// 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.
// Implements methods to remove frames from profiles.
package profile
import (
"fmt"
"regexp"
"strings"
)
var (
reservedNames = []string{"(anonymous namespace)", "operator()"}
bracketRx = func() *regexp.Regexp {
var quotedNames []string
for _, name := range append(reservedNames, "(") {
quotedNames = append(quotedNames, regexp.QuoteMeta(name))
}
return regexp.MustCompile(strings.Join(quotedNames, "|"))
}()
)
// simplifyFunc does some primitive simplification of function names.
func simplifyFunc(f string) string {
// Account for leading '.' on the PPC ELF v1 ABI.
funcName := strings.TrimPrefix(f, ".")
// Account for unsimplified names -- try to remove the argument list by trimming
// starting from the first '(', but skipping reserved names that have '('.
for _, ind := range bracketRx.FindAllStringSubmatchIndex(funcName, -1) {
foundReserved := false
for _, res := range reservedNames {
if funcName[ind[0]:ind[1]] == res {
foundReserved = true
break
}
}
if !foundReserved {
funcName = funcName[:ind[0]]
break
}
}
return funcName
}
// Prune removes all nodes beneath a node matching dropRx, and not
// matching keepRx. If the root node of a Sample matches, the sample
// will have an empty stack.
func (p *Profile) Prune(dropRx, keepRx *regexp.Regexp) {
prune := make(map[uint64]bool)
pruneBeneath := make(map[uint64]bool)
// simplifyFunc can be expensive, so cache results.
// Note that the same function name can be encountered many times due
// different lines and addresses in the same function.
pruneCache := map[string]bool{} // Map from function to whether or not to prune
pruneFromHere := func(s string) bool {
if r, ok := pruneCache[s]; ok {
return r
}
funcName := simplifyFunc(s)
if dropRx.MatchString(funcName) {
if keepRx == nil || !keepRx.MatchString(funcName) {
pruneCache[s] = true
return true
}
}
pruneCache[s] = false
return false
}
for _, loc := range p.Location {
var i int
for i = len(loc.Line) - 1; i >= 0; i-- {
if fn := loc.Line[i].Function; fn != nil && fn.Name != "" {
if pruneFromHere(fn.Name) {
break
}
}
}
if i >= 0 {
// Found matching entry to prune.
pruneBeneath[loc.ID] = true
// Remove the matching location.
if i == len(loc.Line)-1 {
// Matched the top entry: prune the whole location.
prune[loc.ID] = true
} else {
loc.Line = loc.Line[i+1:]
}
}
}
// Prune locs from each Sample
for _, sample := range p.Sample {
// Scan from the root to the leaves to find the prune location.
// Do not prune frames before the first user frame, to avoid
// pruning everything.
foundUser := false
for i := len(sample.Location) - 1; i >= 0; i-- {
id := sample.Location[i].ID
if !prune[id] && !pruneBeneath[id] {
foundUser = true
continue
}
if !foundUser {
continue
}
if prune[id] {
sample.Location = sample.Location[i+1:]
break
}
if pruneBeneath[id] {
sample.Location = sample.Location[i:]
break
}
}
}
}
// RemoveUninteresting prunes and elides profiles using built-in
// tables of uninteresting function names.
func (p *Profile) RemoveUninteresting() error {
var keep, drop *regexp.Regexp
var err error
if p.DropFrames != "" {
if drop, err = regexp.Compile("^(" + p.DropFrames + ")$"); err != nil {
return fmt.Errorf("failed to compile regexp %s: %v", p.DropFrames, err)
}
if p.KeepFrames != "" {
if keep, err = regexp.Compile("^(" + p.KeepFrames + ")$"); err != nil {
return fmt.Errorf("failed to compile regexp %s: %v", p.KeepFrames, err)
}
}
p.Prune(drop, keep)
}
return nil
}
// PruneFrom removes all nodes beneath the lowest node matching dropRx, not including itself.
//
// Please see the example below to understand this method as well as
// the difference from Prune method.
//
// A sample contains Location of [A,B,C,B,D] where D is the top frame and there's no inline.
//
// PruneFrom(A) returns [A,B,C,B,D] because there's no node beneath A.
// Prune(A, nil) returns [B,C,B,D] by removing A itself.
//
// PruneFrom(B) returns [B,C,B,D] by removing all nodes beneath the first B when scanning from the bottom.
// Prune(B, nil) returns [D] because a matching node is found by scanning from the root.
func (p *Profile) PruneFrom(dropRx *regexp.Regexp) {
pruneBeneath := make(map[uint64]bool)
for _, loc := range p.Location {
for i := 0; i < len(loc.Line); i++ {
if fn := loc.Line[i].Function; fn != nil && fn.Name != "" {
funcName := simplifyFunc(fn.Name)
if dropRx.MatchString(funcName) {
// Found matching entry to prune.
pruneBeneath[loc.ID] = true
loc.Line = loc.Line[i:]
break
}
}
}
}
// Prune locs from each Sample
for _, sample := range p.Sample {
// Scan from the bottom leaf to the root to find the prune location.
for i, loc := range sample.Location {
if pruneBeneath[loc.ID] {
sample.Location = sample.Location[i:]
break
}
}
}
}
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