golang prune 代码
文件路径：/src/cmd/vendor/github.com/google/pprof/profile/prune.go
/ 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)
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 != "" {
funcName := simplifyFunc(fn.Name)
if dropRx.MatchString(funcName) {
if keepRx == nil || !keepRx.MatchString(funcName) {
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
}
}
}
}