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// Copyright 2014 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.
// Implements methods to remove frames from profiles.
package profile
import (
"fmt"
"regexp"
)
// 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 := fn.Name
// Account for leading '.' on the PPC ELF v1 ABI.
if funcName[0] == '.' {
funcName = funcName[1:]
}
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
}