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2002-06-04 Marcus Brinkmann <marcus@g10code.de>

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* gpgme.texi (Multi Threading): Document new autodetection.
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Marcus Brinkmann 2002-06-04 12:12:08 +00:00
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commit e202b91008
2 changed files with 36 additions and 9 deletions
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@ -1,3 +1,7 @@
2002-06-04 Marcus Brinkmann <marcus@g10code.de>
* gpgme.texi (Multi Threading): Document new autodetection.
2002-06-04 Marcus Brinkmann <marcus@g10code.de>
* Makefile.am (DISTCLEANFILES): New variable.

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doc/gpgme.texi
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@ -450,17 +450,40 @@ If the following requirements are met, there should be no race
conditions to worry about:
@itemize @bullet
@item
@acronym{GPGME} supports the thread libraries pthread and GNU Pth.
The support for this has to be enabled at compile time.
@acronym{GPGME} will automatically detect the location in which the
thread libraries are installed and activate the support for them.
Support for other thread libraries is very easy to add. Please
contact us if you have the need.
@item
If you link your program dynamically to @acronym{GPGME} and your
supported thread library, @acronym{GPGME} will automatically detect
the presence of this library and activate its use. If you link to
both pthread and GNU Pth, @acronym{GPGME} will use the pthread
support. This feature requires weak symbol support.
@item
If you link your program statically to @acronym{GPGME}, there is
currently no easy way to make sure that @acronym{GPGME} detects the
presence of the thread library. This will be solved in a future
version.
@item
The function @code{gpgme_check_version} must be called before any
other function in the library, because it initializes the locking
subsystem in @acronym{GPGME}. To achieve this in all generality, it
is necessary to synchronize the call to this function with all other
calls to functions in the library, using the synchronization
mechanisms available in your thread library. Otherwise, specific
compiler or CPU memory cache optimizations could lead to the situation
where a thread is started and uses @acronym{GPGME} before the effects
of the initialization are visible for this thread. It doesn't even
suffice to call @code{gpgme_check_version} before creating this other
other function in the library, because it initializes the thread
support subsystem in @acronym{GPGME}. To achieve this in all
generality, it is necessary to synchronize the call to this function
with all other calls to functions in the library, using the
synchronization mechanisms available in your thread library.
Otherwise, specific compiler or CPU memory cache optimizations could
lead to the situation where a thread is started and uses
@acronym{GPGME} before the effects of the initialization are visible
for this thread. It doesn't even suffice to call
@code{gpgme_check_version} before creating this other
thread@footnote{In SMP systems the new thread could be started on
another CPU before the effects of the initialization are seen by that
CPU's memory cache. Not doing proper synchronization here leads to