Web Worker improvements and fixes

- Do not clean up the documentElement in enableProllyfill if it is
  currently being rendered.
- Moved Worker event handlers to before postMessage is called.

dist/diffhtml.js

@@ -265,6 +265,8 @@ var _transitions = _dereq_('./transitions');
 
 var _custom = _dereq_('./element/custom');
 
+var _tree = _dereq_('./node/tree');
+
 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
 
 /**
@@ -550,8 +552,12 @@ function enableProllyfill() {
 
     // After the initial render, clean up the resources, no point in lingering.
     documentElement.addEventListener('renderComplete', function render() {
+      var elementMeta = _tree.TreeCache.get(documentElement) || {};
+
       // Release resources allocated to the element.
-      documentElement.diffRelease(documentElement);
+      if (!elementMeta.isRendering) {
+        documentElement.diffRelease(documentElement);
+      }
 
       // Remove this event listener.
       documentElement.removeEventListener('renderComplete', render);
@@ -574,7 +580,7 @@ function enableProllyfill() {
   }
 }
 
-},{"./element/custom":1,"./errors":4,"./node/patch":7,"./node/release":8,"./transitions":13}],6:[function(_dereq_,module,exports){
+},{"./element/custom":1,"./errors":4,"./node/patch":7,"./node/release":8,"./node/tree":10,"./transitions":13}],6:[function(_dereq_,module,exports){
 'use strict';
 
 Object.defineProperty(exports, "__esModule", {
@@ -858,13 +864,13 @@ function patchNode(element, newHTML, options) {
     if (typeof newHTML !== 'string') {
       transferObject.newTree = (0, _make2.default)(newHTML);
 
+      // Wait for the worker to finish processing and then apply the patchset.
+      worker.onmessage = (0, _render.completeWorkerRender)(element, elementMeta);
+
       // Transfer this buffer to the worker, which will take over and process the
       // markup.
       worker.postMessage(transferObject);
 
-      // Wait for the worker to finish processing and then apply the patchset.
-      worker.onmessage = (0, _render.completeWorkerRender)(element, elementMeta);
-
       return;
     }
 
@@ -875,12 +881,12 @@ function patchNode(element, newHTML, options) {
     // Add properties to send to worker.
     transferObject.isInner = options.inner;
 
+    // Wait for the worker to finish processing and then apply the patchset.
+    worker.onmessage = (0, _render.completeWorkerRender)(element, elementMeta);
+
     // Transfer this buffer to the worker, which will take over and process the
     // markup.
     worker.postMessage(transferObject);
-
-    // Wait for the worker to finish processing and then apply the patchset.
-    worker.onmessage = (0, _render.completeWorkerRender)(element, elementMeta);
   } else {
     // We're rendering in the UI thread.
     elementMeta.isRendering = true;
@@ -951,10 +957,14 @@ function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { de
 function releaseNode(element) {
   var elementMeta = _tree.TreeCache.get(element);
 
+  // Do not remove an element that is in process of rendering. User intentions
+  // come first, so if we are cleaning up an element being used by another part
+  // of the code, keep it alive.
   if (elementMeta) {
     // If there is a worker associated with this element, then kill it.
     if (elementMeta.worker) {
       elementMeta.worker.terminate();
+      delete elementMeta.worker;
     }
 
     // If there was a tree set up, recycle the memory allocated for it.
@@ -1488,7 +1498,11 @@ function process(element, patches) {
                     }
 
                     // Append the element first, before doing the replacement.
-                    patch.old.parentNode.insertBefore(patch.new, patch.old.nextSibling);
+                    if (patch.old.nextSibling) {
+                      patch.old.parentNode.insertBefore(patch.new, patch.old.nextSibling);
+                    } else {
+                      patch.old.parentNode.appendChild(patch.new);
+                    }
 
                     // Removed state for transitions API.
                     var allPromises = [];
@@ -2623,7 +2637,7 @@ function startup(worker) {
     syncNode(oldTree, newTree, patches);
 
     // Protect the current `oldTree` so that no Nodes will be accidentally
-    // recycled in the
+    // recycled in the cleanup process.
     protectElement(oldTree);
 
     // Send the patches back to the userland.

lib/index.js

@@ -2,6 +2,7 @@ import patchNode from './node/patch';
 import releaseNode from './node/release';
 import { states } from './transitions';
 import { components } from './element/custom';
+import { TreeCache } from './node/tree';
 
 import { TransitionStateError, DOMException } from './errors';
 // Export the custom Error constructors so that instanceof checks can be made
@@ -288,8 +289,12 @@ export function enableProllyfill() {
 
     // After the initial render, clean up the resources, no point in lingering.
     documentElement.addEventListener('renderComplete', function render() {
+      var elementMeta = TreeCache.get(documentElement) || {};
+
       // Release resources allocated to the element.
-      documentElement.diffRelease(documentElement);
+      if (!elementMeta.isRendering) {
+        documentElement.diffRelease(documentElement);
+      }
 
       // Remove this event listener.
       documentElement.removeEventListener('renderComplete', render);

lib/node/patch.js

@@ -71,6 +71,7 @@ export default function patchNode(element, newHTML, options) {
     return elementMeta.renderBuffer;
   }
 
+
   // If the operation is `innerHTML`, but the contents haven't changed.
   var sameInnerHTML = options.inner && element.innerHTML === newHTML;
   // If the operation is `outerHTML`, but the contents haven't changed.
@@ -138,13 +139,13 @@ export default function patchNode(element, newHTML, options) {
     if (typeof newHTML !== 'string') {
       transferObject.newTree = makeNode(newHTML);
 
+      // Wait for the worker to finish processing and then apply the patchset.
+      worker.onmessage = completeWorkerRender(element, elementMeta);
+
       // Transfer this buffer to the worker, which will take over and process the
       // markup.
       worker.postMessage(transferObject);
 
-      // Wait for the worker to finish processing and then apply the patchset.
-      worker.onmessage = completeWorkerRender(element, elementMeta);
-
       return;
     }
 
@@ -155,12 +156,12 @@ export default function patchNode(element, newHTML, options) {
     // Add properties to send to worker.
     transferObject.isInner = options.inner;
 
+    // Wait for the worker to finish processing and then apply the patchset.
+    worker.onmessage = completeWorkerRender(element, elementMeta);
+
     // Transfer this buffer to the worker, which will take over and process the
     // markup.
     worker.postMessage(transferObject);
-
-    // Wait for the worker to finish processing and then apply the patchset.
-    worker.onmessage = completeWorkerRender(element, elementMeta);
   }
   else {
     // We're rendering in the UI thread.

lib/node/release.js

@@ -10,10 +10,14 @@ import makeNode from './make';
 export default function releaseNode(element) {
   let elementMeta = TreeCache.get(element);
 
+  // Do not remove an element that is in process of rendering. User intentions
+  // come first, so if we are cleaning up an element being used by another part
+  // of the code, keep it alive.
   if (elementMeta) {
     // If there is a worker associated with this element, then kill it.
     if (elementMeta.worker) {
       elementMeta.worker.terminate();
+      delete elementMeta.worker;
     }
 
     // If there was a tree set up, recycle the memory allocated for it.

lib/patches/process.js

@@ -185,9 +185,13 @@ export default function process(element, patches) {
             'document root?');
         }
 
-
         // Append the element first, before doing the replacement.
-        patch.old.parentNode.insertBefore(patch.new, patch.old.nextSibling);
+        if (patch.old.nextSibling) {
+          patch.old.parentNode.insertBefore(patch.new, patch.old.nextSibling);
+        }
+        else {
+          patch.old.parentNode.appendChild(patch.new);
+        }
 
         // Removed state for transitions API.
         let allPromises = [];

lib/worker/source.js

@@ -73,7 +73,7 @@ export default function startup(worker) {
     syncNode(oldTree, newTree, patches);
 
     // Protect the current `oldTree` so that no Nodes will be accidentally
-    // recycled in the
+    // recycled in the cleanup process.
     protectElement(oldTree);
 
     // Send the patches back to the userland.

package.json

@@ -9,7 +9,7 @@
   "scripts": {
     "start": "http-server",
     "build": "browserify -t [ babelify --presets [ es2015 ] ] -s diff lib/index.js | derequire > dist/diffhtml.js",
-    "watch": "watchify -t [ babelify --presets [ es2015 ] ] -s diff lib/index.js -o dist/diffhtml.js -v",
+    "watch": "watchify -t [ babelify --presets [ es2015 ] ] -s diff lib/index.js -o 'derequire > dist/diffhtml.js' -v",
     "jshint": "jshint lib/**/*.js",
     "test": "npm run jshint && karma start --single-run"
   },