[wtp-dev] Submission for PMC approval (1.5.1) 142408 - TaglibIndex creat

[Nitin Dahyabhai <nitind@xxxxxxxxxx>]

https://bugs.eclipse.org/bugs/show_bug.cgi?id=142408

The subject bug was moved forward at
the behest of bug 154971 - TaglibIndexer causing performance problems during
project migration [1].  When the build path of a dynamic web project
is modified, the JSP Taglib Index rescans the entire build path to ensure
it has up to date knowledge of the custom tags available for that project.
 Several significant performance problems were found in this area.
 First, it was reindexing the build path immediately instead of waiting
for a request requiring the updated information to be made.  Second,
the cached information of a project included the build path information
from projects that it required (to support proper visibility of exported
build path entries), duplicating the information kept in that project's
corresponding cache object and the time taken to discover it.  Third,
this duplication required that other projects in the workspace that depended
on *this* project had to be re-indexed as a result of the build path change.
 Modifying multiple projects' build paths thus meant rescanning each
project's build path multiple times, and it is expensive to do a full rescan
even once.

The patch added to 154971 addresses
the first issue, but not the second and third.  The patch attached
to 142408 builds on those changes allowing the individual cache objects
to interact with each other, reusing the information shared in each and
drastically cutting down on the time spent reindexing the build paths.


And as a reminder, PMC votes should
be made within the bug itself.

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=154971

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Nitin Dahyabhai