You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
289 lines
10 KiB
289 lines
10 KiB
package p2p
|
|
|
|
import (
|
|
"fmt"
|
|
"sort"
|
|
"strconv"
|
|
|
|
"github.com/gogo/protobuf/proto"
|
|
tmsync "github.com/tendermint/tendermint/internal/libs/sync"
|
|
"github.com/tendermint/tendermint/libs/log"
|
|
)
|
|
|
|
const defaultCapacity uint = 1048576 // 1MB
|
|
|
|
// wrappedEnvelope wraps a p2p Envelope with its precomputed size.
|
|
type wrappedEnvelope struct {
|
|
envelope Envelope
|
|
size uint
|
|
}
|
|
|
|
// assert the WDDR scheduler implements the queue interface at compile-time
|
|
var _ queue = (*wdrrScheduler)(nil)
|
|
|
|
// wdrrQueue implements a Weighted Deficit Round Robin (WDRR) scheduling
|
|
// algorithm via the queue interface. A WDRR queue is created per peer, where
|
|
// the queue will have N number of flows. Each flow corresponds to a p2p Channel,
|
|
// so there are n input flows and a single output source, the peer's connection.
|
|
//
|
|
// The WDRR scheduler contains a shared buffer with a fixed capacity.
|
|
//
|
|
// Each flow has the following:
|
|
// - quantum: The number of bytes that is added to the deficit counter of the
|
|
// flow in each round. The flow can send at most quantum bytes at a time. Each
|
|
// flow has its own unique quantum, which gives the queue its weighted nature.
|
|
// A higher quantum corresponds to a higher weight/priority. The quantum is
|
|
// computed as MaxSendBytes * Priority.
|
|
// - deficit counter: The number of bytes that the flow is allowed to transmit
|
|
// when it is its turn.
|
|
//
|
|
// See: https://en.wikipedia.org/wiki/Deficit_round_robin
|
|
type wdrrScheduler struct {
|
|
logger log.Logger
|
|
metrics *Metrics
|
|
chDescs []ChannelDescriptor
|
|
capacity uint
|
|
size uint
|
|
chPriorities map[ChannelID]uint
|
|
buffer map[ChannelID][]wrappedEnvelope
|
|
quanta map[ChannelID]uint
|
|
deficits map[ChannelID]uint
|
|
|
|
closer *tmsync.Closer
|
|
doneCh *tmsync.Closer
|
|
|
|
enqueueCh chan Envelope
|
|
dequeueCh chan Envelope
|
|
}
|
|
|
|
func newWDRRScheduler(
|
|
logger log.Logger,
|
|
m *Metrics,
|
|
chDescs []ChannelDescriptor,
|
|
enqueueBuf, dequeueBuf, capacity uint,
|
|
) *wdrrScheduler {
|
|
|
|
// copy each ChannelDescriptor and sort them by channel priority
|
|
chDescsCopy := make([]ChannelDescriptor, len(chDescs))
|
|
copy(chDescsCopy, chDescs)
|
|
sort.Slice(chDescsCopy, func(i, j int) bool { return chDescsCopy[i].Priority > chDescsCopy[j].Priority })
|
|
|
|
var (
|
|
buffer = make(map[ChannelID][]wrappedEnvelope)
|
|
chPriorities = make(map[ChannelID]uint)
|
|
quanta = make(map[ChannelID]uint)
|
|
deficits = make(map[ChannelID]uint)
|
|
)
|
|
|
|
for _, chDesc := range chDescsCopy {
|
|
chID := ChannelID(chDesc.ID)
|
|
chPriorities[chID] = uint(chDesc.Priority)
|
|
buffer[chID] = make([]wrappedEnvelope, 0)
|
|
quanta[chID] = chDesc.MaxSendBytes * uint(chDesc.Priority)
|
|
}
|
|
|
|
return &wdrrScheduler{
|
|
logger: logger.With("queue", "wdrr"),
|
|
metrics: m,
|
|
capacity: capacity,
|
|
chPriorities: chPriorities,
|
|
chDescs: chDescsCopy,
|
|
buffer: buffer,
|
|
quanta: quanta,
|
|
deficits: deficits,
|
|
closer: tmsync.NewCloser(),
|
|
doneCh: tmsync.NewCloser(),
|
|
enqueueCh: make(chan Envelope, enqueueBuf),
|
|
dequeueCh: make(chan Envelope, dequeueBuf),
|
|
}
|
|
}
|
|
|
|
// enqueue returns an unbuffered write-only channel which a producer can send on.
|
|
func (s *wdrrScheduler) enqueue() chan<- Envelope {
|
|
return s.enqueueCh
|
|
}
|
|
|
|
// dequeue returns an unbuffered read-only channel which a consumer can read from.
|
|
func (s *wdrrScheduler) dequeue() <-chan Envelope {
|
|
return s.dequeueCh
|
|
}
|
|
|
|
func (s *wdrrScheduler) closed() <-chan struct{} {
|
|
return s.closer.Done()
|
|
}
|
|
|
|
// close closes the WDRR queue. After this call enqueue() will block, so the
|
|
// caller must select on closed() as well to avoid blocking forever. The
|
|
// enqueue() and dequeue() along with the internal channels will NOT be closed.
|
|
// Note, close() will block until all externally spawned goroutines have exited.
|
|
func (s *wdrrScheduler) close() {
|
|
s.closer.Close()
|
|
<-s.doneCh.Done()
|
|
}
|
|
|
|
// start starts the WDRR queue process in a blocking goroutine. This must be
|
|
// called before the queue can start to process and accept Envelopes.
|
|
func (s *wdrrScheduler) start() {
|
|
go s.process()
|
|
}
|
|
|
|
// process starts a blocking WDRR scheduler process, where we continuously
|
|
// evaluate if we need to attempt to enqueue an Envelope or schedule Envelopes
|
|
// to be dequeued and subsequently read and sent on the source connection.
|
|
// Internally, each p2p Channel maps to a flow, where each flow has a deficit
|
|
// and a quantum.
|
|
//
|
|
// For each Envelope requested to be enqueued, we evaluate if there is sufficient
|
|
// capacity in the shared buffer to add the Envelope. If so, it is added.
|
|
// Otherwise, we evaluate all flows of lower priority where we attempt find an
|
|
// existing Envelope in the shared buffer of sufficient size that can be dropped
|
|
// in place of the incoming Envelope. If there is no such Envelope that can be
|
|
// dropped, then the incoming Envelope is dropped.
|
|
//
|
|
// When there is nothing to be enqueued, we perform the WDRR algorithm and
|
|
// determine which Envelopes can be dequeued. For each Envelope that can be
|
|
// dequeued, it is sent on the dequeueCh. Specifically, for each flow, if it is
|
|
// non-empty, its deficit counter is incremented by its quantum value. Then, the
|
|
// value of the deficit counter is a maximal amount of bytes that can be sent at
|
|
// this round. If the deficit counter is greater than the Envelopes's message
|
|
// size at the head of the queue (HoQ), this envelope can be sent and the value
|
|
// of the counter is decremented by the message's size. Then, the size of the
|
|
// next Envelopes's message is compared to the counter value, etc. Once the flow
|
|
// is empty or the value of the counter is insufficient, the scheduler will skip
|
|
// to the next flow. If the flow is empty, the value of the deficit counter is
|
|
// reset to 0.
|
|
//
|
|
// XXX/TODO: Evaluate the single goroutine scheduler mechanism. In other words,
|
|
// evaluate the effectiveness and performance of having a single goroutine
|
|
// perform handling both enqueueing and dequeueing logic. Specifically, there
|
|
// is potentially contention between reading off of enqueueCh and trying to
|
|
// enqueue while also attempting to perform the WDRR algorithm and find the next
|
|
// set of Envelope(s) to send on the dequeueCh. Alternatively, we could consider
|
|
// separate scheduling goroutines, but then that requires the use of mutexes and
|
|
// possibly a degrading performance.
|
|
func (s *wdrrScheduler) process() {
|
|
defer s.doneCh.Close()
|
|
|
|
for {
|
|
select {
|
|
case <-s.closer.Done():
|
|
return
|
|
|
|
case e := <-s.enqueueCh:
|
|
// attempt to enqueue the incoming Envelope
|
|
chIDStr := strconv.Itoa(int(e.channelID))
|
|
wEnv := wrappedEnvelope{envelope: e, size: uint(proto.Size(e.Message))}
|
|
msgSize := wEnv.size
|
|
|
|
s.metrics.PeerPendingSendBytes.With("peer_id", string(e.To)).Add(float64(msgSize))
|
|
|
|
// If we're at capacity, we need to either drop the incoming Envelope or
|
|
// an Envelope from a lower priority flow. Otherwise, we add the (wrapped)
|
|
// envelope to the flow's queue.
|
|
if s.size+wEnv.size > s.capacity {
|
|
chPriority := s.chPriorities[e.channelID]
|
|
|
|
var (
|
|
canDrop bool
|
|
dropIdx int
|
|
dropChID ChannelID
|
|
)
|
|
|
|
// Evaluate all lower priority flows and determine if there exists an
|
|
// Envelope that is of equal or greater size that we can drop in favor
|
|
// of the incoming Envelope.
|
|
for i := len(s.chDescs) - 1; i >= 0 && uint(s.chDescs[i].Priority) < chPriority && !canDrop; i-- {
|
|
currChID := ChannelID(s.chDescs[i].ID)
|
|
flow := s.buffer[currChID]
|
|
|
|
for j := 0; j < len(flow) && !canDrop; j++ {
|
|
if flow[j].size >= wEnv.size {
|
|
canDrop = true
|
|
dropIdx = j
|
|
dropChID = currChID
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
// If we can drop an existing Envelope, drop it and enqueue the incoming
|
|
// Envelope.
|
|
if canDrop {
|
|
chIDStr = strconv.Itoa(int(dropChID))
|
|
chPriority = s.chPriorities[dropChID]
|
|
msgSize = s.buffer[dropChID][dropIdx].size
|
|
|
|
// Drop Envelope for the lower priority flow and update the queue's
|
|
// buffer size
|
|
s.size -= msgSize
|
|
s.buffer[dropChID] = append(s.buffer[dropChID][:dropIdx], s.buffer[dropChID][dropIdx+1:]...)
|
|
|
|
// add the incoming Envelope and update queue's buffer size
|
|
s.size += wEnv.size
|
|
s.buffer[e.channelID] = append(s.buffer[e.channelID], wEnv)
|
|
s.metrics.PeerQueueMsgSize.With("ch_id", chIDStr).Set(float64(wEnv.size))
|
|
}
|
|
|
|
// We either dropped the incoming Enevelope or one from an existing
|
|
// lower priority flow.
|
|
s.metrics.PeerQueueDroppedMsgs.With("ch_id", chIDStr).Add(1)
|
|
s.logger.Debug(
|
|
"dropped envelope",
|
|
"ch_id", chIDStr,
|
|
"priority", chPriority,
|
|
"capacity", s.capacity,
|
|
"msg_size", msgSize,
|
|
)
|
|
} else {
|
|
// we have sufficient capacity to enqueue the incoming Envelope
|
|
s.metrics.PeerQueueMsgSize.With("ch_id", chIDStr).Set(float64(wEnv.size))
|
|
s.buffer[e.channelID] = append(s.buffer[e.channelID], wEnv)
|
|
s.size += wEnv.size
|
|
}
|
|
|
|
default:
|
|
// perform the WDRR algorithm
|
|
for _, chDesc := range s.chDescs {
|
|
chID := ChannelID(chDesc.ID)
|
|
|
|
// only consider non-empty flows
|
|
if len(s.buffer[chID]) > 0 {
|
|
// bump flow's quantum
|
|
s.deficits[chID] += s.quanta[chID]
|
|
|
|
// grab the flow's current deficit counter and HoQ (wrapped) Envelope
|
|
d := s.deficits[chID]
|
|
we := s.buffer[chID][0]
|
|
|
|
// While the flow is non-empty and we can send the current Envelope
|
|
// on the dequeueCh:
|
|
//
|
|
// 1. send the Envelope
|
|
// 2. update the scheduler's shared buffer's size
|
|
// 3. update the flow's deficit
|
|
// 4. remove from the flow's queue
|
|
// 5. grab the next HoQ Envelope and flow's deficit
|
|
for len(s.buffer[chID]) > 0 && d >= we.size {
|
|
s.metrics.PeerSendBytesTotal.With(
|
|
"chID", fmt.Sprint(chID),
|
|
"peer_id", string(we.envelope.To)).Add(float64(we.size))
|
|
s.dequeueCh <- we.envelope
|
|
s.size -= we.size
|
|
s.deficits[chID] -= we.size
|
|
s.buffer[chID] = s.buffer[chID][1:]
|
|
|
|
if len(s.buffer[chID]) > 0 {
|
|
d = s.deficits[chID]
|
|
we = s.buffer[chID][0]
|
|
}
|
|
}
|
|
}
|
|
|
|
// reset the flow's deficit to zero if it is empty
|
|
if len(s.buffer[chID]) == 0 {
|
|
s.deficits[chID] = 0
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|