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Ensure that blob: URLs will be revoked when pages are cleaned-up/destroyed

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Natively supported JPEG images are sent as-is, using a `blob:` or possibly a `data` URL, to the main-thread for loading/decoding.
However there's currently no attempt at releasing these resources, which are held alive by `blob:` URLs, which seems unfortunately given that images can be arbitrarily large.

As mentioned in https://developer.mozilla.org/en-US/docs/Web/API/URL/createObjectURL the lifetime of these URLs are tied to the document, hence they are not being removed when a page is cleaned-up/destroyed (e.g. when being removed from the `PDFPageViewBuffer` in the viewer).
This is easy to test with the help of `about:memory` (in Firefox), which clearly shows the number of `blob:` URLs becomming arbitrarily large *without* this patch. With this patch however the `blob:` URLs are immediately release upon clean-up as expected, and the memory consumption should thus be considerably reduced for long documents with (simple) JPEG images.
This commit is contained in:
Jonas Jenwald 2019-03-14 14:01:55 +01:00
parent 80135378ca
commit 983b25f863
2 changed files with 30 additions and 2 deletions
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11
src/display/display_utils.js
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@ -480,6 +480,16 @@ function deprecated(details) {
console.log('Deprecated API usage: ' + details);
}
function releaseImageResources(img) {
assert(img instanceof Image, 'Invalid `img` parameter.');
const url = img.src;
if (typeof url === 'string' && url.startsWith('blob:') &&
URL.revokeObjectURL) {
URL.revokeObjectURL(url);
}
}
export {
PageViewport,
RenderingCancelledException,
@ -496,4 +506,5 @@ export {
isValidFetchUrl,
loadScript,
deprecated,
releaseImageResources,
};