From c17302413265d12def0d1e14954754016e115579 Mon Sep 17 00:00:00 2001
From: Daniel Sanchez Quiros <sanchez.quiros.daniel@gmail.com>
Date: Fri, 7 Oct 2022 12:20:59 +0200
Subject: [PATCH] Callback RwLock -> Mutex

---
 waku/src/events/mod.rs | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/waku/src/events/mod.rs b/waku/src/events/mod.rs
index 535e3e3..b623c16 100644
--- a/waku/src/events/mod.rs
+++ b/waku/src/events/mod.rs
@@ -1,17 +1,25 @@
+//! Asynchronous events require a callback to be registered.
+//! An example of an asynchronous event that might be emitted is receiving a message.
+//! When an event is emitted, this callback will be triggered receiving a [`Signal`]
+
 // std
 use std::ffi::{c_char, CStr};
 use std::ops::Deref;
-use std::sync::RwLock;
+use std::sync::Mutex;
 // crates
 use once_cell::sync::Lazy;
 use serde::{Deserialize, Serialize};
 // internal
 use crate::general::{WakuMessage, WakuPubSubTopic};
 
+// TODO: Signal and even can possibly be merged into a single Signal object with side tagged and aliased type
+/// Event signal
 #[derive(Serialize, Deserialize)]
 pub struct Signal {
+    /// Type of signal being emitted. Currently, only message is available
     #[serde(alias = "type")]
     _type: String,
+    /// Format depends on the type of signal
     event: Event,
 }
 
@@ -49,12 +57,12 @@ impl WakuMessageEvent {
 
 /// Shared callback slot. Callbacks are registered here so they can be accessed by the extern "C"
 #[allow(clippy::type_complexity)]
-static CALLBACK: Lazy<RwLock<Box<dyn FnMut(Signal) + Send + Sync>>> =
-    Lazy::new(|| RwLock::new(Box::new(|_| {})));
+static CALLBACK: Lazy<Mutex<Box<dyn FnMut(Signal) + Send + Sync>>> =
+    Lazy::new(|| Mutex::new(Box::new(|_| {})));
 
 /// Register global callback
 fn set_callback<F: FnMut(Signal) + Send + Sync + 'static>(f: F) {
-    *CALLBACK.write().unwrap() = Box::new(f);
+    *CALLBACK.lock().unwrap() = Box::new(f);
 }
 
 /// Wrapper callback, it transformst the `*const c_char` into a [`Signal`]
@@ -66,7 +74,7 @@ extern "C" fn callback(data: *const c_char) {
     let data: Signal = serde_json::from_str(raw_response).expect("Parsing signal to succeed");
     (CALLBACK
         .deref()
-        .write()
+        .lock()
         .expect("Access to the shared callback")
         .as_mut())(data)
 }