Deprecation of the LLVM SVN server

[sqlbyme]

Hi,
This is just a friendly reminder of the upcoming deprecation and shutdown of the SVN server. As announced during the last US Developers Conference, way back in 2019, the SVN server would remain in a read-only state for 1 year. It has been more than a year now and it is time to let the server enjoy a well deserved retirement. We are planning on turning the service off on January 5th, 2021. Please plan accordingly if, for some reason, you are still reliant on the SVN service being available. Thanks for your time and attention. I hope you all are having a nice day and staying safe.

Respectfully,
Mike Edwards

[njames93]

Hi Mike,

Not sure if anyone else has brought this up, but since turning the svn
server off, phab is no longer able to display commit details for older
commits to the svn server.

https://reviews.llvm.org/rL202984
As an example, results in an error like this:

[sqlbyme]

Hi Nathan,

Bummer! I had no idea Phabricator was connected to the SVN server in this way. I’ll have to see if I can get a conversation going with the Phabricator maintainers and see if there is a way we can address this. Thanks for the heads up.

-Mike

[mehdi_amini]

Hi,

Can you clarify why is this important or why is a feature we need to preserve? Are these URLs posted and referenced anywhere?

The whole “LLVM repo” in phabricator is disabled right now and can’t be browsed really: https://reviews.llvm.org/diffusion/L/ ; phab only provides a frontend for the repository, not an entire copy of it I believe.

Thanks,

[jh7370]

The key situation where I’d use it is if I’m tracing back the review and commit history of some older change. Often commits will be referenced within Phabricator reviews as rLXXXXXXX, which would previously allow you to click on them to get to the commit (this might in turn have links to other commits/reviews etc). Using the SVN id to look up the git commit is possible, just more time consuming.

James

[njames93]

The key situation where I'd use it is if I'm tracing back the review
and commit history of some older change. Often commits will be
referenced within Phabricator reviews as rLXXXXXXX, which would
previously allow you to click on them to get to the commit (this
might in turn have links to other commits/reviews etc). Using the SVN
id to look up the git commit is possible, just more time consuming.

James

Thats my reasoning for raising this. It just makes life simpler when
referencing those older commits.

~Nathan

[ychen]

+1

[rnk]

Could we copy the entire SVN repo into the Phab instance, so it can satisfy its svn queries from the local filesystem?

[mehdi_amini]

I generated apache2 rewrite rules for these URLs to redirect to the monorepo equivalent:

$ git rev-list 40c47680eb2a1cb9bb7f8598c319335731bd5204 | while read commit ; do SVNREV=$(git log --format=%B -n 1 $commit | grep ‘^llvm-svn: [0-9]*$’ | awk ‘{print $2 }’) ; [[ ! -z “$SVNREV” ]] && echo “RewriteRule ^/rL$SVNREV /rG$commit [R=301,L]” ; done

RewriteRule ^/rL375504 /rG40c47680eb2a1cb9bb7f8598c319335731bd5204 [R=301,L]
RewriteRule ^/rL375503 /rG3ef017d0669e0dfa7e34a6e58d80c8f307db6d8c [R=301,L]
RewriteRule ^/rL375502 /rG95290827d7d01c63ac57b2cf5204215ba4ee4b06 [R=301,L]
RewriteRule ^/rL375501 /rGe4af9de36ca60483040af381edd10e716e7b077d [R=301,L]
RewriteRule ^/rL375500 /rGe5dd30f77e10b3fa3395312045c06e5e15f9620e [R=301,L]
RewriteRule ^/rL375499 /rG5b99c189b3bfc0faa157f7ca39652c0bb8c315a7 [R=301,L]
RewriteRule ^/rL375498 /rG734c74ba14be0f4421ccd9f720e5b9309248e0f7 [R=301,L]
RewriteRule ^/rL375497 /rGf2c8f3b181e1a0f1a45e6893d15317386bf73977 [R=301,L]

…

It’s in place now on phabricator.

[Michael_Kruse2]

This is a good solution. Thank you. Although I wonder how well Apache
can copy with that many rewrite rules.

Michael

[mehdi_amini]

I don’t know, I’ll keep an eye on the load, so far so good (see below).

Note that:

1. The rules are loaded in the apache2 config and not in the .htaccess (I’m not sure but I’d suspect the later to may incur some cost on a per-request basis?)
2. I first match negatively match the pattern (the common case), before going through the huge amount of individual rules:

RewriteCond %{REQUEST_URI} !^/rL[0-9]$ RewriteRule ^(.)$ /index.php?path=$1 [B,L,QSA] # Config for SVN → GIT url rewrite Include …/svn_url_rewrite.apache.conf

Best,