Add deadline API for tracked messages (#224)

* Add deadline API for tracked messages

to get a slice of tracked message values that have exceeded their
deadline within a given time range into the past.

* Switch name and impl to "cordon" track values that have exceeded deadline

so that the `GC` can delete them without double checking.

Author: meatballhat

queue/client.go

@@ -69,6 +69,36 @@ type OnGCFunc func(ctx context.Context, trackValues []string) error
 // of the current server time as a way of limiting the keyspace scanned. As a special
 // case, any value <= -1 will result in all keys being scanned.
 func (c *Client) GC(ctx context.Context, nTimeDigits int, f OnGCFunc) (uint64, uint64, error) {
+	pipe := c.rdb.Pipeline()
+	presortedGarbageCmd := pipe.SMembers(ctx, MetaPresortedGarbageSet)
+	pipe.Del(ctx, MetaPresortedGarbageSet)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return 0, 0, err
+	}
+
+	presortedGarbage := presortedGarbageCmd.Val()
+
+	if len(presortedGarbage) > 0 {
+		toDelete := []string{}
+		for _, key := range presortedGarbage {
+			trackValue, deadline, ok := strings.Cut(key, ":")
+			if !ok {
+				continue
+			}
+
+			toDelete = append(
+				toDelete,
+				trackValue,
+				fmt.Sprintf("%s:expiry:%s", trackValue, deadline),
+			)
+		}
+
+		if err := c.rdb.HDel(ctx, MetaCancelationHash, toDelete...).Err(); err != nil {
+			return 0, 0, err
+		}
+	}
+
 	now, err := c.rdb.Time(ctx).Result()
 	if err != nil {
 		return 0, 0, err
@@ -171,11 +201,23 @@ func (c *Client) gcProcessBatch(ctx context.Context, f OnGCFunc, idsToDelete, ke
 		}
 	}
 
-	return c.rdb.HDel(
-		ctx,
-		MetaCancelationHash,
-		keysToDelete...,
-	).Result()
+	nDeleted, err := c.rdb.HDel(ctx, MetaCancelationHash, keysToDelete...).Result()
+	if err != nil {
+		return nDeleted, err
+	}
+
+	// NOTE: ZRem requires an explicit []any which cannot be automatically
+	// converted from a []string.
+	zremArgs := make([]any, len(idsToDelete))
+	for i, id := range idsToDelete {
+		zremArgs[i] = id
+	}
+
+	if err := c.rdb.ZRem(ctx, MetaDeadlinesZSet, zremArgs...).Err(); err != nil {
+		return nDeleted, err
+	}
+
+	return nDeleted, nil
 }
 
 func (c *Client) callOnGC(ctx context.Context, f OnGCFunc, idsToDelete []string) error {
@@ -213,6 +255,60 @@ func (c *Client) callOnGC(ctx context.Context, f OnGCFunc, idsToDelete []string)
 	return f(ctx, trackValues)
 }
 
+// CordonDeadlineExceeded selects a chunk of "track values" that have exceeded their
+// deadline within a given duration into the past, moves them into the "presorted garbage"
+// set for use with `GC`, and returns them as a slice. The times are truncated to the
+// second because the deadlines scored set uses unix timestamps as scores.
+func (c *Client) CordonDeadlineExceeded(ctx context.Context, within time.Duration) ([]string, error) {
+	start, err := c.rdb.Time(ctx).Result()
+	if err != nil {
+		return []string{}, err
+	}
+
+	pipe := c.rdb.Pipeline()
+	zRangeOpts := &redis.ZRangeBy{
+		Min: strconv.Itoa(int(start.Add(-within).Unix())),
+		Max: strconv.Itoa(int(start.Add(1 * time.Second).Unix())),
+	}
+
+	zRangeCmd := c.rdb.ZRangeByScoreWithScores(
+		ctx,
+		MetaDeadlinesZSet,
+		zRangeOpts,
+	)
+
+	c.rdb.ZRemRangeByScore(
+		ctx,
+		MetaDeadlinesZSet,
+		zRangeOpts.Min,
+		zRangeOpts.Max,
+	)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return []string{}, err
+	}
+
+	trackValues := zRangeCmd.Val()
+
+	if len(trackValues) == 0 {
+		return []string{}, nil
+	}
+
+	ret := make([]string, len(trackValues))
+	sMembers := make([]any, len(trackValues))
+
+	for i, trackValue := range trackValues {
+		sMembers[i] = fmt.Sprintf("%s:%d", trackValue.Member, int(trackValue.Score))
+		ret[i] = fmt.Sprintf("%v", trackValue.Member)
+	}
+
+	if err := c.rdb.SAdd(ctx, MetaPresortedGarbageSet, sMembers...).Err(); err != nil {
+		return ret, err
+	}
+
+	return ret, nil
+}
+
 // Len calculates the aggregate length (XLEN) of the queue. It adds up the
 // lengths of all the streams in the queue.
 func (c *Client) Len(ctx context.Context, name string) (int64, error) {