perf: don't retransmit unchanged threads

appinfo/routes.php

@@ -233,7 +233,7 @@
 		[
 			'name' => 'messages#getThread',
 			'url' => '/api/messages/{id}/thread',
-			'verb' => 'GET'
+			'verb' => 'POST'
 		],
 		[
 			'name' => 'messages#setFlags',

lib/Controller/MessagesController.php

@@ -318,13 +318,13 @@
 	 * @NoAdminRequired
 	 * @NoCSRFRequired
 	 *
-	 * @param int $id
+	 * @param int[] $knownIds Known database ids of envelopes
 	 *
 	 * @return JSONResponse
 	 * @throws ClientException
 	 */
 	#[TrapError]
-	public function getThread(int $id): JSONResponse {
+	public function getThread(int $id, array $knownIds): JSONResponse {
 		try {
 			$message = $this->mailManager->getMessage($this->currentUserId, $id);
 			$mailbox = $this->mailManager->getMailbox($this->currentUserId, $message->getMailboxId());
@@ -337,7 +337,15 @@
 			return new JSONResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		return new JSONResponse($this->mailManager->getThread($account, $message->getThreadRootId()));
+		$thread = $this->mailManager->getThread($account, $message->getThreadRootId());
+		foreach ($thread as $envelope) {
+			if (!in_array($envelope->getId(), $knownIds)) {
+				// Thread changed -> send it
+				return new JSONResponse($thread);
+			}
+		}
+
+		return new JSONResponse([], Http::STATUS_NO_CONTENT);
 	}
 
 	/**

src/service/MessageService.js

@@ -58,11 +58,19 @@ export function fetchEnvelopes(accountId, mailboxId, query, cursor, limit) {
 			throw convertAxiosError(error)
 		})
 }
-export const fetchThread = async (id) => {
+export const fetchThread = async (id, knownIds) => {
 	const url = generateUrl('apps/mail/api/messages/{id}/thread', {
 		id,
 	})
-	const resp = await axios.get(url)
+	const resp = await axios.post(url, {
+		knownIds,
+	})
+
+	// Thread is up to date
+	if (resp.status === 204) {
+		return []
+	}
+
 	return resp.data
 }
 

src/store/mainStore/actions.js

@@ -1190,12 +1190,16 @@ export default function mainStoreActions() {
 		},
 		async fetchThread(id) {
 			return handleHttpAuthErrors(async () => {
-				const thread = await fetchThread(id)
-				this.addEnvelopeThreadMutation({
-					id,
-					thread,
-				})
-				return thread
+				const knownDatabaseIds = this.envelopes[id]?.thread ?? []
+				const thread = await fetchThread(id, knownDatabaseIds)
+				if (thread.length > 0) {
+					this.addEnvelopeThreadMutation({
+						id,
+						thread,
+					})
+				}
+
+				return this.getEnvelopeThread(id)
 			})
 		},
 		async fetchMessage(id) {