feat: Kill roomsynctoken_shortstatehash dead

changelog.d/917.bugfix.md

@@ -1 +1 @@
-Adjusted legacy sync logic to no longer use the `roomsynctoken_shortstatehash` database column. Once this change has been confirmed to be stable and reliable, a future update will remove it entirely, significantly decreasing database sizes. Contributed by @ginger.
+Adjusted legacy sync logic to allow the `roomsynctoken_shortstatehash` database column to be dropped, massively reducing database sizes, especially for old deployments. Contributed by @ginger.

src/database/engine.rs

@@ -17,7 +17,7 @@ use std::{
 	},
 };
 
-use conduwuit::{Err, Result, debug, info, warn};
+use conduwuit::{Err, Result, debug, err, info, warn};
 use rocksdb::{
 	AsColumnFamilyRef, BoundColumnFamily, DBCommon, DBWithThreadMode, MultiThreaded,
 	WaitForCompactOptions,
@@ -127,6 +127,12 @@ impl Engine {
 
 		sequence
 	}
+
+	pub fn drop_column(&self, name: &str) -> Result {
+		self.db
+			.drop_cf(name)
+			.map_err(|err| err!("Failed to drop {name}: {err}"))
+	}
 }
 
 impl Drop for Engine {

src/service/migrations.rs

@@ -240,6 +240,19 @@ async fn migrate(services: &Services) -> Result<()> {
 			.map_err(|e| err!("Failed to run 'split_userid_password' migration': {e}"))?;
 	}
 
+	if db["global"]
+		.get(DROP_ROOMSYNCTOKEN_SHORTSTATEHASH)
+		.await
+		.is_not_found()
+	{
+		info!("Running migration 'drop_roomsynctoken_shortstatehash'");
+		obliterate_roomsynctoken_shortstatehash_with_extreme_prejudice(services)
+			.await
+			.map_err(|e| {
+				err!("Failed to run 'drop_roomsynctoken_shortstatehash' migration': {e}")
+			})?;
+	}
+
 	assert_eq!(
 		services.globals.db.database_version().await,
 		DATABASE_VERSION,
@@ -873,3 +886,14 @@ async fn split_userid_password(services: &Services) -> Result {
 	db.db.sort()?;
 	Ok(())
 }
+
+const DROP_ROOMSYNCTOKEN_SHORTSTATEHASH: &str = "drop_roomsynctoken_shortstatehash";
+async fn obliterate_roomsynctoken_shortstatehash_with_extreme_prejudice(
+	services: &Services,
+) -> Result {
+	services.db.db.drop_column("roomsynctoken_shortstatehash")?;
+
+	info!("Cleared roomsynctoken_shortstatehash.");
+
+	Ok(())
+}