Use single SQL query for fetching backfill queue items

backfillqueue.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	log "maunium.net/go/maulogger/v2"
+
 	"maunium.net/go/mautrix-whatsapp/database"
 )
 
@@ -32,19 +33,16 @@ type BackfillQueue struct {
 	log log.Logger
 }
 
-// Immediate backfills should happen first, then deferred backfills and lastly
-// media backfills.
+// RunLoop fetches backfills from the database, prioritizing immediate and forward backfills
 func (bq *BackfillQueue) RunLoop(user *User) {
 	for {
-		if immediate := bq.BackfillQuery.GetNext(user.MXID, database.BackfillImmediate); immediate != nil {
-			bq.ImmediateBackfillRequests <- immediate
-			immediate.MarkDone()
-		} else if backfill := bq.BackfillQuery.GetNext(user.MXID, database.BackfillDeferred); backfill != nil {
-			bq.DeferredBackfillRequests <- backfill
+		if backfill := bq.BackfillQuery.GetNext(user.MXID); backfill != nil {
+			if backfill.BackfillType == database.BackfillImmediate || backfill.BackfillType == database.BackfillForward {
+				bq.ImmediateBackfillRequests <- backfill
+			} else {
+				bq.DeferredBackfillRequests <- backfill
+			}
 			backfill.MarkDone()
-		} else if mediaBackfill := bq.BackfillQuery.GetNext(user.MXID, database.BackfillMedia); mediaBackfill != nil {
-			bq.DeferredBackfillRequests <- mediaBackfill
-			mediaBackfill.MarkDone()
 		} else {
 			select {
 			case <-bq.ReCheckQueue:

database/backfillqueue.go

@@ -30,14 +30,17 @@ type BackfillType int
 
 const (
 	BackfillImmediate BackfillType = 0
-	BackfillDeferred               = 1
-	BackfillMedia                  = 2
+	BackfillForward   BackfillType = 100
+	BackfillDeferred  BackfillType = 200
+	BackfillMedia     BackfillType = 300
 )
 
 func (bt BackfillType) String() string {
 	switch bt {
 	case BackfillImmediate:
 		return "IMMEDIATE"
+	case BackfillForward:
+		return "FORWARD"
 	case BackfillDeferred:
 		return "DEFERRED"
 	case BackfillMedia:
@@ -80,16 +83,15 @@ const (
 		SELECT queue_id, user_mxid, type, priority, portal_jid, portal_receiver, time_start, time_end, max_batch_events, max_total_events, batch_delay
 		FROM backfill_queue
 		WHERE user_mxid=$1
-			AND type=$2
 			AND completed_at IS NULL
-		ORDER BY priority, queue_id
+		ORDER BY type, priority, queue_id
 		LIMIT 1
 	`
 )
 
 // GetNext returns the next backfill to perform
-func (bq *BackfillQuery) GetNext(userID id.UserID, backfillType BackfillType) (backfill *Backfill) {
-	rows, err := bq.db.Query(getNextBackfillQuery, userID, backfillType)
+func (bq *BackfillQuery) GetNext(userID id.UserID) (backfill *Backfill) {
+	rows, err := bq.db.Query(getNextBackfillQuery, userID)
 	defer rows.Close()
 	if err != nil || rows == nil {
 		bq.log.Error(err)

database/upgrades/2022-04-29-backfillqueue-type-order.go

@@ -0,0 +1,20 @@
+package upgrades
+
+import (
+	"database/sql"
+)
+
+func init() {
+	upgrades[41] = upgrade{"Update backfill queue tables to be sortable by priority", func(tx *sql.Tx, ctx context) error {
+		_, err := tx.Exec(`
+			UPDATE backfill_queue
+				SET type=CASE
+					WHEN type=1 THEN 200
+				    WHEN type=2 THEN 300
+				    ELSE type
+				END
+				WHERE type=1 OR type=2
+		`)
+		return err
+	}}
+}

database/upgrades/upgrades.go

@@ -40,7 +40,7 @@ type upgrade struct {
 	fn      upgradeFunc
 }
 
-const NumberOfUpgrades = 41
+const NumberOfUpgrades = 42
 
 var upgrades [NumberOfUpgrades]upgrade