[3.2.1 Backport] CBG-4151: Memory-based rev cache size

base/stats.go

@@ -85,6 +85,7 @@ const (
 	StatAddedVersion3dot1dot3dot1 = "3.1.3.1"
 	StatAddedVersion3dot1dot4     = "3.1.4"
 	StatAddedVersion3dot2dot0     = "3.2.0"
+	StatAddedVersion3dot2dot1     = "3.2.1"
 	StatAddedVersion3dot3dot0     = "3.3.0"
 
 	StatDeprecatedVersionNotDeprecated = ""
@@ -425,12 +426,16 @@ type CacheStats struct {
 	NumSkippedSeqs *SgwIntStat `json:"num_skipped_seqs"`
 	// The total number of pending sequences. These are out-of-sequence entries waiting to be cached.
 	PendingSeqLen *SgwIntStat `json:"pending_seq_len"`
+	// Total number of items in the rev cache
+	RevisionCacheNumItems *SgwIntStat `json:"revision_cache_num_items"`
 	// The total number of revision cache bypass operations performed.
 	RevisionCacheBypass *SgwIntStat `json:"rev_cache_bypass"`
 	// The total number of revision cache hits.
 	RevisionCacheHits *SgwIntStat `json:"rev_cache_hits"`
 	// The total number of revision cache misses.
 	RevisionCacheMisses *SgwIntStat `json:"rev_cache_misses"`
+	// Total memory used by the rev cache
+	RevisionCacheTotalMemory *SgwIntStat `json:"revision_cache_total_memory"`
 	// The current length of the pending skipped sequence slice.
 	SkippedSeqLen *SgwIntStat `json:"skipped_seq_len"`
 	// The current capacity of the skipped sequence slice
@@ -1320,6 +1325,10 @@ func (d *DbStats) initCacheStats() error {
 	if err != nil {
 		return err
 	}
+	resUtil.RevisionCacheNumItems, err = NewIntStat(SubsystemCacheKey, "revision_cache_num_items", StatUnitNoUnits, RevCacheNumItemsDesc, StatAddedVersion3dot2dot1, StatDeprecatedVersionNotDeprecated, StatStabilityCommitted, labelKeys, labelVals, prometheus.GaugeValue, 0)
+	if err != nil {
+		return err
+	}
 	resUtil.RevisionCacheBypass, err = NewIntStat(SubsystemCacheKey, "rev_cache_bypass", StatUnitNoUnits, RevCacheBypassDesc, StatAddedVersion3dot0dot0, StatDeprecatedVersionNotDeprecated, StatStabilityCommitted, labelKeys, labelVals, prometheus.GaugeValue, 0)
 	if err != nil {
 		return err
@@ -1332,6 +1341,10 @@ func (d *DbStats) initCacheStats() error {
 	if err != nil {
 		return err
 	}
+	resUtil.RevisionCacheTotalMemory, err = NewIntStat(SubsystemCacheKey, "revision_cache_total_memory", StatUnitNoUnits, RevCacheMemoryDesc, StatAddedVersion3dot2dot1, StatDeprecatedVersionNotDeprecated, StatStabilityCommitted, labelKeys, labelVals, prometheus.GaugeValue, 0)
+	if err != nil {
+		return err
+	}
 	resUtil.SkippedSeqLen, err = NewIntStat(SubsystemCacheKey, "skipped_seq_len", StatUnitNoUnits, SkippedSeqLengthDesc, StatAddedVersion3dot0dot0, StatDeprecatedVersionNotDeprecated, StatStabilityCommitted, labelKeys, labelVals, prometheus.GaugeValue, 0)
 	if err != nil {
 		return err
@@ -1377,9 +1390,11 @@ func (d *DbStats) unregisterCacheStats() {
 	prometheus.Unregister(d.CacheStats.SkippedSeqCap)
 	prometheus.Unregister(d.CacheStats.NumCurrentSeqsSkipped)
 	prometheus.Unregister(d.CacheStats.PendingSeqLen)
+	prometheus.Unregister(d.CacheStats.RevisionCacheNumItems)
 	prometheus.Unregister(d.CacheStats.RevisionCacheBypass)
 	prometheus.Unregister(d.CacheStats.RevisionCacheHits)
 	prometheus.Unregister(d.CacheStats.RevisionCacheMisses)
+	prometheus.Unregister(d.CacheStats.RevisionCacheTotalMemory)
 	prometheus.Unregister(d.CacheStats.SkippedSeqLen)
 	prometheus.Unregister(d.CacheStats.ViewQueries)
 }

base/stats_descriptions.go

@@ -119,6 +119,8 @@ const (
 
 	PendingSeqLengthDesc = "The total number of pending sequences. These are out-of-sequence entries waiting to be cached."
 
+	RevCacheNumItemsDesc = "The total number of items in the revision cache."
+
 	RevCacheBypassDesc = "The total number of revision cache bypass operations performed."
 
 	RevCacheHitsDesc = "The total number of revision cache hits. This metric can be used to calculate the ratio of revision cache hits: " +
@@ -127,6 +129,8 @@ const (
 	RevCacheMissesDesc = "The total number of revision cache misses. This metric can be used to calculate the ratio of revision cache misses: " +
 		"Rev Cache Miss Ratio = rev_cache_misses / (rev_cache_hits + rev_cache_misses)"
 
+	RevCacheMemoryDesc = "The approximation of total memory taken up by rev cache for documents. This is measured by the raw document body, the channels allocated to a document and its revision history."
+
 	SkippedSeqLengthDesc = "The current length of the pending skipped sequence slice."
 
 	SkippedSeqCapDesc = "The current capacity of the skipped sequence slice."

db/changes.go

@@ -137,7 +137,7 @@ func (db *DatabaseCollectionWithUser) addDocToChangeEntry(ctx context.Context, e
 }
 
 func (db *DatabaseCollectionWithUser) AddDocToChangeEntryUsingRevCache(ctx context.Context, entry *ChangeEntry, revID string) (err error) {
-	rev, err := db.getRev(ctx, entry.ID, revID, 0, nil, RevCacheIncludeBody)
+	rev, err := db.getRev(ctx, entry.ID, revID, 0, nil)
 	if err != nil {
 		return err
 	}
@@ -325,7 +325,7 @@ func (db *DatabaseCollectionWithUser) buildRevokedFeed(ctx context.Context, ch c
 
 // UserHasDocAccess checks whether the user has access to the active revision of the document
 func UserHasDocAccess(ctx context.Context, collection *DatabaseCollectionWithUser, docID string) (bool, error) {
-	currentRev, err := collection.revisionCache.GetActive(ctx, docID, false)
+	currentRev, err := collection.revisionCache.GetActive(ctx, docID)
 	if err != nil {
 		if base.IsDocNotFoundError(err) {
 			return false, nil

db/crud.go

@@ -258,7 +258,7 @@ func (db *DatabaseCollectionWithUser) GetRev(ctx context.Context, docID, revID s
 	if history {
 		maxHistory = math.MaxInt32
 	}
-	return db.getRev(ctx, docID, revID, maxHistory, nil, RevCacheOmitBody)
+	return db.getRev(ctx, docID, revID, maxHistory, nil)
 }
 
 // Returns the body of the current revision of a document
@@ -278,7 +278,7 @@ func (db *DatabaseCollectionWithUser) Get1xRevBody(ctx context.Context, docid, r
 
 // Retrieves rev with request history specified as collection of revids (historyFrom)
 func (db *DatabaseCollectionWithUser) Get1xRevBodyWithHistory(ctx context.Context, docid, revid string, maxHistory int, historyFrom []string, attachmentsSince []string, showExp bool) (Body, error) {
-	rev, err := db.getRev(ctx, docid, revid, maxHistory, historyFrom, RevCacheIncludeBody)
+	rev, err := db.getRev(ctx, docid, revid, maxHistory, historyFrom)
 	if err != nil {
 		return nil, err
 	}
@@ -305,14 +305,14 @@ func (db *DatabaseCollectionWithUser) Get1xRevBodyWithHistory(ctx context.Contex
 //   - attachmentsSince is nil to return no attachment bodies, otherwise a (possibly empty) list of
 //     revisions for which the client already has attachments and doesn't need bodies. Any attachment
 //     that hasn't changed since one of those revisions will be returned as a stub.
-func (db *DatabaseCollectionWithUser) getRev(ctx context.Context, docid, revid string, maxHistory int, historyFrom []string, includeBody bool) (revision DocumentRevision, err error) {
+func (db *DatabaseCollectionWithUser) getRev(ctx context.Context, docid, revid string, maxHistory int, historyFrom []string) (revision DocumentRevision, err error) {
 	if revid != "" {
 		// Get a specific revision body and history from the revision cache
 		// (which will load them if necessary, by calling revCacheLoader, above)
-		revision, err = db.revisionCache.Get(ctx, docid, revid, includeBody, RevCacheOmitDelta)
+		revision, err = db.revisionCache.Get(ctx, docid, revid, RevCacheOmitDelta)
 	} else {
 		// No rev ID given, so load active revision
-		revision, err = db.revisionCache.GetActive(ctx, docid, includeBody)
+		revision, err = db.revisionCache.GetActive(ctx, docid)
 	}
 
 	if err != nil {
@@ -373,7 +373,7 @@ func (db *DatabaseCollectionWithUser) GetDelta(ctx context.Context, docID, fromR
 		return nil, nil, nil
 	}
 
-	fromRevision, err := db.revisionCache.Get(ctx, docID, fromRevID, RevCacheOmitBody, RevCacheIncludeDelta)
+	fromRevision, err := db.revisionCache.Get(ctx, docID, fromRevID, RevCacheIncludeDelta)
 
 	// If the fromRevision is a removal cache entry (no body), but the user has access to that removal, then just
 	// return 404 missing to indicate that the body of the revision is no longer available.
@@ -413,7 +413,7 @@ func (db *DatabaseCollectionWithUser) GetDelta(ctx context.Context, docID, fromR
 
 		// db.DbStats.StatsDeltaSync().Add(base.StatKeyDeltaCacheMisses, 1)
 		db.dbStats().DeltaSync().DeltaCacheMiss.Add(1)
-		toRevision, err := db.revisionCache.Get(ctx, docID, toRevID, RevCacheOmitBody, RevCacheIncludeDelta)
+		toRevision, err := db.revisionCache.Get(ctx, docID, toRevID, RevCacheIncludeDelta)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -549,38 +549,36 @@ func (col *DatabaseCollectionWithUser) authorizeDoc(doc *Document, revid string)
 
 // Gets a revision of a document. If it's obsolete it will be loaded from the database if possible.
 // inline "_attachments" properties in the body will be extracted and returned separately if present (pre-2.5 metadata, or backup revisions)
-func (c *DatabaseCollection) getRevision(ctx context.Context, doc *Document, revid string) (bodyBytes []byte, body Body, attachments AttachmentsMeta, err error) {
+func (c *DatabaseCollection) getRevision(ctx context.Context, doc *Document, revid string) (bodyBytes []byte, attachments AttachmentsMeta, err error) {
 	bodyBytes = doc.getRevisionBodyJSON(ctx, revid, c.RevisionBodyLoader)
 
 	// No inline body, so look for separate doc:
 	if bodyBytes == nil {
 		if !doc.History.contains(revid) {
-			return nil, nil, nil, ErrMissing
+			return nil, nil, ErrMissing
 		}
 
 		bodyBytes, err = c.getOldRevisionJSON(ctx, doc.ID, revid)
 		if err != nil || bodyBytes == nil {
-			return nil, nil, nil, err
+			return nil, nil, err
 		}
 	}
 
 	// optimistically grab the doc body and to store as a pre-unmarshalled version, as well as anticipating no inline attachments.
 	if doc.CurrentRev == revid {
-		body = doc._body
 		attachments = doc.Attachments
 	}
 
 	// handle backup revision inline attachments, or pre-2.5 meta
-	if inlineAtts, cleanBodyBytes, cleanBody, err := extractInlineAttachments(bodyBytes); err != nil {
-		return nil, nil, nil, err
+	if inlineAtts, cleanBodyBytes, _, err := extractInlineAttachments(bodyBytes); err != nil {
+		return nil, nil, err
 	} else if len(inlineAtts) > 0 {
 		// we found some inline attachments, so merge them with attachments, and update the bodies
 		attachments = mergeAttachments(inlineAtts, attachments)
 		bodyBytes = cleanBodyBytes
-		body = cleanBody
 	}
 
-	return bodyBytes, body, attachments, nil
+	return bodyBytes, attachments, nil
 }
 
 // mergeAttachments copies the docAttachments map, and merges pre25Attachments into it.
@@ -705,7 +703,7 @@ func (db *DatabaseCollectionWithUser) get1xRevFromDoc(ctx context.Context, doc *
 				return nil, false, ErrDeleted
 			}
 		}
-		if bodyBytes, _, attachments, err = db.getRevision(ctx, doc, revid); err != nil {
+		if bodyBytes, attachments, err = db.getRevision(ctx, doc, revid); err != nil {
 			return nil, false, err
 		}
 	}
@@ -742,7 +740,7 @@ func (db *DatabaseCollectionWithUser) get1xRevFromDoc(ctx context.Context, doc *
 // Returns the body and rev ID of the asked-for revision or the most recent available ancestor.
 func (db *DatabaseCollectionWithUser) getAvailableRev(ctx context.Context, doc *Document, revid string) ([]byte, string, AttachmentsMeta, error) {
 	for ; revid != ""; revid = doc.History[revid].Parent {
-		if bodyBytes, _, attachments, _ := db.getRevision(ctx, doc, revid); bodyBytes != nil {
+		if bodyBytes, attachments, _ := db.getRevision(ctx, doc, revid); bodyBytes != nil {
 			return bodyBytes, revid, attachments, nil
 		}
 	}
@@ -2155,15 +2153,14 @@ func (db *DatabaseCollectionWithUser) updateAndReturnDoc(ctx context.Context, do
 
 		revChannels := doc.History[newRevID].Channels
 		documentRevision := DocumentRevision{
-			DocID:            docid,
-			RevID:            newRevID,
-			BodyBytes:        storedDocBytes,
-			History:          encodeRevisions(ctx, docid, history),
-			Channels:         revChannels,
-			Attachments:      doc.Attachments,
-			Expiry:           doc.Expiry,
-			Deleted:          doc.History[newRevID].Deleted,
-			_shallowCopyBody: storedDoc.Body(ctx),
+			DocID:       docid,
+			RevID:       newRevID,
+			BodyBytes:   storedDocBytes,
+			History:     encodeRevisions(ctx, docid, history),
+			Channels:    revChannels,
+			Attachments: doc.Attachments,
+			Expiry:      doc.Expiry,
+			Deleted:     doc.History[newRevID].Deleted,
 		}
 
 		if createNewRevIDSkipped {
@@ -2261,7 +2258,7 @@ func getAttachmentIDsForLeafRevisions(ctx context.Context, db *DatabaseCollectio
 	})
 
 	for _, leafRevision := range documentLeafRevisions {
-		_, _, attachmentMeta, err := db.getRevision(ctx, doc, leafRevision)
+		_, attachmentMeta, err := db.getRevision(ctx, doc, leafRevision)
 		if err != nil {
 			return nil, err
 		}

db/database_test.go

@@ -402,8 +402,13 @@ func TestGetRemovedAsUser(t *testing.T) {
 	// Manually remove the temporary backup doc from the bucket
 	// Manually flush the rev cache
 	// After expiry from the rev cache and removal of doc backup, try again
-	cacheHitCounter, cacheMissCounter := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses
-	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(DefaultRevisionCacheShardCount, DefaultRevisionCacheSize, backingStoreMap, cacheHitCounter, cacheMissCounter)
+	cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStat := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses, db.DatabaseContext.DbStats.Cache().RevisionCacheNumItems, db.DatabaseContext.DbStats.Cache().RevisionCacheTotalMemory
+	cacheOptions := &RevisionCacheOptions{
+		MaxBytes:     0,
+		MaxItemCount: DefaultRevisionCacheSize,
+		ShardCount:   DefaultRevisionCacheShardCount,
+	}
+	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(cacheOptions, backingStoreMap, cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStat)
 	err = collection.PurgeOldRevisionJSON(ctx, "doc1", rev2id)
 	assert.NoError(t, err, "Purge old revision JSON")
 
@@ -514,9 +519,11 @@ func TestGetRemovalMultiChannel(t *testing.T) {
 	_, rev1Digest := ParseRevID(ctx, rev1ID)
 	_, rev2Digest := ParseRevID(ctx, rev2ID)
 
+	var interfaceListChannels []interface{}
+	interfaceListChannels = append(interfaceListChannels, "ABC")
 	bodyExpected := Body{
 		"k2":       "v2",
-		"channels": []string{"ABC"},
+		"channels": interfaceListChannels,
 		BodyRevisions: Revisions{
 			RevisionsStart: 2,
 			RevisionsIds:   []string{rev2Digest, rev1Digest},
@@ -752,8 +759,13 @@ func TestGetRemoved(t *testing.T) {
 	// Manually remove the temporary backup doc from the bucket
 	// Manually flush the rev cache
 	// After expiry from the rev cache and removal of doc backup, try again
-	cacheHitCounter, cacheMissCounter := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses
-	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(DefaultRevisionCacheShardCount, DefaultRevisionCacheSize, backingStoreMap, cacheHitCounter, cacheMissCounter)
+	cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStat := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses, db.DatabaseContext.DbStats.Cache().RevisionCacheNumItems, db.DatabaseContext.DbStats.Cache().RevisionCacheTotalMemory
+	cacheOptions := &RevisionCacheOptions{
+		MaxBytes:     0,
+		MaxItemCount: DefaultRevisionCacheSize,
+		ShardCount:   DefaultRevisionCacheShardCount,
+	}
+	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(cacheOptions, backingStoreMap, cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStat)
 	err = collection.PurgeOldRevisionJSON(ctx, "doc1", rev2id)
 	assert.NoError(t, err, "Purge old revision JSON")
 
@@ -821,8 +833,13 @@ func TestGetRemovedAndDeleted(t *testing.T) {
 	// Manually remove the temporary backup doc from the bucket
 	// Manually flush the rev cache
 	// After expiry from the rev cache and removal of doc backup, try again
-	cacheHitCounter, cacheMissCounter := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses
-	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(DefaultRevisionCacheShardCount, DefaultRevisionCacheSize, backingStoreMap, cacheHitCounter, cacheMissCounter)
+	cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStats := db.DatabaseContext.DbStats.Cache().RevisionCacheHits, db.DatabaseContext.DbStats.Cache().RevisionCacheMisses, db.DatabaseContext.DbStats.Cache().RevisionCacheNumItems, db.DatabaseContext.DbStats.Cache().RevisionCacheTotalMemory
+	cacheOptions := &RevisionCacheOptions{
+		MaxBytes:     0,
+		MaxItemCount: DefaultRevisionCacheSize,
+		ShardCount:   DefaultRevisionCacheShardCount,
+	}
+	collection.dbCtx.revisionCache = NewShardedLRURevisionCache(cacheOptions, backingStoreMap, cacheHitCounter, cacheMissCounter, cacheNumItems, memoryCacheStats)
 	err = collection.PurgeOldRevisionJSON(ctx, "doc1", rev2id)
 	assert.NoError(t, err, "Purge old revision JSON")
 
@@ -3321,3 +3338,60 @@ func TestBadDCPStart(t *testing.T) {
 
 	dbCtx.Close(ctx)
 }
+
+func TestInject1xBodyProperties(t *testing.T) {
+	db, ctx := setupTestDB(t)
+	defer db.Close(ctx)
+
+	collection, ctx := GetSingleDatabaseCollectionWithUser(ctx, t, db)
+
+	rev1ID, _, err := collection.Put(ctx, "doc", Body{"test": "doc"})
+	require.NoError(t, err)
+	var rev2Body Body
+	rev2Data := `{"key":"value", "_attachments": {"hello.txt": {"data":"aGVsbG8gd29ybGQ="}}}`
+	require.NoError(t, base.JSONUnmarshal([]byte(rev2Data), &rev2Body))
+	_, rev2ID, err := collection.PutExistingRevWithBody(ctx, "doc", rev2Body, []string{"2-abc", rev1ID}, true)
+	require.NoError(t, err)
+
+	docRev, err := collection.GetRev(ctx, "doc", rev2ID, true, nil)
+	require.NoError(t, err)
+
+	// mock expiry on doc
+	exp := time.Now()
+	docRev.Expiry = &exp
+
+	newDoc, err := docRev.Inject1xBodyProperties(ctx, collection, docRev.History, nil, true)
+	require.NoError(t, err)
+	var resBody Body
+	require.NoError(t, resBody.Unmarshal(newDoc))
+
+	// cast to map of interface given we have injected the properties runtime has no concept of the AttachmentMeta and Revisions types
+	revs := resBody[BodyRevisions].(map[string]interface{})
+	atts := resBody[BodyAttachments].(map[string]interface{})
+
+	assert.NotNil(t, atts)
+	assert.NotNil(t, revs)
+	assert.Equal(t, "doc", resBody[BodyId])
+	assert.Equal(t, "2-abc", resBody[BodyRev])
+	assert.Equal(t, exp.Format(time.RFC3339), resBody[BodyExpiry])
+	assert.Equal(t, "value", resBody["key"])
+
+	// mock doc deleted
+	docRev.Deleted = true
+
+	newDoc, err = docRev.Inject1xBodyProperties(ctx, collection, docRev.History, []string{"2-abc"}, true)
+	require.NoError(t, err)
+	require.NoError(t, resBody.Unmarshal(newDoc))
+
+	// cast to map of interface given we have injected the properties runtime has no concept of the AttachmentMeta and Revisions types
+	revs = resBody[BodyRevisions].(map[string]interface{})
+	atts = resBody[BodyAttachments].(map[string]interface{})
+
+	assert.NotNil(t, atts)
+	assert.NotNil(t, revs)
+	assert.Equal(t, "doc", resBody[BodyId])
+	assert.Equal(t, "2-abc", resBody[BodyRev])
+	assert.Equal(t, exp.Format(time.RFC3339), resBody[BodyExpiry])
+	assert.Equal(t, "value", resBody["key"])
+	assert.True(t, resBody[BodyDeleted].(bool))
+}