Golang Trace.Fork方法代码示例

// close sends resolve intent commands for all key ranges this
// transaction has covered, clears the keys cache and closes the
// metadata heartbeat. Any keys listed in the resolved slice have
// already been resolved and do not receive resolve intent commands.
func (tm *txnMetadata) close(trace *tracer.Trace, txn *proto.Transaction, resolved []proto.Key, sender client.Sender, stopper *stop.Stopper) {
	close(tm.txnEnd) // stop heartbeat
	trace.Event("coordinator stops")
	if tm.keys.Len() > 0 {
		if log.V(2) {
			log.Infof("cleaning up %d intent(s) for transaction %s", tm.keys.Len(), txn)
		}
	}
	// TODO(tschottdorf): Should create a Batch here.
	for _, o := range tm.keys.GetOverlaps(proto.KeyMin, proto.KeyMax) {
		// If the op was range based, end key != start key: resolve a range.
		var call proto.Call
		key := o.Key.Start().(proto.Key)
		endKey := o.Key.End().(proto.Key)
		if !key.Next().Equal(endKey) {
			call.Args = &proto.InternalResolveIntentRangeRequest{
				RequestHeader: proto.RequestHeader{
					Timestamp: txn.Timestamp,
					Key:       key,
					EndKey:    endKey,
					User:      security.RootUser,
					Txn:       txn,
				},
			}
			call.Reply = &proto.InternalResolveIntentRangeResponse{}
		} else {
			// Check if the key has already been resolved; skip if yes.
			found := false
			for _, k := range resolved {
				if key.Equal(k) {
					found = true
				}
			}
			if found {
				continue
			}
			call.Args = &proto.InternalResolveIntentRequest{
				RequestHeader: proto.RequestHeader{
					Timestamp: txn.Timestamp,
					Key:       key,
					User:      security.RootUser,
					Txn:       txn,
				},
			}
			call.Reply = &proto.InternalResolveIntentResponse{}
		}
		// We don't care about the reply channel; these are best
		// effort. We simply fire and forget, each in its own goroutine.
		ctx := tracer.ToCtx(context.Background(), trace.Fork())
		stopper.RunAsyncTask(func() {
			if log.V(2) {
				log.Infof("cleaning up intent %q for txn %s", call.Args.Header().Key, txn)
			}
			sender.Send(ctx, call)
			if call.Reply.Header().Error != nil {
				log.Warningf("failed to cleanup %q intent: %s", call.Args.Header().Key, call.Reply.Header().GoError())
			}
		})
	}
	tm.keys.Clear()
}

// resolve sends resolve intent commands for all key ranges this transaction
// has covered. Any keys listed in the resolved slice have already been
// resolved and are skipped.
func (tm *txnMetadata) resolve(trace *tracer.Trace, resolved []proto.Key, sender client.Sender) {
	txn := &tm.txn
	if tm.keys.Len() > 0 {
		if log.V(2) {
			log.Infof("cleaning up %d intent(s) for transaction %s", tm.keys.Len(), txn)
		}
	}
	// TODO(tschottdorf): Should create a Batch here. However, we're resolving
	// intents and if those are on meta records, there may be a certain order
	// in which they need to be resolved so that they can get routed to the
	// correct range. Since a batch runs its commands one by one and we don't
	// know the correct order, we prefer to fire them off in parallel.
	var wg sync.WaitGroup
	for _, o := range tm.keys.GetOverlaps(proto.KeyMin, proto.KeyMax) {
		// If the op was range based, end key != start key: resolve a range.
		var call proto.Call
		key := o.Key.Start().(proto.Key)
		endKey := o.Key.End().(proto.Key)
		if !key.Next().Equal(endKey) {
			call.Args = &proto.InternalResolveIntentRangeRequest{
				RequestHeader: proto.RequestHeader{
					Timestamp: txn.Timestamp,
					Key:       key,
					EndKey:    endKey,
					User:      security.RootUser,
					Txn:       txn,
				},
			}
			call.Reply = &proto.InternalResolveIntentRangeResponse{}
		} else {
			// Check if the key has already been resolved; skip if yes.
			found := false
			for _, k := range resolved {
				if key.Equal(k) {
					if log.V(2) {
						log.Warningf("skipping previously resolved intent at %q", k)
					}
					found = true
				}
			}
			if found {
				continue
			}
			call.Args = &proto.InternalResolveIntentRequest{
				RequestHeader: proto.RequestHeader{
					Timestamp: txn.Timestamp,
					Key:       key,
					User:      security.RootUser,
					Txn:       txn,
				},
			}
			call.Reply = &proto.InternalResolveIntentResponse{}
		}
		ctx := tracer.ToCtx(context.Background(), trace.Fork())
		if log.V(2) {
			log.Infof("cleaning up intent %q for txn %s", call.Args.Header().Key, txn)
		}
		// Each operation gets their own goroutine. We only want to return to
		// the caller after the operations have finished.
		wg.Add(1)
		go func() {
			sender.Send(ctx, call)
			wg.Done()
			if call.Reply.Header().Error != nil {
				log.Warningf("failed to cleanup %q intent: %s", call.Args.Header().Key, call.Reply.Header().GoError())
			}
		}()
	}
	defer trace.Epoch("waiting for intent resolution")()
	wg.Wait()
	tm.keys.Clear()
}