Golang BatchRequest.CmdID方法代碼示例

func (tc *TxnCoordSender) heartbeat(id string, trace *tracer.Trace, ctx context.Context) bool {
	tc.Lock()
	proceed := true
	txnMeta := tc.txns[id]
	// Before we send a heartbeat, determine whether this transaction
	// should be considered abandoned. If so, exit heartbeat.
	if txnMeta.hasClientAbandonedCoord(tc.clock.PhysicalNow()) {
		// TODO(tschottdorf): should we be more proactive here?
		// The client might be continuing the transaction
		// through another coordinator, but in the most likely
		// case it's just gone and the open transaction record
		// could block concurrent operations.
		if log.V(1) {
			log.Infof("transaction %s abandoned; stopping heartbeat",
				txnMeta.txn)
		}
		proceed = false
	}
	// txnMeta.txn is possibly replaced concurrently,
	// so grab a copy before unlocking.
	txn := txnMeta.txn
	tc.Unlock()
	if !proceed {
		return false
	}

	hb := &roachpb.HeartbeatTxnRequest{}
	hb.Key = txn.Key
	ba := roachpb.BatchRequest{}
	ba.Timestamp = tc.clock.Now()
	ba.CmdID = ba.GetOrCreateCmdID(ba.Timestamp.WallTime)
	ba.Txn = txn.Clone()
	ba.Add(hb)

	epochEnds := trace.Epoch("heartbeat")
	_, err := tc.wrapped.Send(ctx, ba)
	epochEnds()
	// If the transaction is not in pending state, then we can stop
	// the heartbeat. It's either aborted or committed, and we resolve
	// write intents accordingly.
	if err != nil {
		log.Warningf("heartbeat to %s failed: %s", txn, err)
	}
	// TODO(bdarnell): once we have gotten a heartbeat response with
	// Status != PENDING, future heartbeats are useless. However, we
	// need to continue the heartbeatLoop until the client either
	// commits or abandons the transaction. We could save a little
	// pointless work by restructuring this loop to stop sending
	// heartbeats between the time that the transaction is aborted and
	// the client finds out. Furthermore, we could use this information
	// to send TransactionAbortedErrors to the client so it can restart
	// immediately instead of running until its EndTransaction.
	return true
}

// Send implements Sender.
// TODO(tschottdorf): We actually don't want to chop EndTransaction off for
// single-range requests (but that happens now since EndTransaction has the
// isAlone flag). Whether it is one or not is unknown right now (you can only
// find out after you've sent to the Range/looked up a descriptor that suggests
// that you're multi-range. In those cases, the wrapped sender should return an
// error so that we split and retry once the chunk which contains
// EndTransaction (i.e. the last one).
func (cs *chunkingSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
	if len(ba.Requests) < 1 {
		panic("empty batch")
	}

	// Deterministically create ClientCmdIDs for all parts of the batch if
	// a CmdID is already set (otherwise, leave them empty).
	var nextID func() roachpb.ClientCmdID
	empty := roachpb.ClientCmdID{}
	if empty == ba.CmdID {
		nextID = func() roachpb.ClientCmdID {
			return empty
		}
	} else {
		rng := rand.New(rand.NewSource(ba.CmdID.Random))
		id := ba.CmdID
		nextID = func() roachpb.ClientCmdID {
			curID := id             // copy
			id.Random = rng.Int63() // adjust for next call
			return curID
		}
	}

	parts := ba.Split()
	var rplChunks []*roachpb.BatchResponse
	for _, part := range parts {
		ba.Requests = part
		ba.CmdID = nextID()
		rpl, err := cs.f(ctx, ba)
		if err != nil {
			return nil, err
		}
		// Propagate transaction from last reply to next request. The final
		// update is taken and put into the response's main header.
		ba.Txn.Update(rpl.Header().Txn)

		rplChunks = append(rplChunks, rpl)
	}

	reply := rplChunks[0]
	for _, rpl := range rplChunks[1:] {
		reply.Responses = append(reply.Responses, rpl.Responses...)
	}
	lastHeader := rplChunks[len(rplChunks)-1].BatchResponse_Header
	reply.Error = lastHeader.Error
	reply.Timestamp = lastHeader.Timestamp
	reply.Txn = ba.Txn
	return reply, nil
}

// SendWrappedWith is a convenience function which wraps the request in a batch
// and sends it via the provided Sender at the given timestamp. It returns the
// unwrapped response or an error. It's valid to pass a `nil` context;
// context.Background() is used in that case.
func SendWrappedWith(sender Sender, ctx context.Context, h roachpb.Header, args roachpb.Request) (roachpb.Response, error) {
	if ctx == nil {
		ctx = context.Background()
	}
	ba := roachpb.BatchRequest{}
	ba.Header = h
	ba.CmdID = ba.GetOrCreateCmdID(0)
	ba.Add(args)

	br, pErr := sender.Send(ctx, ba)
	if err := pErr.GoError(); err != nil {
		return nil, err
	}
	unwrappedReply := br.Responses[0].GetInner()
	unwrappedReply.Header().Txn = br.Txn
	return unwrappedReply, nil
}

// Send implements the batch.Sender interface. If the request is part of a
// transaction, the TxnCoordSender adds the transaction to a map of active
// transactions and begins heartbeating it. Every subsequent request for the
// same transaction updates the lastUpdate timestamp to prevent live
// transactions from being considered abandoned and garbage collected.
// Read/write mutating requests have their key or key range added to the
// transaction's interval tree of key ranges for eventual cleanup via resolved
// write intents; they're tagged to an outgoing EndTransaction request, with
// the receiving replica in charge of resolving them.
func (tc *TxnCoordSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
	if err := tc.maybeBeginTxn(&ba); err != nil {
		return nil, roachpb.NewError(err)
	}
	ba.CmdID = ba.GetOrCreateCmdID(tc.clock.PhysicalNow())
	var startNS int64

	// This is the earliest point at which the request has a ClientCmdID and/or
	// TxnID (if applicable). Begin a Trace which follows this request.
	trace := tc.tracer.NewTrace(tracer.Coord, &ba)
	defer trace.Finalize()
	defer trace.Epoch("sending batch")()
	ctx = tracer.ToCtx(ctx, trace)

	var id string // optional transaction ID
	if ba.Txn != nil {
		// If this request is part of a transaction...
		id = string(ba.Txn.ID)
		// Verify that if this Transaction is not read-only, we have it on
		// file. If not, refuse writes - the client must have issued a write on
		// another coordinator previously.
		if ba.Txn.Writing && ba.IsTransactionWrite() {
			tc.Lock()
			_, ok := tc.txns[id]
			tc.Unlock()
			if !ok {
				return nil, roachpb.NewError(util.Errorf("transaction must not write on multiple coordinators"))
			}
		}

		// Set the timestamp to the original timestamp for read-only
		// commands and to the transaction timestamp for read/write
		// commands.
		if ba.IsReadOnly() {
			ba.Timestamp = ba.Txn.OrigTimestamp
		} else {
			ba.Timestamp = ba.Txn.Timestamp
		}

		if rArgs, ok := ba.GetArg(roachpb.EndTransaction); ok {
			et := rArgs.(*roachpb.EndTransactionRequest)
			if len(et.Key) != 0 {
				return nil, roachpb.NewError(util.Errorf("EndTransaction must not have a Key set"))
			}
			et.Key = ba.Txn.Key
			// Remember when EndTransaction started in case we want to
			// be linearizable.
			startNS = tc.clock.PhysicalNow()
			if len(et.Intents) > 0 {
				// TODO(tschottdorf): it may be useful to allow this later.
				// That would be part of a possible plan to allow txns which
				// write on multiple coordinators.
				return nil, roachpb.NewError(util.Errorf("client must not pass intents to EndTransaction"))
			}
			tc.Lock()
			txnMeta, metaOK := tc.txns[id]
			if id != "" && metaOK {
				et.Intents = txnMeta.intents()
			}
			tc.Unlock()

			if intents := ba.GetIntents(); len(intents) > 0 {
				// Writes in Batch, so EndTransaction is fine. Should add
				// outstanding intents to EndTransaction, though.
				// TODO(tschottdorf): possible issues when the batch fails,
				// but the intents have been added anyways.
				// TODO(tschottdorf): some of these intents may be covered
				// by others, for example {[a,b), a}). This can lead to
				// some extra requests when those are non-local to the txn
				// record. But it doesn't seem worth optimizing now.
				et.Intents = append(et.Intents, intents...)
			} else if !metaOK {
				// If we don't have the transaction, then this must be a retry
				// by the client. We can no longer reconstruct a correct
				// request so we must fail.
				//
				// TODO(bdarnell): if we had a GetTransactionStatus API then
				// we could lookup the transaction and return either nil or
				// TransactionAbortedError instead of this ambivalent error.
				return nil, roachpb.NewError(util.Errorf("transaction is already committed or aborted"))
			}
			if len(et.Intents) == 0 {
				// If there aren't any intents, then there's factually no
				// transaction to end. Read-only txns have all of their state in
				// the client.
				return nil, roachpb.NewError(util.Errorf("cannot commit a read-only transaction"))
			}
			if log.V(1) {
				for _, intent := range et.Intents {
					trace.Event(fmt.Sprintf("intent: [%s,%s)", intent.Key, intent.EndKey))
				}
//.........這裏部分代碼省略.........

// resetClientCmdID sets the client command ID if the call is for a
// read-write method. The client command ID provides idempotency
// protection in conjunction with the server.
func resetClientCmdID(ba *roachpb.BatchRequest) {
	ba.CmdID = roachpb.ClientCmdID{
		WallTime: time.Now().UnixNano(),
		Random:   rand.Int63(),
	}
}

// TestTruncateWithSpanAndDescriptor verifies that a batch request is truncated with a
// range span and the range of a descriptor found in cache.
func TestTruncateWithSpanAndDescriptor(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()

	if err := g.SetNodeDescriptor(&roachpb.NodeDescriptor{NodeID: 1}); err != nil {
		t.Fatal(err)
	}
	nd := &roachpb.NodeDescriptor{
		NodeID:  roachpb.NodeID(1),
		Address: util.MakeUnresolvedAddr(testAddress.Network(), testAddress.String()),
	}
	if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(1)), nd, time.Hour); err != nil {
		t.Fatal(err)
	}

	// Fill mockRangeDescriptorDB with two descriptors. When a
	// range descriptor is looked up by key "b", return the second
	// descriptor whose range is ["a", "c") and partially overlaps
	// with the first descriptor's range.
	var descriptor1 = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKeyMin,
		EndKey:   roachpb.RKey("b"),
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	var descriptor2 = roachpb.RangeDescriptor{
		RangeID:  2,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("c"),
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	descDB := mockRangeDescriptorDB(func(key roachpb.RKey, _ lookupOptions) ([]roachpb.RangeDescriptor, error) {
		desc := descriptor1
		if key.Equal(roachpb.RKey("b")) {
			desc = descriptor2
		}
		return []roachpb.RangeDescriptor{desc}, nil
	})

	// Define our rpcSend stub which checks the span of the batch
	// requests. The first request should be the point request on
	// "a". The second request should be on "b".
	first := true
	var testFn rpcSendFn = func(_ rpc.Options, method string, addrs []net.Addr, getArgs func(addr net.Addr) proto.Message, getReply func() proto.Message, _ *rpc.Context) ([]proto.Message, error) {
		if method != "Node.Batch" {
			return nil, util.Errorf("unexpected method %v", method)
		}

		ba := getArgs(testAddress).(*roachpb.BatchRequest)
		rs := keys.Range(*ba)
		if first {
			if !(rs.Key.Equal(roachpb.RKey("a")) && rs.EndKey.Equal(roachpb.RKey("a").Next())) {
				t.Errorf("Unexpected span [%s,%s)", rs.Key, rs.EndKey)
			}
			first = false
		} else {
			if !(rs.Key.Equal(roachpb.RKey("b")) && rs.EndKey.Equal(roachpb.RKey("b").Next())) {
				t.Errorf("Unexpected span [%s,%s)", rs.Key, rs.EndKey)
			}
		}

		batchReply := getReply().(*roachpb.BatchResponse)
		reply := &roachpb.PutResponse{}
		batchReply.Add(reply)
		return []proto.Message{batchReply}, nil
	}

	ctx := &DistSenderContext{
		RPCSend:           testFn,
		RangeDescriptorDB: descDB,
	}
	ds := NewDistSender(ctx, g)

	// Send a batch request contains two puts. In the first
	// attempt, the range of the descriptor found in the cache is
	// ["a", "b"). The request is truncated to contain only the put
	// on "a".
	//
	// In the second attempt, The range of the descriptor found in
	// the cache is ["a", c"), but the put on "a" will not be
	// resent. The request is truncated to contain only the put on "b".
	ba := roachpb.BatchRequest{}
	ba.CmdID = ba.GetOrCreateCmdID(0)
	ba.Txn = &roachpb.Transaction{Name: "test"}
	val := roachpb.MakeValueFromString("val")
	ba.Add(roachpb.NewPut(keys.RangeTreeNodeKey(roachpb.RKey("a")), val).(*roachpb.PutRequest))
	ba.Add(roachpb.NewPut(keys.RangeTreeNodeKey(roachpb.RKey("b")), val).(*roachpb.PutRequest))
//.........這裏部分代碼省略.........

//.........這裏部分代碼省略.........
					}
					// With an active intent, GC ignores MVCC metadata & intent value.
					startIdx = 2
				}
				// See if any values may be GC'd.
				if gcTS := gc.Filter(keys[startIdx:], vals[startIdx:]); !gcTS.Equal(roachpb.ZeroTimestamp) {
					// TODO(spencer): need to split the requests up into
					// multiple requests in the event that more than X keys
					// are added to the request.
					gcArgs.Keys = append(gcArgs.Keys, roachpb.GCRequest_GCKey{Key: expBaseKey, Timestamp: gcTS})
				}
			}
		}
	}

	// Iterate through the keys and values of this replica's range.
	for ; iter.Valid(); iter.Next() {
		baseKey, ts, isValue, err := engine.MVCCDecodeKey(iter.Key())
		if err != nil {
			log.Errorf("unable to decode MVCC key: %q: %v", iter.Key(), err)
			continue
		}
		if !isValue {
			// Moving to the next key (& values).
			processKeysAndValues()
			expBaseKey = baseKey
			keys = []roachpb.EncodedKey{iter.Key()}
			vals = [][]byte{iter.Value()}
		} else {
			if !baseKey.Equal(expBaseKey) {
				log.Errorf("unexpectedly found a value for %q with ts=%s; expected key %q", baseKey, ts, expBaseKey)
				continue
			}
			keys = append(keys, iter.Key())
			vals = append(vals, iter.Value())
		}
	}
	if iter.Error() != nil {
		return iter.Error()
	}
	// Handle last collected set of keys/vals.
	processKeysAndValues()

	// Process push transactions in parallel.
	var wg sync.WaitGroup
	for _, txn := range txnMap {
		wg.Add(1)
		go gcq.pushTxn(repl, now, txn, updateOldestIntent, &wg)
	}
	wg.Wait()

	// Resolve all intents.
	var intents []roachpb.Intent
	for id, txn := range txnMap {
		if txn.Status != roachpb.PENDING {
			for _, intent := range intentMap[id] {
				intent.Txn = *txn
				intents = append(intents, intent)
			}
		}
	}

	done := true
	if len(intents) > 0 {
		done = false
		repl.resolveIntents(repl.context(), intents)
	}

	// Set start and end keys.
	if len(gcArgs.Keys) > 0 {
		done = false
		gcArgs.Key = gcArgs.Keys[0].Key
		gcArgs.EndKey = gcArgs.Keys[len(gcArgs.Keys)-1].Key.Next()
	}

	if done {
		return nil
	}

	// Send GC request through range.
	gcMeta.OldestIntentNanos = proto.Int64(oldestIntentNanos)
	gcArgs.GCMeta = *gcMeta

	var ba roachpb.BatchRequest
	ba.CmdID = ba.GetOrCreateCmdID(now.WallTime)
	// Technically not needed since we're talking directly to the Range.
	ba.RangeID = desc.RangeID
	ba.Add(gcArgs)
	if _, pErr := repl.Send(repl.context(), ba); pErr != nil {
		return pErr.GoError()
	}

	// Store current timestamp as last verification for this replica, as
	// we've just successfully scanned.
	if err := repl.SetLastVerificationTimestamp(now); err != nil {
		log.Errorf("failed to set last verification timestamp for replica %s: %s", repl, err)
	}

	return nil
}