Deduplicate FS database, EDU persistence table (#1207)

* Deduplicate FS database, add some EDU persistence groundwork

* Extend TransactionWriter to use optional existing transaction, use that for FS SQLite database writes

* Fix build due to bad keyserver import

* Working EDU persistence

* gocyclo, unsurprisingly

* Remove unused

* Update copyright notices

2 files changed, 115 insertions, 54 deletions

diff --git a/federationsender/queue/destinationqueue.go b/federationsender/queue/destinationqueue.go
index 57c8cff6..b7582bf9 100644
--- a/federationsender/queue/destinationqueue.go
+++ b/federationsender/queue/destinationqueue.go
@@ -22,6 +22,7 @@ import (
 	"time"
 
 	"github.com/matrix-org/dendrite/federationsender/storage"
+	"github.com/matrix-org/dendrite/federationsender/storage/shared"
 	"github.com/matrix-org/dendrite/federationsender/types"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrix"
@@ -31,8 +32,11 @@ import (
 	"go.uber.org/atomic"
 )
 
-const maxPDUsPerTransaction = 50
-const queueIdleTimeout = time.Second * 30
+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
@@ -49,20 +53,19 @@ type destinationQueue struct {
 	backingOff         atomic.Bool                             // true if we're backing off
 	statistics         *types.ServerStatistics                 // statistics about this remote server
 	incomingInvites    chan *gomatrixserverlib.InviteV2Request // invites to send
-	incomingEDUs       chan *gomatrixserverlib.EDU             // EDUs to send
 	transactionIDMutex sync.Mutex                              // protects transactionID
 	transactionID      gomatrixserverlib.TransactionID         // last transaction ID
 	transactionCount   atomic.Int32                            // how many events in this transaction so far
-	pendingEDUs        []*gomatrixserverlib.EDU                // owned by backgroundSend
 	pendingInvites     []*gomatrixserverlib.InviteV2Request    // owned by backgroundSend
 	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(nid int64) {
+func (oq *destinationQueue) sendEvent(receipt *shared.Receipt) {
 	if oq.statistics.Blacklisted() {
 		// If the destination is blacklisted then drop the event.
 		log.Infof("%s is blacklisted; dropping event", oq.destination)
@@ -86,9 +89,9 @@ func (oq *destinationQueue) sendEvent(nid int64) {
 		context.TODO(),
 		oq.transactionID, // the current transaction ID
 		oq.destination,   // the destination server name
-		[]int64{nid},     // NID from federationsender_queue_json table
+		receipt,          // NIDs from federationsender_queue_json table
 	); err != nil {
-		log.WithError(err).Errorf("failed to associate PDU NID %d with destination %q", nid, oq.destination)
+		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
@@ -107,13 +110,34 @@ func (oq *destinationQueue) sendEvent(nid int64) {
 // 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(ev *gomatrixserverlib.EDU) {
+func (oq *destinationQueue) sendEDU(receipt *shared.Receipt) {
 	if oq.statistics.Blacklisted() {
 		// If the destination is blacklisted then drop the event.
+		log.Infof("%s is blacklisted; dropping ephemeral event", 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 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)
+	// Wake up the queue if it's asleep.
 	oq.wakeQueueIfNeeded()
-	oq.incomingEDUs <- ev
+	// If we're blocking on waiting PDUs then tell the queue that we
+	// have work to do.
+	select {
+	case oq.notifyEDUs <- true:
+	default:
+	}
 }
 
 // sendInvite adds the invite event to the pending queue for the
@@ -166,6 +190,28 @@ func (oq *destinationQueue) waitForPDUs() chan bool {
 	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() {
@@ -177,7 +223,7 @@ func (oq *destinationQueue) backgroundSend() {
 	defer oq.running.Store(false)
 
 	for {
-		pendingPDUs := false
+		pendingPDUs, pendingEDUs := false, false
 
 		// If we have nothing to do then wait either for incoming events, or
 		// until we hit an idle timeout.
@@ -186,18 +232,10 @@ func (oq *destinationQueue) backgroundSend() {
 			// We were woken up because there are new PDUs waiting in the
 			// database.
 			pendingPDUs = true
-		case edu := <-oq.incomingEDUs:
-			// EDUs are handled in-memory for now. We will try to keep
-			// the ordering intact.
-			// TODO: Certain EDU types need persistence, e.g. send-to-device
-			oq.pendingEDUs = append(oq.pendingEDUs, edu)
-			// If there are any more things waiting in the channel queue
-			// then read them. This is safe because we guarantee only
-			// having one goroutine per destination queue, so the channel
-			// isn't being consumed anywhere else.
-			for len(oq.incomingEDUs) > 0 {
-				oq.pendingEDUs = append(oq.pendingEDUs, <-oq.incomingEDUs)
-			}
+		case <-oq.waitForEDUs():
+			// We were woken up because there are new PDUs waiting in the
+			// database.
+			pendingEDUs = true
 		case invite := <-oq.incomingInvites:
 			// There's no strict ordering requirement for invites like
 			// there is for transactions, so we put the invite onto the
@@ -238,16 +276,15 @@ func (oq *destinationQueue) backgroundSend() {
 		}
 
 		// If we have pending PDUs or EDUs then construct a transaction.
-		if pendingPDUs || len(oq.pendingEDUs) > 0 {
+		if pendingPDUs || pendingEDUs {
 			// Try sending the next transaction and see what happens.
-			transaction, terr := oq.nextTransaction(oq.pendingEDUs)
+			transaction, terr := oq.nextTransaction()
 			if terr != nil {
 				// We failed to send the transaction.
 				if giveUp := oq.statistics.Failure(); giveUp {
 					// 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.
-					oq.cleanPendingEDUs()
 					oq.cleanPendingInvites()
 					log.Infof("Blacklisting %q due to errors", oq.destination)
 					return
@@ -265,8 +302,6 @@ func (oq *destinationQueue) backgroundSend() {
 				// If we successfully sent the transaction then clear out
 				// the pending events and EDUs, and wipe our transaction ID.
 				oq.statistics.Success()
-				// Clean up the in-memory buffers.
-				oq.cleanPendingEDUs()
 			}
 		}
 
@@ -294,15 +329,6 @@ func (oq *destinationQueue) backgroundSend() {
 	}
 }
 
-// cleanPendingEDUs cleans out the pending EDU buffer, removing
-// all references so that the underlying objects can be GC'd.
-func (oq *destinationQueue) cleanPendingEDUs() {
-	for i := 0; i < len(oq.pendingEDUs); i++ {
-		oq.pendingEDUs[i] = nil
-	}
-	oq.pendingEDUs = []*gomatrixserverlib.EDU{}
-}
-
 // cleanPendingInvites cleans out the pending invite buffer,
 // removing all references so that the underlying objects can
 // be GC'd.
@@ -316,9 +342,8 @@ func (oq *destinationQueue) cleanPendingInvites() {
 // 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(
-	pendingEDUs []*gomatrixserverlib.EDU,
-) (bool, error) {
+// 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
@@ -343,7 +368,7 @@ func (oq *destinationQueue) nextTransaction(
 	// actually retrieve that many events.
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
 	defer cancel()
-	txid, pdus, err := oq.db.GetNextTransactionPDUs(
+	txid, pdus, pduReceipt, err := oq.db.GetNextTransactionPDUs(
 		ctx,                   // context
 		oq.destination,        // server name
 		maxPDUsPerTransaction, // max events to retrieve
@@ -353,9 +378,19 @@ func (oq *destinationQueue) nextTransaction(
 		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(pendingEDUs) == 0 {
+	if len(pdus) == 0 && len(edus) == 0 {
 		return false, nil
 	}
 
@@ -377,7 +412,7 @@ func (oq *destinationQueue) nextTransaction(
 	}
 
 	// Do the same for pending EDUS in the queue.
-	for _, edu := range pendingEDUs {
+	for _, edu := range edus {
 		t.EDUs = append(t.EDUs, *edu)
 	}
 
@@ -393,12 +428,17 @@ func (oq *destinationQueue) nextTransaction(
 	switch err.(type) {
 	case nil:
 		// Clean up the transaction in the database.
-		if err = oq.db.CleanTransactionPDUs(
-			context.Background(),
-			t.Destination,
-			t.TransactionID,
-		); err != nil {
-			log.WithError(err).Errorf("failed to clean transaction %q for server %q", t.TransactionID, t.Destination)
+		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:
diff --git a/federationsender/queue/queue.go b/federationsender/queue/queue.go
index 46c9fddb..e488a34a 100644
--- a/federationsender/queue/queue.go
+++ b/federationsender/queue/queue.go
@@ -61,12 +61,23 @@ func NewOutgoingQueues(
 		queues:     map[gomatrixserverlib.ServerName]*destinationQueue{},
 	}
 	// Look up which servers we have pending items for and then rehydrate those queues.
-	if serverNames, err := db.GetPendingServerNames(context.Background()); err == nil {
-		for _, serverName := range serverNames {
-			queues.getQueue(serverName).wakeQueueIfNeeded()
+	serverNames := map[gomatrixserverlib.ServerName]struct{}{}
+	if names, err := db.GetPendingPDUServerNames(context.Background()); err == nil {
+		for _, serverName := range names {
+			serverNames[serverName] = struct{}{}
 		}
 	} else {
-		log.WithError(err).Error("Failed to get server names for destination queue hydration")
+		log.WithError(err).Error("Failed to get PDU server names for destination queue hydration")
+	}
+	if names, err := db.GetPendingEDUServerNames(context.Background()); err == nil {
+		for _, serverName := range names {
+			serverNames[serverName] = struct{}{}
+		}
+	} else {
+		log.WithError(err).Error("Failed to get EDU server names for destination queue hydration")
+	}
+	for serverName := range serverNames {
+		queues.getQueue(serverName).wakeQueueIfNeeded()
 	}
 	return queues
 }
@@ -91,9 +102,9 @@ func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *d
 			destination:      destination,
 			client:           oqs.client,
 			statistics:       oqs.statistics.ForServer(destination),
-			incomingEDUs:     make(chan *gomatrixserverlib.EDU, 128),
 			incomingInvites:  make(chan *gomatrixserverlib.InviteV2Request, 128),
 			notifyPDUs:       make(chan bool, 1),
+			notifyEDUs:       make(chan bool, 1),
 			interruptBackoff: make(chan bool),
 			signing:          oqs.signing,
 		}
@@ -196,8 +207,18 @@ func (oqs *OutgoingQueues) SendEDU(
 		}).Info("Sending EDU event")
 	}
 
+	ephemeralJSON, err := json.Marshal(e)
+	if err != nil {
+		return fmt.Errorf("json.Marshal: %w", err)
+	}
+
+	nid, err := oqs.db.StoreJSON(context.TODO(), string(ephemeralJSON))
+	if err != nil {
+		return fmt.Errorf("sendevent: oqs.db.StoreJSON: %w", err)
+	}
+
 	for _, destination := range destinations {
-		oqs.getQueue(destination).sendEDU(e)
+		oqs.getQueue(destination).sendEDU(nid)
 	}
 
 	return nil