[iOS] Throw away linked code when navigating to a new page.

[Andreas Kling]

We can keep our peak memory usage down by throwing away linked code when navigating to a new page.
Since linked code is tied to a specific global object, it won't be useful to the incoming page.
In the event of a backwards navigation, the cost of relinking that code is far lower than the memory cost of keeping it around.

[Andreas Kling]

Created attachment 270619 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 270619 [details]
Patch

Clearing flags on attachment: 270619

Committed r196104: <http://trac.webkit.org/changeset/196104>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[WebKit Commit Bot]

Re-opened since this is blocked by bug 153940

[Andreas Kling]

Created attachment 270795 [details]
Patch for relanding

Let's try to re-land this with a fix: don't throw away code unless we're navigating away from an existing history item.
Or basically only do this if the navigation is PageCache-eligible.

[WebKit Commit Bot]

Comment on attachment 270795 [details]
Patch for relanding

Clearing flags on attachment: 270795

Committed r196217: <http://trac.webkit.org/changeset/196217>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Andreas Kling]

Rolled out in <https://trac.webkit.org/changeset/202139>

[Andreas Kling]

Created attachment 281556 [details]
Patch

Same thing again, but this time we only do it if we haven't navigated in the last 2 seconds.
This looks a bit cheesy at first sight, but I can't think of a simpler fix for the excessive work problem.

[Andreas Kling]

Created attachment 281557 [details]
Patch

[WebKit Commit Bot]

Attachment 281557 [details] did not pass style-queue:


ERROR: Source/WebCore/platform/MemoryPressureHandler.cpp:43:  Alphabetical sorting problem.  [build/include_order] [4]
Total errors found: 1 in 4 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Antti Koivisto]

Comment on attachment 281557 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=281557&action=review

> Source/WebCore/platform/MemoryPressureHandler.cpp:167
> +    const auto minimumTimeSinceNavigation = std::chrono::seconds(2);

Could just say 

const auto minimumTimeSinceNavigation = 2s;

[Andreas Kling]

Created attachment 281559 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 281559 [details]
Patch for landing

Clearing flags on attachment: 281559

Committed r202166: <http://trac.webkit.org/changeset/202166>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.