improve memory leak a little

1 files changed, 14 insertions, 2 deletions

diff --git a/src/observable.ts b/src/observable.ts
index 15a1a2e..5185c9f 100644
--- a/src/observable.ts
+++ b/src/observable.ts
@@ -5,6 +5,9 @@
 */
 export class OVar<T> {
     private _value: T
+    private weak = false; // if weak, the source will be unsubscribed from, if all listeners are removed
+    private disabled = false
+    private cancel_source?: () => void
     private observers: ((v: T) => unknown)[] = []
 
     constructor(initial: T) {
@@ -16,8 +19,16 @@ export class OVar<T> {
     change() { this.observers.forEach(o => o(this._value)) }
 
     onchange(handler: (v: T) => unknown): () => void {
+        if (this.disabled) throw new Error("obervable is disabled");
         this.observers.push(handler)
-        return () => this.observers = this.observers.filter(o => o != handler)
+        if (this.observers.length > 16) console.warn("likely memory leak here:", this);
+        return () => {
+            this.observers = this.observers.filter(o => o != handler)
+            if (this.observers.length == 0 && this.weak) {
+                this.cancel_source!()
+                this.disabled = true
+            }
+        }
     }
     onchangeinit(handler: (v: T) => unknown): () => void {
         const abort = this.onchange(handler)
@@ -26,7 +37,8 @@ export class OVar<T> {
     }
     map<U>(fn: (v: T) => U): OVar<U> {
         const uv = new OVar(fn(this.value))
-        this.onchange(v => uv.value = fn(v))
+        uv.cancel_source = this.onchange(v => uv.value = fn(v))
+        uv.weak = true
         return uv;
     }
     wait_for(val: T) {