pcre library needs to be upgrade to pcre2

[c-taylor]

List of Plugins to convert still:

• Cachekey (@bryancall)
• Prefetch (@moonchen)
• Regex Remap (@traeak)
• Regex revalidate (@traeak)
• Slice (@cmcfarlen)
• Url Sig (@bneradt)
• Maxmind ACL (@ezelkow1)
• Header rewrite (@cmcfarlen)
• Geo IP (@brbzull0)
• Access Control (@bneradt)
• Cookie Remap (@serrislew)

Current issues are:

• pcre library is no longer maintained; author working on pcre2
• pcre jit support in ATS is incomplete
  • https://issues.apache.org/jira/browse/TS-3143
  • https://issues.apache.org/jira/browse/TS-3144
• Precompilation is not consistently implemented
• Library review
  • Should probably look at pcre2/je2 (or others)

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Whilst looking at some high RPS rate tests libpcre was starting to 'feature' in traces.
The obvious optimisation for libpcre is to use the jit support, which probably lends itself well to constrained lists of regex.

However, given the lack of maintenance on the current library an "architectural review" is probably required before more effort is spent...

[c-taylor]

It looks like trafficserver has an inconsistent approach: It precompiles the expressions, replacing the need/benefit of the jit in header_rewrite, but elsewhere makes no attempt.

Perhaps someone can confirm…

[jeredfloyd]

There is a new Fedora tracking bug for this issue: https://bugzilla.redhat.com/show_bug.cgi?id=2128391

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. Marking it stale to flag it for further consideration by the community.

[maskit]

Just to tell the bot this is not stale, we are going to do this by version 10.0 release.

[bgermann]

On the corresponding Debian bug, there is a patch available.

[kenballus]

libpcre3-dev has been removed from the Trixie repositories, so trafficserver can no longer be built on Debian testing.

[jeredfloyd]

This is also a blocker for RHEL 10 support: https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/10-beta/html-single/considerations_in_adopting_rhel_10/index#removed-packages