[Gnu-arch-users] Speeding up mirroring

[James Blackwell]

As was previously discussed, archive-mirror could be much faster than it
currently is. In fact, an archive-mirror command on average takes 1-2
minutes and about 2.6 megabytes of bandwidth, even if nothing changes. 

So after we all discussed it for awhile, we decided to take the following
plan of attack to shorten mirroring times by performing the following:


The process during commit:
--------------------------

In libarch/commit.c[arch_commit()], right between arch_finish_commit() and
arch_snap_inode_sig(), call arch_update_serial(), which will perform the
following:

1. generate a random id and call it Commit-ID
2. generate a string that contains the date from the commiter's machine
   and call it Local-Commit-Date
3. If cat/branch/version/Status is in the archive, delete it.
4. Create cat/branch/version/Status
5. If cat/branch/Last-Modified is in the archive, delete it.
6. Create cat/branch/Status
7. If cat/Last-Modified is in the archive, delete it.
8. Create cat/Status
9. If Last-Modified is in the top level dir of the archive, delete it.
10. Create /Status

The contents of Status in each case will be:

Commit-ID: The commit id from step #2
Local-Commit-Date: The comitter's date from step #3


The process during push-mirror:
----------------------------------
First, open up the local and remote archive

If the /Last-Modified file exists in the local archive, get the Commit-ID
and call it Local-ID.

If the /Last-Modified file exists in remote archive, get the Commit-ID
and call it Remote-ID.

If ( ! Local-ID == Remote-ID)
       Repeat the steps for every category
          Repeat the steps for every branch
            Repeat the steps for every version.


The process during archive-mirror:
----------------------------------

This is the same process as push-mirror, adjusted accordingly.


-- 
James Blackwell      Using I.T. to bring more             570-407-0488
Owner, Inframix      business to your business     http://inframix.com

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