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Re: Tree-conflicts: HEADS UP: update failure with tc-siblings :0

From: Julian Foad <julianfoad_at_btopenworld.com>
Date: Mon, 17 Nov 2008 15:10:29 +0000

On Sun, 2008-11-16 at 06:39 +0100, Neels J. Hofmeyr wrote:
> Neels J. Hofmeyr wrote:
> > Stephen Butler wrote:
> >>> CMD: svn status -v -u -q ...
> >>> D 2 1 jrandom /A/B/E/beta
> >>> D C * 1 1 jrandom /A/B/E/alpha
> >>> D C 2 2 jrandom /A/B/E
> >>> D * 1 1 jrandom /A/B/lambda
> >>> 2 1 jrandom /A/B/F
> >> The missing ' C' for lambda is still missing on trunk. It appears
> >> that two log files are written in /A/B/.svn, for lambda and for E, and
> >> svn_wc__run_log() reads both of them, but the content of the first log
> >> file isn't written to the entry.
> >>
> >> Strange. I'll keep digging.
> I've also done some digging now and am busy fixing it. (Steve, I know you
> are or have been on this. Shout if I'm duplicating your work or something.)
> Let's explain the problem:
> run_log() reads two modify-entry commands from a log file:
> <modify-entry
> name=""
> tree-conflicts="B:dir:update:edited:deleted"/>
> <modify-entry
> name=""
> tree-conflicts="mu:file:update:edited:deleted"/>
> It calls log_do_modify_entry() on both of them.
> Common sense says that this tree-conflicts data should be concatenated.
> But log_do_modify_entry() *replaces* the information that is already there.
> So the first new conflict is overwritten by the second.
> Ok, let's step one layer out of this onion. There is the function
> svn_wc__loggy_add_tree_conflict() which writes these tree-conflicts to the
> log. This function first checks what other tree-conflicts there are in the
> entry, adds the new tree-conflicts data and replaces the whole
> tree-conflicts data in the entry with the new list.
> The problem is that if in one directory, two tree-conflicts appear in the
> same run and are recorded using the same log, the second tree-conflict
> addition again reads the *old* list of conflicts from the entry, appends the
> second entry and writes the whole thing out. So, any earlier tree-conflicts
> that were queued in the log file and aren't in the official entry yet get
> overwritten with the latest one.
> I am busy on a patch that first collects all new tree-conflicts upon update
> in the parent dir baton as svn_wc_conflict_description_t* in an apr_array
> and logs them all at once on close_directory() (in update_editor.c).


I only appreciated this solution that you're working on after I'd read
and responded to the rest of the thread, and said we should try to solve
the "adm_access entries cache gets out of sync" problem. But this
solution you're working on is possibly a good solution too, though it
doesn't exactly remove the source of the problem.

> The patch won't make it today, but there are questions I'd like to send out
> already:
> 1)
> In libsvn_wc/update_editor.c, around line 1632 in do_entry_deletion(), it says:
> [[[
> if (tree_conflict != NULL)
> {
> /* Run the log immediately, so that the tree conflict is recorded. */
> SVN_ERR(svn_wc__write_log(adm_access, *log_number, log_item, pool));
> SVN_ERR(svn_wc__run_log(adm_access, NULL, pool));
> *log_number = 0;
> }
> ]]]
> Can anyone remember why that would be necessary?

I can't.

> 2)
> We use svn_wc_conflict_description_create_tree() to make a new conflict
> description struct. The fact that this function also *allocates* the memory
> makes it a little harder to push a new description onto an
> apr_array_header_t, since apr_array_push() is also allocating memory and
> returning it to be written in.
> I'm currently solving this by not storing conflict description structs, but
> only pointers to them in the apr_array. I thus avoid changing the signature
> of svn_wc_conflict_description_create_tree(), which would otherwise break
> with the conventions of svn_wc_conflict_description_create_text() and
> svn_wc_conflict_description_create_prop(). Do you guys agree with that, or
> would you rather change the function signature or even signatureS?

Yes, storing pointers is a good solution.

- Julian

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Received on 2008-11-17 16:10:51 CET

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