feat(overmind-react): add suspense experiment and optimize memory

Author: christianalfoni

packages/node_modules/overmind-react/src/index.ts

@@ -34,6 +34,7 @@ export interface IConnect<Config extends IConfiguration> {
     effects: Overmind<Config>['effects']
     addMutationListener: Overmind<Config>['addMutationListener']
     reaction: Overmind<Config>['reaction']
+    suspend: <T>(cb: () => T) => T
   }
 }
 
@@ -108,7 +109,7 @@ export const createHook = <Config extends IConfiguration>(): (() => {
         reaction: overmind.reaction,
       }
     }
-    const { current: tree } = react.useRef<any>(
+    const [tree] = react.useState<any>(() =>
       (overmind as any).proxyStateTree.getTrackStateTree()
     )
 
@@ -170,12 +171,36 @@ export const createHook = <Config extends IConfiguration>(): (() => {
       tree.track(forceRerender)
     }
 
+    const suspend = (cb) => {
+      const value = cb()
+
+      if (value === null || value === undefined) {
+        ;(overmind as any).proxyStateTree.disposeTree(tree)
+
+        throw new Promise((resolve) => {
+          const dispose = overmind.addFlushListener(() => {
+            const newValue = cb()
+
+            if (newValue === null || newValue === undefined) {
+              return
+            }
+
+            dispose()
+            resolve()
+          })
+        })
+      }
+
+      return value
+    }
+
     return {
       state: tree.state,
       actions: overmind.actions,
       effects: overmind.effects,
       addMutationListener: overmind.addMutationListener,
       reaction: overmind.reaction,
+      suspend,
     }
   }
 }