From 3110ac1fbb3c4f88bcfb3ab892238e9b9e1c4bcf Mon Sep 17 00:00:00 2001
From: Zixuan Chen <remch183@outlook.com>
Date: Thu, 17 Oct 2024 00:41:06 +0800
Subject: [PATCH] fix: avoid auto unsubscribe (due to gc) in js env

---
 Cargo.lock                  |  1 +
 crates/loro-wasm/Cargo.toml |  1 +
 crates/loro-wasm/src/lib.rs | 20 +++++++++++++++++---
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index a50d623e2..c99ad79ee 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1482,6 +1482,7 @@ dependencies = [
  "js-sys",
  "loro-internal 0.16.12",
  "loro-rle 0.16.12",
+ "once_cell",
  "serde",
  "serde-wasm-bindgen 0.6.5",
  "serde_json",
diff --git a/crates/loro-wasm/Cargo.toml b/crates/loro-wasm/Cargo.toml
index e0cb2b936..162bba66b 100644
--- a/crates/loro-wasm/Cargo.toml
+++ b/crates/loro-wasm/Cargo.toml
@@ -21,6 +21,7 @@ rle = { path = "../rle", package = "loro-rle" }
 tracing-wasm = "0.2.1"
 tracing = { version = "0.1", features = ["release_max_level_warn"] }
 serde_json = "1"
+once_cell.workspace = true
 
 [features]
 default = []
diff --git a/crates/loro-wasm/src/lib.rs b/crates/loro-wasm/src/lib.rs
index d2b4a0f91..54f25e394 100644
--- a/crates/loro-wasm/src/lib.rs
+++ b/crates/loro-wasm/src/lib.rs
@@ -28,7 +28,7 @@ use loro_internal::{
 };
 use rle::HasLength;
 use serde::{Deserialize, Serialize};
-use std::{cell::RefCell, cmp::Ordering, rc::Rc, sync::Arc};
+use std::{cell::RefCell, cmp::Ordering, mem::ManuallyDrop, rc::Rc, sync::Arc};
 use wasm_bindgen::{__rt::IntoJsResult, prelude::*, throw_val};
 use wasm_bindgen_derive::TryFromJsValue;
 
@@ -4240,9 +4240,23 @@ fn js_to_export_mode(js_mode: JsExportMode) -> JsResult<ExportMode<'static>> {
 }
 
 fn subscription_to_js_function_callback(sub: Subscription) -> JsValue {
-    let mut sub = Some(sub);
+    use once_cell::sync::Lazy;
+    use std::collections::HashMap;
+    use std::sync::Mutex;
+
+    static SUBSCRIPTION_MAP: Lazy<Mutex<HashMap<usize, Subscription>>> =
+        Lazy::new(|| Mutex::new(HashMap::new()));
+    static NEXT_ID: Lazy<Mutex<usize>> = Lazy::new(|| Mutex::new(0));
+
+    let id = {
+        let mut id = NEXT_ID.lock().unwrap();
+        *id += 1;
+        *id
+    };
+
+    SUBSCRIPTION_MAP.lock().unwrap().insert(id, sub);
     let closure = Closure::wrap(Box::new(move || {
-        if let Some(sub) = sub.take() {
+        if let Some(sub) = SUBSCRIPTION_MAP.lock().unwrap().remove(&id) {
             sub.unsubscribe();
         }
     }) as Box<dyn FnMut()>);