fix: do not purge if file missing

Author: Luca Bianconi

Diff for: buildcache/directory_cache.go

@@ -36,15 +36,16 @@ func (dc *directoryCache) basePath() *paths.Path {
 	return paths.New(dc.baseDir)
 }
 
-func (dc *directoryCache) isExpired(key string, ttl time.Duration) bool {
+func (dc *directoryCache) isExpired(key string) time.Duration {
 	modTime, _ := dc.modTime(key)
-	return time.Since(modTime) >= ttl
+	return dc.ttl - time.Since(modTime)
 }
 
 func (dc *directoryCache) modTime(key string) (time.Time, error) {
 	fileInfo, err := dc.basePath().Join(key, lastUsedFileName).Stat()
 	if err != nil {
-		return time.Unix(0, 0), err
+		// folders with a missing last used file are not purged
+		return time.Now().Add(time.Minute), err
 	}
 
 	return fileInfo.ModTime(), nil
@@ -75,20 +76,27 @@ func (dc *directoryCache) Purge() error {
 		return err
 	}
 	for _, file := range files {
-		if file.IsDir() && dc.isExpired(file.Base(), dc.ttl) {
-			subDir := dc.basePath().Join(file.Base())
-			modTime, _ := dc.modTime(file.Base())
-			logrus.Tracef(`Purging cache directory "%s". Expired by %s\n`, subDir, (time.Since(modTime) - dc.ttl))
-			err := subDir.RemoveAll()
-
-			if err != nil {
-				logrus.Tracef(`Error while pruning cache directory "%s".\n%s\n`, subDir, errors.WithStack(err))
-			}
+		if file.IsDir() {
+			dc.removeIfExpired(file)
 		}
 	}
 	return nil
 }
 
+func (dc *directoryCache) removeIfExpired(dir *paths.Path) {
+	lifeExpectancy := dc.isExpired(dir.Base())
+	if lifeExpectancy > 0 {
+		return
+	}
+	subDir := dc.basePath().Join(dir.Base())
+	logrus.Tracef(`Purging cache directory "%s". Expired by %s\n`, subDir, lifeExpectancy)
+	err := subDir.RemoveAll()
+
+	if err != nil {
+		logrus.Tracef(`Error while pruning cache directory "%s".\n%s\n`, subDir, errors.WithStack(err))
+	}
+}
+
 func newDirectoryCache(baseDir string, ttl time.Duration) *directoryCache {
 	return &directoryCache{
 		baseDir: baseDir,

Diff for: internal/integrationtest/compile_1/compile_test.go

@@ -122,25 +122,25 @@ func compileWithCachePurgeNeeded(t *testing.T, env *integrationtest.Environment,
 	// create directories that must be purged
 	baseDir := paths.TempDir().Join("arduino", "sketches")
 
-	// purge case: hold file too old
+	// purge case: last used file too old
 	oldDir1 := baseDir.Join("test_old_sketch_1")
 	require.NoError(t, os.MkdirAll(oldDir1.String(), 0770))
 	require.NoError(t, oldDir1.Join(".last-used").WriteFile([]byte{}))
 	require.NoError(t, os.Chtimes(oldDir1.Join(".last-used").String(), time.Now(), time.Unix(0, 0)))
-	// purge case: hold file not existing
-	oldDir2 := baseDir.Join("test_old_sketch_2")
-	require.NoError(t, os.MkdirAll(oldDir2.String(), 0770))
+	// no purge case: last used file not existing
+	missingFileDir := baseDir.Join("test_sketch_2")
+	require.NoError(t, os.MkdirAll(missingFileDir.String(), 0770))
 
-	defer os.RemoveAll(oldDir1.String())
-	defer os.RemoveAll(oldDir2.String())
+	defer oldDir1.RemoveAll()
+	defer missingFileDir.RemoveAll()
 
 	customEnv := cli.GetDefaultEnv()
 	customEnv["ARDUINO_BUILD_CACHE_COMPILATIONS_BEFORE_PURGE"] = "1"
 	compileWithSimpleSketchCustomEnv(t, env, cli, customEnv)
 
 	// check that purge has been run
 	require.NoFileExists(t, oldDir1.String())
-	require.NoFileExists(t, oldDir2.String())
+	require.DirExists(t, missingFileDir.String())
 }
 
 func compileWithSimpleSketchCustomEnv(t *testing.T, env *integrationtest.Environment, cli *integrationtest.ArduinoCLI, customEnv map[string]string) {

Diff for: legacy/builder/phases/core_builder.go

@@ -121,7 +121,6 @@ func compileCore(ctx *types.Context, buildPath *paths.Path, buildCachePath *path
 
 	// archive core.a
 	if targetArchivedCore != nil && !ctx.OnlyUpdateCompilationDatabase {
-		targetArchivedCore.Parent().MkdirAll()
 		err := archiveFile.CopyTo(targetArchivedCore)
 		buildcache.Used(targetArchivedCore.Parent())
 		if ctx.Verbose {