feat: Add command to purge sync tokens for empty rooms

src/admin/room/commands.rs

@@ -83,3 +83,169 @@ pub(super) async fn purge_sync_tokens(&self, room: OwnedRoomOrAliasId) -> Result
 	))
 	.await
 }
+
+#[admin_command]
+pub(super) async fn purge_empty_room_tokens(
+	&self,
+	yes: bool,
+	target_disabled: bool,
+	target_banned: bool,
+	dry_run: bool,
+) -> Result {
+	use conduwuit::{debug, info};
+
+	if !yes && !dry_run {
+		return Err!(
+			"Please confirm this operation with --yes as it may delete tokens from many rooms, \
+			 or use --dry-run to simulate"
+		);
+	}
+
+	let mode = if dry_run { "Simulating" } else { "Starting" };
+
+	let mut total_rooms_processed = 0;
+	let mut empty_rooms_processed = 0;
+	let mut total_tokens_deleted = 0;
+	let mut error_count = 0;
+	let mut skipped_rooms = 0;
+
+	info!("{} purge of sync tokens for rooms with no local users", mode);
+
+	// Get all rooms in the server
+	let all_rooms = self
+		.services
+		.rooms
+		.metadata
+		.iter_ids()
+		.collect::<Vec<_>>()
+		.await;
+
+	info!("Found {} rooms total on the server", all_rooms.len());
+
+	// Filter rooms based on options
+	let mut rooms = Vec::new();
+	for room_id in all_rooms {
+		// Filter rooms based on targeting options
+		let is_disabled = self.services.rooms.metadata.is_disabled(room_id).await;
+		let is_banned = self.services.rooms.metadata.is_banned(room_id).await;
+
+		// If targeting specific types of rooms, only include matching rooms
+		if (target_disabled || target_banned)
+			&& !((target_disabled && is_disabled) || (target_banned && is_banned))
+		{
+			debug!("Skipping room {} as it doesn't match targeting criteria", room_id);
+			skipped_rooms += 1;
+			continue;
+		}
+
+		rooms.push(room_id);
+	}
+
+	// Total number of rooms we'll be checking
+	let total_rooms = rooms.len();
+	info!(
+		"Processing {} rooms after filtering (skipped {} rooms)",
+		total_rooms, skipped_rooms
+	);
+
+	// Process each room
+	for room_id in rooms {
+		total_rooms_processed += 1;
+
+		// Count local users in this room
+		let local_users_count = self
+			.services
+			.rooms
+			.state_cache
+			.local_users_in_room(room_id)
+			.count()
+			.await;
+
+		// Only process rooms with no local users
+		if local_users_count == 0 {
+			empty_rooms_processed += 1;
+
+			// In dry run mode, just count what would be deleted, don't actually delete
+			debug!(
+				"Room {} has no local users, {}",
+				room_id,
+				if dry_run {
+					"would purge sync tokens"
+				} else {
+					"purging sync tokens"
+				}
+			);
+
+			if dry_run {
+				// For dry run mode, count tokens without deleting
+				match self.services.rooms.user.count_room_tokens(room_id).await {
+					| Ok(count) =>
+						if count > 0 {
+							debug!("Would delete {} sync tokens for room {}", count, room_id);
+							total_tokens_deleted += count;
+						} else {
+							debug!("No sync tokens found for room {}", room_id);
+						},
+					| Err(e) => {
+						debug!("Error counting sync tokens for room {}: {:?}", room_id, e);
+						error_count += 1;
+					},
+				}
+			} else {
+				// Real deletion mode
+				match self.services.rooms.user.delete_room_tokens(room_id).await {
+					| Ok(count) =>
+						if count > 0 {
+							debug!("Deleted {} sync tokens for room {}", count, room_id);
+							total_tokens_deleted += count;
+						} else {
+							debug!("No sync tokens found for room {}", room_id);
+						},
+					| Err(e) => {
+						debug!("Error purging sync tokens for room {}: {:?}", room_id, e);
+						error_count += 1;
+					},
+				}
+			}
+		} else {
+			debug!("Room {} has {} local users, skipping", room_id, local_users_count);
+		}
+
+		// Log progress periodically
+		if total_rooms_processed % 100 == 0 || total_rooms_processed == total_rooms {
+			info!(
+				"Progress: {}/{} rooms processed, {} empty rooms found, {} tokens {}",
+				total_rooms_processed,
+				total_rooms,
+				empty_rooms_processed,
+				total_tokens_deleted,
+				if dry_run { "would be deleted" } else { "deleted" }
+			);
+		}
+	}
+
+	let action = if dry_run { "would be deleted" } else { "deleted" };
+	info!(
+		"Finished {}: processed {} empty rooms out of {} total, {} tokens {}, errors: {}",
+		if dry_run {
+			"purge simulation"
+		} else {
+			"purging sync tokens"
+		},
+		empty_rooms_processed,
+		total_rooms,
+		total_tokens_deleted,
+		action,
+		error_count
+	);
+
+	let mode_msg = if dry_run { "DRY RUN: " } else { "" };
+	self.write_str(&format!(
+		"{}Successfully processed {empty_rooms_processed} empty rooms (out of {total_rooms} \
+		 total rooms), {total_tokens_deleted} tokens {}. Skipped {skipped_rooms} rooms based on \
+		 filters. Failed for {error_count} rooms.",
+		mode_msg,
+		if dry_run { "would be deleted" } else { "deleted" }
+	))
+	.await
+}

src/admin/room/mod.rs

@@ -63,4 +63,27 @@ pub(super) enum RoomCommand {
 		#[arg(value_parser)]
 		room: OwnedRoomOrAliasId,
 	},
+
+	/// - Delete sync tokens for all rooms that have no local users
+	///
+	/// By default, processes all empty rooms. You can use --target-disabled
+	/// and/or --target-banned to exclusively process rooms matching those
+	/// conditions.
+	PurgeEmptyRoomTokens {
+		/// Confirm you want to delete tokens from potentially many rooms
+		#[arg(long)]
+		yes: bool,
+
+		/// Only purge rooms that have federation disabled
+		#[arg(long)]
+		target_disabled: bool,
+
+		/// Only purge rooms that have been banned
+		#[arg(long)]
+		target_banned: bool,
+
+		/// Perform a dry run without actually deleting any tokens
+		#[arg(long)]
+		dry_run: bool,
+	},
 }

src/service/rooms/user/mod.rs

@@ -128,6 +128,31 @@ pub async fn get_token_shortstatehash(
 		.deserialized()
 }
 
+/// Count how many sync tokens exist for a room without deleting them
+///
+/// This is useful for dry runs to see how many tokens would be deleted
+#[implement(Service)]
+pub async fn count_room_tokens(&self, room_id: &RoomId) -> Result<usize> {
+	use futures::TryStreamExt;
+
+	let shortroomid = self.services.short.get_shortroomid(room_id).await?;
+
+	// Create a prefix to search by - all entries for this room will start with its
+	// short ID
+	let prefix = &[shortroomid];
+
+	// Collect all keys into a Vec and count them
+	let keys = self
+		.db
+		.roomsynctoken_shortstatehash
+		.keys_prefix_raw(prefix)
+		.map_ok(|_| ()) // We only need to count, not store the keys
+		.try_collect::<Vec<_>>()
+		.await?;
+
+	Ok(keys.len())
+}
+
 /// Delete all sync tokens associated with a room
 ///
 /// This helps clean up the database as these tokens are never otherwise removed