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[api-major] Only create a StatTimer for pages when enableStats == true (issue 5215)

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Unless the debugging tools (i.e. `PDFBug`) are enabled, or the `browsertest` is running, the `PDFPageProxy.stats` aren't actually used for anything.
Rather than initializing unnecessary `StatTimer` instances, we can simply re-use *one* dummy class (with static methods) for every page. Note that by using a dummy `StatTimer` in this way, rather than letting `PDFPageProxy.stats` be undefined, we don't need to guard *every* single stats collection callsite.

Since it wouldn't make much sense to attempt to use `PDFPageProxy.stats` when stat collection is disabled, it was instead changed to a "private" property (i.e. `PDFPageProxy._stats`) and a getter was added for accessing `PDFPageProxy.stats`. This getter will now return `null` when stat collection is disabled, making that case easy to handle.

For benchmarking purposes, the test-suite used to re-create the `StatTimer` after loading/rendering each page. However, modifying properties on various API code from the outside in this way seems very error-prone, and is an anti-pattern that we really should avoid at all cost. Hence the `PDFPageProxy.cleanup` method was modified to accept an optional parameter, which will take care of resetting `this.stats` when necessary, and `test/driver.js` was updated accordingly.

Finally, a tiny bit more validation was added on the viewer side, to ensure that all the code we're attempting to access is defined when handling `PDFPageProxy` stats.
This commit is contained in:
Jonas Jenwald 2017-12-06 16:30:04 +01:00
parent 50b72dec6e
commit 7c5ba9aad5
5 changed files with 59 additions and 19 deletions
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7
web/app.js
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@ -1668,7 +1668,8 @@ function webViewerPageRendered(evt) {
thumbnailView.setImage(pageView);
}
if (PDFJS.pdfBug && Stats.enabled && pageView.stats) {
if (PDFJS.pdfBug && typeof Stats !== 'undefined' && Stats.enabled &&
pageView.stats) {
Stats.add(pageNumber, pageView.stats);
}
@ -1957,9 +1958,9 @@ function webViewerPageChanging(evt) {
}
// we need to update stats
if (PDFJS.pdfBug && Stats.enabled) {
if (PDFJS.pdfBug && typeof Stats !== 'undefined' && Stats.enabled) {
let pageView = PDFViewerApplication.pdfViewer.getPageView(page - 1);
if (pageView.stats) {
if (pageView && pageView.stats) {
Stats.add(page, pageView.stats);
}
}