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[api-minor] Change PDFDocumentProxy.cleanup/PDFPageProxy.cleanup to return data

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This patch makes the following changes, to improve these API methods:

 - Let `PDFPageProxy.cleanup` return a boolean indicating if clean-up actually happened, since ongoing rendering will block clean-up.
   Besides being used in other parts of this patch, it seems that an API user may also be interested in the return value given that clean-up isn't *guaranteed* to happen.

 - Let `PDFDocumentProxy.cleanup` return the promise indicating when clean-up is finished.

 - Improve the JSDoc comment for `PDFDocumentProxy.cleanup` to mention that clean-up is triggered on *both* threads (without going into unnecessary specifics regarding what *exactly* said data actually is).
   Add a note in the JSDoc comment about not calling this method when rendering is ongoing.

 - Change `WorkerTransport.startCleanup` to throw an `Error` if it's called when rendering is ongoing, to prevent rendering from breaking.
   Please note that this won't stop *worker-thread* clean-up from happening (since there's no general "something is rendering"-flag), however I'm not sure if that's really a problem; but please don't quote me on that :-)
   All of the caches that's being cleared in `Catalog.cleanup`, on the worker-thread, *should* be re-filled automatically even if cleared *during* parsing/rendering, and the only thing that probably happens is that e.g. font data would have to be re-parsed.
  On the main-thread, on the other hand, clearing the caches is more-or-less guaranteed to cause rendering errors, since the rendering code in `src/display/canvas.js` isn't able to re-request any image/font data that's suddenly being pulled out from under it.

 - Last, but not least, add a couple of basic unit-tests for the clean-up functionality.
This commit is contained in:
Jonas Jenwald 2020-02-07 15:48:58 +01:00
parent a5fec297c0
commit 7117ee03d6
2 changed files with 105 additions and 6 deletions
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26
src/display/api.js
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@ -758,10 +758,16 @@ class PDFDocumentProxy {
}
/**
* Cleans up resources allocated by the document, e.g. created `@font-face`.
* Cleans up resources allocated by the document, on both the main- and
* worker-threads.
*
* NOTE: Do not, under any circumstances, call this method when rendering is
* currently ongoing since that may lead to rendering errors.
*
* @returns {Promise} A promise that is resolved when clean-up has finished.
*/
cleanup() {
this._transport.startCleanup();
return this._transport.startCleanup();
}
/**
@ -1269,10 +1275,11 @@ class PDFPageProxy {
* Cleans up resources allocated by the page.
* @param {boolean} [resetStats] - Reset page stats, if enabled.
* The default value is `false`.
* @returns {boolean} Indicating if clean-up was successfully run.
*/
cleanup(resetStats = false) {
this.pendingCleanup = true;
this._tryCleanup(resetStats);
return this._tryCleanup(resetStats);
}
/**
@ -1290,7 +1297,7 @@ class PDFPageProxy {
);
})
) {
return;
return false;
}
Object.keys(this.intentStates).forEach(intent => {
@ -1302,6 +1309,7 @@ class PDFPageProxy {
this._stats = new StatTimer();
}
this.pendingCleanup = false;
return true;
}
/**
@ -2555,11 +2563,17 @@ class WorkerTransport {
}
startCleanup() {
this.messageHandler.sendWithPromise("Cleanup", null).then(() => {
return this.messageHandler.sendWithPromise("Cleanup", null).then(() => {
for (let i = 0, ii = this.pageCache.length; i < ii; i++) {
const page = this.pageCache[i];
if (page) {
page.cleanup();
const cleanupSuccessful = page.cleanup();
if (!cleanupSuccessful) {
throw new Error(
`startCleanup: Page ${i + 1} is currently rendering.`
);
}
}
}
this.commonObjs.clear();