With the changes made in PR 11069, it's no longer necessary to include the `pageIndex`/`intent` parameters when sending 'GetOperatorList' data. In the previous implementation these properties were used to associate the `OperatorList` with the correct `RenderTask`, however now that `ReadableStream`s are used that's handled automatically and it's thus dead code at this point.
Note how the sent values have inconsistent types, with a boolean in one case and an object in the other (normal) case.
Furthermore, explicitly sending a `supportTypedArray: true` property seems superfluous at least to me.
This check was added in PR 2445, however it's no longer necessary since all data[1] is now loaded on the main-thread (and then transferred to the worker-thread).
Furthermore, by default the Fetch API is now (usually) used rather than `XMLHttpRequest`.
All in all, while these checks *were* necessary at one point that's no longer the case and they can thus be removed.
---
[1] This includes both the actual PDF data, as well as the CMap data.
It recently occurred to me that the CMap data should be an excellent candidate for transfering.
This will help reduce peak memory usage for PDF documents using CMaps, since transfering of data avoids duplicating it on both the main- and worker-threads.
Unfortunately it's not possible to actually transfer data when *returning* data through `sendWithPromise`, and another solution had to be used.
Initially I looked at using one message for requesting the data, and another message for returning the actual CMap data. While that should have worked, it would have meant adding a lot more complexity particularly on the worker-thread.
Hence the simplest solution, at least in my opinion, is to utilize `sendWithStream` since that makes it *really* easy to transfer the CMap data. (This required PR 11115 to land first, since otherwise CMap fetch errors won't propagate correctly to the worker-thread.)
Please note that the patch *purposely* only changes the API to Worker communication, and not the API *itself* since changing the interface of `CMapReaderFactory` would be a breaking change.
Furthermore, given the relatively small size of the `.bcmap` files (the largest one is smaller than the default range-request size) streaming doesn't really seem necessary either.
These functions aren't returning anything, now that they're using `ReadableStream`s, and it thus doesn't seem necessary to re-throw errors (also given the console message that's caused by it).
*Please note:* The majority of this patch was written by Yury, and it's simply been rebased and slightly extended to prevent issues when dealing with `RenderingCancelledException`.
By leveraging streams this (finally) provides a simple way in which parsing can be aborted on the worker-thread, which will ultimately help save resources.
With this patch worker-thread parsing will *only* be aborted when the document is destroyed, and not when rendering is cancelled. There's a couple of reasons for this:
- The API currently expects the *entire* OperatorList to be extracted, or an Error to occur, once it's been started. Hence additional re-factoring/re-writing of the API code will be necessary to properly support cancelling and re-starting of OperatorList parsing in cases where the `lastChunk` hasn't yet been seen.
- Even with the above addressed, immediately cancelling when encountering a `RenderingCancelledException` will lead to worse performance in e.g. the default viewer. When zooming and/or rotation of the document occurs it's very likely that `cancel` will be (almost) immediately followed by a new `render` call. In that case you'd obviously *not* want to abort parsing on the worker-thread, since then you'd risk throwing away a partially parsed Page and thus be forced to re-parse it again which will regress perceived performance.
- This patch is already *somewhat* risky, given that it touches fundamentally important/critical code, and trying to keep it somewhat small should hopefully reduce the risk of regressions (and simplify reviewing as well).
Time permitting, once this has landed and been in Nightly for awhile, I'll try to work on the remaining points outlined above.
Co-Authored-By: Yury Delendik <ydelendik@mozilla.com>
Co-Authored-By: Jonas Jenwald <jonas.jenwald@gmail.com>
Given that the different types of `Stream`s will never be cached, this thus implies that the `XRef.cache` Array will *always* be more-or-less sparse.
Generally speaking, the longer the document the more sparse the `XRef.cache` will thus become. For example, looking at the `pdf.pdf` file from the test-suite: The length of the `XRef.cache` Array will be a few hundred thousand elements, with approximately 95% of them being empty.
Hence it seems pretty clear that an Array isn't really the best data-structure for this kind of cache, and this patch thus changes it to a Map instead.
This patch-series was tested using the PDF file from issue 2618, i.e. http://bugzilla-attachments.gnome.org/attachment.cgi?id=226471, with the following manifest file:
```
[
{ "id": "issue2618",
"file": "../web/pdfs/issue2618.pdf",
"md5": "",
"rounds": 200,
"type": "eq"
}
]
```
which gave the following results when comparing this patch-series against the `master` branch:
```
-- Grouped By browser, stat --
browser | stat | Count | Baseline(ms) | Current(ms) | +/- | % | Result(P<.05)
------- | ------------ | ----- | ------------ | ----------- | --- | ----- | -------------
Firefox | Overall | 200 | 2736 | 2736 | 1 | 0.02 |
Firefox | Page Request | 200 | 2 | 2 | 0 | -8.26 | faster
Firefox | Rendering | 200 | 2733 | 2734 | 1 | 0.03 |
```
The relevant methods are usually not hot enough for these changes to have an easily measurable effect, however there's been a lot of other cases where similiar inlining has helped performance. (And these changes may help offset the changes made in the next patch.)
For very large and complex PDF files this will help performance *slightly*, since `Parser.getObj` is called *a lot* during parsing in the worker.
This patch was tested using the PDF file from issue 2618, i.e. http://bugzilla-attachments.gnome.org/attachment.cgi?id=226471, with the following manifest file:
```
[
{ "id": "issue2618",
"file": "../web/pdfs/issue2618.pdf",
"md5": "",
"rounds": 200,
"type": "eq"
}
]
```
which gave the following results when comparing this patch against the `master` branch:
```
-- Grouped By browser, stat --
browser | stat | Count | Baseline(ms) | Current(ms) | +/- | % | Result(P<.05)
------- | ------------ | ----- | ------------ | ----------- | --- | ----- | -------------
Firefox | Overall | 200 | 2847 | 2830 | -17 | -0.60 | faster
Firefox | Page Request | 200 | 2 | 2 | 0 | -7.14 |
Firefox | Rendering | 200 | 2844 | 2827 | -17 | -0.60 | faster
```
Looking at this again, it struck me that added functionality in `Util.intersect` is probably more confusing than helpful in general; sorry about the churn in this code!
Based on the parameter name you'd probably expect it to only match when the intersection is `[0, 0, 0, 0]` and not when only one component is zero, hence the `skipEmpty` parameter thus feels too tightly coupled to the `Page.view` getter.
This is based on a real-world PDF file I encountered very recently[1], although I'm currently unable to recall where I saw it.
Note that different PDF viewers handle these sort of errors differently, with Adobe Reader outright failing to render the attached PDF file whereas PDFium mostly handles it "correctly".
The patch makes the following notable changes:
- Refactor the `cropBox` and `mediaBox` getters, on the `Page`, to reduce unnecessary duplication. (This will also help in the future, if support for extracting additional page bounding boxes are added to the API.)
- Ensure that the page bounding boxes, i.e. `cropBox` and `mediaBox`, are never empty to prevent issues/weirdness in the viewer.
- Ensure that the `view` getter on the `Page` will never return an empty intersection of the `cropBox` and `mediaBox`.
- Add an *optional* parameter to `Util.intersect`, to allow checking that the computed intersection isn't actually empty.
- Change `Util.intersect` to have consistent return types, since Arrays are of type `Object` and falling back to returning a `Boolean` thus seem strange.
---
[1] In that case I believe that only the `cropBox` was empty, but it seemed like a good idea to attempt to fix a bunch of related cases all at once.
The current code will only consider the `cropBox` and `mediaBox` as equal when they both point to the *same* underlying Array. In the case where a PDF file actually specifies both boxes independently, with the exact same values in each, the comparison will currently fail and lead to an unneeded intersection computation.
With the changes to the `StreamType`/`FontType` "enums" in PR 11029, one unfortunate result is that `getStats` now *always* returns empty Arrays. Something that everyone, myself included, apparently missed is that you obviously cannot index an Array with Strings :-)
I wrongly assumed that the unit-tests would catch any bugs, but they apparently suffered from the same issue as the code in `src/core/`.
Another possible option could perhaps be to use `Set`s, rather than objects, but that will require larger changes since `LoopbackPort` (in `src/display/api.js`) doesn't support them.
Firefox telemetry supports using string labels now. Convert our integers
that we used for categories to just use strings.
The upstream work will happen in:
https://bugzilla.mozilla.org/show_bug.cgi?id=1566882
There's a number of spots in the current code, and tests, where `cancel` methods are not called with appropriate arguments (leading to Promises not being rejected with Errors as intended).
In some cases the cancel `reason` is implicitly set to `undefined`, and in others the cancel `reason` is just a plain String. To address this inconsistency, the patch changes things such that cancelling is done with `AbortException`s everywhere instead.
This patch will not incur any (measurable) overhead, since the glyphlist is already quite long and one more entry won't really matter, which is important given that this sort of PDF corruption ought to be very rare.
Furthermore, this patch purposely does *not* add a bunch of similarly modified ligature names on pure speculation. Any similar additions, for other ligatures, should only be made if there's real-world examples of PDF files where that's actually necessary.
For very large and complex PDF files this will help performance slightly, since `EvaluatorPreprocessor.read` is called a lot during parsing in the worker.
This patch was tested using the PDF file from issue 2618, i.e. http://bugzilla-attachments.gnome.org/attachment.cgi?id=226471, using the following manifest file:
```
[
{ "id": "issue2618",
"file": "../web/pdfs/issue2618.pdf",
"md5": "",
"rounds": 200,
"type": "eq"
}
]
```
This gave the following results when comparing this patch against the `master` branch:
```
-- Grouped By browser, stat --
browser | stat | Count | Baseline(ms) | Current(ms) | +/- | % | Result(P<.05)
------- | ------------ | ----- | ------------ | ----------- | --- | ----- | -------------
Firefox | Overall | 200 | 3402 | 3358 | -43 | -1.28 | faster
Firefox | Page Request | 200 | 1 | 1 | 0 | 26.71 |
Firefox | Rendering | 200 | 3401 | 3357 | -44 | -1.28 | faster
```
For very large and complex PDF files this will help performance slightly, since `Parser.shift` is called *a lot* during parsing.
This patch was tested using the PDF file from issue 2618, i.e. http://bugzilla-attachments.gnome.org/attachment.cgi?id=226471 (with well over *four million* `Parser.shift` calls for just the one page), using the following manifest file:
```
[
{ "id": "issue2618",
"file": "../web/pdfs/issue2618.pdf",
"md5": "",
"rounds": 100,
"type": "eq"
}
]
```
This gave the following results when comparing this patch against the `master` branch:
```
-- Grouped By browser, stat --
browser | stat | Count | Baseline(ms) | Current(ms) | +/- | % | Result(P<.05)
------- | ------------ | ----- | ------------ | ----------- | --- | ----- | -------------
Firefox | Overall | 100 | 3386 | 3322 | -65 | -1.92 | faster
Firefox | Page Request | 100 | 1 | 1 | 0 | -8.08 |
Firefox | Rendering | 100 | 3385 | 3321 | -65 | -1.92 | faster
```
The way that this method handles documents without an `ID` entry in the Trailer dictionary feels overly complicated to me. Hence this patch adds `getByteRange` methods to the various Stream implementations[1], and utilize that rather than manually calling `ensureRange` when computing a fallback `fingerprint`.
---
[1] Note that `PDFDocument` is only ever initialized with either a `Stream` or a `ChunkedStream`, hence why the `DecodeStream.getByteRange` method isn't implemented.
*Please note:* A a similar change was attempted in PR 5005, but it was subsequently backed out in PR 5069.
Unfortunately I don't think anyone ever tried to debug *exactly* why it didn't work, since it ought to have worked, and having re-tested this now I'm not able to reproduce the problem any more. However, given just how inefficient the current code is, with thousands of strictly unnecessary function calls for each `find` invocation, I'd really like to try fixing this again.
This reduces the total number of function calls, when reading the XRef table respectively when fetching uncompressed XRef entries.
Note in particular the `XRef.readXRefTable` method, where there're *two* back-to-back `isCmd` checks rather than just one.
A lot of the `new Parser()` call-sites look quite unwieldy/ugly as-is, with a bunch of somewhat randomly ordered arguments, which we can avoid by changing the constructor to accept an object instead. As an added bonus, this provides better documentation without having to add inline argument comments in the code.
See https://github.com/mozilla/eslint-plugin-no-unsanitized
Since we've generally never allowed e.g. `innerHTML`, which is enforced during review, there's only one linting failure with this patch. (Which is white-listed, according to the existing comment and the fact that it's test-only code.)
Since all other `IPDFStream` implementations live in their own files, it seems reasonable for these to do so as well.
Furthermore, converts all of the relevant code to ES6 classes and updates the interface definitions to mark a couple of methods `async`.
The border `width` will instead fallback to the default value of `1`, rather than ignoring it altoghether, to also ensure that e.g. `LinkAnnotation`s become clickable as intended.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1552113
Usually when the worker is terminated it will also be completely destroyed/removed, which means that any global caches (such as the ones in `src/core/primitive.js`) should be automatically cleared in the process.
However, for certain ways of loading the `pdf.worker.js` file, e.g. passing in a re-usable worker to `getDocument`, using the `workerPort` functionality, or even disabling workers completely (even though this is never a good idea), the worker file may be kept in memory and these caches will not be cleared as expected.
The purpose of these caches is to reduce peak memory usage, by only ever having *a single* instance of a particular object.
However, as-is these caches are never cleared and they will thus remain until the worker is destroyed. This could very well have a negative effect on total memory usage, particularly for large/long documents, hence it seems to make sense to clear out these caches together with various other ones.
This is similar to the existing caching used to reduced the number of `Cmd` and `Name` objects.
With the `tracemonkey.pdf` file, this patch changes the number of `Ref` objects as follows (in the default viewer):
| | Loading the first page | Loading *all* the pages |
|----------|------------------------|-------------------------|
| `master` | 332 | 3265 |
| `patch` | 163 | 996 |
The specification states that `CreationDate` is only available for
markup annotations instead of for all annotation types.
Moreover, popup annotations are not markup annotations according to the
specification, so the creation date inheritance from the parent
annotation is also removed there (note that only the modification date
is used in e.g., the viewer).
