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dendrite/federationsender/queue/destinationqueue.go
2020-09-29 17:08:47 +01:00

382 lines
14 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/federationsender/statistics"
"github.com/matrix-org/dendrite/federationsender/storage"
"github.com/matrix-org/dendrite/federationsender/storage/shared"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/gomatrix"
"github.com/matrix-org/gomatrixserverlib"
"github.com/sirupsen/logrus"
log "github.com/sirupsen/logrus"
"go.uber.org/atomic"
)
const (
maxPDUsPerTransaction = 50
maxEDUsPerTransaction = 50
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 {
db storage.Database
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
statistics *statistics.ServerStatistics // statistics about this remote server
transactionIDMutex sync.Mutex // protects transactionID
transactionID gomatrixserverlib.TransactionID // last transaction ID
transactionCount atomic.Int32 // how many events in this transaction so far
notifyPDUs chan bool // interrupts idle wait for PDUs
notifyEDUs chan bool // interrupts idle wait for EDUs
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(receipt *shared.Receipt) {
// Create a transaction ID. We'll either do this if we don't have
// one made up yet, or if we've exceeded the number of maximum
// events allowed in a single tranaction. We'll reset the counter
// when we do.
oq.transactionIDMutex.Lock()
if oq.transactionID == "" || oq.transactionCount.Load() >= maxPDUsPerTransaction {
now := gomatrixserverlib.AsTimestamp(time.Now())
oq.transactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
oq.transactionCount.Store(0)
}
oq.transactionIDMutex.Unlock()
// 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(),
oq.transactionID, // the current transaction ID
oq.destination, // the destination server name
receipt, // NIDs from federationsender_queue_json table
); err != nil {
log.WithError(err).Errorf("failed to associate PDU receipt %q with destination %q", receipt.String(), oq.destination)
return
}
// We've successfully added a PDU to the transaction so increase
// the counter.
oq.transactionCount.Add(1)
// Check if the destination is blacklisted. If it isn't then wake
// up the queue.
if !oq.statistics.Blacklisted() {
// Wake up the queue if it's asleep.
oq.wakeQueueIfNeeded()
// If we're blocking on waiting PDUs then tell the queue that we
// have work to do.
select {
case oq.notifyPDUs <- true:
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(receipt *shared.Receipt) {
// 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 federationsender_queue_json table
); err != nil {
log.WithError(err).Errorf("failed to associate EDU receipt %q with destination %q", receipt.String(), oq.destination)
return
}
// We've successfully added an EDU to the transaction so increase
// the counter.
oq.transactionCount.Add(1)
// Check if the destination is blacklisted. If it isn't then wake
// up the queue.
if !oq.statistics.Blacklisted() {
// Wake up the queue if it's asleep.
oq.wakeQueueIfNeeded()
// If we're blocking on waiting EDUs then tell the queue that we
// have work to do.
select {
case oq.notifyEDUs <- true:
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()
}
}
// waitForPDUs returns a channel for pending PDUs, which will be
// used in backgroundSend select. It returns a closed channel if
// there is something pending right now, or an open channel if
// we're waiting for something.
func (oq *destinationQueue) waitForPDUs() chan bool {
pendingPDUs, err := oq.db.GetPendingPDUCount(context.TODO(), oq.destination)
if err != nil {
log.WithError(err).Errorf("Failed to get pending PDU count on queue %q", oq.destination)
}
// If there are PDUs pending right now then we'll return a closed
// channel. This will mean that the backgroundSend will not block.
if pendingPDUs > 0 {
ch := make(chan bool, 1)
close(ch)
return ch
}
// If there are no PDUs pending right now then instead we'll return
// the notify channel, so that backgroundSend can pick up normal
// notifications from sendEvent.
return oq.notifyPDUs
}
// waitForEDUs returns a channel for pending EDUs, which will be
// used in backgroundSend select. It returns a closed channel if
// there is something pending right now, or an open channel if
// we're waiting for something.
func (oq *destinationQueue) waitForEDUs() chan bool {
pendingEDUs, err := oq.db.GetPendingEDUCount(context.TODO(), oq.destination)
if err != nil {
log.WithError(err).Errorf("Failed to get pending EDU count on queue %q", oq.destination)
}
// If there are EDUs pending right now then we'll return a closed
// channel. This will mean that the backgroundSend will not block.
if pendingEDUs > 0 {
ch := make(chan bool, 1)
close(ch)
return ch
}
// If there are no EDUs pending right now then instead we'll return
// the notify channel, so that backgroundSend can pick up normal
// notifications from sendEvent.
return oq.notifyEDUs
}
// backgroundSend is the worker goroutine for sending events.
// nolint:gocyclo
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
}
defer oq.running.Store(false)
for {
pendingPDUs, pendingEDUs := false, false
// If we have nothing to do then wait either for incoming events, or
// until we hit an idle timeout.
select {
case <-oq.waitForPDUs():
// We were woken up because there are new PDUs waiting in the
// database.
pendingPDUs = true
case <-oq.waitForEDUs():
// We were woken up because there are new PDUs waiting in the
// database.
pendingEDUs = true
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.
log.Tracef("Queue %q has been idle for %s, going to sleep", oq.destination, queueIdleTimeout)
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.
log.Warnf("Blacklisting %q due to exceeding backoff threshold", oq.destination)
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)
log.Warnf("Backing off %q for %s", oq.destination, duration)
select {
case <-time.After(duration):
case <-oq.interruptBackoff:
}
}
// If we have pending PDUs or EDUs then construct a transaction.
if pendingPDUs || pendingEDUs {
// Try sending the next transaction and see what happens.
transaction, terr := oq.nextTransaction()
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()
}
}
}
}
// nextTransaction creates a new transaction from the pending event
// queue and sends it. Returns true if a transaction was sent or
// false otherwise.
// nolint:gocyclo
func (oq *destinationQueue) nextTransaction() (bool, error) {
// Before we do anything, we need to roll over the transaction
// ID that is being used to coalesce events into the next TX.
// Otherwise it's possible that we'll pick up an incomplete
// transaction and end up nuking the rest of the events at the
// cleanup stage.
oq.transactionIDMutex.Lock()
oq.transactionID = ""
oq.transactionIDMutex.Unlock()
oq.transactionCount.Store(0)
// 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())
// Ask the database for any pending PDUs from the next transaction.
// maxPDUsPerTransaction is an upper limit but we probably won't
// actually retrieve that many events.
ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
defer cancel()
txid, pdus, pduReceipt, err := oq.db.GetNextTransactionPDUs(
ctx, // context
oq.destination, // server name
maxPDUsPerTransaction, // max events to retrieve
)
if err != nil {
log.WithError(err).Errorf("failed to get next transaction PDUs for server %q", oq.destination)
return false, fmt.Errorf("oq.db.GetNextTransactionPDUs: %w", err)
}
edus, eduReceipt, err := oq.db.GetNextTransactionEDUs(
ctx, // context
oq.destination, // server name
maxEDUsPerTransaction, // max events to retrieve
)
if err != nil {
log.WithError(err).Errorf("failed to get next transaction EDUs for server %q", oq.destination)
return false, fmt.Errorf("oq.db.GetNextTransactionEDUs: %w", err)
}
// 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, nil
}
// Pick out the transaction ID from the database. If we didn't
// get a transaction ID (i.e. because there are no PDUs but only
// EDUs) then generate a transaction ID.
t.TransactionID = txid
if t.TransactionID == "" {
now := gomatrixserverlib.AsTimestamp(time.Now())
t.TransactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
}
// Go through PDUs that we retrieved from the database, if any,
// and add them into the transaction.
for _, pdu := range pdus {
// 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())
}
// Do the same for pending EDUS in the queue.
for _, edu := range edus {
t.EDUs = append(t.EDUs, *edu)
}
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(context.Background(), time.Second*30)
defer cancel()
_, err = oq.client.SendTransaction(ctx, t)
switch err.(type) {
case nil:
// Clean up the transaction in the database.
if pduReceipt != nil {
//logrus.Infof("Cleaning PDUs %q", pduReceipt.String())
if err = oq.db.CleanPDUs(context.Background(), oq.destination, pduReceipt); err != nil {
log.WithError(err).Errorf("failed to clean PDUs %q for server %q", pduReceipt.String(), t.Destination)
}
}
if eduReceipt != nil {
//logrus.Infof("Cleaning EDUs %q", eduReceipt.String())
if err = oq.db.CleanEDUs(context.Background(), oq.destination, eduReceipt); err != nil {
log.WithError(err).Errorf("failed to clean EDUs %q for server %q", eduReceipt.String(), t.Destination)
}
}
return true, nil
case gomatrix.HTTPError:
// Report that we failed to send the transaction and we
// will retry again, subject to backoff.
return false, err
default:
log.WithFields(log.Fields{
"destination": oq.destination,
log.ErrorKey: err,
}).Info("problem sending transaction")
return false, err
}
}