Language statistics bar for repositories (#8037)

* Implementation for calculating language statistics

Impement saving code language statistics to database

Implement rendering langauge stats

Add primary laguage to show in repository list

Implement repository stats indexer queue

Add indexer test

Refactor to use queue module

* Do not timeout for queues

vendor/github.com/src-d/enry/v2/data/heuristics.go

@@ -0,0 +1,35 @@
+package data
+
+import "github.com/src-d/enry/v2/data/rule"
+
+// Heuristics implements a rule-based content matching engine.
+
+// Heuristics is a number of sequntially applied rule.Heuristic where a
+// matching one disambiguages language(s) for a single file extension.
+type Heuristics []rule.Heuristic
+
+// Match returns languages identified by the matching rule of the heuristic.
+func (hs Heuristics) Match(data []byte) []string {
+	var matchedLangs []string
+	for _, heuristic := range hs {
+		if heuristic.Match(data) {
+			for _, langOrAlias := range heuristic.Languages() {
+				lang, ok := LanguageByAlias(langOrAlias)
+				if !ok { // should never happen
+					// reaching here means language name/alias in heuristics.yml
+					// is not consistent with languages.yml
+					// but we do not surface any such error at the API
+					continue
+				}
+				matchedLangs = append(matchedLangs, lang)
+			}
+			break
+		}
+	}
+	return matchedLangs
+}
+
+// matchString is a convenience used only in tests.
+func (hs *Heuristics) matchString(data string) []string {
+	return hs.Match([]byte(data))
+}