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Prove index build on unexpected sequence, reuse allocations when possible #7304

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Merged
neilalexander merged 1 commit into from
Sep 12, 2025
Merged

Prove index build on unexpected sequence, reuse allocations when possible #7304

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16 changes: 12 additions & 4 deletions server/filestore.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6849,11 +6849,19 @@ func (mb *msgBlock) indexCacheBuf(buf []byte) error {
dms := uint64(mb.dmap.Size())
idxSz := mbLastSeq - mbFirstSeq + 1

if mb.cache == nil {
if mb.cache == nil || mb.cache.buf == nil {
// Approximation, may adjust below.
fseq = mbFirstSeq
idx = make([]uint32, 0, idxSz)
mb.cache = &cache{}
if mb.cache != nil && mb.cache.idx != nil {
idx = mb.cache.idx[:0]
} else {
idx = make([]uint32, 0, idxSz)
}
if mb.cache == nil {
mb.cache = &cache{}
} else {
*mb.cache = cache{}
}
} else {
fseq = mb.cache.fseq
idx = mb.cache.idx
Expand Down Expand Up @@ -7535,7 +7543,7 @@ func (mb *msgBlock) cacheLookupEx(seq uint64, sm *StoreMsg, doCopy bool) (*Store
return nil, errDeletedMsg
}

if seq != fsm.seq {
if seq != fsm.seq { // See TestFileStoreInvalidIndexesRebuilt.
recycleMsgBlockBuf(mb.cache.buf)
mb.cache.buf = nil
return nil, fmt.Errorf("sequence numbers for cache load did not match, %d vs %d", seq, fsm.seq)
Expand Down
44 changes: 44 additions & 0 deletions server/filestore_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1746,6 +1746,50 @@ func TestFileStorePartialIndexes(t *testing.T) {
})
}

func TestFileStoreInvalidIndexesRebuilt(t *testing.T) {
testFileStoreAllPermutations(t, func(t *testing.T, fcfg FileStoreConfig) {
fs, err := newFileStoreWithCreated(fcfg, StreamConfig{Name: "zzz", Storage: FileStorage}, time.Now(), prf(&fcfg), nil)
require_NoError(t, err)
defer fs.Stop()

toSend := 5
for i := 0; i < toSend; i++ {
fs.StoreMsg("foo", nil, []byte("ok-1"), 0)
}
fs.FlushAllPending()

// Now we're going to mangle the in-memory cache by changing
// the sequence number of the first message. We also need to
// trick the cache into believing the hash is already validated
// so we don't fail on that. This is specifically testing the
// seq != fsm.seq condition.
mb := fs.selectMsgBlock(1)
require_NotNil(t, mb)
require_NoError(t, mb.loadMsgs())
require_True(t, mb.cacheAlreadyLoaded())
ri, rl, _, err := mb.slotInfo(0)
require_NoError(t, err)
require_NotNil(t, mb.cache)
require_NotNil(t, mb.cache.buf)
slot := mb.cache.buf[ri : ri+rl]
require_Equal(t, binary.LittleEndian.Uint64(slot[4:]), 1)
binary.LittleEndian.PutUint64(slot[4:], 12345)
mb.cache.idx[0] = (mb.cache.idx[0] | cbit)

// Expect an error on the first instance and for cacheLookupEx
// to discard the cache.
_, err = mb.cacheLookupEx(1, nil, false)
require_Error(t, err)
require_True(t, mb.cache.buf == nil)

// Now fetchMsg should notice and rebuild the index with the
// correct sequence from disk.
sm, _, err := mb.fetchMsg(1, nil)
require_NoError(t, err)
require_Equal(t, sm.seq, 1)
})
}

func TestFileStoreSnapshot(t *testing.T) {
testFileStoreAllPermutations(t, func(t *testing.T, fcfg FileStoreConfig) {
subj, msg := "foo", []byte("Hello Snappy!")
Expand Down