Add tagshow/taghide commands to select a subset of tags in a profile

internal/driver/commands.go

@@ -199,7 +199,12 @@ var pprofVariables = variables{
 	"tagignore": &variable{stringKind, "", "", helpText(
 		"Discard samples with tags in range or matched by regexp",
 		"Discard samples that do include a node with a tag matching this regexp.")},
-
+	"tagshow": &variable{stringKind, "", "", helpText(
+		"Only consider tags matching this regexp",
+		"Discard tags that do not match this regexp")},
+	"taghide": &variable{stringKind, "", "", helpText(
+		"Skip tags matching this regexp",
+		"Discard tags that match this regexp")},
 	// Heap profile options
 	"divide_by": &variable{floatKind, "1", "", helpText(
 		"Ratio to divide all samples before visualization",

internal/driver/driver_focus.go

@@ -50,6 +50,12 @@ func applyFocus(prof *profile.Profile, v variables, ui plugin.UI) error {
 	warnNoMatches(tagfocus == nil || tfm, "TagFocus", ui)
 	warnNoMatches(tagignore == nil || tim, "TagIgnore", ui)
 
+	tagshow, err := compileRegexOption("tagshow", v["tagshow"].value, err)
+	taghide, err := compileRegexOption("taghide", v["taghide"].value, err)
+	tns, tnh := prof.FilterTagsByName(tagshow, taghide)
+	warnNoMatches(tagshow == nil || tns, "TagShow", ui)
+	warnNoMatches(tagignore == nil || tnh, "TagHide", ui)
+
 	if prunefrom != nil {
 		prof.PruneFrom(prunefrom)
 	}

profile/filter.go

@@ -73,6 +73,36 @@ func (p *Profile) FilterSamplesByName(focus, ignore, hide, show *regexp.Regexp)
 	return
 }
 
+// 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) {
+	matchShow := 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 !matchShow(lab) {
+				delete(s.Label, lab)
+			}
+		}
+		for lab := range s.NumLabel {
+			if !matchShow(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.

profile/profile_test.go

@@ -507,6 +507,49 @@ func TestFilter(t *testing.T) {
 	}
 }
 
+func TestTagFilter(t *testing.T) {
+     // Perform several forms of tag filtering on the test profile.
+
+	type filterTestcase struct {
+		include, exclude *regexp.Regexp
+		im, em bool
+		count int
+	}
+
+	countTags := func (p *Profile) map[string]bool {
+		  tags := make(map[string]bool)
+
+		  for _, s := range p.Sample {
+		      for l := range s.Label {
+		      	  tags[l] = true
+		      }		      
+		      for l := range s.NumLabel {
+		      	  tags[l] = true
+		      }		      
+		  }
+		  return tags
+	}	
+
+	for tx, tc := range []filterTestcase{
+		{nil, nil, true, false, 3},
+		{regexp.MustCompile("notfound"), nil, false, false, 0},
+		{regexp.MustCompile("key1"), nil, true, false, 1},
+		{nil, regexp.MustCompile("key[12]"), true, true, 1},
+	} {
+		prof := testProfile.Copy()
+		gim, gem := prof.FilterTagsByName(tc.include, tc.exclude)
+		if  gim != tc.im {
+			t.Errorf("Filter #%d, got include match=%v, want %v", tx, gim, tc.im)
+		}		
+		if  gem != tc.em {
+			t.Errorf("Filter #%d, got exclude match=%v, want %v", tx, gem, tc.em)
+		}		
+		if  tags := countTags(prof) ; len(tags) != tc.count {
+			t.Errorf("Filter #%d, got %d tags[%v], want %d", tx, len(tags), tags, tc.count)
+		}		
+	}
+}
+
 // locationHash constructs a string to use as a hashkey for a sample, based on its locations
 func locationHash(s *Sample) string {
 	var tb string