profile.go

// Copyright 2013 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.

// This file provides support for parsing coverage profiles
// generated by "go test -coverprofile=cover.out".
// It is a copy of golang.org/x/tools/cover/profile.go.

package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"math"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

// Profile represents the profiling data for a specific file.
type Profile struct {
	FileName string
	Mode     string
	Blocks   []ProfileBlock
}

// ProfileBlock represents a single block of profiling data.
type ProfileBlock struct {
	StartLine, StartCol int
	EndLine, EndCol     int
	NumStmt, Count      int
}

type byFileName []*Profile

func (p byFileName) Len() int           { return len(p) }
func (p byFileName) Less(i, j int) bool { return p[i].FileName < p[j].FileName }
func (p byFileName) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

// ParseProfiles parses profile data in the specified file and returns a
// Profile for each source file described therein.
func ParseProfiles(fileName string) ([]*Profile, error) {
	pf, err := os.Open(fileName)
	if err != nil {
		return nil, err
	}
	defer pf.Close()

	files := make(map[string]*Profile)
	buf := bufio.NewReader(pf)
	// First line is "mode: foo", where foo is "set", "count", or "atomic".
	// Rest of file is in the format
	//	encoding/base64/base64.go:34.44,37.40 3 1
	// where the fields are: name.go:line.column,line.column numberOfStatements count
	s := bufio.NewScanner(buf)
	mode := ""
	for s.Scan() {
		line := s.Text()
		if mode == "" {
			const p = "mode: "
			if !strings.HasPrefix(line, p) || line == p {
				return nil, fmt.Errorf("bad mode line: %v", line)
			}
			mode = line[len(p):]
			continue
		}
		m := lineRe.FindStringSubmatch(line)
		if m == nil {
			return nil, fmt.Errorf("line %q doesn't match expected format: %v", m, lineRe)
		}
		fn := m[1]
		p := files[fn]
		if p == nil {
			p = &Profile{
				FileName: fn,
				Mode:     mode,
			}
			files[fn] = p
		}
		p.Blocks = append(p.Blocks, ProfileBlock{
			StartLine: toInt(m[2]),
			StartCol:  toInt(m[3]),
			EndLine:   toInt(m[4]),
			EndCol:    toInt(m[5]),
			NumStmt:   toInt(m[6]),
			Count:     toInt(m[7]),
		})
	}
	if err := s.Err(); err != nil {
		return nil, err
	}
	for _, p := range files {
		sort.Sort(blocksByStart(p.Blocks))
		// Merge samples from the same location.
		j := 1
		for i := 1; i < len(p.Blocks); i++ {
			b := p.Blocks[i]
			last := p.Blocks[j-1]
			if b.StartLine == last.StartLine &&
				b.StartCol == last.StartCol &&
				b.EndLine == last.EndLine &&
				b.EndCol == last.EndCol {
				if b.NumStmt != last.NumStmt {
					return nil, fmt.Errorf("inconsistent NumStmt: changed from %d to %d", last.NumStmt, b.NumStmt)
				}
				if mode == "set" {
					p.Blocks[j-1].Count |= b.Count
				} else {
					p.Blocks[j-1].Count += b.Count
				}
				continue
			}
			p.Blocks[j] = b
			j++
		}
		p.Blocks = p.Blocks[:j]
	}
	// Generate a sorted slice.
	profiles := make([]*Profile, 0, len(files))
	for _, profile := range files {
		profiles = append(profiles, profile)
	}
	sort.Sort(byFileName(profiles))
	return profiles, nil
}

type blocksByStart []ProfileBlock

func (b blocksByStart) Len() int      { return len(b) }
func (b blocksByStart) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b blocksByStart) Less(i, j int) bool {
	bi, bj := b[i], b[j]
	return bi.StartLine < bj.StartLine || bi.StartLine == bj.StartLine && bi.StartCol < bj.StartCol
}

var lineRe = regexp.MustCompile(`^(.+):([0-9]+).([0-9]+),([0-9]+).([0-9]+) ([0-9]+) ([0-9]+)$`)

func toInt(s string) int {
	i, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return i
}

// Boundary represents the position in a source file of the beginning or end of a
// block as reported by the coverage profile. In HTML mode, it will correspond to
// the opening or closing of a <span> tag and will be used to colorize the source
type Boundary struct {
	Offset int     // Location as a byte offset in the source file.
	Start  bool    // Is this the start of a block?
	Count  int     // Event count from the cover profile.
	Norm   float64 // Count normalized to [0..1].
	Index  int     // Order in input file.
}

// Boundaries returns a Profile as a set of Boundary objects within the provided src.
func (p *Profile) Boundaries(src []byte) (boundaries []Boundary) {
	// Find maximum count.
	max := 0
	for _, b := range p.Blocks {
		if b.Count > max {
			max = b.Count
		}
	}
	// Divisor for normalization.
	divisor := math.Log(float64(max))

	// boundary returns a Boundary, populating the Norm field with a normalized Count.
	index := 0
	boundary := func(offset int, start bool, count int) Boundary {
		b := Boundary{Offset: offset, Start: start, Count: count, Index: index}
		index++
		if !start || count == 0 {
			return b
		}
		if max <= 1 {
			b.Norm = 0.8 // Profile is in "set" mode; we want a heat map. Use cov8 in the CSS.
		} else if count > 0 {
			b.Norm = math.Log(float64(count)) / divisor
		}
		return b
	}

	line, col := 1, 2 // TODO: Why is this 2?
	for si, bi := 0, 0; si < len(src) && bi < len(p.Blocks); {
		b := p.Blocks[bi]
		if b.StartLine == line && b.StartCol == col {
			boundaries = append(boundaries, boundary(si, true, b.Count))
		}
		if b.EndLine == line && b.EndCol == col || line > b.EndLine {
			boundaries = append(boundaries, boundary(si, false, 0))
			bi++
			continue // Don't advance through src; maybe the next block starts here.
		}
		if src[si] == '\n' {
			line++
			col = 0
		}
		col++
		si++
	}
	sort.Sort(boundariesByPos(boundaries))
	return
}

type boundariesByPos []Boundary

func (b boundariesByPos) Len() int      { return len(b) }
func (b boundariesByPos) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b boundariesByPos) Less(i, j int) bool {
	if b[i].Offset == b[j].Offset {
		// Boundaries at the same offset should be ordered according to
		// their original position.
		return b[i].Index < b[j].Index
	}
	return b[i].Offset < b[j].Offset
}

// Pkg describes a single package, compatible with the JSON output from 'go list'; see 'go help list'.
type Pkg struct {
	ImportPath string
	Dir        string
	Error      *struct {
		Err string
	}
}

func findPkgs(profiles []*Profile) (map[string]*Pkg, error) {
	// Run go list to find the location of every package we care about.
	pkgs := make(map[string]*Pkg)
	var list []string
	for _, profile := range profiles {
		if strings.HasPrefix(profile.FileName, ".") || filepath.IsAbs(profile.FileName) {
			// Relative or absolute path.
			continue
		}
		pkg := path.Dir(profile.FileName)
		if _, ok := pkgs[pkg]; !ok {
			pkgs[pkg] = nil
			list = append(list, pkg)
		}
	}

	if len(list) == 0 {
		return pkgs, nil
	}

	// Note: usually run as "go tool cover" in which case $GOROOT is set,
	// in which case runtime.GOROOT() does exactly what we want.
	// goTool := filepath.Join(runtime.GOROOT(), "bin/go")
	cmd := exec.Command("go", append([]string{"list", "-e", "-json"}, list...)...)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	stdout, err := cmd.Output()
	if err != nil {
		return nil, fmt.Errorf("cannot run go list: %v\n%s", err, stderr.Bytes())
	}
	dec := json.NewDecoder(bytes.NewReader(stdout))
	for {
		var pkg Pkg
		err := dec.Decode(&pkg)
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, fmt.Errorf("decoding go list json: %v", err)
		}
		pkgs[pkg.ImportPath] = &pkg
	}
	return pkgs, nil
}

// findFile finds the location of the named file in GOROOT, GOPATH etc.
func findFile(pkgs map[string]*Pkg, file string) (string, error) {
	if strings.HasPrefix(file, ".") || filepath.IsAbs(file) {
		// Relative or absolute path.
		return file, nil
	}
	pkg := pkgs[path.Dir(file)]
	if pkg != nil {
		if pkg.Dir != "" {
			return filepath.Join(pkg.Dir, path.Base(file)), nil
		}
		if pkg.Error != nil {
			return "", errors.New(pkg.Error.Err)
		}
	}
	return "", fmt.Errorf("did not find package for %s in go list output", file)
}