Golang Timestamp.Less方法代码示例

// getInternal implements the actual logic of get function.
// The values of multiple versions for the given key should
// be organized as follows:
// ...
// keyA : keyMetatata of keyA
// keyA_Timestamp_n : value of version_n
// keyA_Timestamp_n-1 : value of version_n-1
// ...
// keyA_Timestamp_0 : value of version_0
// keyB : keyMetadata of keyB
// ...
func (mvcc *MVCC) getInternal(key Key, timestamp hlc.Timestamp, txnID string) ([]byte, hlc.Timestamp, string, error) {
	keyMetadata := &keyMetadata{}
	ok, err := GetI(mvcc.engine, key, keyMetadata)
	if err != nil || !ok {
		return nil, hlc.Timestamp{}, "", err
	}
	// If the read timestamp is greater than the latest one, we can just
	// fetch the value without a scan.
	if !timestamp.Less(keyMetadata.Timestamp) {
		if len(keyMetadata.TxnID) > 0 && (len(txnID) == 0 || keyMetadata.TxnID != txnID) {
			return nil, hlc.Timestamp{}, "", &writeIntentError{TxnID: keyMetadata.TxnID}
		}

		latestKey := mvccEncodeKey(key, keyMetadata.Timestamp)
		val, err := mvcc.engine.Get(latestKey)
		return val, keyMetadata.Timestamp, keyMetadata.TxnID, err
	}

	nextKey := mvccEncodeKey(key, timestamp)
	// We use the PrefixEndKey(key) as the upper bound for scan.
	// If there is no other version after nextKey, it won't return
	// the value of the next key.
	kvs, err := mvcc.engine.Scan(nextKey, PrefixEndKey(key), 1)
	if len(kvs) > 0 {
		_, ts := mvccDecodeKey(kvs[0].Key)
		return kvs[0].Value, ts, "", err
	}
	return nil, hlc.Timestamp{}, "", err
}

// UpdateDeadlineMaybe sets the transactions deadline to the lower of the
// current one (if any) and the passed value.
func (txn *Txn) UpdateDeadlineMaybe(deadline hlc.Timestamp) bool {
	if txn.deadline == nil || deadline.Less(*txn.deadline) {
		txn.deadline = &deadline
		return true
	}
	return false
}

func replicaGCShouldQueueImpl(
	now, lastCheck, lastActivity hlc.Timestamp, isCandidate bool,
) (bool, float64) {
	timeout := ReplicaGCQueueInactivityThreshold
	var priority float64

	if isCandidate {
		// If the range is a candidate (which happens if its former replica set
		// ignores it), let it expire much earlier.
		timeout = ReplicaGCQueueCandidateTimeout
		priority++
	} else if now.Less(lastCheck.Add(ReplicaGCQueueInactivityThreshold.Nanoseconds(), 0)) {
		// Return false immediately if the previous check was less than the
		// check interval in the past. Note that we don't do this is the
		// replica is in candidate state, in which case we want to be more
		// aggressive - a failed rebalance attempt could have checked this
		// range, and candidate state suggests that a retry succeeded. See
		// #7489.
		return false, 0
	}

	shouldQ := lastActivity.Add(timeout.Nanoseconds(), 0).Less(now)

	if !shouldQ {
		return false, 0
	}

	return shouldQ, priority
}

// UpdateObservedTimestamp stores a timestamp off a node's clock for future
// operations in the transaction. When multiple calls are made for a single
// nodeID, the lowest timestamp prevails.
func (t *Transaction) UpdateObservedTimestamp(nodeID NodeID, maxTS hlc.Timestamp) {
	if t.ObservedTimestamps == nil {
		t.ObservedTimestamps = make(map[NodeID]hlc.Timestamp)
	}
	if ts, ok := t.ObservedTimestamps[nodeID]; !ok || maxTS.Less(ts) {
		t.ObservedTimestamps[nodeID] = maxTS
	}
}

// isAsOf analyzes a select statement to bypass the logic in newPlan(),
// since that requires the transaction to be started already. If the returned
// timestamp is not nil, it is the timestamp to which a transaction should
// be set.
func isAsOf(planMaker *planner, stmt parser.Statement, max hlc.Timestamp) (*hlc.Timestamp, error) {
	s, ok := stmt.(*parser.Select)
	if !ok {
		return nil, nil
	}
	sc, ok := s.Select.(*parser.SelectClause)
	if !ok {
		return nil, nil
	}
	if len(sc.From) != 1 {
		return nil, nil
	}
	ate, ok := sc.From[0].(*parser.AliasedTableExpr)
	if !ok {
		return nil, nil
	}
	if ate.AsOf.Expr == nil {
		return nil, nil
	}
	te, err := ate.AsOf.Expr.TypeCheck(nil, parser.TypeString)
	if err != nil {
		return nil, err
	}
	d, err := te.Eval(&planMaker.evalCtx)
	if err != nil {
		return nil, err
	}
	ds, ok := d.(*parser.DString)
	if !ok {
		return nil, fmt.Errorf("AS OF SYSTEM TIME expected string, got %s", ds.Type())
	}
	// Allow nanosecond precision because the timestamp is only used by the
	// system and won't be returned to the user over pgwire.
	dt, err := parser.ParseDTimestamp(string(*ds), planMaker.session.Location, time.Nanosecond)
	if err != nil {
		return nil, err
	}
	ts := hlc.Timestamp{
		WallTime: dt.Time.UnixNano(),
	}
	if max.Less(ts) {
		return nil, fmt.Errorf("cannot specify timestamp in the future")
	}
	return &ts, nil
}

// Covers returns true if the given timestamp can be served by the Lease.
// This is the case if the timestamp precedes the Lease's stasis period.
// Note that the fact that a lease convers a timestamp is not enough for the
// holder of the lease to be able to serve a read with that timestamp;
// pendingLeaderLeaseRequest.TransferInProgress() should also be consulted to
// account for possible lease transfers.
func (l Lease) Covers(timestamp hlc.Timestamp) bool {
	return timestamp.Less(l.StartStasis)
}

// add the specified timestamp to the cache as covering the range of
// keys from start to end. If end is nil, the range covers the start
// key only. txnID is nil for no transaction. readTSCache specifies
// whether the command adding this timestamp should update the read
// timestamp; false to update the write timestamp cache.
func (tc *timestampCache) add(
	start, end roachpb.Key,
	timestamp hlc.Timestamp,
	txnID *uuid.UUID,
	readTSCache bool,
) {
	// This gives us a memory-efficient end key if end is empty.
	if len(end) == 0 {
		end = start.Next()
		start = end[:len(start)]
	}
	tc.latest.Forward(timestamp)
	// Only add to the cache if the timestamp is more recent than the
	// low water mark.
	if tc.lowWater.Less(timestamp) {
		tcache := tc.wCache
		if readTSCache {
			tcache = tc.rCache
		}

		addRange := func(r interval.Range) {
			value := cacheValue{timestamp: timestamp, txnID: txnID}
			key := tcache.MakeKey(r.Start, r.End)
			entry := makeCacheEntry(key, value)
			tcache.AddEntry(entry)
		}
		r := interval.Range{
			Start: interval.Comparable(start),
			End:   interval.Comparable(end),
		}

		// Check existing, overlapping entries and truncate/split/remove if
		// superseded and in the past. If existing entries are in the future,
		// subtract from the range/ranges that need to be added to cache.
		for _, entry := range tcache.GetOverlaps(r.Start, r.End) {
			cv := entry.Value.(*cacheValue)
			key := entry.Key.(*cache.IntervalKey)
			sCmp := r.Start.Compare(key.Start)
			eCmp := r.End.Compare(key.End)
			if !timestamp.Less(cv.timestamp) {
				// The existing interval has a timestamp less than or equal to the new interval.
				// Compare interval ranges to determine how to modify existing interval.
				switch {
				case sCmp == 0 && eCmp == 0:
					// New and old are equal; replace old with new and avoid the need to insert new.
					//
					// New: ------------
					// Old: ------------
					//
					// New: ------------
					*cv = cacheValue{timestamp: timestamp, txnID: txnID}
					tcache.MoveToEnd(entry)
					return
				case sCmp <= 0 && eCmp >= 0:
					// New contains or is equal to old; delete old.
					//
					// New: ------------      ------------      ------------
					// Old:   --------    or    ----------  or  ----------
					//
					// Old:
					tcache.DelEntry(entry)
				case sCmp > 0 && eCmp < 0:
					// Old contains new; split up old into two.
					//
					// New:     ----
					// Old: ------------
					//
					// Old: ----    ----
					oldEnd := key.End
					key.End = r.Start

					key := tcache.MakeKey(r.End, oldEnd)
					newEntry := makeCacheEntry(key, *cv)
					tcache.AddEntryAfter(newEntry, entry)
				case eCmp >= 0:
					// Left partial overlap; truncate old end.
					//
					// New:     --------          --------
					// Old: --------      or  ------------
					//
					// Old: ----              ----
					key.End = r.Start
				case sCmp <= 0:
					// Right partial overlap; truncate old start.
					//
					// New: --------          --------
					// Old:     --------  or  ------------
					//
					// Old:         ----              ----
					key.Start = r.End
				default:
					panic(fmt.Sprintf("no overlap between %v and %v", key.Range, r))
				}
			} else {
				// The existing interval has a timestamp greater than the new interval.
//.........这里部分代码省略.........

// TestTxnCoordSenderHeartbeat verifies periodic heartbeat of the
// transaction record.
func TestTxnCoordSenderHeartbeat(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	// Set heartbeat interval to 1ms for testing.
	sender.heartbeatInterval = 1 * time.Millisecond

	initialTxn := client.NewTxn(context.Background(), *s.DB)
	if err := initialTxn.Put(roachpb.Key("a"), []byte("value")); err != nil {
		t.Fatal(err)
	}

	// Verify 3 heartbeats.
	var heartbeatTS hlc.Timestamp
	for i := 0; i < 3; i++ {
		util.SucceedsSoon(t, func() error {
			txn, pErr := getTxn(sender, &initialTxn.Proto)
			if pErr != nil {
				t.Fatal(pErr)
			}
			// Advance clock by 1ns.
			// Locking the TxnCoordSender to prevent a data race.
			sender.Lock()
			s.Manual.Increment(1)
			sender.Unlock()
			if txn.LastHeartbeat != nil && heartbeatTS.Less(*txn.LastHeartbeat) {
				heartbeatTS = *txn.LastHeartbeat
				return nil
			}
			return errors.Errorf("expected heartbeat")
		})
	}

	// Sneakily send an ABORT right to DistSender (bypassing TxnCoordSender).
	{
		var ba roachpb.BatchRequest
		ba.Add(&roachpb.EndTransactionRequest{
			Commit: false,
			Span:   roachpb.Span{Key: initialTxn.Proto.Key},
		})
		ba.Txn = &initialTxn.Proto
		if _, pErr := sender.wrapped.Send(context.Background(), ba); pErr != nil {
			t.Fatal(pErr)
		}
	}

	util.SucceedsSoon(t, func() error {
		sender.Lock()
		defer sender.Unlock()
		if txnMeta, ok := sender.txns[*initialTxn.Proto.ID]; !ok {
			t.Fatal("transaction unregistered prematurely")
		} else if txnMeta.txn.Status != roachpb.ABORTED {
			return fmt.Errorf("transaction is not aborted")
		}
		return nil
	})

	// Trying to do something else should give us a TransactionAbortedError.
	_, err := initialTxn.Get("a")
	assertTransactionAbortedError(t, err)
}