lazy-construct presence; avoids useless db queries in sender and syncer.

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client_server/sync.rs

@@ -571,7 +571,7 @@ async fn process_presence_updates(
 	presence_updates: &mut HashMap<OwnedUserId, PresenceEvent>, since: u64, syncing_user: &OwnedUserId,
 ) -> Result<()> {
 	// Take presence updates
-	for (user_id, _, presence_event) in services().presence.presence_since(since) {
+	for (user_id, _, presence_bytes) in services().presence.presence_since(since) {
 		if !services()
 			.rooms
 			.state_cache
@@ -580,6 +580,8 @@ async fn process_presence_updates(
 			continue;
 		}
 
+		use crate::service::presence::Presence;
+		let presence_event = Presence::from_json_bytes_to_event(&presence_bytes, &user_id)?;
 		match presence_updates.entry(user_id) {
 			Entry::Vacant(slot) => {
 				slot.insert(presence_event);

src/database/key_value/presence.rs

@@ -92,16 +92,13 @@ impl service::presence::Data for KeyValueDatabase {
 		Ok(())
 	}
 
-	fn presence_since<'a>(&'a self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, PresenceEvent)> + 'a> {
+	fn presence_since<'a>(&'a self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, Vec<u8>)> + 'a> {
 		Box::new(
 			self.presenceid_presence
 				.iter()
-				.flat_map(|(key, presence_bytes)| -> Result<(OwnedUserId, u64, PresenceEvent)> {
+				.flat_map(|(key, presence_bytes)| -> Result<(OwnedUserId, u64, Vec<u8>)> {
 					let (count, user_id) = presenceid_parse(&key)?;
-					let presence = Presence::from_json_bytes(&presence_bytes)?;
+					Ok((user_id, count, presence_bytes))
-					let presence_event = presence.to_presence_event(&user_id)?;
-
-					Ok((user_id, count, presence_event))
 				})
 				.filter(move |(_, count, _)| *count > since),
 		)

src/service/presence/data.rs

@@ -17,5 +17,5 @@ pub trait Data: Send + Sync {
 
 	/// Returns the most recent presence updates that happened after the event
 	/// with id `since`.
-	fn presence_since<'a>(&'a self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, PresenceEvent)> + 'a>;
+	fn presence_since<'a>(&'a self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, Vec<u8>)> + 'a>;
 }

src/service/presence/mod.rs

@@ -35,6 +35,11 @@ impl Presence {
 		}
 	}
 
+	pub fn from_json_bytes_to_event(bytes: &[u8], user_id: &UserId) -> Result<PresenceEvent> {
+		let presence = Self::from_json_bytes(bytes)?;
+		presence.to_presence_event(user_id)
+	}
+
 	pub fn from_json_bytes(bytes: &[u8]) -> Result<Self> {
 		serde_json::from_slice(bytes).map_err(|_| Error::bad_database("Invalid presence data in database"))
 	}
@@ -169,7 +174,7 @@ impl Service {
 
 	/// Returns the most recent presence updates that happened after the event
 	/// with id `since`.
-	pub fn presence_since(&self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, PresenceEvent)>> {
+	pub fn presence_since(&self, since: u64) -> Box<dyn Iterator<Item = (OwnedUserId, u64, Vec<u8>)>> {
 		self.db.presence_since(since)
 	}
 

src/service/sending/mod.rs

@@ -28,7 +28,7 @@ use ruma::{
 use tokio::sync::{Mutex, Semaphore};
 use tracing::{error, warn};
 
-use crate::{services, utils::calculate_hash, Config, Error, PduEvent, Result};
+use crate::{service::presence::Presence, services, utils::calculate_hash, Config, Error, PduEvent, Result};
 
 pub mod appservice;
 pub mod data;
@@ -493,7 +493,7 @@ pub fn select_edus_presence(
 ) -> Result<bool> {
 	// Look for presence updates for this server
 	let mut presence_updates = Vec::new();
-	for (user_id, count, presence_event) in services().presence.presence_since(since) {
+	for (user_id, count, presence_bytes) in services().presence.presence_since(since) {
 		*max_edu_count = cmp::max(count, *max_edu_count);
 
 		if user_id.server_name() != services().globals.server_name() {
@@ -508,6 +508,7 @@ pub fn select_edus_presence(
 			continue;
 		}
 
+		let presence_event = Presence::from_json_bytes_to_event(&presence_bytes, &user_id)?;
 		presence_updates.push(PresenceUpdate {
 			user_id,
 			presence: presence_event.content.presence,