regex/doc/html/boost_regex/background/thread_safety.html
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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_regex.background.thread_safety"></a><a class="link" href="thread_safety.html" title="Thread Safety">Thread Safety</a>
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<p>
The Boost.Regex library is thread safe when Boost is: you can verify that
Boost is in thread safe mode by checking to see if <code class="computeroutput"><span class="identifier">BOOST_HAS_THREADS</span></code>
is defined: this macro is set automatically by the config system when threading
support is turned on in your compiler.
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<p>
Class <a class="link" href="../ref/basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a>
and its typedefs regex and wregex are thread safe, in that compiled regular
expressions can safely be shared between threads. The matching algorithms
<a class="link" href="../ref/regex_match.html" title="regex_match"><code class="computeroutput"><span class="identifier">regex_match</span></code></a>,
<a class="link" href="../ref/regex_search.html" title="regex_search"><code class="computeroutput"><span class="identifier">regex_search</span></code></a>,
and <a class="link" href="../ref/regex_replace.html" title="regex_replace"><code class="computeroutput"><span class="identifier">regex_replace</span></code></a>
are all re-entrant and thread safe. Class <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a> is now thread safe,
in that the results of a match can be safely copied from one thread to another
(for example one thread may find matches and push <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a> instances onto a queue,
while another thread pops them off the other end), otherwise use a separate
instance of <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a>
per thread.
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<p>
The <a class="link" href="../ref/posix.html" title="POSIX Compatible C API's">POSIX API functions</a> are
all re-entrant and thread safe, regular expressions compiled with regcomp
can also be shared between threads.
</p>
<p>
The <a class="link" href="../ref/deprecated/old_regex.html" title="High Level Class RegEx (Deprecated)">class RegEx</a>
is only thread safe if each thread gets its own RegEx instance (apartment
threading) - this is a consequence of RegEx handling both compiling and matching
regular expressions.
</p>
<p>
Finally note that changing the global locale invalidates all compiled regular
expressions, therefore calling <code class="computeroutput"><span class="identifier">set_locale</span></code>
from one thread while another uses regular expressions will produce unpredictable
results.
</p>
<p>
There is also a requirement that there is only one thread executing prior
to the start of main().
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<td align="right"><div class="copyright-footer">Copyright &#169; 1998-2013 John Maddock<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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