fix: cache adjust restore order of exact key matches (#2267)

* wip: adjust restore order

* fixup

* add tests

* cleanup

* fix typo

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
(cherry picked from commit f825e42ce200fc4973c3f28797ffba942d322d38)

pkg/artifactcache/handler.go

@@ -35,7 +35,7 @@ type Handler struct {
 	server   *http.Server
 	logger   logrus.FieldLogger
 
-	gcing int32 // TODO: use atomic.Bool when we can use Go 1.19
+	gcing atomic.Bool
 	gcAt  time.Time
 
 	outboundIP string
@@ -170,7 +170,7 @@ func (h *Handler) find(w http.ResponseWriter, r *http.Request, _ httprouter.Para
 	}
 	defer db.Close()
 
-	cache, err := h.findCache(db, keys, version)
+	cache, err := findCache(db, keys, version)
 	if err != nil {
 		h.responseJSON(w, r, 500, err)
 		return
@@ -206,32 +206,17 @@ func (h *Handler) reserve(w http.ResponseWriter, r *http.Request, _ httprouter.P
 	api.Key = strings.ToLower(api.Key)
 
 	cache := api.ToCache()
-	cache.FillKeyVersionHash()
 	db, err := h.openDB()
 	if err != nil {
 		h.responseJSON(w, r, 500, err)
 		return
 	}
 	defer db.Close()
-	if err := db.FindOne(cache, bolthold.Where("KeyVersionHash").Eq(cache.KeyVersionHash)); err != nil {
-		if !errors.Is(err, bolthold.ErrNotFound) {
-			h.responseJSON(w, r, 500, err)
-			return
-		}
-	} else {
-		h.responseJSON(w, r, 400, fmt.Errorf("already exist"))
-		return
-	}
 
 	now := time.Now().Unix()
 	cache.CreatedAt = now
 	cache.UsedAt = now
-	if err := db.Insert(bolthold.NextSequence(), cache); err != nil {
-		h.responseJSON(w, r, 500, err)
-		return
-	}
-	// write back id to db
-	if err := db.Update(cache.ID, cache); err != nil {
+	if err := insertCache(db, cache); err != nil {
 		h.responseJSON(w, r, 500, err)
 		return
 	}
@@ -364,56 +349,51 @@ func (h *Handler) middleware(handler httprouter.Handle) httprouter.Handle {
 }
 
 // if not found, return (nil, nil) instead of an error.
-func (h *Handler) findCache(db *bolthold.Store, keys []string, version string) (*Cache, error) {
-	if len(keys) == 0 {
-		return nil, nil
+func findCache(db *bolthold.Store, keys []string, version string) (*Cache, error) {
+	cache := &Cache{}
+	for _, prefix := range keys {
+		// if a key in the list matches exactly, don't return partial matches
+		if err := db.FindOne(cache,
+			bolthold.Where("Key").Eq(prefix).
+				And("Version").Eq(version).
+				And("Complete").Eq(true).
+				SortBy("CreatedAt").Reverse()); err == nil || !errors.Is(err, bolthold.ErrNotFound) {
+			if err != nil {
+				return nil, fmt.Errorf("find cache: %w", err)
 			}
-	key := keys[0] // the first key is for exact match.
-
-	cache := &Cache{
-		Key:     key,
-		Version: version,
-	}
-	cache.FillKeyVersionHash()
-
-	if err := db.FindOne(cache, bolthold.Where("KeyVersionHash").Eq(cache.KeyVersionHash)); err != nil {
-		if !errors.Is(err, bolthold.ErrNotFound) {
-			return nil, err
-		}
-	} else if cache.Complete {
 			return cache, nil
 		}
-	stop := fmt.Errorf("stop")
-
-	for _, prefix := range keys[1:] {
-		found := false
 		prefixPattern := fmt.Sprintf("^%s", regexp.QuoteMeta(prefix))
 		re, err := regexp.Compile(prefixPattern)
 		if err != nil {
 			continue
 		}
-		if err := db.ForEach(bolthold.Where("Key").RegExp(re).And("Version").Eq(version).SortBy("CreatedAt").Reverse(), func(v *Cache) error {
-			if !strings.HasPrefix(v.Key, prefix) {
-				return stop
+		if err := db.FindOne(cache,
+			bolthold.Where("Key").RegExp(re).
+				And("Version").Eq(version).
+				And("Complete").Eq(true).
+				SortBy("CreatedAt").Reverse()); err != nil {
+			if errors.Is(err, bolthold.ErrNotFound) {
+				continue
 			}
-			if v.Complete {
-				cache = v
-				found = true
-				return stop
+			return nil, fmt.Errorf("find cache: %w", err)
 		}
-			return nil
-		}); err != nil {
-			if !errors.Is(err, stop) {
-				return nil, err
-			}
-		}
-		if found {
 		return cache, nil
 	}
-	}
 	return nil, nil
 }
 
+func insertCache(db *bolthold.Store, cache *Cache) error {
+	if err := db.Insert(bolthold.NextSequence(), cache); err != nil {
+		return fmt.Errorf("insert cache: %w", err)
+	}
+	// write back id to db
+	if err := db.Update(cache.ID, cache); err != nil {
+		return fmt.Errorf("write back id to db: %w", err)
+	}
+	return nil
+}
+
 func (h *Handler) useCache(id int64) {
 	db, err := h.openDB()
 	if err != nil {
@@ -428,14 +408,21 @@ func (h *Handler) useCache(id int64) {
 	_ = db.Update(cache.ID, cache)
 }
 
+const (
+	keepUsed   = 30 * 24 * time.Hour
+	keepUnused = 7 * 24 * time.Hour
+	keepTemp   = 5 * time.Minute
+	keepOld    = 5 * time.Minute
+)
+
 func (h *Handler) gcCache() {
-	if atomic.LoadInt32(&h.gcing) != 0 {
+	if h.gcing.Load() {
 		return
 	}
-	if !atomic.CompareAndSwapInt32(&h.gcing, 0, 1) {
+	if !h.gcing.CompareAndSwap(false, true) {
 		return
 	}
-	defer atomic.StoreInt32(&h.gcing, 0)
+	defer h.gcing.Store(false)
 
 	if time.Since(h.gcAt) < time.Hour {
 		h.logger.Debugf("skip gc: %v", h.gcAt.String())
@@ -444,37 +431,18 @@ func (h *Handler) gcCache() {
 	h.gcAt = time.Now()
 	h.logger.Debugf("gc: %v", h.gcAt.String())
 
-	const (
-		keepUsed   = 30 * 24 * time.Hour
-		keepUnused = 7 * 24 * time.Hour
-		keepTemp   = 5 * time.Minute
-	)
-
 	db, err := h.openDB()
 	if err != nil {
 		return
 	}
 	defer db.Close()
 
+	// Remove the caches which are not completed for a while, they are most likely to be broken.
 	var caches []*Cache
-	if err := db.Find(&caches, bolthold.Where("UsedAt").Lt(time.Now().Add(-keepTemp).Unix())); err != nil {
-		h.logger.Warnf("find caches: %v", err)
-	} else {
-		for _, cache := range caches {
-			if cache.Complete {
-				continue
-			}
-			h.storage.Remove(cache.ID)
-			if err := db.Delete(cache.ID, cache); err != nil {
-				h.logger.Warnf("delete cache: %v", err)
-				continue
-			}
-			h.logger.Infof("deleted cache: %+v", cache)
-		}
-	}
-
-	caches = caches[:0]
-	if err := db.Find(&caches, bolthold.Where("UsedAt").Lt(time.Now().Add(-keepUnused).Unix())); err != nil {
+	if err := db.Find(&caches, bolthold.
+		Where("UsedAt").Lt(time.Now().Add(-keepTemp).Unix()).
+		And("Complete").Eq(false),
+	); err != nil {
 		h.logger.Warnf("find caches: %v", err)
 	} else {
 		for _, cache := range caches {
@@ -487,8 +455,11 @@ func (h *Handler) gcCache() {
 		}
 	}
 
+	// Remove the old caches which have not been used recently.
 	caches = caches[:0]
-	if err := db.Find(&caches, bolthold.Where("CreatedAt").Lt(time.Now().Add(-keepUsed).Unix())); err != nil {
+	if err := db.Find(&caches, bolthold.
+		Where("UsedAt").Lt(time.Now().Add(-keepUnused).Unix()),
+	); err != nil {
 		h.logger.Warnf("find caches: %v", err)
 	} else {
 		for _, cache := range caches {
@@ -500,6 +471,55 @@ func (h *Handler) gcCache() {
 			h.logger.Infof("deleted cache: %+v", cache)
 		}
 	}
+
+	// Remove the old caches which are too old.
+	caches = caches[:0]
+	if err := db.Find(&caches, bolthold.
+		Where("CreatedAt").Lt(time.Now().Add(-keepUsed).Unix()),
+	); err != nil {
+		h.logger.Warnf("find caches: %v", err)
+	} else {
+		for _, cache := range caches {
+			h.storage.Remove(cache.ID)
+			if err := db.Delete(cache.ID, cache); err != nil {
+				h.logger.Warnf("delete cache: %v", err)
+				continue
+			}
+			h.logger.Infof("deleted cache: %+v", cache)
+		}
+	}
+
+	// Remove the old caches with the same key and version, keep the latest one.
+	// Also keep the olds which have been used recently for a while in case of the cache is still in use.
+	if results, err := db.FindAggregate(
+		&Cache{},
+		bolthold.Where("Complete").Eq(true),
+		"Key", "Version",
+	); err != nil {
+		h.logger.Warnf("find aggregate caches: %v", err)
+	} else {
+		for _, result := range results {
+			if result.Count() <= 1 {
+				continue
+			}
+			result.Sort("CreatedAt")
+			caches = caches[:0]
+			result.Reduction(&caches)
+			for _, cache := range caches[:len(caches)-1] {
+				if time.Since(time.Unix(cache.UsedAt, 0)) < keepOld {
+					// Keep it since it has been used recently, even if it's old.
+					// Or it could break downloading in process.
+					continue
+				}
+				h.storage.Remove(cache.ID)
+				if err := db.Delete(cache.ID, cache); err != nil {
+					h.logger.Warnf("delete cache: %v", err)
+					continue
+				}
+				h.logger.Infof("deleted cache: %+v", cache)
+			}
+		}
+	}
 }
 
 func (h *Handler) responseJSON(w http.ResponseWriter, r *http.Request, code int, v ...any) {

pkg/artifactcache/handler_test.go

@@ -10,9 +10,11 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/timshannon/bolthold"
 	"go.etcd.io/bbolt"
 )
 
@@ -78,6 +80,9 @@ func TestHandler(t *testing.T) {
 	t.Run("duplicate reserve", func(t *testing.T) {
 		key := strings.ToLower(t.Name())
 		version := "c19da02a2bd7e77277f1ac29ab45c09b7d46a4ee758284e26bb3045ad11d9d20"
+		var first, second struct {
+			CacheID uint64 `json:"cacheId"`
+		}
 		{
 			body, err := json.Marshal(&Request{
 				Key:     key,
@@ -89,10 +94,8 @@ func TestHandler(t *testing.T) {
 			require.NoError(t, err)
 			assert.Equal(t, 200, resp.StatusCode)
 
-			got := struct {
-				CacheID uint64 `json:"cacheId"`
-			}{}
-			require.NoError(t, json.NewDecoder(resp.Body).Decode(&got))
+			require.NoError(t, json.NewDecoder(resp.Body).Decode(&first))
+			assert.NotZero(t, first.CacheID)
 		}
 		{
 			body, err := json.Marshal(&Request{
@@ -103,8 +106,13 @@ func TestHandler(t *testing.T) {
 			require.NoError(t, err)
 			resp, err := http.Post(fmt.Sprintf("%s/caches", base), "application/json", bytes.NewReader(body))
 			require.NoError(t, err)
-			assert.Equal(t, 400, resp.StatusCode)
+			assert.Equal(t, 200, resp.StatusCode)
+
+			require.NoError(t, json.NewDecoder(resp.Body).Decode(&second))
+			assert.NotZero(t, second.CacheID)
 		}
+
+		assert.NotEqual(t, first.CacheID, second.CacheID)
 	})
 
 	t.Run("upload with bad id", func(t *testing.T) {
@@ -341,9 +349,9 @@ func TestHandler(t *testing.T) {
 		version := "c19da02a2bd7e77277f1ac29ab45c09b7d46a4ee758284e26bb3045ad11d9d20"
 		key := strings.ToLower(t.Name())
 		keys := [3]string{
-			key + "_a",
-			key + "_a_b",
 			key + "_a_b_c",
+			key + "_a_b",
+			key + "_a",
 		}
 		contents := [3][]byte{
 			make([]byte, 100),
@@ -354,6 +362,7 @@ func TestHandler(t *testing.T) {
 			_, err := rand.Read(contents[i])
 			require.NoError(t, err)
 			uploadCacheNormally(t, base, keys[i], version, contents[i])
+			time.Sleep(time.Second) // ensure CreatedAt of caches are different
 		}
 
 		reqKeys := strings.Join([]string{
@@ -361,11 +370,18 @@ func TestHandler(t *testing.T) {
 			key + "_a_b",
 			key + "_a",
 		}, ",")
-		var archiveLocation string
-		{
+
 		resp, err := http.Get(fmt.Sprintf("%s/cache?keys=%s&version=%s", base, reqKeys, version))
 		require.NoError(t, err)
 		require.Equal(t, 200, resp.StatusCode)
+
+		/*
+			Expect `key_a_b` because:
+			- `key_a_b_x" doesn't match any caches.
+			- `key_a_b" matches `key_a_b` and `key_a_b_c`, but `key_a_b` is newer.
+		*/
+		except := 1
+
 		got := struct {
 			Result          string `json:"result"`
 			ArchiveLocation string `json:"archiveLocation"`
@@ -373,17 +389,14 @@ func TestHandler(t *testing.T) {
 		}{}
 		require.NoError(t, json.NewDecoder(resp.Body).Decode(&got))
 		assert.Equal(t, "hit", got.Result)
-			assert.Equal(t, keys[1], got.CacheKey)
-			archiveLocation = got.ArchiveLocation
-		}
-		{
-			resp, err := http.Get(archiveLocation) //nolint:gosec
+		assert.Equal(t, keys[except], got.CacheKey)
+
+		contentResp, err := http.Get(got.ArchiveLocation)
 		require.NoError(t, err)
-			require.Equal(t, 200, resp.StatusCode)
-			got, err := io.ReadAll(resp.Body)
+		require.Equal(t, 200, contentResp.StatusCode)
+		content, err := io.ReadAll(contentResp.Body)
 		require.NoError(t, err)
-			assert.Equal(t, contents[1], got)
-		}
+		assert.Equal(t, contents[except], content)
 	})
 
 	t.Run("case insensitive", func(t *testing.T) {
@@ -409,6 +422,110 @@ func TestHandler(t *testing.T) {
 			assert.Equal(t, key+"_abc", got.CacheKey)
 		}
 	})
+
+	t.Run("exact keys are preferred (key 0)", func(t *testing.T) {
+		version := "c19da02a2bd7e77277f1ac29ab45c09b7d46a4ee758284e26bb3045ad11d9d20"
+		key := strings.ToLower(t.Name())
+		keys := [3]string{
+			key + "_a",
+			key + "_a_b_c",
+			key + "_a_b",
+		}
+		contents := [3][]byte{
+			make([]byte, 100),
+			make([]byte, 200),
+			make([]byte, 300),
+		}
+		for i := range contents {
+			_, err := rand.Read(contents[i])
+			require.NoError(t, err)
+			uploadCacheNormally(t, base, keys[i], version, contents[i])
+			time.Sleep(time.Second) // ensure CreatedAt of caches are different
+		}
+
+		reqKeys := strings.Join([]string{
+			key + "_a",
+			key + "_a_b",
+		}, ",")
+
+		resp, err := http.Get(fmt.Sprintf("%s/cache?keys=%s&version=%s", base, reqKeys, version))
+		require.NoError(t, err)
+		require.Equal(t, 200, resp.StatusCode)
+
+		/*
+			Expect `key_a` because:
+			- `key_a` matches `key_a`, `key_a_b` and `key_a_b_c`, but `key_a` is an exact match.
+			- `key_a_b` matches `key_a_b` and `key_a_b_c`, but previous key had a match
+		*/
+		expect := 0
+
+		got := struct {
+			ArchiveLocation string `json:"archiveLocation"`
+			CacheKey        string `json:"cacheKey"`
+		}{}
+		require.NoError(t, json.NewDecoder(resp.Body).Decode(&got))
+		assert.Equal(t, keys[expect], got.CacheKey)
+
+		contentResp, err := http.Get(got.ArchiveLocation)
+		require.NoError(t, err)
+		require.Equal(t, 200, contentResp.StatusCode)
+		content, err := io.ReadAll(contentResp.Body)
+		require.NoError(t, err)
+		assert.Equal(t, contents[expect], content)
+	})
+
+	t.Run("exact keys are preferred (key 1)", func(t *testing.T) {
+		version := "c19da02a2bd7e77277f1ac29ab45c09b7d46a4ee758284e26bb3045ad11d9d20"
+		key := strings.ToLower(t.Name())
+		keys := [3]string{
+			key + "_a",
+			key + "_a_b_c",
+			key + "_a_b",
+		}
+		contents := [3][]byte{
+			make([]byte, 100),
+			make([]byte, 200),
+			make([]byte, 300),
+		}
+		for i := range contents {
+			_, err := rand.Read(contents[i])
+			require.NoError(t, err)
+			uploadCacheNormally(t, base, keys[i], version, contents[i])
+			time.Sleep(time.Second) // ensure CreatedAt of caches are different
+		}
+
+		reqKeys := strings.Join([]string{
+			"------------------------------------------------------",
+			key + "_a",
+			key + "_a_b",
+		}, ",")
+
+		resp, err := http.Get(fmt.Sprintf("%s/cache?keys=%s&version=%s", base, reqKeys, version))
+		require.NoError(t, err)
+		require.Equal(t, 200, resp.StatusCode)
+
+		/*
+			Expect `key_a` because:
+			- `------------------------------------------------------` doesn't match any caches.
+			- `key_a` matches `key_a`, `key_a_b` and `key_a_b_c`, but `key_a` is an exact match.
+			- `key_a_b` matches `key_a_b` and `key_a_b_c`, but previous key had a match
+		*/
+		expect := 0
+
+		got := struct {
+			ArchiveLocation string `json:"archiveLocation"`
+			CacheKey        string `json:"cacheKey"`
+		}{}
+		require.NoError(t, json.NewDecoder(resp.Body).Decode(&got))
+		assert.Equal(t, keys[expect], got.CacheKey)
+
+		contentResp, err := http.Get(got.ArchiveLocation)
+		require.NoError(t, err)
+		require.Equal(t, 200, contentResp.StatusCode)
+		content, err := io.ReadAll(contentResp.Body)
+		require.NoError(t, err)
+		assert.Equal(t, contents[expect], content)
+	})
 }
 
 func uploadCacheNormally(t *testing.T, base, key, version string, content []byte) {
@@ -469,3 +586,112 @@ func uploadCacheNormally(t *testing.T, base, key, version string, content []byte
 		assert.Equal(t, content, got)
 	}
 }
+
+func TestHandler_gcCache(t *testing.T) {
+	dir := filepath.Join(t.TempDir(), "artifactcache")
+	handler, err := StartHandler(dir, "", 0, nil)
+	require.NoError(t, err)
+
+	defer func() {
+		require.NoError(t, handler.Close())
+	}()
+
+	now := time.Now()
+
+	cases := []struct {
+		Cache *Cache
+		Kept  bool
+	}{
+		{
+			// should be kept, since it's used recently and not too old.
+			Cache: &Cache{
+				Key:       "test_key_1",
+				Version:   "test_version",
+				Complete:  true,
+				UsedAt:    now.Unix(),
+				CreatedAt: now.Add(-time.Hour).Unix(),
+			},
+			Kept: true,
+		},
+		{
+			// should be removed, since it's not complete and not used for a while.
+			Cache: &Cache{
+				Key:       "test_key_2",
+				Version:   "test_version",
+				Complete:  false,
+				UsedAt:    now.Add(-(keepTemp + time.Second)).Unix(),
+				CreatedAt: now.Add(-(keepTemp + time.Hour)).Unix(),
+			},
+			Kept: false,
+		},
+		{
+			// should be removed, since it's not used for a while.
+			Cache: &Cache{
+				Key:       "test_key_3",
+				Version:   "test_version",
+				Complete:  true,
+				UsedAt:    now.Add(-(keepUnused + time.Second)).Unix(),
+				CreatedAt: now.Add(-(keepUnused + time.Hour)).Unix(),
+			},
+			Kept: false,
+		},
+		{
+			// should be removed, since it's used but too old.
+			Cache: &Cache{
+				Key:       "test_key_3",
+				Version:   "test_version",
+				Complete:  true,
+				UsedAt:    now.Unix(),
+				CreatedAt: now.Add(-(keepUsed + time.Second)).Unix(),
+			},
+			Kept: false,
+		},
+		{
+			// should be kept, since it has a newer edition but be used recently.
+			Cache: &Cache{
+				Key:       "test_key_1",
+				Version:   "test_version",
+				Complete:  true,
+				UsedAt:    now.Add(-(keepOld - time.Minute)).Unix(),
+				CreatedAt: now.Add(-(time.Hour + time.Second)).Unix(),
+			},
+			Kept: true,
+		},
+		{
+			// should be removed, since it has a newer edition and not be used recently.
+			Cache: &Cache{
+				Key:       "test_key_1",
+				Version:   "test_version",
+				Complete:  true,
+				UsedAt:    now.Add(-(keepOld + time.Second)).Unix(),
+				CreatedAt: now.Add(-(time.Hour + time.Second)).Unix(),
+			},
+			Kept: false,
+		},
+	}
+
+	db, err := handler.openDB()
+	require.NoError(t, err)
+	for _, c := range cases {
+		require.NoError(t, insertCache(db, c.Cache))
+	}
+	require.NoError(t, db.Close())
+
+	handler.gcAt = time.Time{} // ensure gcCache will not skip
+	handler.gcCache()
+
+	db, err = handler.openDB()
+	require.NoError(t, err)
+	for i, v := range cases {
+		t.Run(fmt.Sprintf("%d_%s", i, v.Cache.Key), func(t *testing.T) {
+			cache := &Cache{}
+			err = db.Get(v.Cache.ID, cache)
+			if v.Kept {
+				assert.NoError(t, err)
+			} else {
+				assert.ErrorIs(t, err, bolthold.ErrNotFound)
+			}
+		})
+	}
+	require.NoError(t, db.Close())
+}

pkg/artifactcache/model.go

@@ -1,10 +1,5 @@
 package artifactcache
 
-import (
-	"crypto/sha256"
-	"fmt"
-)
-
 type Request struct {
 	Key     string `json:"key" `
 	Version string `json:"version"`
@@ -32,13 +27,8 @@ type Cache struct {
 	ID        uint64 `json:"id" boltholdKey:"ID"`
 	Key       string `json:"key" boltholdIndex:"Key"`
 	Version   string `json:"version" boltholdIndex:"Version"`
-	KeyVersionHash string `json:"keyVersionHash" boltholdUnique:"KeyVersionHash"`
 	Size      int64  `json:"cacheSize"`
-	Complete       bool   `json:"complete"`
+	Complete  bool   `json:"complete" boltholdIndex:"Complete"`
 	UsedAt    int64  `json:"usedAt" boltholdIndex:"UsedAt"`
 	CreatedAt int64  `json:"createdAt" boltholdIndex:"CreatedAt"`
 }
-
-func (c *Cache) FillKeyVersionHash() {
-	c.KeyVersionHash = fmt.Sprintf("%x", sha256.Sum256([]byte(fmt.Sprintf("%s:%s", c.Key, c.Version))))
-}