Hi Pavel,
I fully concur with your reasoning for removing the jszip feature.
In script.js you left in the checks whether the *SearchIndex variables are
undefined:
if (!moduleSearchIndex) {
...
}
These if-statements can be removed as the conditions will always be true (the
vars are declared a few lines above but not assigned any value, so they will
always be undefined). It’s ok to just invoke createElem(…) for all
scripts/index files.
I also wonder if there is any benefit left in creating the script tags
dynamically vs. just adding them to the pages statically. I’m fine with keeping
it that way for now, but maybe we could file another issue to check if there’s
any reason to keep this over static <script> tags.
Everything else looks good to me.
Hannes
> Am 28.01.2020 um 16:55 schrieb Pavel Rappo <[email protected]>:
>
> Hello,
>
> Please review the change for https://bugs.openjdk.java.net/browse/JDK-8237909:
>
> http://cr.openjdk.java.net/~prappo/8237909/webrev.00/
>
> This change removes the "zipped index files" feature, which was introduced as
> part of 8141492: Implement search feature in javadoc.
>
> The "zipped index files" feature consists of generating the zipped index files
> on the back end, and fetching & unzipping mechanics on the front end.
>
> When documenting source files, the standard doclet accumulates index which is
> later used by the JavaScript code serving the interactive search. The index
> is written in two formats, .js (JavaScript) and .json (JSON). The latter is
> then zipped.
>
> When a browser accesses the pages using "http://"; urls, the .zip index files
> are
> transferred using XHR. Those files are then unzipped by the browser, using the
> JSZip library, and parsed as JSON. If the transfer of the .zip index files
> fails
> for whatever reason, the browser falls back on the alternative mechanism. This
> mechanism transfers the .js index files by referring to them from dynamically
> inserted <script src="... .js"> elements. Those files then are not
> additionally
> parsed, as they are already data hardcoded in JavaScript code.
>
> One of the reasons the .zip index files transfer may fail is using javadoc
> pages
> in the "standalone" mode. When a browser accesses "file://" urls, there's no
> HTTP server to send the XHR requests to. So the fallback mechanism kicks in
> and
> the browser loads the .js index files instead.
>
> Analysis
> ========
>
> From what I understand, the original intent was to reduce the transfer size of
> the index files. The observations made during the recent upgrade of JSZip
> (JDK-8236700) suggest that the feature is not working as intended. It is not
> clear if it ever did. The proposal is to remove it for the following reasons:
>
> 1. The feature in its current state does more harm than good (see JDK-8236922)
> 2. Fixing, debugging, testing, and evolving require expertise beyond that of
> typical for the javadoc area
> 3. The feature significantly complicates the front end and less so the back
> end
> code
> 4. The feature relies on the 3rd party libraries, which require tracking &
> periodical upgrades
> 5. The difference in size between the .zip and .js files is not that big (see
> below)
> 6. The index files are transferred once and then used from cache
> 7. Modern HTTP servers provide compression. This makes the net result
> virtually the same, compare:
>
> | (current) js + zip, MB | (proposal) js files, MB
> ------------------+------------------------+------------------------
> no compression 7.4 5.8
> HTTP compression 2.7 1.4
>
> Had this feature worked as intended, we would always transfer only the zipped
> index files and the transfer size would not depend on whether the server uses
> HTTP compression. But does this really outweigh the reasons stated above?
>
> Summing all up. Removing the zipped index files feature will make the overall
> interactive search feature (JDK-8141492) more robust. It will be less
> complicated, have fewer dependencies (JSZip, JSZip Utils), and will push the
> optimization down to HTTP.
>
> Testing
> =======
>
> Here is how I tested this change.
>
> 1. make clean && make docs
> 2. Standalone test
> 2.1. Opened the browser at file://...images/docs/index.html
> 3. HTTP test
> 3.1. Started an HTTP server at build/...images/docs
> 3.2. Opened the browser at http://localhost...images/docs/index.html
>
> Browser cache was cleared each time immediately before accessing the
> index.html page.
> In both cases I checked that no zipped index files or the related JavaScript
> libraries were accessed, and that the search worked as intended.
>
> I also tried to access the resulting javadoc pages, served by an HTTP server
> on
> my laptop, from a couple of mobile devices, all of which were on the same WiFi
> network. Everything worked as intended.
>
> Thanks,
> -Pavel
>
