metacache: Add trashcan (#10820)

Add trashcan that keeps recently updated lists after bucket deletion.
All caches were deleted once a bucket was deleted, so caches still running would report errors. Now they are canceled.
Fix `.minio.sys` not being transient.

cmd/metacache-bucket.go

@@ -204,6 +204,7 @@ func (b *bucketMetacache) findCache(o listPathOptions) metacache {
 
 	// Check if exists already.
 	if c, ok := b.caches[o.ID]; ok {
+		debugPrint("returning existing %v", o.ID)
 		return c
 	}
 
@@ -279,6 +280,7 @@ func (b *bucketMetacache) findCache(o listPathOptions) metacache {
 	best = o.newMetacache()
 	b.caches[o.ID] = best
 	b.updated = true
+	debugPrint("returning new cache %s, bucket: %v", best.id, best.bucket)
 	return best
 }
 
@@ -442,17 +444,6 @@ func (b *bucketMetacache) deleteCache(id string) {
 	}
 	b.mu.Unlock()
 	if ok {
-		ctx := context.Background()
-		objAPI := newObjectLayerFn()
-		if objAPI == nil {
-			logger.LogIf(ctx, errors.New("bucketMetacache: no object layer"))
-			return
-		}
-		ez, ok := objAPI.(*erasureServerSets)
-		if !ok {
-			logger.LogIf(ctx, errors.New("bucketMetacache: expected objAPI to be *erasureServerSets"))
-			return
-		}
-		ez.deleteAll(ctx, minioMetaBucket, metacachePrefixForID(c.bucket, c.id))
+		c.delete(context.Background())
 	}
 }

cmd/metacache-manager.go

@@ -32,12 +32,14 @@ import (
 // Therefore no cluster locks are required.
 var localMetacacheMgr = &metacacheManager{
 	buckets: make(map[string]*bucketMetacache),
+	trash:   make(map[string]metacache),
 }
 
 type metacacheManager struct {
 	mu      sync.RWMutex
 	init    sync.Once
 	buckets map[string]*bucketMetacache
+	trash   map[string]metacache // Recently deleted lists.
 }
 
 const metacacheManagerTransientBucket = "**transient**"
@@ -78,11 +80,56 @@ func (m *metacacheManager) initManager() {
 				logger.LogIf(bg, v.save(bg))
 			}
 			m.mu.RUnlock()
+			m.mu.Lock()
+			for k, v := range m.trash {
+				if time.Since(v.lastUpdate) > metacacheMaxRunningAge {
+					v.delete(context.Background())
+					delete(m.trash, k)
+				}
+			}
+			m.mu.Unlock()
 		}
 		m.getTransient().deleteAll()
 	}()
 }
 
+// findCache will get a metacache.
+func (m *metacacheManager) findCache(ctx context.Context, o listPathOptions) metacache {
+	if o.Transient || isReservedOrInvalidBucket(o.Bucket, false) {
+		return m.getTransient().findCache(o)
+	}
+	m.mu.RLock()
+	b, ok := m.buckets[o.Bucket]
+	if ok {
+		m.mu.RUnlock()
+		return b.findCache(o)
+	}
+	if meta, ok := m.trash[o.ID]; ok {
+		m.mu.RUnlock()
+		return meta
+	}
+	m.mu.RUnlock()
+	return m.getBucket(ctx, o.Bucket).findCache(o)
+}
+
+// updateCacheEntry will update non-transient state.
+func (m *metacacheManager) updateCacheEntry(update metacache) (metacache, error) {
+	m.mu.RLock()
+	if meta, ok := m.trash[update.id]; ok {
+		m.mu.RUnlock()
+		return meta, nil
+	}
+
+	b, ok := m.buckets[update.bucket]
+	if ok {
+		m.mu.RUnlock()
+		return b.updateCacheEntry(update)
+	}
+	m.mu.RUnlock()
+	// We should have either a trashed bucket or this
+	return metacache{}, errVolumeNotFound
+}
+
 // getBucket will get a bucket metacache or load it from disk if needed.
 func (m *metacacheManager) getBucket(ctx context.Context, bucket string) *bucketMetacache {
 	m.init.Do(m.initManager)
@@ -118,6 +165,7 @@ func (m *metacacheManager) getBucket(ctx context.Context, bucket string) *bucket
 	b, err := loadBucketMetaCache(ctx, bucket)
 	if err != nil {
 		m.mu.Unlock()
+		logger.LogIf(ctx, err)
 		return m.getTransient()
 	}
 	if b.bucket != bucket {
@@ -130,22 +178,43 @@ func (m *metacacheManager) getBucket(ctx context.Context, bucket string) *bucket
 
 // deleteBucketCache will delete the bucket cache if it exists.
 func (m *metacacheManager) deleteBucketCache(bucket string) {
+	m.init.Do(m.initManager)
 	m.mu.Lock()
-	defer m.mu.Unlock()
 	b, ok := m.buckets[bucket]
 	if !ok {
+		m.mu.Unlock()
 		return
 	}
-	b.deleteAll()
 	delete(m.buckets, bucket)
+	m.mu.Unlock()
+
+	// Since deletes may take some time we try to do it without
+	// holding lock to m all the time.
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	for k, v := range b.caches {
+		if time.Since(v.lastUpdate) > metacacheMaxRunningAge {
+			v.delete(context.Background())
+			continue
+		}
+		v.error = "Bucket deleted"
+		v.status = scanStateError
+		m.mu.Lock()
+		m.trash[k] = v
+		m.mu.Unlock()
+	}
 }
 
 // deleteAll will delete all caches.
 func (m *metacacheManager) deleteAll() {
+	m.init.Do(m.initManager)
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	for _, b := range m.buckets {
+	for bucket, b := range m.buckets {
 		b.deleteAll()
+		if !b.transient {
+			delete(m.buckets, bucket)
+		}
 	}
 }
 
@@ -165,9 +234,9 @@ func (o listPathOptions) checkMetacacheState(ctx context.Context, rpc *peerRESTC
 	o.Create = false
 	var cache metacache
 	if !o.Transient {
-		if rpc == nil {
+		if rpc == nil || o.Transient {
 			// Local
-			cache = localMetacacheMgr.getBucket(ctx, o.Bucket).findCache(o)
+			cache = localMetacacheMgr.findCache(ctx, o)
 		} else {
 			c, err := rpc.GetMetacacheListing(ctx, o)
 			if err != nil {
@@ -175,8 +244,6 @@ func (o listPathOptions) checkMetacacheState(ctx context.Context, rpc *peerRESTC
 			}
 			cache = *c
 		}
-	} else {
-		cache = localMetacacheMgr.getTransient().findCache(o)
 	}
 
 	if cache.status == scanStateNone || cache.fileNotFound {

cmd/metacache-server-sets.go

@@ -91,9 +91,13 @@ func (z *erasureServerSets) listPath(ctx context.Context, o listPathOptions) (en
 		o.OldestCycle = globalNotificationSys.findEarliestCleanBloomFilter(ctx, path.Join(o.Bucket, o.BaseDir))
 		var cache metacache
 		rpc := globalNotificationSys.restClientFromHash(o.Bucket)
-		if rpc == nil {
+		if isReservedOrInvalidBucket(o.Bucket, false) {
+			rpc = nil
+			o.Transient = true
+		}
+		if rpc == nil || o.Transient {
 			// Local
-			cache = localMetacacheMgr.getBucket(ctx, o.Bucket).findCache(o)
+			cache = localMetacacheMgr.findCache(ctx, o)
 		} else {
 			c, err := rpc.GetMetacacheListing(ctx, o)
 			if err != nil {
@@ -103,8 +107,8 @@ func (z *erasureServerSets) listPath(ctx context.Context, o listPathOptions) (en
 					return entries, io.EOF
 				}
 				logger.LogIf(ctx, err)
-				cache = localMetacacheMgr.getTransient().findCache(o)
 				o.Transient = true
+				cache = localMetacacheMgr.findCache(ctx, o)
 			} else {
 				cache = *c
 			}

cmd/metacache-set.go

@@ -255,7 +255,7 @@ func (o *listPathOptions) updateMetacacheListing(m metacache, rpc *peerRESTClien
 		return localMetacacheMgr.getTransient().updateCacheEntry(m)
 	}
 	if rpc == nil {
-		return localMetacacheMgr.getBucket(GlobalContext, o.Bucket).updateCacheEntry(m)
+		return localMetacacheMgr.updateCacheEntry(m)
 	}
 	return rpc.UpdateMetacacheListing(context.Background(), m)
 }

cmd/metacache.go

@@ -17,9 +17,14 @@
 package cmd
 
 import (
+	"context"
+	"errors"
+	"fmt"
 	"path"
 	"strings"
 	"time"
+
+	"github.com/minio/minio/cmd/logger"
 )
 
 type scanStatus uint8
@@ -132,3 +137,21 @@ func baseDirFromPrefix(prefix string) string {
 	}
 	return b
 }
+
+// delete all cache data on disks.
+func (m *metacache) delete(ctx context.Context) {
+	if m.bucket == "" || m.id == "" {
+		logger.LogIf(ctx, fmt.Errorf("metacache.delete: bucket (%s) or id (%s) empty", m.bucket, m.id))
+	}
+	objAPI := newObjectLayerFn()
+	if objAPI == nil {
+		logger.LogIf(ctx, errors.New("metacache.delete: no object layer"))
+		return
+	}
+	ez, ok := objAPI.(*erasureServerSets)
+	if !ok {
+		logger.LogIf(ctx, errors.New("metacache.delete: expected objAPI to be *erasureServerSets"))
+		return
+	}
+	ez.deleteAll(ctx, minioMetaBucket, metacachePrefixForID(m.bucket, m.id))
+}

cmd/peer-rest-server.go

@@ -634,13 +634,7 @@ func (s *peerRESTServer) UpdateMetacacheListingHandler(w http.ResponseWriter, r
 		s.writeErrorResponse(w, err)
 		return
 	}
-	b := localMetacacheMgr.getBucket(ctx, req.bucket)
-	if b == nil {
-		s.writeErrorResponse(w, errServerNotInitialized)
-		return
-	}
-
-	cache, err := b.updateCacheEntry(req)
+	cache, err := localMetacacheMgr.updateCacheEntry(req)
 	if err != nil {
 		s.writeErrorResponse(w, err)
 		return