Merge "Prefetch /diff requests when expanding all diffs"

polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js

@@ -1279,6 +1279,14 @@ class GrFileList extends mixinBehaviors( [
   _renderInOrder(files, diffElements, initialCount) {
     let iter = 0;
 
+    for (const file of files) {
+      const path = file.path;
+      const diffElem = this._findDiffByPath(path, diffElements);
+      if (diffElem) {
+        diffElem.prefetchDiff();
+      }
+    }
+
     return (new Promise(resolve => {
       this.dispatchEvent(new CustomEvent('reload-drafts', {
         detail: {resolve},

polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html

@@ -95,6 +95,7 @@ suite('gr-file-list tests', () => {
       });
       stub('gr-diff-host', {
         reload() { return Promise.resolve(); },
+        prefetchDiff() {},
       });
 
       // Element must be wrapped in an element with direct access to the
@@ -1106,6 +1107,7 @@ suite('gr-file-list tests', () => {
         reload() {
           done();
         },
+        prefetchDiff() {},
         cancel() {},
         getCursorStops() { return []; },
         addEventListener(eventName, callback) {
@@ -1163,6 +1165,7 @@ suite('gr-file-list tests', () => {
       const diffs = [{
         path: 'p0',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(callCount++, 2);
           return Promise.resolve();
@@ -1170,6 +1173,7 @@ suite('gr-file-list tests', () => {
       }, {
         path: 'p1',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(callCount++, 1);
           return Promise.resolve();
@@ -1177,6 +1181,7 @@ suite('gr-file-list tests', () => {
       }, {
         path: 'p2',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(callCount++, 0);
           return Promise.resolve();
@@ -1199,6 +1204,7 @@ suite('gr-file-list tests', () => {
       const diffs = [{
         path: 'p0',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(reviewStub.callCount, 2);
           assert.equal(callCount++, 2);
@@ -1207,6 +1213,7 @@ suite('gr-file-list tests', () => {
       }, {
         path: 'p1',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(reviewStub.callCount, 1);
           assert.equal(callCount++, 1);
@@ -1215,6 +1222,7 @@ suite('gr-file-list tests', () => {
       }, {
         path: 'p2',
         style: {},
+        prefetchDiff() {},
         reload() {
           assert.equal(reviewStub.callCount, 0);
           assert.equal(callCount++, 0);
@@ -1237,6 +1245,7 @@ suite('gr-file-list tests', () => {
       const diffs = [{
         path: 'p',
         style: {},
+        prefetchDiff() {},
         reload() { return Promise.resolve(); },
       }];
 
@@ -1566,6 +1575,7 @@ suite('gr-file-list tests', () => {
       });
       stub('gr-diff-host', {
         reload() { return Promise.resolve(); },
+        prefetchDiff() {},
       });
 
       // Element must be wrapped in an element with direct access to the

polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.js

@@ -218,6 +218,11 @@ class GrDiffHost extends mixinBehaviors( [
         notify: true,
       },
 
+      _fetchDiffPromise: {
+        type: Object,
+        value: null,
+      },
+
       /** @type {?Object} */
       _blame: {
         type: Object,
@@ -535,8 +540,21 @@ class GrDiffHost extends mixinBehaviors( [
         !this.noAutoRender;
   }
 
+  // TODO(milutin): Use rest-api with fetchCacheURL instead of this.
+  prefetchDiff() {
+    if (!!this.changeNum && !!this.patchRange && !!this.path
+        && this._fetchDiffPromise === null) {
+      this._fetchDiffPromise = this._getDiff();
+    }
+  }
+
   /** @return {!Promise<!Object>} */
   _getDiff() {
+    if (this._fetchDiffPromise !== null) {
+      const fetchDiffPromise = this._fetchDiffPromise;
+      this._fetchDiffPromise = null;
+      return fetchDiffPromise;
+    }
     // Wrap the diff request in a new promise so that the error handler
     // rejects the promise, allowing the error to be handled in the .catch.
     return new Promise((resolve, reject) => {
@@ -907,6 +925,7 @@ class GrDiffHost extends mixinBehaviors( [
       return;
     }
 
+    this._fetchDiffPromise = null;
     if (preferredWhitespaceLevel !== loadedWhitespaceLevel &&
         !noRenderOnPrefsChange) {
       this.reload();

polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.html

@@ -445,6 +445,19 @@ suite('gr-diff-host tests', () => {
       });
     });
 
+    test('prefetch getDiff', done => {
+      const diffRestApiStub = sandbox.stub(element.$.restAPI, 'getDiff')
+          .returns(Promise.resolve({content: []}));
+      element.changeNum = 123;
+      element.patchRange = {basePatchNum: 1, patchNum: 2};
+      element.path = 'file.txt';
+      element.prefetchDiff();
+      element._getDiff().then(() =>{
+        assert.isTrue(diffRestApiStub.calledOnce);
+        done();
+      });
+    });
+
     test('_getDiff handles null diff responses', done => {
       stub('gr-rest-api-interface', {
         getDiff() { return Promise.resolve(null); },