[lib] improve processOutboundP2PMessages in terms of performance

Summary:
[ENG-9096](https://linear.app/comm/issue/ENG-9096/improve-processoutboundp2pmessages-in-terms-of-performance)

We need to do it per device, not per message to avoid creating multiple sessions in parallel.

Test Plan: Test DM ops (text messages, settings, reactions, etc.)

Reviewers: tomek, marcin

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13204

lib/tunnelbroker/peer-to-peer-context.js

@@ -26,6 +26,7 @@ import {
 } from '../types/tunnelbroker/peer-to-peer-message-types.js';
 import { getConfig } from '../utils/config.js';
 import { getMessageForException } from '../utils/errors.js';
+import { entries } from '../utils/objects.js';
 import { olmSessionErrors } from '../utils/olm-utils.js';
 
 type PeerToPeerContextType = {
@@ -128,53 +129,60 @@ async function processOutboundP2PMessages(
     }
   };
 
-  for (const peerDeviceID in devicesMap) {
-    for (const message of devicesMap[peerDeviceID]) {
-      if (message.status === outboundP2PMessageStatuses.persisted) {
-        try {
-          const result = await olmAPI.encryptAndPersist(
-            message.plaintext,
-            message.deviceID,
-            message.messageID,
-          );
-
-          const encryptedMessage: OutboundP2PMessage = {
-            ...message,
-            ciphertext: JSON.stringify(result),
-          };
-          await sendMessageToPeer(encryptedMessage);
-        } catch (e) {
-          if (!e.message?.includes(olmSessionErrors.sessionDoesNotExists)) {
-            console.log(`Error sending messages to peer ${peerDeviceID}`, e);
-            break;
-          }
+  const devicePromises = entries(devicesMap).map(
+    async ([peerDeviceID, deviceMessages]) => {
+      for (const message of deviceMessages) {
+        if (message.status === outboundP2PMessageStatuses.persisted) {
           try {
-            await peerOlmSessionsCreator(message.userID, peerDeviceID);
             const result = await olmAPI.encryptAndPersist(
               message.plaintext,
               message.deviceID,
               message.messageID,
             );
+
             const encryptedMessage: OutboundP2PMessage = {
               ...message,
               ciphertext: JSON.stringify(result),
             };
-
             await sendMessageToPeer(encryptedMessage);
-          } catch (err) {
-            console.log(`Error sending messages to peer ${peerDeviceID}`, err);
-            break;
+          } catch (e) {
+            if (!e.message?.includes(olmSessionErrors.sessionDoesNotExists)) {
+              console.log(`Error sending messages to peer ${peerDeviceID}`, e);
+              break;
+            }
+            try {
+              await peerOlmSessionsCreator(message.userID, peerDeviceID);
+              const result = await olmAPI.encryptAndPersist(
+                message.plaintext,
+                message.deviceID,
+                message.messageID,
+              );
+              const encryptedMessage: OutboundP2PMessage = {
+                ...message,
+                ciphertext: JSON.stringify(result),
+              };
+
+              await sendMessageToPeer(encryptedMessage);
+            } catch (err) {
+              console.log(
+                `Error sending messages to peer ${peerDeviceID}`,
+                err,
+              );
+              break;
+            }
           }
+        } else if (message.status === outboundP2PMessageStatuses.encrypted) {
+          await sendMessageToPeer(message);
+        } else if (message.status === outboundP2PMessageStatuses.sent) {
+          // Handle edge-case when message was sent, but it wasn't updated
+          // in the message store.
+          sentMessagesMap[message.messageID] = true;
         }
-      } else if (message.status === outboundP2PMessageStatuses.encrypted) {
-        await sendMessageToPeer(message);
-      } else if (message.status === outboundP2PMessageStatuses.sent) {
-        // Handle edge-case when message was sent, but it wasn't updated
-        // in the message store.
-        sentMessagesMap[message.messageID] = true;
       }
-    }
-  }
+    },
+  );
+
+  await Promise.all(devicePromises);
   return Object.keys(sentMessagesMap);
 }