[zones] monkey patch Dexie and handle errors

SQUASHED: AUTO-COMMIT-src-client-lang-lang-zone.js,AUTO-COMMIT-src-external-dexie3.js,AUTO-COMMIT-src-external-dexie.js,AUTO-COMMIT-test-lang-test.js,

Author: onsetsu

src/client/lang/lang-zone.js

@@ -1,6 +1,8 @@
 import 'lang';
 import Dexie from "src/external/dexie3.js";
 
+const { incrementExpectedAwaits, newPSD, decrementExpectedAwaits } = Dexie.Promise;
+
 const global = self;
 
 function exposeGlobal(key, value) {
@@ -20,8 +22,15 @@ function exposeGlobal(key, value) {
 - intended to be exchangeable in case of future standard or library advancements
 - <span style='background: red'>!only modify if you know what you are doing and understand the **long-term consequences**!</span>
 - currently implemented as a lightweight wrapper around [Dexie.Promise](https://dexie.org/docs/Promise/Promise.PSD)
+  - Caution: we <span style='background: red'>monkey-patched Dexie</span> to access `incrementExpectedAwaits` and `decrementExpectedAwaits` to correctly detect native await on primitives
+
 MD*/
 
+// check if `incrementExpectedAwaits` and `decrementExpectedAwaits` are available
+if (![incrementExpectedAwaits, decrementExpectedAwaits].every(func => typeof func === 'function')) {
+  throw new Error('Dexie not monkey-patched to expose `incrementExpectedAwaits` and `decrementExpectedAwaits`');
+}
+
 const globalZone = (() => {
   let zone = Dexie.Promise.PSD;
 
@@ -33,9 +42,12 @@ const globalZone = (() => {
     }
   }
 
+  
   return zone;
 })();
 
+
+
 const Zone = {
 
   get root() { return globalZone; },
@@ -44,8 +56,34 @@ const Zone = {
 
 };
 
+export function withZone(scopeFunc, zoneProps = {}) {
+  let returnValue;
+  try {
+    incrementExpectedAwaits();
+
+    newPSD(() => {
+      returnValue = scopeFunc.call();
+    }, zoneProps);
+    
+    return returnValue;
+  } finally {
+    if (returnValue && typeof returnValue.then === 'function') {
+      (async () => {
+        try {
+          await returnValue;
+        } catch(e) {
+        } finally {
+          decrementExpectedAwaits();
+        }
+      })();
+    } else {
+      decrementExpectedAwaits();
+    }
+  }
+}
+
 function runZoned(fn, { zoneValues } = {} ) {
-  return Dexie.Promise.newPSD(fn, zoneValues);
+  return withZone(fn, zoneValues);
 }
 
 exposeGlobal('Zone', Zone);

src/external/dexie.js

@@ -1,3 +1,10 @@
+// =============================================================================
+// ========================== MONKEY PATCHED TO ================================
+// ========================= PROVIDE ZONE ACCESS ===============================
+// =============================================================================
+// =============================================================================
+// =============================================================================
+
 /*
  * Dexie.js - a minimalistic wrapper for IndexedDB
  * ===============================================
@@ -888,6 +895,8 @@ props(Promise, {
     //task: {get: ()=>task},
     newPSD: newScope,
     usePSD: usePSD,
+    incrementExpectedAwaits: incrementExpectedAwaits,
+    decrementExpectedAwaits: decrementExpectedAwaits,
     scheduler: {
         get: function () { return asap$1; },
         set: function (value) { asap$1 = value; }

src/external/dexie3.js

@@ -141,6 +141,69 @@ describe('Zones', function() {
       expect(innerZone).to.have.property('p', 42);
     });
 
+    it('tracks zones over native await on primitive values', async () => {
+      let callback;
+      const prom = new Promise(resolve => callback = resolve);
+
+      let innerZone;
+      async function f3() {
+        await 42;
+        assert.strictEqual(Zone.current, innerZone);
+        callback()
+      }
+      async function f2() {
+        await f3();
+      }
+      
+      await runZoned(async () => {
+        innerZone = Zone.current;
+        await f2();
+      });
+      
+      await prom;
+    });
+
+    it('handles errors correctly', async () => {
+      let catchCalled = false;
+      let finallyCalled = false;
+      
+      const expectedError = new Error('expected')
+      
+      try {
+        await runZoned(async () => {
+          throw expectedError;
+        });
+      } catch (e) {
+        catchCalled = true;
+      } finally {
+        finallyCalled = true
+      }
+      
+      expect(catchCalled).to.be.true;
+      expect(finallyCalled).to.be.true;
+    });
+
+    it('handles errors correctly after native await on a primitive', async () => {
+      let catchCalled = false;
+      let finallyCalled = false;
+      
+      const expectedError = new Error('expected')
+      
+      try {
+        await runZoned(async () => {
+          await 42;
+          throw expectedError;
+        });
+      } catch (e) {
+        catchCalled = true;
+      } finally {
+        finallyCalled = true
+      }
+      
+      expect(catchCalled).to.be.true;
+      expect(finallyCalled).to.be.true;
+    });
+
   });
 
 });