Detect premature worker load error

[Rob--W]

Rejects the ready promise when the worker fails to load, e.g. due to network errors.

[kyoshino]

This PR is required for Firefox 45+, because new Worker() no longer throws a SecurityError when the worker failed to load due to an origin issue, according to Bug 1260388 and Bug 1260961. Any load errors must be caught with the error handler, otherwise the fallback function will never get called. See my site compatibility doc for details.

[kyoshino]

this._setupFakeWorker(); is needed here to call the fallback function.

[Rob--W]

Done; I've overwritten the previous commit, with the following changes (see PR for full change set).

@@ -1303,15 +1303,22 @@ var PDFWorker = (function PDFWorkerClosure() {
           var worker = new Worker(workerSrc);
           var messageHandler = new MessageHandler('main', 'worker', worker);
           var terminateEarly = function() {
-            this._readyCapability.reject(new Error('Worker was destroyed'));
-            messageHandler.destroy();
             worker.removeEventListener('error', onWorkerError);
+            messageHandler.destroy();
             worker.terminate();
+            if (this.destroyed) {
+              this._readyCapability.reject(new Error('Worker was destroyed'));
+            } else {
+              // Fall back to fake worker if the termination is caused by an
+              // error (e.g. NetworkError / SecurityError).
+              this._setupFakeWorker();
+            }
           }.bind(this);

           var onWorkerError = function(event) {
-            if (!event.message && !this.destroyed && !this._webWorker) {
-              // Worker failed to initialize due to a load error.
+            if (!this._webWorker) {
+              // Worker failed to initialize due to an error. Clean up and fall
+              // back to the fake worker.
               terminateEarly();
             }   
           }.bind(this);

[Snuffleupagus]

This PR is required for Firefox 45+, because new Worker() no longer throws a SecurityError when the worker failed to load due to an origin issue, according to Bug 1260388 and Bug 1260961.

If I'm understanding the bugs correctly, this issue only affect custom deployments of PDF.js, and not the version built-in to Firefox!?
That seems like an important distinction to me, since it means we won't need to uplift the fix to Firefox.

[kyoshino]

I think the build-in version in Firefox is NOT affected.

[yurydelendik]

Looks good.

/botio test

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_test from @yurydelendik received. Current queue size: 0

Live output at: http://107.22.172.223:8877/f90f21d7f244cd5/output.txt

[pdfjsbot]

From: Bot.io (Linux)

---

Received

Command cmd_test from @yurydelendik received. Current queue size: 0

Live output at: http://107.21.233.14:8877/75c21ae65928459/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Success

Full output at http://107.22.172.223:8877/f90f21d7f244cd5/output.txt

Total script time: 20.08 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[pdfjsbot]

From: Bot.io (Linux)

---

Success

Full output at http://107.21.233.14:8877/75c21ae65928459/output.txt

Total script time: 22.68 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[yurydelendik]

Thank you for the patch.

[kyoshino]

Awesome, thank you!

[kyoshino]

@yurydelendik Any ETA on PDF.js v1.4.187?

[yurydelendik]

Any ETA on PDF.js v1.4.187?

@kyoshino you can download library from the mozilla/pdfjs-dist repo. the viewer package will be available as soon we are release next beta. You can build it yourself using gulp generic.

[kyoshino]

Oh I see, thanks. I'll mention it in my site compat doc.