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From Philip Martin <phi...@codematters.co.uk>
Subject Re: Building the apr runtime library appropriately for the worker MPM
Date Thu, 04 Apr 2013 00:44:48 GMT
Ben Reser <ben@reser.org> writes:

> On Wed, Apr 3, 2013 at 12:29 PM, Jeff Trawick <trawick@gmail.com> wrote:
>> I'm not aware of any apr_file_lock() use within httpd, so you wouldn't
>> regress anything (unless you're using third-party modules that use
>> apr_file_lock).  But I guess you've introduced a third-party module that
>> uses apr_file_lock() or you wouldn't be asking about this?
>
> Subversion uses apr_file_lock() and by extension so does mod_dav_svn.

The main place we use this is in the FSFS backend.  On multi-threaded
Unix systems we also use a mutex to ensure that only a single thread in
each process locks the file.  So the use of fcntl() should be OK here as
far as Subversion is concerned.

There is also a lock for the BDB backend that is only used for certain
admin operations and those operations have a restriction that the caller
is responsible for calling the functions in a single-threaded context.
These functions are used by the single-threaded svnadmin program.

-- 
Philip

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