linguist: Update version to invalidate cache

In the previous commit we've created a fix in the language stats, but
there still might be faulty values cached. To invalidate those, update
the version so we'll always recalculate stats from scratch unless it was
calculated with the fix in place.

2 files changed, 27 insertions, 1 deletions

diff --git a/internal/gitaly/linguist/language_stats.go b/internal/gitaly/linguist/language_stats.go
index 62655d48b..e65a90c9a 100644
--- a/internal/gitaly/linguist/language_stats.go
+++ b/internal/gitaly/linguist/language_stats.go
@@ -16,7 +16,7 @@ const (
 	// a cached version of the language statistics. The name is
 	// intentionally different from what the linguist gem uses.
 	languageStatsFilename = "gitaly-language.stats"
-	languageStatsVersion  = "v1:gitaly"
+	languageStatsVersion  = "v2:gitaly"
 )
 
 // languageStats takes care of accumulating and caching language statistics for
diff --git a/internal/gitaly/linguist/language_stats_test.go b/internal/gitaly/linguist/language_stats_test.go
index 07904769d..a64f8ad90 100644
--- a/internal/gitaly/linguist/language_stats_test.go
+++ b/internal/gitaly/linguist/language_stats_test.go
@@ -3,6 +3,9 @@
 package linguist
 
 import (
+	"compress/zlib"
+	"encoding/json"
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -54,6 +57,29 @@ func TestNewLanguageStats(t *testing.T) {
 				require.Empty(t, stats.ByFile)
 			},
 		},
+		{
+			desc: "incorrect version cache",
+			run: func(t *testing.T, repo *localrepo.Repo, repoPath string) {
+				stats, err := newLanguageStats(repo)
+				require.NoError(t, err)
+
+				stats.Totals["C"] = 555
+				stats.Version = "faulty"
+
+				// Copy save() behavior, but with a faulty version
+				file, err := os.OpenFile(filepath.Join(repoPath, languageStatsFilename), os.O_WRONLY|os.O_CREATE, 0o755)
+				require.NoError(t, err)
+				w := zlib.NewWriter(file)
+				require.NoError(t, json.NewEncoder(w).Encode(stats))
+				require.NoError(t, w.Close())
+				require.NoError(t, file.Sync())
+				require.NoError(t, file.Close())
+
+				newStats, err := newLanguageStats(repo)
+				require.Error(t, err, fmt.Errorf("new language stats version mismatch %s vs %s", languageStatsVersion, "faulty"))
+				require.Empty(t, newStats.Totals)
+			},
+		},
 	} {
 		t.Run(tc.desc, func(t *testing.T) {
 			repoProto, repoPath := gittest.InitRepo(t, cfg, cfg.Storages[0])