := range p.Sample {
for i, idx := range reMap {
values[i] = s.Value[idx]
}
s.Value = s.Value[:len(values)]
copy(s.Value, values)
}
return nil
}
func searchValueType(vts []*ValueType, s string) int {
for i, vt := range vts {
if vt.Type == s {
return i
}
}
return -1
}
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