internal/dnfjson: fix caching bug with multidir caches

Part of the fix for COMPOSER-2068

internal/dnfjson/cache.go

@@ -114,6 +114,10 @@ func newRPMCache(path string, maxSize uint64) *rpmCache {
 // later use of the cache. eg. touchRepo
 func (r *rpmCache) updateInfo() {
 	dirs, _ := os.ReadDir(r.root)
+	// reset to make sure accumulation works properly
+	r.size = 0
+	r.repoElements = make(map[string]pathInfo)
+	r.repoRecency = nil
 	for _, d := range dirs {
 		r.updateCacheDirInfo(filepath.Join(r.root, d.Name()))
 	}
@@ -186,9 +190,12 @@ func (r *rpmCache) updateCacheDirInfo(path string) {
 	// sort IDs by mtime (oldest first)
 	sort.Slice(repoIDs, sortFunc)
 
-	r.size = totalSize
-	r.repoElements = repos
-	r.repoRecency = repoIDs
+	r.size += totalSize
+	// TODO: replace loop with maps.Copy() introduced in Go 1.21
+	for k, v := range repos {
+		r.repoElements[k] = v
+	}
+	copy(r.repoRecency, repoIDs)
 }
 
 func (r *rpmCache) shrink() error {

internal/dnfjson/cache_test.go

@@ -172,6 +172,24 @@ func TestCacheRead(t *testing.T) {
 	}
 }
 
+func TestMultiDirCacheRead(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("MultiDir", func(t *testing.T) {
+		testCacheRoot := t.TempDir()
+		// Cache is now per-distro, use the name of the config as a distro name
+		size1 := createTestCache(filepath.Join(testCacheRoot, "rhel84-aarch64"), testCfgs["rhel84-aarch64"])
+		size2 := createTestCache(filepath.Join(testCacheRoot, "fake-real"), testCfgs["fake-real"])
+
+		// Cache covers all distros, pass in top directory
+		cache := newRPMCache(testCacheRoot, 1048576) // 1 MiB, but doesn't matter for this test
+
+		nrepos := len(getRepoIDs(testCfgs["rhel84-aarch64"])) + len(getRepoIDs(testCfgs["fake-real"]))
+		assert.Equal(size1+size2, cache.size)
+		assert.Equal(nrepos, len(cache.repoElements))
+		assert.Equal(nrepos, len(cache.repoRecency))
+	})
+}
+
 func sizeSum(cfg testCache, repoIDFilter ...string) uint64 {
 	var sum uint64
 	for path, info := range cfg {