refactor instantiation

Author: guybedford

core/register-loader.js

@@ -98,11 +98,6 @@ function createLoadRecord (state, key, registration) {
       // will be the array of dependency load record or a module namespace
       dependencyInstantiations: undefined,
 
-      // indicates if the load and all its dependencies are instantiated and linked
-      // but not yet executed
-      // mostly just a performance shortpath to avoid rechecking the promises above
-      linked: false
-
       // NB optimization and way of ensuring module objects in setters
       // indicates setters which should run pre-execution of that dependency
       // setters is then just for completely executed module objects
@@ -133,12 +128,9 @@ RegisterLoader.prototype[Loader.resolveInstantiate] = function (key, parentKey)
       throw instantiated.evalError;
     }
 
-    if (instantiated.linkRecord.linked)
-      return ensureEvaluate(loader, instantiated, instantiated.linkRecord, registry, state, undefined);
-
-    return instantiateDeps(loader, instantiated, instantiated.linkRecord, registry, state, [instantiated])
+    return deepInstantiateDeps(loader, instantiated, link, registry, state)
     .then(function () {
-      return ensureEvaluate(loader, instantiated, instantiated.linkRecord, registry, state, undefined);
+      return ensureEvaluate(loader, instantiated, link, registry, state, undefined);
     });
   });
 };
@@ -244,13 +236,6 @@ function instantiate (loader, load, link, registry, state) {
       registerDeclarative(loader, load, link, registration[1]);
     }
 
-    // shortpath to instantiateDeps
-    if (!link.dependencies.length) {
-      link.linked = true;
-      if (loader.trace)
-        traceLoad(loader, load, link);
-    }
-
     return load;
   })
   .catch(function (err) {
@@ -372,16 +357,16 @@ function registerDeclarative (loader, load, link, declare) {
   }
 }
 
-function instantiateDeps (loader, load, link, registry, state, seen) {
-  return (link.depsInstantiatePromise || (link.depsInstantiatePromise = Promise.resolve()
-  .then(function () {
-    var depsInstantiatePromises = Array(link.dependencies.length);
+function instantiateDeps (loader, load, link, registry, state) {
+  if (link.depsInstantiatePromise)
+    return link.depsInstantiatePromise;
 
-    for (var i = 0; i < link.dependencies.length; i++)
-      depsInstantiatePromises[i] = resolveInstantiateDep(loader, link.dependencies[i], load.key, registry, state, loader.trace && link.depMap || (link.depMap = {}));
+  var depsInstantiatePromises = Array(link.dependencies.length);
 
-    return Promise.all(depsInstantiatePromises);
-  })
+  for (var i = 0; i < link.dependencies.length; i++)
+    depsInstantiatePromises[i] = resolveInstantiateDep(loader, link.dependencies[i], load.key, registry, state, loader.trace && link.depMap || (link.depMap = {}));
+
+  var depsInstantiatePromise = Promise.all(depsInstantiatePromises)
   .then(function (dependencyInstantiations) {
     link.dependencyInstantiations = dependencyInstantiations;
 
@@ -406,43 +391,58 @@ function instantiateDeps (loader, load, link, registry, state, seen) {
         }
       }
     }
-  })))
-  .then(function () {
-    // now deeply instantiateDeps on each dependencyInstantiation that is a load record
-    var deepDepsInstantiatePromises = [];
 
-    for (var i = 0; i < link.dependencies.length; i++) {
-      var depLoad = link.dependencyInstantiations[i];
-      var depLink = depLoad.linkRecord;
-
-      if (!depLink || depLink.linked)
-        continue;
-
-      if (seen.indexOf(depLoad) !== -1) {
-        deepDepsInstantiatePromises.push(depLink.depsInstantiatePromise);
-        continue;
-      }
-      seen.push(depLoad);
-
-      deepDepsInstantiatePromises.push(instantiateDeps(loader, depLoad, depLoad.linkRecord, registry, state, seen));
-    }
+    return load;
+  });
 
-    return Promise.all(deepDepsInstantiatePromises);
-  })
-  .then(function () {
-    // as soon as all dependencies instantiated, we are ready for evaluation so can add to the registry
-    // this can run multiple times, but so what
-    link.linked = true;
-    if (loader.trace)
+  if (loader.trace)
+    depsInstantiatePromise = depsInstantiatePromise.then(function () {
       traceLoad(loader, load, link);
+      return load;
+    });
 
-    return load;
-  })
-  .catch(function (err) {
+  depsInstantiatePromise = depsInstantiatePromise.catch(function (err) {
     // throw up the instantiateDeps stack
-    link.depsInstantiatePromise = undefined;
     throw addToError(err, 'Loading ' + load.key);
   });
+
+  depsInstantiatePromise.catch(function () {});
+
+  return link.depsInstantiatePromise = depsInstantiatePromise;
+}
+
+function deepInstantiateDeps (loader, load, link, registry, state) {
+  return new Promise(function (resolve, reject) {
+    var seen = [];
+    var loadCnt = 0;
+    function queueLoad (load) {
+      var link = load.linkRecord;
+      if (!link)
+        return;
+
+      if (seen.indexOf(load) !== -1)
+        return;
+      seen.push(load);
+      
+      loadCnt++;
+      instantiateDeps(loader, load, link, registry, state)
+      .then(processLoad, reject);
+    }
+    function processLoad (load) {
+      loadCnt--;
+      var link = load.linkRecord;
+      if (link) {
+        for (var i = 0; i < link.dependencies.length; i++) {
+          var depLoad = link.dependencyInstantiations[i];
+          if (!(depLoad instanceof ModuleNamespace))
+            queueLoad(depLoad);
+        }
+      }
+      if (loadCnt === 0)
+        resolve();
+    }
+    queueLoad(load);
+  });
 }
 
 /*