From 043eb35be6baf3d3f512b6634b56b25f86d19d7a Mon Sep 17 00:00:00 2001
From: daiwei <daiwei521@126.com>
Date: Fri, 3 Jan 2025 09:17:19 +0800
Subject: [PATCH 1/3] feat(effectScope): allow multiple  calls by tracking call
 count

---
 .../reactivity/__tests__/effectScope.spec.ts     | 13 +++++++++++++
 packages/reactivity/src/effectScope.ts           | 16 +++++++++++++---
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/packages/reactivity/__tests__/effectScope.spec.ts b/packages/reactivity/__tests__/effectScope.spec.ts
index debbdafb1e7..84310b985f2 100644
--- a/packages/reactivity/__tests__/effectScope.spec.ts
+++ b/packages/reactivity/__tests__/effectScope.spec.ts
@@ -296,6 +296,19 @@ describe('reactivity/effect/scope', () => {
     })
   })
 
+  it('calling on() and off() multiple times inside an active scope should not break currentScope', () => {
+    const parentScope = effectScope()
+    parentScope.run(() => {
+      const childScope = effectScope(true)
+      childScope.on()
+      childScope.on()
+      childScope.off()
+      childScope.off()
+      childScope.off()
+      expect(getCurrentScope()).toBe(parentScope)
+    })
+  })
+
   it('should pause/resume EffectScope', async () => {
     const counter = reactive({ num: 0 })
     const fnSpy = vi.fn(() => counter.num)
diff --git a/packages/reactivity/src/effectScope.ts b/packages/reactivity/src/effectScope.ts
index 80f42db6484..cca0b113149 100644
--- a/packages/reactivity/src/effectScope.ts
+++ b/packages/reactivity/src/effectScope.ts
@@ -8,6 +8,10 @@ export class EffectScope {
    * @internal
    */
   private _active = true
+  /**
+   * @internal track `on` calls, allow `on` call multiple times
+   */
+  private _onCallCount = 0
   /**
    * @internal
    */
@@ -105,8 +109,11 @@ export class EffectScope {
    * @internal
    */
   on(): void {
-    this.prevScope = activeEffectScope
-    activeEffectScope = this
+    this._onCallCount++
+    if (this._onCallCount === 1) {
+      this.prevScope = activeEffectScope
+      activeEffectScope = this
+    }
   }
 
   /**
@@ -114,7 +121,10 @@ export class EffectScope {
    * @internal
    */
   off(): void {
-    activeEffectScope = this.prevScope
+    this._onCallCount = Math.max(0, this._onCallCount - 1)
+    if (this._onCallCount === 0) {
+      activeEffectScope = this.prevScope
+    }
   }
 
   stop(fromParent?: boolean): void {

From d92c37a8ec5be193283516533617ad5241cd596d Mon Sep 17 00:00:00 2001
From: Evan You <evan@vuejs.org>
Date: Wed, 8 Jan 2025 18:00:49 +0800
Subject: [PATCH 2/3] refactor: simplify implementation

---
 packages/reactivity/src/effectScope.ts | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/packages/reactivity/src/effectScope.ts b/packages/reactivity/src/effectScope.ts
index cca0b113149..4079e2a9d61 100644
--- a/packages/reactivity/src/effectScope.ts
+++ b/packages/reactivity/src/effectScope.ts
@@ -11,7 +11,7 @@ export class EffectScope {
   /**
    * @internal track `on` calls, allow `on` call multiple times
    */
-  private _onCallCount = 0
+  private _on = 0
   /**
    * @internal
    */
@@ -109,8 +109,7 @@ export class EffectScope {
    * @internal
    */
   on(): void {
-    this._onCallCount++
-    if (this._onCallCount === 1) {
+    if (++this._on === 1) {
       this.prevScope = activeEffectScope
       activeEffectScope = this
     }
@@ -121,8 +120,7 @@ export class EffectScope {
    * @internal
    */
   off(): void {
-    this._onCallCount = Math.max(0, this._onCallCount - 1)
-    if (this._onCallCount === 0) {
+    if (this._on > 0 && --this._on === 0) {
       activeEffectScope = this.prevScope
     }
   }

From 499af49d51214b86626927c328873bab787c7006 Mon Sep 17 00:00:00 2001
From: Evan You <evan@vuejs.org>
Date: Wed, 8 Jan 2025 18:02:11 +0800
Subject: [PATCH 3/3] chore: also unset prevScope on off

---
 packages/reactivity/src/effectScope.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/reactivity/src/effectScope.ts b/packages/reactivity/src/effectScope.ts
index 4079e2a9d61..9ca24c08857 100644
--- a/packages/reactivity/src/effectScope.ts
+++ b/packages/reactivity/src/effectScope.ts
@@ -122,6 +122,7 @@ export class EffectScope {
   off(): void {
     if (this._on > 0 && --this._on === 0) {
       activeEffectScope = this.prevScope
+      this.prevScope = undefined
     }
   }