profile.go

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package cover provides support for parsing coverage profiles
     6  // generated by "go test -coverprofile=cover.out".
     7  package cover // import "golang.org/x/tools/cover"
     8  
     9  import (
    10  	"bufio"
    11  	"errors"
    12  	"fmt"
    13  	"io"
    14  	"math"
    15  	"os"
    16  	"sort"
    17  	"strconv"
    18  	"strings"
    19  )
    20  
    21  // Profile represents the profiling data for a specific file.
    22  type Profile struct {
    23  	FileName string
    24  	Mode     string
    25  	Blocks   []ProfileBlock
    26  }
    27  
    28  // ProfileBlock represents a single block of profiling data.
    29  type ProfileBlock struct {
    30  	StartLine, StartCol int
    31  	EndLine, EndCol     int
    32  	NumStmt, Count      int
    33  }
    34  
    35  type byFileName []*Profile
    36  
    37  func (p byFileName) Len() int           { return len(p) }
    38  func (p byFileName) Less(i, j int) bool { return p[i].FileName < p[j].FileName }
    39  func (p byFileName) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
    40  
    41  // ParseProfiles parses profile data in the specified file and returns a
    42  // Profile for each source file described therein.
    43  func ParseProfiles(fileName string) ([]*Profile, error) {
    44  	pf, err := os.Open(fileName)
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  	defer pf.Close()
    49  	return ParseProfilesFromReader(pf)
    50  }
    51  
    52  // ParseProfilesFromReader parses profile data from the Reader and
    53  // returns a Profile for each source file described therein.
    54  func ParseProfilesFromReader(rd io.Reader) ([]*Profile, error) {
    55  	// First line is "mode: foo", where foo is "set", "count", or "atomic".
    56  	// Rest of file is in the format
    57  	//	encoding/base64/base64.go:34.44,37.40 3 1
    58  	// where the fields are: name.go:line.column,line.column numberOfStatements count
    59  	files := make(map[string]*Profile)
    60  	s := bufio.NewScanner(rd)
    61  	mode := ""
    62  	for s.Scan() {
    63  		line := s.Text()
    64  		if mode == "" {
    65  			const p = "mode: "
    66  			if !strings.HasPrefix(line, p) || line == p {
    67  				return nil, fmt.Errorf("bad mode line: %v", line)
    68  			}
    69  			mode = line[len(p):]
    70  			continue
    71  		}
    72  		fn, b, err := parseLine(line)
    73  		if err != nil {
    74  			return nil, fmt.Errorf("line %q doesn't match expected format: %v", line, err)
    75  		}
    76  		p := files[fn]
    77  		if p == nil {
    78  			p = &Profile{
    79  				FileName: fn,
    80  				Mode:     mode,
    81  			}
    82  			files[fn] = p
    83  		}
    84  		p.Blocks = append(p.Blocks, b)
    85  	}
    86  	if err := s.Err(); err != nil {
    87  		return nil, err
    88  	}
    89  	for _, p := range files {
    90  		sort.Sort(blocksByStart(p.Blocks))
    91  		// Merge samples from the same location.
    92  		j := 1
    93  		for i := 1; i < len(p.Blocks); i++ {
    94  			b := p.Blocks[i]
    95  			last := p.Blocks[j-1]
    96  			if b.StartLine == last.StartLine &&
    97  				b.StartCol == last.StartCol &&
    98  				b.EndLine == last.EndLine &&
    99  				b.EndCol == last.EndCol {
   100  				if b.NumStmt != last.NumStmt {
   101  					return nil, fmt.Errorf("inconsistent NumStmt: changed from %d to %d", last.NumStmt, b.NumStmt)
   102  				}
   103  				if mode == "set" {
   104  					p.Blocks[j-1].Count |= b.Count
   105  				} else {
   106  					p.Blocks[j-1].Count += b.Count
   107  				}
   108  				continue
   109  			}
   110  			p.Blocks[j] = b
   111  			j++
   112  		}
   113  		p.Blocks = p.Blocks[:j]
   114  	}
   115  	// Generate a sorted slice.
   116  	profiles := make([]*Profile, 0, len(files))
   117  	for _, profile := range files {
   118  		profiles = append(profiles, profile)
   119  	}
   120  	sort.Sort(byFileName(profiles))
   121  	return profiles, nil
   122  }
   123  
   124  // parseLine parses a line from a coverage file.
   125  // It is equivalent to the regex
   126  // ^(.+):([0-9]+)\.([0-9]+),([0-9]+)\.([0-9]+) ([0-9]+) ([0-9]+)$
   127  //
   128  // However, it is much faster: https://golang.org/cl/179377
   129  func parseLine(l string) (fileName string, block ProfileBlock, err error) {
   130  	end := len(l)
   131  
   132  	b := ProfileBlock{}
   133  	b.Count, end, err = seekBack(l, ' ', end, "Count")
   134  	if err != nil {
   135  		return "", b, err
   136  	}
   137  	b.NumStmt, end, err = seekBack(l, ' ', end, "NumStmt")
   138  	if err != nil {
   139  		return "", b, err
   140  	}
   141  	b.EndCol, end, err = seekBack(l, '.', end, "EndCol")
   142  	if err != nil {
   143  		return "", b, err
   144  	}
   145  	b.EndLine, end, err = seekBack(l, ',', end, "EndLine")
   146  	if err != nil {
   147  		return "", b, err
   148  	}
   149  	b.StartCol, end, err = seekBack(l, '.', end, "StartCol")
   150  	if err != nil {
   151  		return "", b, err
   152  	}
   153  	b.StartLine, end, err = seekBack(l, ':', end, "StartLine")
   154  	if err != nil {
   155  		return "", b, err
   156  	}
   157  	fn := l[0:end]
   158  	if fn == "" {
   159  		return "", b, errors.New("a FileName cannot be blank")
   160  	}
   161  	return fn, b, nil
   162  }
   163  
   164  // seekBack searches backwards from end to find sep in l, then returns the
   165  // value between sep and end as an integer.
   166  // If seekBack fails, the returned error will reference what.
   167  func seekBack(l string, sep byte, end int, what string) (value int, nextSep int, err error) {
   168  	// Since we're seeking backwards and we know only ASCII is legal for these values,
   169  	// we can ignore the possibility of non-ASCII characters.
   170  	for start := end - 1; start >= 0; start-- {
   171  		if l[start] == sep {
   172  			i, err := strconv.Atoi(l[start+1 : end])
   173  			if err != nil {
   174  				return 0, 0, fmt.Errorf("couldn't parse %q: %v", what, err)
   175  			}
   176  			if i < 0 {
   177  				return 0, 0, fmt.Errorf("negative values are not allowed for %s, found %d", what, i)
   178  			}
   179  			return i, start, nil
   180  		}
   181  	}
   182  	return 0, 0, fmt.Errorf("couldn't find a %s before %s", string(sep), what)
   183  }
   184  
   185  type blocksByStart []ProfileBlock
   186  
   187  func (b blocksByStart) Len() int      { return len(b) }
   188  func (b blocksByStart) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
   189  func (b blocksByStart) Less(i, j int) bool {
   190  	bi, bj := b[i], b[j]
   191  	return bi.StartLine < bj.StartLine || bi.StartLine == bj.StartLine && bi.StartCol < bj.StartCol
   192  }
   193  
   194  // Boundary represents the position in a source file of the beginning or end of a
   195  // block as reported by the coverage profile. In HTML mode, it will correspond to
   196  // the opening or closing of a <span> tag and will be used to colorize the source
   197  type Boundary struct {
   198  	Offset int     // Location as a byte offset in the source file.
   199  	Start  bool    // Is this the start of a block?
   200  	Count  int     // Event count from the cover profile.
   201  	Norm   float64 // Count normalized to [0..1].
   202  	Index  int     // Order in input file.
   203  }
   204  
   205  // Boundaries returns a Profile as a set of Boundary objects within the provided src.
   206  func (p *Profile) Boundaries(src []byte) (boundaries []Boundary) {
   207  	// Find maximum count.
   208  	max := 0
   209  	for _, b := range p.Blocks {
   210  		if b.Count > max {
   211  			max = b.Count
   212  		}
   213  	}
   214  	// Divisor for normalization.
   215  	divisor := math.Log(float64(max))
   216  
   217  	// boundary returns a Boundary, populating the Norm field with a normalized Count.
   218  	index := 0
   219  	boundary := func(offset int, start bool, count int) Boundary {
   220  		b := Boundary{Offset: offset, Start: start, Count: count, Index: index}
   221  		index++
   222  		if !start || count == 0 {
   223  			return b
   224  		}
   225  		if max <= 1 {
   226  			b.Norm = 0.8 // Profile is in"set" mode; we want a heat map. Use cov8 in the CSS.
   227  		} else if count > 0 {
   228  			b.Norm = math.Log(float64(count)) / divisor
   229  		}
   230  		return b
   231  	}
   232  
   233  	line, col := 1, 2 // TODO: Why is this 2?
   234  	for si, bi := 0, 0; si < len(src) && bi < len(p.Blocks); {
   235  		b := p.Blocks[bi]
   236  		if b.StartLine == line && b.StartCol == col {
   237  			boundaries = append(boundaries, boundary(si, true, b.Count))
   238  		}
   239  		if b.EndLine == line && b.EndCol == col || line > b.EndLine {
   240  			boundaries = append(boundaries, boundary(si, false, 0))
   241  			bi++
   242  			continue // Don't advance through src; maybe the next block starts here.
   243  		}
   244  		if src[si] == '\n' {
   245  			line++
   246  			col = 0
   247  		}
   248  		col++
   249  		si++
   250  	}
   251  	sort.Sort(boundariesByPos(boundaries))
   252  	return
   253  }
   254  
   255  type boundariesByPos []Boundary
   256  
   257  func (b boundariesByPos) Len() int      { return len(b) }
   258  func (b boundariesByPos) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
   259  func (b boundariesByPos) Less(i, j int) bool {
   260  	if b[i].Offset == b[j].Offset {
   261  		// Boundaries at the same offset should be ordered according to
   262  		// their original position.
   263  		return b[i].Index < b[j].Index
   264  	}
   265  	return b[i].Offset < b[j].Offset
   266  }
   267
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