func generateUniqueBytes(nodeID roachpb.NodeID) DBytes {
// Unique bytes are composed of the current time in nanoseconds and the
// node-id. If the nanosecond value is the same on two consecutive calls to
// timeutil.Now() the nanoseconds value is incremented. The node-id is varint
// encoded. Since node-ids are allocated consecutively starting at 1, the
// node-id field will consume 1 or 2 bytes for any reasonably sized cluster.
//
// TODO(pmattis): Do we have to worry about persisting the milliseconds value
// periodically to avoid the clock ever going backwards (e.g. due to NTP
// adjustment)?
nanos := uint64(timeutil.Now().UnixNano())
uniqueBytesState.Lock()
if nanos <= uniqueBytesState.nanos {
nanos = uniqueBytesState.nanos + 1
}
uniqueBytesState.nanos = nanos
uniqueBytesState.Unlock()
b := make([]byte, 0, 8+binary.MaxVarintLen32)
b = encoding.EncodeUint64Ascending(b, nanos)
// We use binary.PutUvarint instead of encoding.EncodeUvarint because the
// former uses less space for values < 128 which is a common occurrence for
// node IDs.
n := binary.PutUvarint(b[len(b):len(b)+binary.MaxVarintLen32], uint64(nodeID))
return DBytes(b[:len(b)+n])
}
// SimulateNetwork runs until the simCallback returns false.
//
// At each cycle, every node gossips a key equal to its address (unique)
// with the cycle as the value. The received cycle value can be used
// to determine the aging of information between any two nodes in the
// network.
//
// At each cycle of the simulation, node 0 gossips the sentinel.
//
// The simulation callback receives the cycle and the network as arguments.
func (n *Network) SimulateNetwork(simCallback func(cycle int, network *Network) bool) {
n.Start()
nodes := n.Nodes
for cycle := 1; ; cycle++ {
// Node 0 gossips sentinel & cluster ID every cycle.
if err := nodes[0].Gossip.AddInfo(
gossip.KeySentinel,
encoding.EncodeUint64Ascending(nil, uint64(cycle)),
time.Hour,
); err != nil {
log.Fatal(context.TODO(), err)
}
if err := nodes[0].Gossip.AddInfo(
gossip.KeyClusterID,
encoding.EncodeUint64Ascending(nil, uint64(cycle)),
0*time.Second,
); err != nil {
log.Fatal(context.TODO(), err)
}
// Every node gossips every cycle.
for _, node := range nodes {
if err := node.Gossip.AddInfo(
node.Addr().String(),
encoding.EncodeUint64Ascending(nil, uint64(cycle)),
time.Hour,
); err != nil {
log.Fatal(context.TODO(), err)
}
node.Gossip.SimulationCycle()
}
// If the simCallback returns false, we're done with the
// simulation; exit the loop. This condition is tested here
// instead of in the for statement in order to guarantee
// we run at least one iteration of this loop in order to
// gossip the cluster ID and sentinel.
if !simCallback(cycle, n) {
break
}
time.Sleep(5 * time.Millisecond)
}
log.Infof(context.TODO(), "gossip network simulation: total infos sent=%d, received=%d", n.infosSent(), n.infosReceived())
}
// StartNode initializes a gossip instance for the simulation node and
// starts it.
func (n *Network) StartNode(node *Node) error {
node.Gossip.Start(node.Addr())
node.Gossip.EnableSimulationCycler(true)
n.nodeIDAllocator++
node.Gossip.NodeID.Set(context.TODO(), n.nodeIDAllocator)
if err := node.Gossip.SetNodeDescriptor(&roachpb.NodeDescriptor{
NodeID: node.Gossip.NodeID.Get(),
Address: util.MakeUnresolvedAddr(node.Addr().Network(), node.Addr().String()),
}); err != nil {
return err
}
if err := node.Gossip.AddInfo(node.Addr().String(),
encoding.EncodeUint64Ascending(nil, 0), time.Hour); err != nil {
return err
}
n.Stopper.RunWorker(func() {
netutil.FatalIfUnexpected(node.Server.Serve(node.Listener))
})
return nil
}
// RaftLogKey returns a system-local key for a Raft log entry.
func RaftLogKey(rangeID roachpb.RangeID, logIndex uint64) roachpb.Key {
key := RaftLogPrefix(rangeID)
key = encoding.EncodeUint64Ascending(key, logIndex)
return key
}
// SetFloat encodes the specified float64 value into the bytes field of the
// receiver, sets the tag and clears the checksum.
func (v *Value) SetFloat(f float64) {
v.RawBytes = make([]byte, headerSize+8)
encoding.EncodeUint64Ascending(v.RawBytes[headerSize:headerSize], math.Float64bits(f))
v.setTag(ValueType_FLOAT)
}