Fix orphaned pvtdata missing entries from stale iterator during elg conversion

Re-create the LevelDB iterator after releasing and re-acquiring purgerLock
in processCollElgEvents. The old snapshot-based iterator yields entries
deleted by the purger during the unlock window, creating eligible missing
data entries with no expiry entry that are never cleaned up.

Signed-off-by: Ady0333 <adityashinde1525@gmail.com>

Author: Ady0333

core/ledger/pvtdatastorage/store.go

@@ -1054,6 +1054,13 @@ func (s *Store) processCollElgEvents() error {
 						s.purgerLock.Unlock()
 						time.Sleep(sleepTime * time.Millisecond)
 						s.purgerLock.Lock()
+						// Re-create the iterator so it reflects any deletes
+						// made by the purger while the lock was released.
+						collItr.Release()
+						collItr, err = s.db.GetIterator(startKey, endKey)
+						if err != nil {
+							return err
+						}
 					}
 				} // entry loop
 

core/ledger/pvtdatastorage/store_test.go

@@ -1765,6 +1765,69 @@ func testutilWaitForCollElgProcToFinish(s *Store) {
 	s.collElgProcSync.waitForDone()
 }
 
+func TestProcessCollElgEventsIteratorRecreatedAfterPurge(t *testing.T) {
+	btlPolicy := btltestutil.SampleBTLPolicy(map[[2]string]uint64{
+		{"ns-1", "coll-1"}: 1,
+	})
+	conf := pvtDataConf()
+	conf.MaxBatchSize = 1
+	conf.BatchesInterval = 500
+
+	env := NewTestStoreEnv(t, "TestCollElgStaleIter", btlPolicy, conf)
+	defer env.Cleanup()
+	s := env.TestStore
+
+	s.purgeInterval = math.MaxUint64
+
+	s.purgerLock.Lock()
+	s.purgerLock.Unlock() //lint:ignore SA2001 syncpoint
+
+	require.NoError(t, s.Commit(0, nil, nil, nil))
+
+	const numBlocks = uint64(10)
+	for blk := uint64(1); blk <= numBlocks; blk++ {
+		missingData := make(ledger.TxMissingPvtData)
+		missingData.Add(1, "ns-1", "coll-1", false)
+		require.NoError(t, s.Commit(blk, nil, missingData, nil))
+	}
+
+	const lastBlock = uint64(15)
+	for blk := numBlocks + 1; blk <= lastBlock; blk++ {
+		require.NoError(t, s.Commit(blk, nil, nil, nil))
+	}
+
+	{
+		key := encodeCollElgKey(lastBlock)
+		m := newCollElgInfo(map[string][]string{"ns-1": []string{"coll-1"}})
+		val, err := encodeCollElgVal(m)
+		require.NoError(t, err)
+		b := s.db.NewUpdateBatch()
+		b.Put(key, val)
+		require.NoError(t, s.db.WriteBatch(b, true))
+	}
+
+	procErr := make(chan error, 1)
+	go func() {
+		procErr <- s.processCollElgEvents()
+	}()
+
+	time.Sleep(100 * time.Millisecond)
+
+	s.purgerLock.Lock()
+	require.NoError(t, s.purgeExpiredData(0, lastBlock))
+	s.purgerLock.Unlock()
+
+	require.NoError(t, <-procErr)
+
+	for blk := uint64(1); blk <= numBlocks; blk++ {
+		k := &missingDataKey{nsCollBlk: nsCollBlk{ns: "ns-1", coll: "coll-1", blkNum: blk}}
+		require.False(t,
+			testElgPrioMissingDataKeyExists(t, s, k),
+			"orphaned eligible prioritized missing data entry must not exist for expired block %d", blk,
+		)
+	}
+}
+
 func produceSamplePvtdata(t *testing.T, txNum uint64, nsColls []string) *ledger.TxPvtData {
 	builder := rwsetutil.NewRWSetBuilder()
 	for _, nsColl := range nsColls {