Re: why my process open .svn/tmp/svn-XXXXXX file? and why are tmpfiles deleted? and why my process can't open the right file after tmp files deleted?

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On Fri, Dec 22, 2017 at 10:32 AM, Keva-Slient <356730059_at_qq.com> wrote:
> ------------------ 原始邮件 ------------------
> 发件人: "Johan Corveleyn";<jcorvel_at_gmail.com>;
> 发送时间: 2017年12月22日(星期五) 下午5:07
> 收件人: "Keva-Slient"<356730059_at_qq.com>;
> 抄送: "users"<users_at_subversion.apache.org>;
> 主题: Re: why my process open .svn/tmp/svn-XXXXXX file? and why are tmpfiles
> deleted? and why my process can't open the right file after tmp files
> deleted?
>
> On Fri, Dec 22, 2017 at 3:33 AM, Keva-Slient <356730059_at_qq.com> wrote:
>> we use svn managing our config files.
>>
>> we lock config file when do committing or writing operation.
>> in client side, only commit operation executes. and svndump in server.
>>
>> our process is always opening file like repo/someconfig/files . it's
>> strang
>> process opened tmp file like repo/.svn/tmp/svn-XXXXXX in some clients.
>>
>> and tmp file was deleted. our process report errors.
>>
>> for example:
>> <8> Sundray-WAC / #lsof |grep online_assist | grep config |sort -k 3
>> 704 /wns/sbin/online_assist /wns/etc/config/.svn/tmp/svn-39HEsA (deleted)
>> 704 /wns/sbin/online_assist /wns/etc/config/.svn/tmp/svn-sTknMU (deleted)
>> 704 /wns/sbin/online_assist /wns/etc/config/.svn/tmp/svn-ynboPV (deleted)
>
> Did you see Bert's reply to your earlier mail? You're asking almost
> the same question.
>
> https://svn.haxx.se/users/archive-2017-12/0125.shtml
>
> As Bert said: Subversion uses the .svn/tmp to create files, fill them
> with content, and move them to the correct location in your working
> copy (to avoid incomplete files appearing in your working copy). Apart
> from that, svn also uses its tmp directory for other temporary files,
> like creating temp files for diffing consecutive version of a file,
> while running an 'svn blame' operation.
>
> Basically, the .svn/tmp folder is an internal implementation detail of
> Subversion. You shouldn't try to mess with it or write scripts around
> it (the internals and behaviour of the .svn folder may change at any
> time in newer svn releases).
>
> Also: we have no idea here what "online-assist" is, and what it does.
> That's not something from the Subversion project, as far as I know. On
> this list we only know about SVN itself, so explain your question /
> problem in terms of svn commands, what you see, and what you were
> expecting instead.
>
> --
> Johan
>
> online-assist is our process name.
> we use svn to manage our config file and binary db files.
>
>
> program must keep the file open and will keep servicing all the time.
> we have to restart program if file in working copy moved to tmp and deleted.
> that's not what we want.
>
> we only use "commit" command in client side.
> is there any solution to avoid this tmp file problem?
> may i change the source code to satisfy our request if there is not any
> solution?
> and should i send this source code question to dev_at_subversion.apache.org ?
>
> i'm now reading source code. i've found some code.
> static const struct work_item_dispatch dispatch_table[] = {
> { OP_FILE_COMMIT, run_file_commit },
> }
> svn_io_file_move
> svn_io_open_unique_file3
> temp_file_create
>
> and one repository only has one client.
> only this client commit to server. it doesn't need updating. cause there
> are not any others writing and committing to this repository.
> there will no conflicting and updating.
> so is it necessary to disable creating temporary file?

It's still not clear what online-assist is really doing. What svn
commands does it execute?

I don't understand why the deletes of the tmp files are a problem. Are
you trying to keep those tmp files open?? That would be bad. You
should NOT depend on those tmp files.

Or is the problem that you're keeping the WORKING files open (as
opposed to the tmp files corresponding to them), and you want to keep
them open even while you're committing them? And subversion replaces
those files from underneath you, when you're committing them?

A possible reason for SVN to replace your working file while when
you're committing it, is keyword-expansion [1]. If you have such
keywords in your source file, and you have the "svn:keywords" property
set on it, SVN really has to change your file when you're committing.

But maybe that "replace file" codepath is executed even when there are
no keywords present and the svn:keywords property is not set... That
might be fixable.

OTOH, there might be other reasons why SVN needs to touch the file
when you're committing it (I haven't looked at the code).

[ Meta: Apache Subversion is open source and has an Apache License 2.0
[2]. Basically, you're free to change the source code to your liking,
and create yourself a custom build / fork. If you want to propose a
change to the core project, you should start a discussion on
dev_at_subversion.apache.org. ]

[1] http://svnbook.red-bean.com/nightly/en/svn.advanced.props.special.keywords.html
[2] https://www.apache.org/licenses/LICENSE-2.0

-- 
Johan