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Re: svn commit: r1488183 - /subversion/trunk/subversion/libsvn_client/merge.c

From: Ivan Zhakov <ivan_at_apache.org>
Date: Wed, 5 Jun 2013 18:12:52 +0400

On Wed, Jun 5, 2013 at 1:50 AM, Julian Foad <julianfoad_at_btopenworld.com> wrote:
> Paul Burba wrote:
>> On Fri, May 31, 2013 at 8:02 AM, <ivan_at_apache.org> wrote:
>>> URL: http://svn.apache.org/r1488183
>>>
>>> --- subversion/trunk/subversion/libsvn_client/merge.c (original)
>>> +++ subversion/trunk/subversion/libsvn_client/merge.c Fri May 31 12:02:32
>>> @@ -12415,14 +12415,15 @@ client_find_automatic_merge(automatic_me
>>> source_and_target_t *s_t = apr_palloc(result_pool, sizeof(*s_t));
>>> automatic_merge_t *merge = apr_palloc(result_pool, sizeof(*merge));
>>>
>>> - /* "Open" the target WC. We're not going to check the target WC for
>>> - * mixed-rev, local mods or switched subtrees yet. After we find out
>>> - * what kind of merge is required, then if a reintegrate-like merge is
>>> - * required we'll do the stricter checks, in do_automatic_merge_locked(). */
>>> + /* "Open" the target WC. Check the target WC for mixed-rev, local mods and
>>> + * switched subtrees yet to faster exit and notify user before contacting
>>> + * with server. After we find out what kind of merge is required, then if
>>> + * a reintegrate-like merge is required we'll do the stricter checks, in
>>> + * do_automatic_merge_locked(). */
>>
>> Hi Ivan,
>>
>> (Julian - ccing you as you originally added this bit of code that Ivan
>> tweaked here)
>>
>> The comment is a bit misleading. We don't *unconditionally* check the
>> target WC for mixed-rev, local mods, and/or switched subtrees, it
>> depends on what the caller asks for. Yes, currently the only two
>> callers of client_find_automatic_merge() unconditionally pass
>> ALLOW_LOCAL_MODS=TRUE and ALLOW_SWITCHED_SUBTREES=TRUE, so the comment
>> here is effectively true, but might not be in the future.
>>
I agree that comment a little bit confusing. Sorry. I'm fine with
Juilan comment fix.

>>> SVN_ERR(open_target_wc(&s_t->target, target_abspath,
>>> - TRUE /*allow_mixed_rev*/,
>>> - TRUE /*allow_local_mods*/,
>>> - TRUE /*allow_switched_subtrees*/,
>>> + allow_mixed_rev,
>>> + allow_local_mods,
>>> + allow_switched_subtrees,
>>
>> Since you were worried about performance with mixed-rev WCs, I wonder
>> if this is better:
>>
>> [[[
>> - /* "Open" the target WC. We're not going to check the target WC for
>> - * mixed-rev, local mods or switched subtrees yet. After we find out
>> - * what kind of merge is required, then if a reintegrate-like merge is
>> - * required we'll do the stricter checks, in do_automatic_merge_locked(). */
>> + /* "Open" the target WC. We're not going to check the target WC for local
>> + mods or switched subtrees yet, but since the check for mixed-revisions
>> + is cheap, easily violated, and required by most merges, check for that
>> + now, before we go through the potentially lengthy process of contacting
>> + the server -- It's bad form to make the user wait, only to learn that
>> + they cannot merge due to the state of their WC: "Uh, why didn't you tell
>> + me that at the start!" Later, if we determine that a reintegrate-like
>> + merge is called for, then we'll do the local mod and switched subtree
>> + checks in do_automatic_merge_locked(). */
>> SVN_ERR(open_target_wc(&s_t->target, target_abspath,
>> - TRUE /*allow_mixed_rev*/,
>> - TRUE /*allow_local_mods*/,
>> - TRUE /*allow_switched_subtrees*/,
>> + allow_mixed_rev,
>> + TRUE, /* allow_local_mods */
>> + TRUE, /* allow_switched_subtrees */
>> ctx, result_pool, scratch_pool));
Working copy with local mods is also typical case IMHO. Is local mods
check expensive?

I'm fine to delay local mods and switched subtrees checks, but I think
it's premature optimization: local operations generally fast, while
remote is slow.

-- 
Ivan Zhakov
VisualSVN Team
Received on 2013-06-05 16:13:51 CEST

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