DevTools: Avoid a race in WorkspaceDiff when UISourceCodes are removed

third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js

Index: third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js
diff --git a/third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js b/third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js
index dcda6053a0a53d24ccfcc00723d5285b0aec96bf..09503face3cff0c06e3f9c036b3399f0161b2cdf 100644
--- a/third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js
+++ b/third_party/WebKit/Source/devtools/front_end/workspace_diff/WorkspaceDiff.js
@@ -89,8 +89,7 @@ WorkspaceDiff.WorkspaceDiff = class extends Common.Object {
    */
   _uiSourceCodeRemoved(event) {
     var uiSourceCode = /** @type {!Workspace.UISourceCode} */ (event.data);
-    this._loadingUISourceCodes.delete(uiSourceCode);
-    this._markAsUnmodified(uiSourceCode);
+    this._removeUISourceCode(uiSourceCode);
   }
 
   /**
@@ -98,10 +97,16 @@ WorkspaceDiff.WorkspaceDiff = class extends Common.Object {
    */
   _projectRemoved(event) {
     var project = /** @type {!Workspace.Project} */ (event.data);
-    for (var uiSourceCode of project.uiSourceCodes()) {
-      this._loadingUISourceCodes.delete(uiSourceCode);
-      this._markAsUnmodified(uiSourceCode);
-    }
+    for (var uiSourceCode of project.uiSourceCodes())
+      this._removeUISourceCode(uiSourceCode);
+  }
+
+  _removeUISourceCode(uiSourceCode) {

[lushnikov, 2017/06/08 00:06:51]

let's jsdoc this

[einbinder, 2017/06/08 01:27:55]

Done.

+    this._loadingUISourceCodes.delete(uiSourceCode);
+    var uiSourceCodeDiff = this._uiSourceCodeDiffs.get(uiSourceCode);
+    if (uiSourceCodeDiff)
+      uiSourceCodeDiff._invalidated = true;
+    this._markAsUnmodified(uiSourceCode);
   }
 
   /**
@@ -171,6 +176,7 @@ WorkspaceDiff.WorkspaceDiff.UISourceCodeDiff = class extends Common.Object {
     uiSourceCode.addEventListener(Workspace.UISourceCode.Events.WorkingCopyCommitted, this._uiSourceCodeChanged, this);
     this._requestDiffPromise = null;
     this._pendingChanges = null;
+    this._invalidated = false;

[lushnikov, 2017/06/08 00:06:51]

how about this._disposed? Feels like a better name

[einbinder, 2017/06/08 01:27:55]

Done.

   }
 
   _uiSourceCodeChanged() {
@@ -188,6 +194,8 @@ WorkspaceDiff.WorkspaceDiff.UISourceCodeDiff = class extends Common.Object {
      * @this {WorkspaceDiff.WorkspaceDiff.UISourceCodeDiff}
      */
     function emitDiffChanged() {
+      if (this._invalidated)
+        return;
       this.dispatchEventToListeners(WorkspaceDiff.Events.DiffChanged);
       this._pendingChanges = null;
     }
@@ -206,10 +214,19 @@ WorkspaceDiff.WorkspaceDiff.UISourceCodeDiff = class extends Common.Object {
    * @return {!Promise<?Diff.Diff.DiffArray>}
    */
   async _innerRequestDiff() {
+    if (this._invalidated)
+      return null;
+
     var current = this._uiSourceCode.workingCopy();
     if (!current && !this._uiSourceCode.contentLoaded())
       current = await this._uiSourceCode.requestContent();

[lushnikov, 2017/06/08 00:06:51]

while we are here: let's add a huge // ------ ASYNC ----- comment like we do

[einbinder, 2017/06/08 01:27:55]

Done.

+    if (this._invalidated)
+      return null;
+
     var baseline = await this._uiSourceCode.requestOriginalContent();

[lushnikov, 2017/06/08 00:06:51]

and let's add the "ASYNC" comment here as well

[einbinder, 2017/06/08 01:27:55]

Done.

+    if (this._invalidated)
+      return null;
+
     if (current === null || baseline === null)
       return null;
     return Diff.Diff.lineDiff(baseline.split('\n'), current.split('\n'));