Improve federation sender performance and behaviour, add backoff

This commit is contained in:
Neil Alexander 2020-05-05 13:20:48 +01:00
parent 9d15312ef6
commit c4ee20c95e
2 changed files with 192 additions and 63 deletions

View file

@ -18,6 +18,7 @@ import (
"context"
"encoding/json"
"fmt"
"math"
"sync"
"time"
@ -28,33 +29,91 @@ import (
"go.uber.org/atomic"
)
const (
// How many times should we tolerate consecutive failures before we
// just blacklist the host altogether? Bear in mind that the backoff
// is exponential, so the max time here to attempt is 2**failures.
FailuresUntilBlacklist = 16
)
// destinationQueue is a queue of events for a single destination.
// It is responsible for sending the events to the destination and
// ensures that only one request is in flight to a given destination
// at a time.
type destinationQueue struct {
rsProducer *producers.RoomserverProducer
client *gomatrixserverlib.FederationClient
origin gomatrixserverlib.ServerName
destination gomatrixserverlib.ServerName
running atomic.Bool
// The running mutex protects sentCounter, lastTransactionIDs and
// pendingEvents, pendingEDUs.
runningMutex sync.Mutex
sentCounter int
lastTransactionIDs []gomatrixserverlib.TransactionID
pendingEvents []*gomatrixserverlib.HeaderedEvent
pendingEDUs []*gomatrixserverlib.EDU
pendingInvites []*gomatrixserverlib.InviteV2Request
rsProducer *producers.RoomserverProducer //
client *gomatrixserverlib.FederationClient //
origin gomatrixserverlib.ServerName //
destination gomatrixserverlib.ServerName //
running atomic.Bool // is the queue worke running?
blacklisted atomic.Bool // is the remote side dead?
backoffUntil atomic.Value // time.Time
idleCounter atomic.Uint32 // how many ticks have we done nothing?
failCounter atomic.Uint32 // how many times have we failed?
sentCounter atomic.Uint32 // how many times have we succeeded?
runningMutex sync.RWMutex // protects the below
lastTransactionIDs []gomatrixserverlib.TransactionID // protected by runningMutex
pendingPDUs []*gomatrixserverlib.HeaderedEvent // protected by runningMutex
pendingEDUs []*gomatrixserverlib.EDU // protected by runningMutex
pendingInvites []*gomatrixserverlib.InviteV2Request // protected by runningMutex
}
// Backoff marks a failure and works out when to back off until. It
// returns true if the worker should give up altogether because of
// too many consecutive failures.
func (oq *destinationQueue) backoff() bool {
// Increase the fail counter.
failCounter := oq.failCounter.Load()
failCounter++
oq.failCounter.Store(failCounter)
// Check that we haven't failed more times than is acceptable.
if failCounter < FailuresUntilBlacklist {
// We're still under the threshold so work out the exponential
// backoff based on how many times we have failed already. The
// worker goroutine will wait until this time before processing
// anything from the queue.
backoffSeconds := math.Exp2(float64(failCounter))
oq.backoffUntil.Store(
time.Now().Add(time.Second * time.Duration(backoffSeconds)),
)
return false // Don't give up yet.
} else {
// We've exceeded the maximum amount of times we're willing
// to back off, which is probably in the region of hours by
// now. Just give up - clear the queues and reset the queue
// back to its default state.
oq.blacklisted.Store(true)
oq.runningMutex.Lock()
oq.pendingPDUs = nil
oq.pendingEDUs = nil
oq.pendingInvites = nil
oq.runningMutex.Unlock()
return true // Give up.
}
}
func (oq *destinationQueue) success() {
// Reset the idle and fail counters.
oq.idleCounter.Store(0)
oq.failCounter.Store(0)
// Increase the sent counter.
sentCounter := oq.failCounter.Load()
oq.sentCounter.Store(sentCounter + 1)
}
// Send event adds the event to the pending queue for the destination.
// If the queue is empty then it starts a background goroutine to
// start sending events to that destination.
func (oq *destinationQueue) sendEvent(ev *gomatrixserverlib.HeaderedEvent) {
if oq.blacklisted.Load() {
// If the destination is blacklisted then drop the event.
return
}
oq.runningMutex.Lock()
defer oq.runningMutex.Unlock()
oq.pendingEvents = append(oq.pendingEvents, ev)
oq.pendingPDUs = append(oq.pendingPDUs, ev)
oq.runningMutex.Unlock()
if !oq.running.Load() {
go oq.backgroundSend()
}
@ -64,9 +123,13 @@ func (oq *destinationQueue) sendEvent(ev *gomatrixserverlib.HeaderedEvent) {
// If the queue is empty then it starts a background goroutine to
// start sending events to that destination.
func (oq *destinationQueue) sendEDU(e *gomatrixserverlib.EDU) {
if oq.blacklisted.Load() {
// If the destination is blacklisted then drop the event.
return
}
oq.runningMutex.Lock()
defer oq.runningMutex.Unlock()
oq.pendingEDUs = append(oq.pendingEDUs, e)
oq.runningMutex.Unlock()
if !oq.running.Load() {
go oq.backgroundSend()
}
@ -76,9 +139,13 @@ func (oq *destinationQueue) sendEDU(e *gomatrixserverlib.EDU) {
// destination. If the queue is empty then it starts a background
// goroutine to start sending events to that destination.
func (oq *destinationQueue) sendInvite(ev *gomatrixserverlib.InviteV2Request) {
if oq.blacklisted.Load() {
// If the destination is blacklisted then drop the event.
return
}
oq.runningMutex.Lock()
defer oq.runningMutex.Unlock()
oq.pendingInvites = append(oq.pendingInvites, ev)
oq.runningMutex.Unlock()
if !oq.running.Load() {
go oq.backgroundSend()
}
@ -86,39 +153,104 @@ func (oq *destinationQueue) sendInvite(ev *gomatrixserverlib.InviteV2Request) {
// backgroundSend is the worker goroutine for sending events.
func (oq *destinationQueue) backgroundSend() {
// Mark the worker as running for its lifetime.
oq.running.Store(true)
defer oq.running.Store(false)
for {
transaction, invites := oq.nextTransaction(), oq.nextInvites()
if !transaction && !invites {
// If the queue is empty then stop processing for this destination.
// TODO: Remove this destination from the queue map.
return
// Wait for our backoff timer.
backoffUntil := time.Now()
if b, ok := oq.backoffUntil.Load().(time.Time); ok {
backoffUntil = b
}
if backoffUntil.After(time.Now()) {
<-time.After(time.Until(backoffUntil))
}
// TODO: handle retries.
// TODO: blacklist uncooperative servers.
// Retrieve any waiting things.
oq.runningMutex.RLock()
pendingPDUs, pendingEDUs := oq.pendingPDUs, oq.pendingEDUs
pendingInvites := oq.pendingInvites
idleCounter, sentCounter := oq.idleCounter.Load(), oq.sentCounter.Load()
oq.runningMutex.RUnlock()
// If we have pending PDUs or EDUs then construct a transaction.
if len(pendingPDUs) > 0 || len(pendingEDUs) > 0 {
// Try sending the next transaction and see what happens.
transaction, terr := oq.nextTransaction(pendingPDUs, pendingEDUs, sentCounter)
if terr != nil {
// We failed to send the transaction.
if giveUp := oq.backoff(); giveUp {
// It's been suggested that we should give up because
// the backoff has exceeded a maximum allowable value.
return
}
continue
}
// If we successfully sent the transaction then clear out
// the pending events and EDUs.
if transaction {
oq.success()
oq.runningMutex.Lock()
oq.pendingPDUs = oq.pendingPDUs[:0]
oq.pendingEDUs = oq.pendingEDUs[:0]
oq.runningMutex.Unlock()
}
}
// Try sending the next invite and see what happens.
if len(pendingInvites) > 0 {
invites, ierr := oq.nextInvites(pendingInvites)
if ierr != nil {
// We failed to send the transaction so increase the
// backoff and give it another go shortly.
oq.backoffUntil.Store(time.Until(backoffUntil) * 2)
continue
}
// If we successfully sent the invites then clear out
// the pending invites.
if invites {
oq.success()
oq.runningMutex.Lock()
oq.pendingInvites = oq.pendingInvites[:0]
oq.runningMutex.Unlock()
}
}
// At this point, if we did everything successfully,
// we can reset the backoff duration.
if idleCounter >= 5 {
// If this worker has been idle for a while then stop
// running it, otherwise the goroutine will just tick
// endlessly. It'll get automatically restarted when
// a new event needs to be sent.
return
} else {
// Otherwise, add to the ticker counter and ask the
// next iteration to wait for a second (to stop CPU
// spinning).
oq.idleCounter.Store(idleCounter + 1)
oq.backoffUntil.Store(time.Now().Add(time.Second))
}
}
}
// nextTransaction creates a new transaction from the pending event
// queue and sends it. Returns true if a transaction was sent or
// false otherwise.
func (oq *destinationQueue) nextTransaction() bool {
oq.runningMutex.Lock()
defer oq.runningMutex.Unlock()
if len(oq.pendingEvents) == 0 && len(oq.pendingEDUs) == 0 {
return false
}
func (oq *destinationQueue) nextTransaction(
pendingPDUs []*gomatrixserverlib.HeaderedEvent,
pendingEDUs []*gomatrixserverlib.EDU,
sentCounter uint32,
) (bool, error) {
t := gomatrixserverlib.Transaction{
PDUs: []json.RawMessage{},
EDUs: []gomatrixserverlib.EDU{},
}
now := gomatrixserverlib.AsTimestamp(time.Now())
t.TransactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.sentCounter))
t.TransactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, sentCounter))
t.Origin = oq.origin
t.Destination = oq.destination
t.OriginServerTS = now
@ -129,19 +261,15 @@ func (oq *destinationQueue) nextTransaction() bool {
oq.lastTransactionIDs = []gomatrixserverlib.TransactionID{t.TransactionID}
for _, pdu := range oq.pendingEvents {
for _, pdu := range pendingPDUs {
// Append the JSON of the event, since this is a json.RawMessage type in the
// gomatrixserverlib.Transaction struct
t.PDUs = append(t.PDUs, (*pdu).JSON())
}
oq.pendingEvents = nil
oq.sentCounter += len(t.PDUs)
for _, edu := range oq.pendingEDUs {
for _, edu := range pendingEDUs {
t.EDUs = append(t.EDUs, *edu)
}
oq.pendingEDUs = nil
oq.sentCounter += len(t.EDUs)
util.GetLogger(context.TODO()).Infof("Sending transaction %q containing %d PDUs, %d EDUs", t.TransactionID, len(t.PDUs), len(t.EDUs))
@ -151,22 +279,18 @@ func (oq *destinationQueue) nextTransaction() bool {
"destination": oq.destination,
log.ErrorKey: err,
}).Info("problem sending transaction")
return false, err
}
return true
return true, nil
}
// nextInvite takes pending invite events from the queue and sends
// them. Returns true if a transaction was sent or false otherwise.
func (oq *destinationQueue) nextInvites() bool {
oq.runningMutex.Lock()
defer oq.runningMutex.Unlock()
if len(oq.pendingInvites) == 0 {
return false
}
for _, inviteReq := range oq.pendingInvites {
func (oq *destinationQueue) nextInvites(
pendingInvites []*gomatrixserverlib.InviteV2Request,
) (bool, error) {
for _, inviteReq := range pendingInvites {
ev, roomVersion := inviteReq.Event(), inviteReq.RoomVersion()
log.WithFields(log.Fields{
@ -186,7 +310,7 @@ func (oq *destinationQueue) nextInvites() bool {
"state_key": ev.StateKey(),
"destination": oq.destination,
}).WithError(err).Error("failed to send invite")
continue
return false, err
}
if _, err = oq.rsProducer.SendInviteResponse(
@ -199,10 +323,9 @@ func (oq *destinationQueue) nextInvites() bool {
"state_key": ev.StateKey(),
"destination": oq.destination,
}).WithError(err).Error("failed to return signed invite to roomserver")
return false, err
}
}
oq.pendingInvites = nil
return true
return true, nil
}

View file

@ -30,7 +30,7 @@ type OutgoingQueues struct {
origin gomatrixserverlib.ServerName
client *gomatrixserverlib.FederationClient
// The queuesMutex protects queues
queuesMutex sync.Mutex
queuesMutex sync.RWMutex
queues map[gomatrixserverlib.ServerName]*destinationQueue
}
@ -68,10 +68,10 @@ func (oqs *OutgoingQueues) SendEvent(
"destinations": destinations, "event": ev.EventID(),
}).Info("Sending event")
oqs.queuesMutex.Lock()
defer oqs.queuesMutex.Unlock()
for _, destination := range destinations {
oqs.queuesMutex.RLock()
oq := oqs.queues[destination]
oqs.queuesMutex.RUnlock()
if oq == nil {
oq = &destinationQueue{
rsProducer: oqs.rsProducer,
@ -79,10 +79,12 @@ func (oqs *OutgoingQueues) SendEvent(
destination: destination,
client: oqs.client,
}
oqs.queuesMutex.Lock()
oqs.queues[destination] = oq
oqs.queuesMutex.Unlock()
}
oq.sendEvent(ev)
go oq.sendEvent(ev)
}
return nil
@ -114,9 +116,9 @@ func (oqs *OutgoingQueues) SendInvite(
"event_id": ev.EventID(),
}).Info("Sending invite")
oqs.queuesMutex.Lock()
defer oqs.queuesMutex.Unlock()
oqs.queuesMutex.RLock()
oq := oqs.queues[destination]
oqs.queuesMutex.RUnlock()
if oq == nil {
oq = &destinationQueue{
rsProducer: oqs.rsProducer,
@ -124,10 +126,12 @@ func (oqs *OutgoingQueues) SendInvite(
destination: destination,
client: oqs.client,
}
oqs.queuesMutex.Lock()
oqs.queues[destination] = oq
oqs.queuesMutex.Unlock()
}
oq.sendInvite(inviteReq)
go oq.sendInvite(inviteReq)
return nil
}
@ -154,10 +158,10 @@ func (oqs *OutgoingQueues) SendEDU(
}).Info("Sending EDU event")
}
oqs.queuesMutex.Lock()
defer oqs.queuesMutex.Unlock()
for _, destination := range destinations {
oqs.queuesMutex.RLock()
oq := oqs.queues[destination]
oqs.queuesMutex.RUnlock()
if oq == nil {
oq = &destinationQueue{
rsProducer: oqs.rsProducer,
@ -165,10 +169,12 @@ func (oqs *OutgoingQueues) SendEDU(
destination: destination,
client: oqs.client,
}
oqs.queuesMutex.Lock()
oqs.queues[destination] = oq
oqs.queuesMutex.Unlock()
}
oq.sendEDU(e)
go oq.sendEDU(e)
}
return nil