Added in ability to get per subject details via StreamInfo.

server/errors.json

@@ -1148,5 +1148,15 @@
     "help": "",
     "url": "",
     "deprecates": ""
+  },
+  {
+    "constant": "JSStreamInfoMaxSubjectsErr",
+    "code": 500,
+    "error_code": 10117,
+    "description": "subject details would exceed maximum allowed",
+    "comment": "",
+    "help": "",
+    "url": "",
+    "deprecates": ""
   }
-]
+]

server/filestore.go

@@ -1,4 +1,4 @@
-// Copyright 2019-2021 The NATS Authors
+// Copyright 2019-2022 The NATS Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -89,6 +89,7 @@ type fileStore struct {
 	aek     cipher.AEAD
 	lmb     *msgBlock
 	blks    []*msgBlock
+	psmc    map[string]uint64
 	hh      hash.Hash64
 	qch     chan struct{}
 	cfs     []*consumerFileStore
@@ -280,6 +281,7 @@ func newFileStoreWithCreated(fcfg FileStoreConfig, cfg StreamConfig, created tim
 	fs := &fileStore{
 		fcfg: fcfg,
 		cfg:  FileStreamInfo{Created: created, StreamConfig: cfg},
+		psmc: make(map[string]uint64),
 		prf:  prf,
 		qch:  make(chan struct{}),
 	}
@@ -879,6 +881,13 @@ func (fs *fileStore) recoverMsgs() error {
 				}
 				fs.state.Msgs += mb.msgs
 				fs.state.Bytes += mb.bytes
+				// Walk the fss for this mb and fill in fs.psmc
+				for subj, ss := range mb.fss {
+					if len(subj) > 0 {
+						fs.psmc[subj] += ss.Msgs
+					}
+				}
+
 			} else {
 				return err
 			}
@@ -988,6 +997,7 @@ func (fs *fileStore) expireMsgsOnRecover() {
 			mb.msgs--
 			purged++
 			// Update fss
+			fs.removePerSubject(sm.subj)
 			mb.removeSeqPerSubject(sm.subj, seq)
 		}
 
@@ -1528,6 +1538,11 @@ func (fs *fileStore) storeRawMsg(subj string, hdr, msg []byte, seq uint64, ts in
 		return err
 	}
 
+	// Adjust top level tracking of per subject msg counts.
+	if len(subj) > 0 {
+		fs.psmc[subj]++
+	}
+
 	// Adjust first if needed.
 	now := time.Unix(0, ts).UTC()
 	if fs.state.Msgs == 0 {
@@ -1724,6 +1739,19 @@ func (fs *fileStore) EraseMsg(seq uint64) (bool, error) {
 	return fs.removeMsg(seq, true, true)
 }
 
+// Convenience function to remove per subject tracking at the filestore level.
+// Lock should be held.
+func (fs *fileStore) removePerSubject(subj string) {
+	if len(subj) == 0 {
+		return
+	}
+	if n, ok := fs.psmc[subj]; ok && n == 1 {
+		delete(fs.psmc, subj)
+	} else if ok {
+		fs.psmc[subj]--
+	}
+}
+
 // Remove a message, optionally rewriting the mb file.
 func (fs *fileStore) removeMsg(seq uint64, secure, needFSLock bool) (bool, error) {
 	fsLock := func() {
@@ -1811,6 +1839,7 @@ func (fs *fileStore) removeMsg(seq uint64, secure, needFSLock bool) (bool, error
 	mb.bytes -= msz
 
 	// If we are tracking multiple subjects here make sure we update that accounting.
+	fs.removePerSubject(sm.subj)
 	mb.removeSeqPerSubject(sm.subj, seq)
 
 	var shouldWriteIndex, firstSeqNeedsUpdate bool
@@ -3274,19 +3303,18 @@ func (mb *msgBlock) cacheLookup(seq uint64) (*fileStoredMsg, error) {
 		mb.llseq = seq
 	}
 
-	// We use the high bit to denote we have already checked the checksum.
-	var hh hash.Hash64
-	if !hashChecked {
-		hh = mb.hh // This will force the hash check in msgFromBuf.
-		mb.cache.idx[seq-mb.cache.fseq] = (bi | hbit)
-	}
-
 	li := int(bi) - mb.cache.off
 	if li >= len(mb.cache.buf) {
 		return nil, errPartialCache
 	}
 	buf := mb.cache.buf[li:]
 
+	// We use the high bit to denote we have already checked the checksum.
+	var hh hash.Hash64
+	if !hashChecked {
+		hh = mb.hh // This will force the hash check in msgFromBuf.
+	}
+
 	// Parse from the raw buffer.
 	subj, hdr, msg, mseq, ts, err := msgFromBuf(buf, hh)
 	if err != nil {
@@ -3297,6 +3325,11 @@ func (mb *msgBlock) cacheLookup(seq uint64) (*fileStoredMsg, error) {
 		return nil, fmt.Errorf("sequence numbers for cache load did not match, %d vs %d", seq, mseq)
 	}
 
+	// Clear the check bit here after we know all is good.
+	if !hashChecked {
+		mb.cache.idx[seq-mb.cache.fseq] = (bi | hbit)
+	}
+
 	return &fileStoredMsg{subj, hdr, msg, seq, ts, mb, int64(bi)}, nil
 }
 
@@ -3451,6 +3484,7 @@ func (fs *fileStore) FastState(state *StreamState) {
 		}
 	}
 	state.Consumers = len(fs.cfs)
+	state.NumSubjects = len(fs.psmc)
 	fs.mu.RUnlock()
 }
 
@@ -3459,7 +3493,9 @@ func (fs *fileStore) State() StreamState {
 	fs.mu.RLock()
 	state := fs.state
 	state.Consumers = len(fs.cfs)
+	state.NumSubjects = len(fs.psmc)
 	state.Deleted = nil // make sure.
+
 	for _, mb := range fs.blks {
 		mb.mu.Lock()
 		fseq := mb.first.seq
@@ -3819,6 +3855,7 @@ func (fs *fileStore) PurgeEx(subject string, sequence, keep uint64) (purged uint
 				mb.msgs--
 				mb.bytes -= rl
 				// FSS updates.
+				fs.removePerSubject(sm.subj)
 				mb.removeSeqPerSubject(sm.subj, seq)
 				// Check for first message.
 				if seq == mb.first.seq {
@@ -3924,6 +3961,9 @@ func (fs *fileStore) purge(fseq uint64) (uint64, error) {
 
 	fs.lmb.writeIndexInfo()
 
+	// Clear any per subject tracking.
+	fs.psmc = make(map[string]uint64)
+
 	cb := fs.scb
 	fs.mu.Unlock()
 
@@ -3988,6 +4028,7 @@ func (fs *fileStore) Compact(seq uint64) (uint64, error) {
 			smb.msgs--
 			purged++
 			// Update fss
+			fs.removePerSubject(sm.subj)
 			smb.removeSeqPerSubject(sm.subj, mseq)
 		}
 	}
@@ -4243,6 +4284,7 @@ func (mb *msgBlock) generatePerSubjectInfo() error {
 	if mb.fss == nil {
 		mb.fss = make(map[string]*SimpleState)
 	}
+
 	fseq, lseq := mb.first.seq, mb.last.seq
 	for seq := fseq; seq <= lseq; seq++ {
 		if sm, _ := mb.cacheLookup(seq); sm != nil && len(sm.subj) > 0 {

server/jetstream_api.go

@@ -321,8 +321,12 @@ type JSApiStreamDeleteResponse struct {
 
 const JSApiStreamDeleteResponseType = "io.nats.jetstream.api.v1.stream_delete_response"
 
+// Maximum number of subject details we will send in the stream info.
+const JSMaxSubjectDetails = 100_000
+
 type JSApiStreamInfoRequest struct {
-	DeletedDetails bool `json:"deleted_details,omitempty"`
+	DeletedDetails bool   `json:"deleted_details,omitempty"`
+	SubjectsFilter string `json:"subjects_filter,omitempty"`
 }
 
 type JSApiStreamInfoResponse struct {
@@ -1697,14 +1701,15 @@ func (s *Server) jsStreamInfoRequest(sub *subscription, c *client, a *Account, s
 	}
 
 	var details bool
+	var subjects string
 	if !isEmptyRequest(msg) {
 		var req JSApiStreamInfoRequest
 		if err := json.Unmarshal(msg, &req); err != nil {
 			resp.Error = NewJSInvalidJSONError()
 			s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
 			return
 		}
-		details = req.DeletedDetails
+		details, subjects = req.DeletedDetails, req.SubjectsFilter
 	}
 
 	mset, err := acc.lookupStream(streamName)
@@ -1730,6 +1735,23 @@ func (s *Server) jsStreamInfoRequest(sub *subscription, c *client, a *Account, s
 		resp.StreamInfo.Sources = mset.sourcesInfo()
 	}
 
+	// Check if they have asked for subject details.
+	if subjects != _EMPTY_ {
+		if mss := mset.store.SubjectsState(subjects); len(mss) > 0 {
+			if len(mss) > JSMaxSubjectDetails {
+				resp.StreamInfo = nil
+				resp.Error = NewJSStreamInfoMaxSubjectsError()
+				s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
+				return
+			}
+			sd := make(map[string]uint64, len(mss))
+			for subj, ss := range mss {
+				sd[subj] = ss.Msgs
+			}
+			resp.StreamInfo.State.Subjects = sd
+		}
+
+	}
 	// Check for out of band catchups.
 	if mset.hasCatchupPeers() {
 		mset.checkClusterInfo(resp.StreamInfo)

server/jetstream_errors_generated.go

@@ -260,6 +260,9 @@ const (
 	// JSStreamHeaderExceedsMaximumErr header size exceeds maximum allowed of 64k
 	JSStreamHeaderExceedsMaximumErr ErrorIdentifier = 10097
 
+	// JSStreamInfoMaxSubjectsErr subject details would exceed maximum allowed
+	JSStreamInfoMaxSubjectsErr ErrorIdentifier = 10117
+
 	// JSStreamInvalidConfigF Stream configuration validation error string ({err})
 	JSStreamInvalidConfigF ErrorIdentifier = 10052
 
@@ -438,6 +441,7 @@ var (
 		JSStreamExternalDelPrefixOverlapsErrF:      {Code: 400, ErrCode: 10022, Description: "stream external delivery prefix {prefix} overlaps with stream subject {subject}"},
 		JSStreamGeneralErrorF:                      {Code: 500, ErrCode: 10051, Description: "{err}"},
 		JSStreamHeaderExceedsMaximumErr:            {Code: 400, ErrCode: 10097, Description: "header size exceeds maximum allowed of 64k"},
+		JSStreamInfoMaxSubjectsErr:                 {Code: 500, ErrCode: 10117, Description: "subject details would exceed maximum allowed"},
 		JSStreamInvalidConfigF:                     {Code: 500, ErrCode: 10052, Description: "{err}"},
 		JSStreamInvalidErr:                         {Code: 500, ErrCode: 10096, Description: "stream not valid"},
 		JSStreamInvalidExternalDeliverySubjErrF:    {Code: 400, ErrCode: 10024, Description: "stream external delivery prefix {prefix} must not contain wildcards"},
@@ -1445,6 +1449,16 @@ func NewJSStreamHeaderExceedsMaximumError(opts ...ErrorOption) *ApiError {
 	return ApiErrors[JSStreamHeaderExceedsMaximumErr]
 }
 
+// NewJSStreamInfoMaxSubjectsError creates a new JSStreamInfoMaxSubjectsErr error: "subject details would exceed maximum allowed"
+func NewJSStreamInfoMaxSubjectsError(opts ...ErrorOption) *ApiError {
+	eopts := parseOpts(opts)
+	if ae, ok := eopts.err.(*ApiError); ok {
+		return ae
+	}
+
+	return ApiErrors[JSStreamInfoMaxSubjectsErr]
+}
+
 // NewJSStreamInvalidConfigError creates a new JSStreamInvalidConfigF error: "{err}"
 func NewJSStreamInvalidConfigError(err error, opts ...ErrorOption) *ApiError {
 	eopts := parseOpts(opts)