podman

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// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Implements methods to remove frames from profiles.
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package profile
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import (
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	"fmt"
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	"regexp"
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	"strings"
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)
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var (
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	reservedNames = []string{"(anonymous namespace)", "operator()"}
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	bracketRx     = func() *regexp.Regexp {
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		var quotedNames []string
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		for _, name := range append(reservedNames, "(") {
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			quotedNames = append(quotedNames, regexp.QuoteMeta(name))
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		}
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		return regexp.MustCompile(strings.Join(quotedNames, "|"))
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	}()
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)
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// simplifyFunc does some primitive simplification of function names.
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func simplifyFunc(f string) string {
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	// Account for leading '.' on the PPC ELF v1 ABI.
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	funcName := strings.TrimPrefix(f, ".")
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	// Account for unsimplified names -- try  to remove the argument list by trimming
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	// starting from the first '(', but skipping reserved names that have '('.
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	for _, ind := range bracketRx.FindAllStringSubmatchIndex(funcName, -1) {
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		foundReserved := false
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		for _, res := range reservedNames {
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			if funcName[ind[0]:ind[1]] == res {
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				foundReserved = true
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				break
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			}
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		}
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		if !foundReserved {
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			funcName = funcName[:ind[0]]
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			break
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		}
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	}
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	return funcName
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}
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// Prune removes all nodes beneath a node matching dropRx, and not
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// matching keepRx. If the root node of a Sample matches, the sample
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// will have an empty stack.
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func (p *Profile) Prune(dropRx, keepRx *regexp.Regexp) {
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	prune := make(map[uint64]bool)
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	pruneBeneath := make(map[uint64]bool)
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	for _, loc := range p.Location {
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		var i int
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		for i = len(loc.Line) - 1; i >= 0; i-- {
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			if fn := loc.Line[i].Function; fn != nil && fn.Name != "" {
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				funcName := simplifyFunc(fn.Name)
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				if dropRx.MatchString(funcName) {
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					if keepRx == nil || !keepRx.MatchString(funcName) {
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						break
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					}
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				}
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			}
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		}
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		if i >= 0 {
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			// Found matching entry to prune.
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			pruneBeneath[loc.ID] = true
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			// Remove the matching location.
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			if i == len(loc.Line)-1 {
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				// Matched the top entry: prune the whole location.
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				prune[loc.ID] = true
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			} else {
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				loc.Line = loc.Line[i+1:]
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			}
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		}
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	}
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	// Prune locs from each Sample
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	for _, sample := range p.Sample {
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		// Scan from the root to the leaves to find the prune location.
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		// Do not prune frames before the first user frame, to avoid
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		// pruning everything.
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		foundUser := false
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		for i := len(sample.Location) - 1; i >= 0; i-- {
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			id := sample.Location[i].ID
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			if !prune[id] && !pruneBeneath[id] {
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				foundUser = true
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				continue
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			}
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			if !foundUser {
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				continue
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			}
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			if prune[id] {
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				sample.Location = sample.Location[i+1:]
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				break
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			}
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			if pruneBeneath[id] {
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				sample.Location = sample.Location[i:]
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				break
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			}
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		}
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	}
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}
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// RemoveUninteresting prunes and elides profiles using built-in
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// tables of uninteresting function names.
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func (p *Profile) RemoveUninteresting() error {
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	var keep, drop *regexp.Regexp
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	var err error
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	if p.DropFrames != "" {
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		if drop, err = regexp.Compile("^(" + p.DropFrames + ")$"); err != nil {
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			return fmt.Errorf("failed to compile regexp %s: %v", p.DropFrames, err)
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		}
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		if p.KeepFrames != "" {
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			if keep, err = regexp.Compile("^(" + p.KeepFrames + ")$"); err != nil {
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				return fmt.Errorf("failed to compile regexp %s: %v", p.KeepFrames, err)
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			}
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		}
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		p.Prune(drop, keep)
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	}
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	return nil
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}
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// PruneFrom removes all nodes beneath the lowest node matching dropRx, not including itself.
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//
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// Please see the example below to understand this method as well as
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// the difference from Prune method.
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//
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// A sample contains Location of [A,B,C,B,D] where D is the top frame and there's no inline.
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//
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// PruneFrom(A) returns [A,B,C,B,D] because there's no node beneath A.
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// Prune(A, nil) returns [B,C,B,D] by removing A itself.
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//
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// PruneFrom(B) returns [B,C,B,D] by removing all nodes beneath the first B when scanning from the bottom.
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// Prune(B, nil) returns [D] because a matching node is found by scanning from the root.
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func (p *Profile) PruneFrom(dropRx *regexp.Regexp) {
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	pruneBeneath := make(map[uint64]bool)
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	for _, loc := range p.Location {
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		for i := 0; i < len(loc.Line); i++ {
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			if fn := loc.Line[i].Function; fn != nil && fn.Name != "" {
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				funcName := simplifyFunc(fn.Name)
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				if dropRx.MatchString(funcName) {
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					// Found matching entry to prune.
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					pruneBeneath[loc.ID] = true
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					loc.Line = loc.Line[i:]
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					break
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				}
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			}
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		}
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	}
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	// Prune locs from each Sample
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	for _, sample := range p.Sample {
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		// Scan from the bottom leaf to the root to find the prune location.
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		for i, loc := range sample.Location {
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			if pruneBeneath[loc.ID] {
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				sample.Location = sample.Location[i:]
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				break
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			}
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		}
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	}
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}
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