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[api-minor] Only use Workers when postMessage transfers are supported (PR 11123 follow-up)

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Given that all modern browsers now support `postMessage` transfers, and have for years, it no longer seems necessary for the PDF.js library to support using Workers unless the `postMessage` transfers functionality is available.
This patch is a follow-up to PR 11123, which made it impossible to *manually* disable `postMessage` transfers for performance reasons (since it increases memory usage), which hasn't caused any bug reports as far as I know.[1]

Hence we'll now only support *proper* Worker implementations, with fully working `postMessage` transfers, and fallback to using "fake" Workers otherwise.

---
[1] At the time of that PR we still "supported" IE, which is why this code was left intact.
This commit is contained in:
Jonas Jenwald 2021-11-19 13:51:18 +01:00
parent 9f4a2cf5ce
commit 6f22327e61
3 changed files with 9 additions and 41 deletions
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17
src/core/worker.js
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@ -75,16 +75,9 @@ class WorkerMessageHandler {
}
testMessageProcessed = true;
// check if Uint8Array can be sent to worker
if (!(data instanceof Uint8Array)) {
handler.send("test", null);
return;
}
// making sure postMessage transfers are working
const supportTransfers = data[0] === 255;
handler.postMessageTransfers = supportTransfers;
handler.send("test", { supportTransfers });
// Ensure that `TypedArray`s can be sent to the worker,
// and that `postMessage` transfers are supported.
handler.send("test", data instanceof Uint8Array && data[0] === 255);
});
handler.on("configure", function wphConfigure(data) {
@ -156,10 +149,6 @@ class WorkerMessageHandler {
const workerHandlerName = docParams.docId + "_worker";
let handler = new MessageHandler(workerHandlerName, docId, port);
// Ensure that postMessage transfers are always correctly enabled/disabled,
// to prevent "DataCloneError" in browsers without transfers support.
handler.postMessageTransfers = docParams.postMessageTransfers;
function ensureNotTerminated() {
if (terminated) {
throw new Error("Worker was terminated");