Merge remote-tracking branch 'ginger/single-event-backfill' into illegal-car-mods

Consuming this flake is pretty annoying since the rocksdb input is
fetched on every build which takes ~ 10 - 20 sec. By removing it and
replacing it with a `pkgs.fetchFromGitea`, we create an intermediate
derivation which is better for caching reasons.

flake.lock

@@ -513,23 +513,6 @@
         "type": "github"
       }
     },
-    "rocksdb": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1753385396,
-        "narHash": "sha256-/Hvy1yTH/0D5aa7bc+/uqFugCQq4InTdwlRw88vA5IY=",
-        "ref": "10.4.fb",
-        "rev": "28d4b7276c16ed3e28af1bd96162d6442ce25923",
-        "revCount": 13318,
-        "type": "git",
-        "url": "https://forgejo.ellis.link/continuwuation/rocksdb"
-      },
-      "original": {
-        "ref": "10.4.fb",
-        "type": "git",
-        "url": "https://forgejo.ellis.link/continuwuation/rocksdb"
-      }
-    },
     "root": {
       "inputs": {
         "attic": "attic",
@@ -539,8 +522,7 @@
         "flake-compat": "flake-compat_3",
         "flake-utils": "flake-utils",
         "nix-filter": "nix-filter",
-        "nixpkgs": "nixpkgs_5",
+        "nixpkgs": "nixpkgs_5"
-        "rocksdb": "rocksdb"
       }
     },
     "rust-analyzer-src": {

flake.nix

@@ -16,10 +16,6 @@
     flake-utils.url = "github:numtide/flake-utils?ref=main";
     nix-filter.url = "github:numtide/nix-filter?ref=main";
     nixpkgs.url = "github:NixOS/nixpkgs?ref=nixpkgs-unstable";
-    rocksdb = {
-      url = "git+https://forgejo.ellis.link/continuwuation/rocksdb?ref=10.4.fb";
-      flake = false;
-    };
   };
 
   outputs =
@@ -65,7 +61,13 @@
                 inherit (self) liburing;
               }).overrideAttrs
                 (old: {
-                  src = inputs.rocksdb;
+                  src = pkgsHost.fetchFromGitea {
+                    domain = "forgejo.ellis.link";
+                    owner = "continuwuation";
+                    repo = "rocksdb";
+                    rev = "10.4.fb";
+                    sha256 = "sha256-/Hvy1yTH/0D5aa7bc+/uqFugCQq4InTdwlRw88vA5IY=";
+                  };
                   version = "v10.4.fb";
                   cmakeFlags =
                     pkgs.lib.subtractLists [

src/admin/debug/commands.rs

@@ -281,15 +281,8 @@ pub(super) async fn get_remote_pdu(
 				vec![(event_id, value, room_id)]
 			};
 
-			info!("Attempting to handle event ID {event_id} as backfilled PDU");
-			self.services
-				.rooms
-				.timeline
-				.backfill_pdu(&server, response.pdu)
-				.await?;
-
 			let text = serde_json::to_string_pretty(&json)?;
-			let msg = "Got PDU from specified server and handled as backfilled";
+			let msg = "Got PDU from specified server:";
 			write!(self, "{msg}. Event body:\n```json\n{text}\n```")
 		},
 	}

src/admin/query/room_timeline.rs

@@ -57,5 +57,5 @@ pub(super) async fn pdus(
 		.try_collect()
 		.await?;
 
-	self.write_str(&format!("{result:#?}")).await
+	self.write_str(&format!("```\n{result:#?}\n```")).await
 }

src/api/client/message.rs

@@ -35,7 +35,7 @@ use ruma::{
 };
 use tracing::warn;
 
-use super::utils::{count_to_token, parse_pagination_token as parse_token};
+use super::utils::{count_to_pagination_token, pagination_token_to_count as parse_token};
 use crate::Ruma;
 
 /// list of safe and common non-state events to ignore if the user is ignored
@@ -181,8 +181,8 @@ pub(crate) async fn get_message_events_route(
 		.collect();
 
 	Ok(get_message_events::v3::Response {
-		start: count_to_token(from),
+		start: count_to_pagination_token(from),
-		end: next_token.map(count_to_token),
+		end: next_token.map(count_to_pagination_token),
 		chunk,
 		state,
 	})

src/api/client/relations.rs

@@ -18,7 +18,7 @@ use ruma::{
 	events::{TimelineEventType, relation::RelationType},
 };
 
-use super::utils::{count_to_token, parse_pagination_token as parse_token};
+use super::utils::{count_to_pagination_token, pagination_token_to_count as parse_token};
 use crate::Ruma;
 
 /// # `GET /_matrix/client/r0/rooms/{roomId}/relations/{eventId}/{relType}/{eventType}`
@@ -193,7 +193,7 @@ async fn paginate_relations_with_filter(
 			| Direction::Forward => events.last(),
 			| Direction::Backward => events.first(),
 		}
-		.map(|(count, _)| count_to_token(*count))
+		.map(|(count, _)| count_to_pagination_token(*count))
 	} else {
 		None
 	};

src/api/client/room/event.rs

@@ -18,7 +18,7 @@ pub(crate) async fn get_room_event_route(
 	let event = services
 		.rooms
 		.timeline
-		.get_pdu(event_id)
+		.get_remote_pdu(room_id, event_id)
 		.map_err(|_| err!(Request(NotFound("Event {} not found.", event_id))));
 
 	let visible = services
@@ -33,11 +33,6 @@ pub(crate) async fn get_room_event_route(
 		return Err!(Request(Forbidden("You don't have permission to view this event.")));
 	}
 
-	debug_assert!(
-		event.event_id() == event_id && event.room_id() == room_id,
-		"Fetched PDU must match requested"
-	);
-
 	event.add_age().ok();
 
 	Ok(get_room_event::v3::Response { event: event.into_format() })

src/api/client/threads.rs

@@ -9,7 +9,7 @@ use conduwuit::{
 use futures::StreamExt;
 use ruma::{api::client::threads::get_threads, uint};
 
-use crate::Ruma;
+use crate::{Ruma, client::utils::pagination_token_to_count};
 
 /// # `GET /_matrix/client/r0/rooms/{roomId}/threads`
 pub(crate) async fn get_threads_route(
@@ -27,7 +27,7 @@ pub(crate) async fn get_threads_route(
 	let from: PduCount = body
 		.from
 		.as_deref()
-		.map(str::parse)
+		.map(pagination_token_to_count)
 		.transpose()?
 		.unwrap_or_else(PduCount::max);
 

src/api/client/utils.rs

@@ -1,28 +1,7 @@
-use conduwuit::{
+use conduwuit::{Result, matrix::pdu::PduCount};
-	Result, err,
-	matrix::pdu::{PduCount, ShortEventId},
-};
 
-/// Parse a pagination token, trying ShortEventId first, then falling back to
+/// Parse a pagination token
-/// PduCount
+pub(crate) fn pagination_token_to_count(token: &str) -> Result<PduCount> { token.parse() }
-pub(crate) fn parse_pagination_token(token: &str) -> Result<PduCount> {
-	// Try parsing as ShortEventId first
-	if let Ok(shorteventid) = token.parse::<ShortEventId>() {
-		// ShortEventId maps directly to a PduCount in our database
-		Ok(PduCount::Normal(shorteventid))
-	} else if let Ok(count) = token.parse::<u64>() {
-		// Fallback to PduCount for backwards compatibility
-		Ok(PduCount::Normal(count))
-	} else if let Ok(count) = token.parse::<i64>() {
-		// Also handle negative counts for backfilled events
-		Ok(PduCount::from_signed(count))
-	} else {
-		Err(err!(Request(InvalidParam("Invalid pagination token"))))
-	}
-}
 
-/// Convert a PduCount to a token string (using the underlying ShortEventId)
+/// Convert a PduCount to a token string
-pub(crate) fn count_to_token(count: PduCount) -> String {
+pub(crate) fn count_to_pagination_token(count: PduCount) -> String { count.to_string() }
-	// The PduCount's unsigned value IS the ShortEventId
-	count.into_unsigned().to_string()
-}

src/core/matrix/pdu/count.rs

@@ -1,6 +1,10 @@
 #![allow(clippy::cast_possible_wrap, clippy::cast_sign_loss, clippy::as_conversions)]
 
-use std::{cmp::Ordering, fmt, fmt::Display, str::FromStr};
+use std::{
+	cmp::Ordering,
+	fmt::{self, Display},
+	str::FromStr,
+};
 
 use ruma::api::Direction;
 

src/service/rooms/timeline/backfill.rs

@@ -1,21 +1,24 @@
 use std::iter::once;
 
+use conduwuit::{Err, PduEvent};
 use conduwuit_core::{
-	Result, debug, implement, info,
+	Result, debug, debug_warn, err, implement, info,
 	matrix::{
 		event::Event,
 		pdu::{PduCount, PduId, RawPduId},
 	},
 	utils::{IterStream, ReadyExt},
-	validated,
+	validated, warn,
 };
 use futures::{FutureExt, StreamExt};
 use ruma::{
-	RoomId, ServerName,
+	CanonicalJsonObject, EventId, RoomId, ServerName,
 	api::federation,
 	events::{
 		StateEventType, TimelineEventType, room::power_levels::RoomPowerLevelsEventContent,
-	}, UInt};
+	},
+	uint,
+};
 use serde_json::value::RawValue as RawJsonValue;
 
 use super::ExtractBody;
@@ -98,7 +101,7 @@ pub async fn backfill_if_required(&self, room_id: &RoomId, from: PduCount) -> Re
 		.boxed();
 
 	while let Some(ref backfill_server) = servers.next().await {
-		info!("Asking {backfill_server} for backfill of room {room_id}");
+		info!("Asking {backfill_server} for backfill in {room_id}");
 		let response = self
 			.services
 			.sending
@@ -107,7 +110,7 @@ pub async fn backfill_if_required(&self, room_id: &RoomId, from: PduCount) -> Re
 				federation::backfill::get_backfill::v1::Request {
 					room_id: room_id.to_owned(),
 					v: vec![first_pdu.1.event_id().to_owned()],
-					limit: UInt::from(self.services.server.config.max_fetch_prev_events),
+					limit: uint!(100),
 				},
 			)
 			.await;
@@ -115,21 +118,137 @@ pub async fn backfill_if_required(&self, room_id: &RoomId, from: PduCount) -> Re
 			| Ok(response) => {
 				for pdu in response.pdus {
 					if let Err(e) = self.backfill_pdu(backfill_server, pdu).boxed().await {
-						info!("Failed to add backfilled pdu in room {room_id}: {e}");
+						debug_warn!("Failed to add backfilled pdu in room {room_id}: {e}");
 					}
 				}
 				return Ok(());
 			},
 			| Err(e) => {
-				info!("{backfill_server} failed to provide backfill for room {room_id}: {e}");
+				warn!("{backfill_server} failed to provide backfill for room {room_id}: {e}");
 			},
 		}
 	}
 
-	info!("No servers could backfill, but backfill was needed in room {room_id}");
+	warn!("No servers could backfill, but backfill was needed in room {room_id}");
 	Ok(())
 }
 
+#[implement(super::Service)]
+#[tracing::instrument(name = "get_remote_pdu", level = "debug", skip(self))]
+pub async fn get_remote_pdu(&self, room_id: &RoomId, event_id: &EventId) -> Result<PduEvent> {
+	let local = self.get_pdu(event_id).await;
+	if local.is_ok() {
+		// We already have this PDU, no need to backfill
+		debug!("We already have {event_id} in {room_id}, no need to backfill.");
+		return local;
+	}
+	debug!("Preparing to fetch event {event_id} in room {room_id} from remote servers.");
+	// Similar to backfill_if_required, but only for a single PDU
+	// Fetch a list of servers to try
+	if self
+		.services
+		.state_cache
+		.room_joined_count(room_id)
+		.await
+		.is_ok_and(|count| count <= 1)
+		&& !self
+			.services
+			.state_accessor
+			.is_world_readable(room_id)
+			.await
+	{
+		// Room is empty (1 user or none), there is no one that can backfill
+		return Err!(Request(NotFound("No one can backfill this PDU, room is empty.")));
+	}
+
+	let power_levels: RoomPowerLevelsEventContent = self
+		.services
+		.state_accessor
+		.room_state_get_content(room_id, &StateEventType::RoomPowerLevels, "")
+		.await
+		.unwrap_or_default();
+
+	let room_mods = power_levels.users.iter().filter_map(|(user_id, level)| {
+		if level > &power_levels.users_default && !self.services.globals.user_is_local(user_id) {
+			Some(user_id.server_name())
+		} else {
+			None
+		}
+	});
+
+	let canonical_room_alias_server = once(
+		self.services
+			.state_accessor
+			.get_canonical_alias(room_id)
+			.await,
+	)
+	.filter_map(Result::ok)
+	.map(|alias| alias.server_name().to_owned())
+	.stream();
+	let mut servers = room_mods
+		.stream()
+		.map(ToOwned::to_owned)
+		.chain(canonical_room_alias_server)
+		.chain(
+			self.services
+				.server
+				.config
+				.trusted_servers
+				.iter()
+				.map(ToOwned::to_owned)
+				.stream(),
+		)
+		.ready_filter(|server_name| !self.services.globals.server_is_ours(server_name))
+		.filter_map(|server_name| async move {
+			self.services
+				.state_cache
+				.server_in_room(&server_name, room_id)
+				.await
+				.then_some(server_name)
+		})
+		.boxed();
+
+	while let Some(ref backfill_server) = servers.next().await {
+		info!("Asking {backfill_server} for event {}", event_id);
+		let value = self
+			.services
+			.sending
+			.send_federation_request(backfill_server, federation::event::get_event::v1::Request {
+				event_id: event_id.to_owned(),
+				include_unredacted_content: Some(false),
+			})
+			.await
+			.and_then(|response| {
+				serde_json::from_str::<CanonicalJsonObject>(response.pdu.get()).map_err(|e| {
+					err!(BadServerResponse(debug_warn!(
+						"Error parsing incoming event {e:?} from {backfill_server}"
+					)))
+				})
+			});
+		let pdu = match value {
+			| Ok(value) => {
+				self.services
+					.event_handler
+					.handle_incoming_pdu(backfill_server, &room_id, &event_id, value, false)
+					.boxed()
+					.await?;
+				debug!("Successfully backfilled {event_id} from {backfill_server}");
+				Some(self.get_pdu(event_id).await)
+			},
+			| Err(e) => {
+				warn!("{backfill_server} failed to provide backfill for room {room_id}: {e}");
+				None
+			},
+		};
+		if let Some(pdu) = pdu {
+			debug!("Fetched {event_id} from {backfill_server}");
+			return pdu;
+		}
+	}
+
+	Err!("No servers could be used to fetch {} in {}.", room_id, event_id)
+}
+
 #[implement(super::Service)]
 #[tracing::instrument(skip(self, pdu), level = "debug")]
 pub async fn backfill_pdu(&self, origin: &ServerName, pdu: Box<RawJsonValue>) -> Result<()> {

src/service/rooms/timeline/data.rs

@@ -3,8 +3,7 @@ use std::{borrow::Borrow, sync::Arc};
 use conduwuit::{
 	Err, PduCount, PduEvent, Result, at, err,
 	result::{LogErr, NotFound},
-	utils,
+	utils::{self, stream::TryReadyExt},
-	utils::stream::TryReadyExt,
 };
 use database::{Database, Deserialized, Json, KeyVal, Map};
 use futures::{FutureExt, Stream, TryFutureExt, TryStreamExt, future::select_ok, pin_mut};