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<p>
programs. It also gives hints for future RRD development to keep the
library thread-safe.</p>
<p>Currently only some RRD operations are implemented in a thread-safe
-way. They all end in the usual ``<code>_r</code>'' suffix.</p>
+way. They all end in the usual "<code>_r</code>" suffix.</p>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p>In order to use librrd in multi-threaded programs you must:</p>
<ul>
-<li></li>
-Link with <em>librrd_th</em> instead of <em>librrd</em> (use <code>-lrrd_th</code> when
-linking)
-<p></p>
-<li></li>
-Use the ``<code>_r</code>'' functions instead of the normal API-functions
-<p></p>
-<li></li>
-Do not use any at-style time specifications. Parsing of such time
-specifications is terribly non-thread-safe.
-<p></p>
-<li></li>
-Never use non *<code>_r</code> functions unless it is explicitly documented that
-the function is tread-safe.
-<p></p>
-<li></li>
-Every thread SHOULD call <code>rrd_get_context()</code> before its first call to
+<li>
+<p>Link with <em class="file">librrd_th</em> instead of <em class="file">librrd</em> (use <code>-lrrd_th</code> when
+linking)</p>
+</li>
+<li>
+<p>Use the "<code>_r</code>" functions instead of the normal API-functions</p>
+</li>
+<li>
+<p>Do not use any at-style time specifications. Parsing of such time
+specifications is terribly non-thread-safe.</p>
+</li>
+<li>
+<p>Never use non *<code>_r</code> functions unless it is explicitly documented that
+the function is tread-safe.</p>
+</li>
+<li>
+<p>Every thread SHOULD call <code>rrd_get_context()</code> before its first call to
any <code>librrd_th</code> function in order to set up thread specific data. This
is not strictly required, but it is the only way to test if memory
allocation can be done by this function. Otherwise the program may die
-with a SIGSEGV in a low-memory situation.
-<p></p>
-<li></li>
-Always call <code>rrd_error_clear()</code> before any call to the
-library. Otherwise the call might fail due to some earlier error.
-<p></p></ul>
+with a SIGSEGV in a low-memory situation.</p>
+</li>
+<li>
+<p>Always call <code>rrd_error_clear()</code> before any call to the
+library. Otherwise the call might fail due to some earlier error.</p>
+</li>
+</ul>
<p>
</p>
<h2><a name="notes_for_rrd_contributors">NOTES FOR RRD CONTRIBUTORS</a></h2>
<p>Some precautions must be followed when developing RRD from now on:</p>
<ul>
-<li></li>
-Only use thread-safe functions in library code. Many often used libc
+<li>
+<p>Only use thread-safe functions in library code. Many often used libc
functions aren't thread-safe. Take care in the following
-situations or when using the following library functions:
+situations or when using the following library functions:</p>
<ul>
-<li></li>
-Direct calls to <code>strerror()</code> must be avoided: use <code>rrd_strerror()</code>
-instead, it provides a per-thread error message.
-<p></p>
-<li></li>
-The <code>getpw*</code>, <code>getgr*</code>, <code>gethost*</code> function families (and some more
-<code>get*</code> functions) are not thread-safe: use the *<code>_r</code> variants
-<p></p>
-<li></li>
-Time functions: <code>asctime</code>, <code>ctime</code>, <code>gmtime</code>, <code>localtime</code>: use
-*<code>_r</code> variants
-<p></p>
-<li></li>
-<code>strtok</code>: use <code>strtok_r</code>
-<p></p>
-<li></li>
-<code>tmpnam</code>: use <code>tmpnam_r</code>
-<p></p>
-<li></li>
-Many others (lookup documentation)
-<p></p></ul>
-<li></li>
-A header file named <em>rrd_is_thread_safe.h</em> is provided
-that works with the GNU C-preprocessor to ``poison'' some of the most
+<li>
+<p>Direct calls to <code>strerror()</code> must be avoided: use <code>rrd_strerror()</code>
+instead, it provides a per-thread error message.</p>
+</li>
+<li>
+<p>The <code>getpw*</code>, <code>getgr*</code>, <code>gethost*</code> function families (and some more
+<code>get*</code> functions) are not thread-safe: use the *<code>_r</code> variants</p>
+</li>
+<li>
+<p>Time functions: <code>asctime</code>, <code>ctime</code>, <code>gmtime</code>, <code>localtime</code>: use
+*<code>_r</code> variants</p>
+</li>
+<li>
+<p><code>strtok</code>: use <code>strtok_r</code></p>
+</li>
+<li>
+<p><code>tmpnam</code>: use <code>tmpnam_r</code></p>
+</li>
+<li>
+<p>Many others (lookup documentation)</p>
+</li>
+</ul>
+</li>
+<li>
+<p>A header file named <em class="file">rrd_is_thread_safe.h</em> is provided
+that works with the GNU C-preprocessor to "poison" some of the most
common non-thread-safe functions using the <code>#pragma GCC poison</code>
directive. Just include this header in source files you want to keep
-thread-safe.
-<p></p>
-<li></li>
-Do not introduce global variables!
+thread-safe.</p>
+</li>
+<li>
+<p>Do not introduce global variables!</p>
<p>If you really, really have to use a global variable you may add a new
-field to the <code>rrd_context</code> structure and modify <em>rrd_error.c</em>,
-<em>rrd_thread_safe.c</em> and <em>rrd_non_thread_safe.c</em></p>
-<p></p>
-<li></li>
-Do not use <code>getopt</code> or <code>getopt_long</code> in *<code>_r</code> (neither directly nor
-indirectly).
+field to the <code>rrd_context</code> structure and modify <em class="file">rrd_error.c</em>,
+<em class="file">rrd_thread_safe.c</em> and <em class="file">rrd_non_thread_safe.c</em></p>
+</li>
+<li>
+<p>Do not use <code>getopt</code> or <code>getopt_long</code> in *<code>_r</code> (neither directly nor
+indirectly).</p>
<p><code>getopt</code> uses global variables and behaves badly in a multi-threaded
application when called concurrently. Instead provide a *_r function
taking all options as function parameters. You may provide argc and
**argv arguments for variable length argument lists. See
<code>rrd_update_r</code> as an example.</p>
-<p></p>
-<li></li>
-Do not use the <code>rrd_parsetime</code> function!
+</li>
+<li>
+<p>Do not use the <code>rrd_parsetime</code> function!</p>
<p>It uses lots of global variables. You may use it in functions not designed
to be thread-safe, like in functions wrapping the <code>_r</code> version of some
operation (e.g., <code>rrd_create</code>, but not in <code>rrd_create_r</code>)</p>
-<p></p></ul>
+</li>
+</ul>
<p>
</p>
<h2><a name="currently_implemented_thread_safe_functions">CURRENTLY IMPLEMENTED THREAD SAFE FUNCTIONS</a></h2>