Source: filter.go in package github.com/google/pprof/profile

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

Implements methods to filter samples from profiles.


import "regexp"

FilterSamplesByName filters the samples in a profile and only keeps samples where at least one frame matches focus but none match ignore. Returns true is the corresponding regexp matched at least one sample.

func (p *Profile) FilterSamplesByName(focus, ignore, hide, show *regexp.Regexp) (fm, im, hm, hnm bool) {
	focusOrIgnore := make(map[uint64]bool)
	hidden := make(map[uint64]bool)
	for _, l := range p.Location {
		if ignore != nil && l.matchesName(ignore) {
			im = true
			focusOrIgnore[l.ID] = false
		} else if focus == nil || l.matchesName(focus) {
			fm = true
			focusOrIgnore[l.ID] = true
		}

		if hide != nil && l.matchesName(hide) {
			hm = true
			l.Line = l.unmatchedLines(hide)
			if len(l.Line) == 0 {
				hidden[l.ID] = true
			}
		}
		if show != nil {
			l.Line = l.matchedLines(show)
			if len(l.Line) == 0 {
				hidden[l.ID] = true
			} else {
				hnm = true
			}
		}
	}

	s := make([]*Sample, 0, len(p.Sample))
	for _, sample := range p.Sample {
		if focusedAndNotIgnored(sample.Location, focusOrIgnore) {
			if len(hidden) > 0 {
				var locs []*Location
				for _, loc := range sample.Location {
					if !hidden[loc.ID] {
						locs = append(locs, loc)
					}
				}

Remove sample with no locations (by not adding it to s).

					continue
				}
				sample.Location = locs
			}
			s = append(s, sample)
		}
	}
	p.Sample = s

	return
}

ShowFrom drops all stack frames above the highest matching frame and returns whether a match was found. If showFrom is nil it returns false and does not modify the profile. Example: consider a sample with frames [A, B, C, B], where A is the root. ShowFrom(nil) returns false and has frames [A, B, C, B]. ShowFrom(A) returns true and has frames [A, B, C, B]. ShowFrom(B) returns true and has frames [B, C, B]. ShowFrom(C) returns true and has frames [C, B]. ShowFrom(D) returns false and drops the sample because no frames remain.

func (p *Profile) ShowFrom(showFrom *regexp.Regexp) (matched bool) {
	if showFrom == nil {
		return false

showFromLocs stores location IDs that matched ShowFrom.

Apply to locations.

	for _, loc := range p.Location {
		if filterShowFromLocation(loc, showFrom) {
			showFromLocs[loc.ID] = true
			matched = true
		}

For all samples, strip locations after the highest matching one.

	s := make([]*Sample, 0, len(p.Sample))
	for _, sample := range p.Sample {
		for i := len(sample.Location) - 1; i >= 0; i-- {
			if showFromLocs[sample.Location[i].ID] {
				sample.Location = sample.Location[:i+1]
				s = append(s, sample)
				break
			}
		}
	}
	p.Sample = s
	return matched
}

filterShowFromLocation tests a showFrom regex against a location, removes lines after the last match and returns whether a match was found. If the mapping is matched, then all lines are kept.

func filterShowFromLocation(loc *Location, showFrom *regexp.Regexp) bool {
	if m := loc.Mapping; m != nil && showFrom.MatchString(m.File) {
		return true
	}
	if i := loc.lastMatchedLineIndex(showFrom); i >= 0 {
		loc.Line = loc.Line[:i+1]
		return true
	}
	return false
}

lastMatchedLineIndex returns the index of the last line that matches a regex, or -1 if no match is found.

func (loc *Location) lastMatchedLineIndex(re *regexp.Regexp) int {
	for i := len(loc.Line) - 1; i >= 0; i-- {
		if fn := loc.Line[i].Function; fn != nil {
			if re.MatchString(fn.Name) || re.MatchString(fn.Filename) {
				return i
			}
		}
	}
	return -1
}

FilterTagsByName filters the tags in a profile and only keeps tags that match show and not hide.

func (p *Profile) FilterTagsByName(show, hide *regexp.Regexp) (sm, hm bool) {
	matchRemove := func(name string) bool {
		matchShow := show == nil || show.MatchString(name)
		matchHide := hide != nil && hide.MatchString(name)

		if matchShow {
			sm = true
		}
		if matchHide {
			hm = true
		}
		return !matchShow || matchHide
	}
	for _, s := range p.Sample {
		for lab := range s.Label {
			if matchRemove(lab) {
				delete(s.Label, lab)
			}
		}
		for lab := range s.NumLabel {
			if matchRemove(lab) {
				delete(s.NumLabel, lab)
			}
		}
	}
	return
}

matchesName returns whether the location matches the regular expression. It checks any available function names, file names, and mapping object filename.

func (loc *Location) matchesName(re *regexp.Regexp) bool {
	for _, ln := range loc.Line {
		if fn := ln.Function; fn != nil {
			if re.MatchString(fn.Name) || re.MatchString(fn.Filename) {
				return true
			}
		}
	}
	if m := loc.Mapping; m != nil && re.MatchString(m.File) {
		return true
	}
	return false
}

unmatchedLines returns the lines in the location that do not match the regular expression.

func (loc *Location) unmatchedLines(re *regexp.Regexp) []Line {
	if m := loc.Mapping; m != nil && re.MatchString(m.File) {
		return nil
	}
	var lines []Line
	for _, ln := range loc.Line {
		if fn := ln.Function; fn != nil {
			if re.MatchString(fn.Name) || re.MatchString(fn.Filename) {
				continue
			}
		}
		lines = append(lines, ln)
	}
	return lines
}

matchedLines returns the lines in the location that match the regular expression.

func (loc *Location) matchedLines(re *regexp.Regexp) []Line {
	if m := loc.Mapping; m != nil && re.MatchString(m.File) {
		return loc.Line
	}
	var lines []Line
	for _, ln := range loc.Line {
		if fn := ln.Function; fn != nil {
			if !re.MatchString(fn.Name) && !re.MatchString(fn.Filename) {
				continue
			}
		}
		lines = append(lines, ln)
	}
	return lines
}

focusedAndNotIgnored looks up a slice of ids against a map of focused/ignored locations. The map only contains locations that are explicitly focused or ignored. Returns whether there is at least one focused location but no ignored locations.

func focusedAndNotIgnored(locs []*Location, m map[uint64]bool) bool {
	var f bool
	for _, loc := range locs {
		if focus, focusOrIgnore := m[loc.ID]; focusOrIgnore {

Found focused location. Must keep searching in case there is an ignored one as well.

				f = true

Found ignored location. Can return false right away.

				return false
			}
		}
	}
	return f
}

TagMatch selects tags for filtering

type TagMatch func(s *Sample) bool

FilterSamplesByTag removes all samples from the profile, except those that match focus and do not match the ignore regular expression.

func (p *Profile) FilterSamplesByTag(focus, ignore TagMatch) (fm, im bool) {
	samples := make([]*Sample, 0, len(p.Sample))
	for _, s := range p.Sample {
		focused, ignored := true, false
		if focus != nil {
			focused = focus(s)
		}
		if ignore != nil {
			ignored = ignore(s)
		}
		fm = fm || focused
		im = im || ignored
		if focused && !ignored {
			samples = append(samples, s)
		}
	}
	p.Sample = samples
	return