From 64db7777dd4059d982ce1b45fdc014cf5f09c77b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A9ry=20Debongnie?= <ged@odoo.com>
Date: Mon, 4 Oct 2021 11:50:20 +0200
Subject: [PATCH] [FIX] component: async issue

This is a tricky commit. The key point is that the Fiber.complete
method, which commits a rendering to the DOM works like this: it
traverses the component tree, patch the corresponding DOM for each
component, calls the mounted/destroy hooks, and reset the currentfiber
of components to null, all synchronously.

However, this means that it is possible for components to initiate a
rendering (which create a new currentFiber) before the currentFiber is
reset to null, so the internal state of owl is corrupted. This can
occurs in a crash, as in the test that accompanies this commit.

To fix this, we take care of resetting the currentFiber first, while we
walk the component tree. Then, the internal state is always consistent
(i.e. a currentFiber to null means that there is no pending rendering)

closes #904
---
 src/component/component.ts    |  2 +-
 src/component/fiber.ts        |  5 +---
 tests/component/async.test.ts | 56 +++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/src/component/component.ts b/src/component/component.ts
index dabf8897..01ce6511 100644
--- a/src/component/component.ts
+++ b/src/component/component.ts
@@ -400,6 +400,7 @@ export class Component<Props extends {} = any, T extends Env = Env> {
     if (currentFiber && !currentFiber.isRendered && !currentFiber.isCompleted) {
       return scheduler.addFiber(currentFiber.root);
     }
+
     // if we aren't mounted at this point, it implies that there is a
     // currentFiber that is already rendered (isRendered is true), so we are
     // about to be mounted
@@ -505,7 +506,6 @@ export class Component<Props extends {} = any, T extends Env = Env> {
     const __owl__ = this.__owl__;
 
     __owl__.status = STATUS.MOUNTED;
-    __owl__.currentFiber = null;
     this.mounted();
     if (__owl__.mountedCB) {
       __owl__.mountedCB();
diff --git a/src/component/fiber.ts b/src/component/fiber.ts
index 07150a91..9ad25c06 100644
--- a/src/component/fiber.ts
+++ b/src/component/fiber.ts
@@ -198,6 +198,7 @@ export class Fiber {
     // build patchQueue
     const patchQueue: Fiber[] = [];
     const doWork: (Fiber) => Fiber | null = function (f) {
+      f.component.__owl__.currentFiber = null;
       patchQueue.push(f);
       return f.child;
     };
@@ -255,10 +256,6 @@ export class Fiber {
           component.__owl__.pvnode!.elm = component.__owl__.vnode!.elm;
         }
       }
-      const compOwl = component.__owl__;
-      if (fiber === compOwl.currentFiber) {
-        compOwl.currentFiber = null;
-      }
     }
 
     // insert into the DOM (mount case)
diff --git a/tests/component/async.test.ts b/tests/component/async.test.ts
index 1425c558..74fdb451 100644
--- a/tests/component/async.test.ts
+++ b/tests/component/async.test.ts
@@ -1388,6 +1388,62 @@ describe("async rendering", () => {
     expect(fixture.innerHTML).toBe("<span>4</span>");
   });
 
+  test("calling render in destroy", async () => {
+    let a: any = null;
+    let c: any = null;
+
+    class C extends Component {
+      static template = xml`
+        <div>
+          <t t-esc="props.fromA"/>
+        </div>`;
+    }
+
+    let flag = false;
+    class B extends Component {
+      static template = xml`<C fromA="props.fromA"/>`;
+      static components = { C };
+
+      setup() {
+        c = this;
+      }
+
+      mounted() {
+        if (flag) {
+          this.render();
+        } else {
+          flag = true;
+        }
+      }
+      willUnmount() {
+        c.render();
+      }
+    }
+
+    class A extends Component {
+      static template = xml`<B t-key="key" fromA="state"/>`;
+      static components = { B };
+      state = "a";
+      key = 1;
+
+      setup() {
+        a = this;
+      }
+    }
+
+    const parent = new A();
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>a</div>");
+
+    a.state = "A";
+    a.key = 2;
+    await a.render();
+    // this nextTick is critical, otherwise jest may silently swallow errors
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe("<div>A</div>");
+  });
+
   test("change state and call manually render: no unnecessary rendering", async () => {
     class Widget extends Component {
       static template = xml`<div><t t-esc="state.val"/></div>`;