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dendrite/federationapi/queue/destinationqueue.go
2022-02-08 16:49:49 +00:00

448 lines
16 KiB
Go

// Copyright 2017 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package queue
import (
"context"
"encoding/json"
"fmt"
"sync"
"time"
"github.com/matrix-org/dendrite/federationapi/statistics"
"github.com/matrix-org/dendrite/federationapi/storage"
"github.com/matrix-org/dendrite/federationapi/storage/shared"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/setup/process"
"github.com/matrix-org/gomatrix"
"github.com/matrix-org/gomatrixserverlib"
"github.com/sirupsen/logrus"
"go.uber.org/atomic"
)
const (
maxPDUsPerTransaction = 50
maxEDUsPerTransaction = 50
maxPDUsInMemory = 128
maxEDUsInMemory = 128
queueIdleTimeout = time.Second * 30
)
// 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 {
queues *OutgoingQueues
db storage.Database
process *process.ProcessContext
signing *SigningInfo
rsAPI api.RoomserverInternalAPI
client *gomatrixserverlib.FederationClient // federation client
origin gomatrixserverlib.ServerName // origin of requests
destination gomatrixserverlib.ServerName // destination of requests
running atomic.Bool // is the queue worker running?
backingOff atomic.Bool // true if we're backing off
overflowed atomic.Bool // the queues exceed maxPDUsInMemory/maxEDUsInMemory, so we should consult the database for more
statistics *statistics.ServerStatistics // statistics about this remote server
transactionIDMutex sync.Mutex // protects transactionID
transactionID gomatrixserverlib.TransactionID // last transaction ID if retrying, or "" if last txn was successful
notify chan struct{} // interrupts idle wait pending PDUs/EDUs
pendingPDUs []*queuedPDU // PDUs waiting to be sent
pendingEDUs []*queuedEDU // EDUs waiting to be sent
pendingMutex sync.RWMutex // protects pendingPDUs and pendingEDUs
interruptBackoff chan bool // interrupts backoff
}
// 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(event *gomatrixserverlib.HeaderedEvent, receipt *shared.Receipt) {
if event == nil {
logrus.Errorf("attempt to send nil PDU with destination %q", oq.destination)
return
}
// Create a database entry that associates the given PDU NID with
// this destination queue. We'll then be able to retrieve the PDU
// later.
if err := oq.db.AssociatePDUWithDestination(
context.TODO(),
"", // TODO: remove this, as we don't need to persist the transaction ID
oq.destination, // the destination server name
receipt, // NIDs from federationapi_queue_json table
); err != nil {
logrus.WithError(err).Errorf("failed to associate PDU %q with destination %q", event.EventID(), oq.destination)
return
}
// Check if the destination is blacklisted. If it isn't then wake
// up the queue.
if !oq.statistics.Blacklisted() {
// If there's room in memory to hold the event then add it to the
// list.
oq.pendingMutex.Lock()
if len(oq.pendingPDUs) < maxPDUsInMemory {
oq.pendingPDUs = append(oq.pendingPDUs, &queuedPDU{
pdu: event,
receipt: receipt,
})
} else {
oq.overflowed.Store(true)
}
oq.pendingMutex.Unlock()
// Wake up the queue if it's asleep.
oq.wakeQueueIfNeeded()
select {
case oq.notify <- struct{}{}:
default:
}
}
}
// sendEDU adds the EDU 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) sendEDU(event *gomatrixserverlib.EDU, receipt *shared.Receipt) {
if event == nil {
logrus.Errorf("attempt to send nil EDU with destination %q", oq.destination)
return
}
// Create a database entry that associates the given PDU NID with
// this destination queue. We'll then be able to retrieve the PDU
// later.
if err := oq.db.AssociateEDUWithDestination(
context.TODO(),
oq.destination, // the destination server name
receipt, // NIDs from federationapi_queue_json table
); err != nil {
logrus.WithError(err).Errorf("failed to associate EDU with destination %q", oq.destination)
return
}
// Check if the destination is blacklisted. If it isn't then wake
// up the queue.
if !oq.statistics.Blacklisted() {
// If there's room in memory to hold the event then add it to the
// list.
oq.pendingMutex.Lock()
if len(oq.pendingEDUs) < maxEDUsInMemory {
oq.pendingEDUs = append(oq.pendingEDUs, &queuedEDU{
edu: event,
receipt: receipt,
})
} else {
oq.overflowed.Store(true)
}
oq.pendingMutex.Unlock()
// Wake up the queue if it's asleep.
oq.wakeQueueIfNeeded()
select {
case oq.notify <- struct{}{}:
default:
}
}
}
// wakeQueueIfNeeded will wake up the destination queue if it is
// not already running. If it is running but it is backing off
// then we will interrupt the backoff, causing any federation
// requests to retry.
func (oq *destinationQueue) wakeQueueIfNeeded() {
// If we are backing off then interrupt the backoff.
if oq.backingOff.CAS(true, false) {
oq.interruptBackoff <- true
}
// If we aren't running then wake up the queue.
if !oq.running.Load() {
// Start the queue.
go oq.backgroundSend()
}
}
// getPendingFromDatabase will look at the database and see if
// there are any persisted events that haven't been sent to this
// destination yet. If so, they will be queued up.
func (oq *destinationQueue) getPendingFromDatabase() {
// Check to see if there's anything to do for this server
// in the database.
retrieved := false
ctx := context.Background()
oq.pendingMutex.Lock()
defer oq.pendingMutex.Unlock()
// Take a note of all of the PDUs and EDUs that we already
// have cached. We will index them based on the receipt,
// which ultimately just contains the index of the PDU/EDU
// in the database.
gotPDUs := map[string]struct{}{}
gotEDUs := map[string]struct{}{}
for _, pdu := range oq.pendingPDUs {
gotPDUs[pdu.receipt.String()] = struct{}{}
}
for _, edu := range oq.pendingEDUs {
gotEDUs[edu.receipt.String()] = struct{}{}
}
if pduCapacity := maxPDUsInMemory - len(oq.pendingPDUs); pduCapacity > 0 {
// We have room in memory for some PDUs - let's request no more than that.
if pdus, err := oq.db.GetPendingPDUs(ctx, oq.destination, pduCapacity); err == nil {
for receipt, pdu := range pdus {
if _, ok := gotPDUs[receipt.String()]; ok {
continue
}
oq.pendingPDUs = append(oq.pendingPDUs, &queuedPDU{receipt, pdu})
retrieved = true
}
} else {
logrus.WithError(err).Errorf("Failed to get pending PDUs for %q", oq.destination)
}
}
if eduCapacity := maxEDUsInMemory - len(oq.pendingEDUs); eduCapacity > 0 {
// We have room in memory for some EDUs - let's request no more than that.
if edus, err := oq.db.GetPendingEDUs(ctx, oq.destination, eduCapacity); err == nil {
for receipt, edu := range edus {
if _, ok := gotEDUs[receipt.String()]; ok {
continue
}
oq.pendingEDUs = append(oq.pendingEDUs, &queuedEDU{receipt, edu})
retrieved = true
}
} else {
logrus.WithError(err).Errorf("Failed to get pending EDUs for %q", oq.destination)
}
}
// If we've retrieved all of the events from the database with room to spare
// in memory then we'll no longer consider this queue to be overflowed.
if len(oq.pendingPDUs) < maxPDUsInMemory && len(oq.pendingEDUs) < maxEDUsInMemory {
oq.overflowed.Store(false)
}
// If we've retrieved some events then notify the destination queue goroutine.
if retrieved {
select {
case oq.notify <- struct{}{}:
default:
}
}
}
// backgroundSend is the worker goroutine for sending events.
func (oq *destinationQueue) backgroundSend() {
// Check if a worker is already running, and if it isn't, then
// mark it as started.
if !oq.running.CAS(false, true) {
return
}
destinationQueueRunning.Inc()
defer destinationQueueRunning.Dec()
defer oq.queues.clearQueue(oq)
defer oq.running.Store(false)
// Mark the queue as overflowed, so we will consult the database
// to see if there's anything new to send.
oq.overflowed.Store(true)
for {
// If we are overflowing memory and have sent things out to the
// database then we can look up what those things are.
if oq.overflowed.Load() {
oq.getPendingFromDatabase()
}
// If we have nothing to do then wait either for incoming events, or
// until we hit an idle timeout.
select {
case <-oq.notify:
// There's work to do, either because getPendingFromDatabase
// told us there is, or because a new event has come in via
// sendEvent/sendEDU.
case <-time.After(queueIdleTimeout):
// The worker is idle so stop the goroutine. It'll get
// restarted automatically the next time we have an event to
// send.
return
}
// If we are backing off this server then wait for the
// backoff duration to complete first, or until explicitly
// told to retry.
until, blacklisted := oq.statistics.BackoffInfo()
if blacklisted {
// It's been suggested that we should give up because the backoff
// has exceeded a maximum allowable value. Clean up the in-memory
// buffers at this point. The PDU clean-up is already on a defer.
logrus.Warnf("Blacklisting %q due to exceeding backoff threshold", oq.destination)
oq.pendingMutex.Lock()
for i := range oq.pendingPDUs {
oq.pendingPDUs[i] = nil
}
for i := range oq.pendingEDUs {
oq.pendingEDUs[i] = nil
}
oq.pendingPDUs = nil
oq.pendingEDUs = nil
oq.pendingMutex.Unlock()
return
}
if until != nil && until.After(time.Now()) {
// We haven't backed off yet, so wait for the suggested amount of
// time.
duration := time.Until(*until)
logrus.Debugf("Backing off %q for %s", oq.destination, duration)
oq.backingOff.Store(true)
destinationQueueBackingOff.Inc()
select {
case <-time.After(duration):
case <-oq.interruptBackoff:
}
destinationQueueBackingOff.Dec()
oq.backingOff.Store(false)
}
// Work out which PDUs/EDUs to include in the next transaction.
oq.pendingMutex.RLock()
pduCount := len(oq.pendingPDUs)
eduCount := len(oq.pendingEDUs)
if pduCount > maxPDUsPerTransaction {
pduCount = maxPDUsPerTransaction
}
if eduCount > maxEDUsPerTransaction {
eduCount = maxEDUsPerTransaction
}
toSendPDUs := oq.pendingPDUs[:pduCount]
toSendEDUs := oq.pendingEDUs[:eduCount]
oq.pendingMutex.RUnlock()
// If we have pending PDUs or EDUs then construct a transaction.
// Try sending the next transaction and see what happens.
transaction, pc, ec, terr := oq.nextTransaction(toSendPDUs, toSendEDUs)
if terr != nil {
// We failed to send the transaction. Mark it as a failure.
oq.statistics.Failure()
} else if transaction {
// If we successfully sent the transaction then clear out
// the pending events and EDUs, and wipe our transaction ID.
oq.statistics.Success()
oq.pendingMutex.Lock()
for i := range oq.pendingPDUs[:pc] {
oq.pendingPDUs[i] = nil
}
for i := range oq.pendingEDUs[:ec] {
oq.pendingEDUs[i] = nil
}
oq.pendingPDUs = oq.pendingPDUs[pc:]
oq.pendingEDUs = oq.pendingEDUs[ec:]
oq.pendingMutex.Unlock()
}
}
}
// 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(
pdus []*queuedPDU,
edus []*queuedEDU,
) (bool, int, int, error) {
// If there's no projected transaction ID then generate one. If
// the transaction succeeds then we'll set it back to "" so that
// we generate a new one next time. If it fails, we'll preserve
// it so that we retry with the same transaction ID.
oq.transactionIDMutex.Lock()
if oq.transactionID == "" {
now := gomatrixserverlib.AsTimestamp(time.Now())
oq.transactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
}
oq.transactionIDMutex.Unlock()
// Create the transaction.
t := gomatrixserverlib.Transaction{
PDUs: []json.RawMessage{},
EDUs: []gomatrixserverlib.EDU{},
}
t.Origin = oq.origin
t.Destination = oq.destination
t.OriginServerTS = gomatrixserverlib.AsTimestamp(time.Now())
t.TransactionID = oq.transactionID
// If we didn't get anything from the database and there are no
// pending EDUs then there's nothing to do - stop here.
if len(pdus) == 0 && len(edus) == 0 {
return false, 0, 0, nil
}
var pduReceipts []*shared.Receipt
var eduReceipts []*shared.Receipt
// Go through PDUs that we retrieved from the database, if any,
// and add them into the transaction.
for _, pdu := range pdus {
if pdu == nil || pdu.pdu == nil {
continue
}
// Append the JSON of the event, since this is a json.RawMessage type in the
// gomatrixserverlib.Transaction struct
t.PDUs = append(t.PDUs, pdu.pdu.JSON())
pduReceipts = append(pduReceipts, pdu.receipt)
}
// Do the same for pending EDUS in the queue.
for _, edu := range edus {
if edu == nil || edu.edu == nil {
continue
}
t.EDUs = append(t.EDUs, *edu.edu)
eduReceipts = append(eduReceipts, edu.receipt)
}
logrus.WithField("server_name", oq.destination).Debugf("Sending transaction %q containing %d PDUs, %d EDUs", t.TransactionID, len(t.PDUs), len(t.EDUs))
// Try to send the transaction to the destination server.
// TODO: we should check for 500-ish fails vs 400-ish here,
// since we shouldn't queue things indefinitely in response
// to a 400-ish error
ctx, cancel := context.WithTimeout(oq.process.Context(), time.Minute*5)
defer cancel()
_, err := oq.client.SendTransaction(ctx, t)
switch err.(type) {
case nil:
// Clean up the transaction in the database.
if pduReceipts != nil {
//logrus.Infof("Cleaning PDUs %q", pduReceipt.String())
if err = oq.db.CleanPDUs(context.Background(), oq.destination, pduReceipts); err != nil {
logrus.WithError(err).Errorf("Failed to clean PDUs for server %q", t.Destination)
}
}
if eduReceipts != nil {
//logrus.Infof("Cleaning EDUs %q", eduReceipt.String())
if err = oq.db.CleanEDUs(context.Background(), oq.destination, eduReceipts); err != nil {
logrus.WithError(err).Errorf("Failed to clean EDUs for server %q", t.Destination)
}
}
// Reset the transaction ID.
oq.transactionIDMutex.Lock()
oq.transactionID = ""
oq.transactionIDMutex.Unlock()
return true, len(t.PDUs), len(t.EDUs), nil
case gomatrix.HTTPError:
// Report that we failed to send the transaction and we
// will retry again, subject to backoff.
return false, 0, 0, err
default:
logrus.WithFields(logrus.Fields{
"destination": oq.destination,
logrus.ErrorKey: err,
}).Debugf("Failed to send transaction %q", t.TransactionID)
return false, 0, 0, err
}
}