From b4fde61884963c7ae82947d61c109cf48fd67571 Mon Sep 17 00:00:00 2001
From: Nikolai Ovtsinnikov <nikolai@zone.ee>
Date: Fri, 15 Dec 2023 12:05:17 +0200
Subject: [PATCH] optimize CPU usage

---
 lib/imap-notifier.js | 45 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/lib/imap-notifier.js b/lib/imap-notifier.js
index 1e7dd09c..dfd4397f 100644
--- a/lib/imap-notifier.js
+++ b/lib/imap-notifier.js
@@ -78,17 +78,42 @@ class ImapNotifier extends EventEmitter {
         this.subscriber.on('message', (channel, message) => {
             if (channel === 'wd_events') {
                 let data;
-                try {
-                    data = JSON.parse(message);
-                } catch (E) {
-                    return;
+                // if e present at beginning, check if p also is present
+                // if no p -> no json parse
+                // if p -> json parse ONLY p
+                // if e not in beginning but p is -> json parse whole
+
+                if (message[2] === 'e') {
+                    for (let i = 6; i < 6 + 24; i++) {
+                        if (!/[0-9ABCDEF]/i.test(message[i])) {
+                            // check for hex char
+                            return; // incorrect e, e HAS to be hex
+                        }
+                    }
+
+                    data = { e: message.slice(6, 6 + 24) };
+
+                    if (message[33] === 'p') {
+                        // parse next JSON only if the payload is actually there
+                        data.p = JSON.parse('{' + message.slice(32, message.length - 1) + '}').p;
+                    }
+                } else {
+                    try {
+                        data = JSON.parse(message);
+                    } catch (E) {
+                        return;
+                    }
                 }
-                if (data.e && !data.p) {
-                    // events without payload are scheduled, these are notifications about changes in journal
-                    scheduleDataEvent(data.e);
-                } else if (data.e) {
-                    // events with payload are triggered immediatelly, these are actions for doing something
-                    this._listeners.emit(data.e, data.p);
+
+                if (this._listeners._events[data.e] && this._listeners._events[data.e].length > 0) {
+                    // do not schedule or fire/emit empty events
+                    if (data.e && !data.p) {
+                        // events without payload are scheduled, these are notifications about changes in journal
+                        scheduleDataEvent(data.e);
+                    } else if (data.e) {
+                        // events with payload are triggered immediatelly, these are actions for doing something
+                        this._listeners.emit(data.e, data.p);
+                    }
                 }
             }
         });