glib-threads.html

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</pre>
<p>
This macro is defined if GLib was compiled with thread support. This
does not necessarily mean that there is a thread implementation
available, but it does mean that the infrastructure is in place and
that once you provide a thread implementation to <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a>, GLib
will be multi-thread safe. If <a class="link" href="glib-Threads.html#G-THREADS-ENABLED:CAPS"><span class="type">G_THREADS_ENABLED</span></a> is not defined, then
Glib is not, and cannot be, multi-thread safe.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2882982"></a><h3>
<a name="G-THREADS-IMPL-POSIX:CAPS"></a>G_THREADS_IMPL_POSIX</h3>
<a class="indexterm" name="id2882995"></a><pre class="programlisting">#define G_THREADS_IMPL_POSIX
</pre>
<p>
This macro is defined if POSIX style threads are used.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883011"></a><h3>
<a name="G-THREADS-IMPL-NONE:CAPS"></a>G_THREADS_IMPL_NONE</h3>
<a class="indexterm" name="id2883025"></a><pre class="programlisting">#define G_THREADS_IMPL_NONE
</pre>
<p>
This macro is defined if no thread implementation is used. You can,
however, provide one to <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> to make GLib multi-thread safe.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883053"></a><h3>
<a name="G-THREAD-ERROR:CAPS"></a>G_THREAD_ERROR</h3>
<a class="indexterm" name="id2883066"></a><pre class="programlisting">#define G_THREAD_ERROR g_thread_error_quark ()
</pre>
<p>
The error domain of the GLib thread subsystem.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883082"></a><h3>
<a name="GThreadError"></a>enum GThreadError</h3>
<a class="indexterm" name="id2883095"></a><pre class="programlisting">typedef enum
{
  G_THREAD_ERROR_AGAIN /* Resource temporarily unavailable */
} GThreadError;
</pre>
<p>
Possible errors of thread related functions.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><a name="G-THREAD-ERROR-AGAIN:CAPS"></a><code class="literal">G_THREAD_ERROR_AGAIN</code></span></p></td>
<td>a thread couldn't be created due to resource
shortage. Try again later.

</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883140"></a><h3>
<a name="GThreadFunctions"></a>GThreadFunctions</h3>
<a class="indexterm" name="id2883152"></a><pre class="programlisting">typedef struct {
  GMutex*  (*mutex_new)           (void);
  void     (*mutex_lock)          (GMutex               *mutex);
  gboolean (*mutex_trylock)       (GMutex               *mutex);
  void     (*mutex_unlock)        (GMutex               *mutex);
  void     (*mutex_free)          (GMutex               *mutex);
  GCond*   (*cond_new)            (void);
  void     (*cond_signal)         (GCond                *cond);
  void     (*cond_broadcast)      (GCond                *cond);
  void     (*cond_wait)           (GCond                *cond,
                                   GMutex               *mutex);
  gboolean (*cond_timed_wait)     (GCond                *cond,
                                   GMutex               *mutex,
                                   GTimeVal             *end_time);
  void      (*cond_free)          (GCond                *cond);
  GPrivate* (*private_new)        (GDestroyNotify        destructor);
  gpointer  (*private_get)        (GPrivate             *private_key);
  void      (*private_set)        (GPrivate             *private_key,
                                   gpointer              data);
  void      (*thread_create)      (GThreadFunc           func,
                                   gpointer              data,
                                   gulong                stack_size,
                                   gboolean              joinable,
                                   gboolean              bound,
                                   GThreadPriority       priority,
                                   gpointer              thread,
                                   GError              **error);
  void      (*thread_yield)       (void);
  void      (*thread_join)        (gpointer              thread);
  void      (*thread_exit)        (void);
  void      (*thread_set_priority)(gpointer              thread,
                                   GThreadPriority       priority);
  void      (*thread_self)        (gpointer              thread);
  gboolean  (*thread_equal)       (gpointer              thread1,
				   gpointer              thread2);
} GThreadFunctions;
</pre>
<p>
This function table is used by <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> to initialize the
thread system. The functions in the table are directly used by their
g_* prepended counterparts (described in this document).  For example,
if you call <a class="link" href="glib-Threads.html#g-mutex-new"><code class="function">g_mutex_new()</code></a> then <code class="function">mutex_new()</code> from the table provided to
<a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> will be called.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Do not use this struct unless you know what you are doing.
</p>
</div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883258"></a><h3>
<a name="g-thread-init"></a>g_thread_init ()</h3>
<a class="indexterm" name="id2883271"></a><pre class="programlisting">void                g_thread_init                       (<a class="link" href="glib-Threads.html#GThreadFunctions">GThreadFunctions</a> *vtable);</pre>
<p>
If you use GLib from more than one thread, you must initialize
the thread system by calling <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a>. Most of the time you 
will only have to call <code class="literal">g_thread_init (NULL)</code>. 
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Do not call <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> with a non-<a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> parameter unless you
really know what you are doing.
</p>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
<a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> must not be called directly or indirectly as a
callback from GLib. Also no mutexes may be currently locked while
calling <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a>.
</p>
</div>
<p>
<a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> might only be called once. On the second call
it will abort with an error. If you want to make sure that the thread
system is initialized, you can do this:
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
if (!g_thread_supported ()) g_thread_init (NULL);
</pre></div>
<p>
</p>
<p>
After that line, either the thread system is initialized or, if no
thread system is available in GLib (i.e. either <a class="link" href="glib-Threads.html#G-THREADS-ENABLED:CAPS"><span class="type">G_THREADS_ENABLED</span></a> is
not defined or <a class="link" href="glib-Threads.html#G-THREADS-IMPL-NONE:CAPS"><span class="type">G_THREADS_IMPL_NONE</span></a> is defined), the program will
abort.
</p>
<p>
If no thread system is available and <em class="parameter"><code>vtable</code></em> is <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> or if not all
elements of <em class="parameter"><code>vtable</code></em> are non-<a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, then <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> will abort.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
To use <a class="link" href="glib-Threads.html#g-thread-init"><code class="function">g_thread_init()</code></a> in your program, you have to link with the
libraries that the command <span class="command"><strong>pkg-config --libs gthread-2.0</strong></span> 
outputs. This is not the case for all the other thread related functions of
GLib. Those can be used without having to link with the thread libraries.
</p>
</div>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>vtable</code></em>&#160;:</span></p></td>
<td>a function table of type <a class="link" href="glib-Threads.html#GThreadFunctions"><span class="type">GThreadFunctions</span></a>, that provides the
entry points to the thread system to be used.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883534"></a><h3>
<a name="g-thread-supported"></a>g_thread_supported ()</h3>
<a class="indexterm" name="id2883548"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            g_thread_supported                  ();</pre>
<p>
This function returns <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the thread system is initialized, and
<a class="link" href="glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> if it is not.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
This function is actually a macro. Apart from taking the address of it
you can however use it as if it was a function.
</p>
</div>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td>
<a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>, if the thread system is initialized.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2883623"></a><h3>
<a name="GThreadFunc"></a>GThreadFunc ()</h3>
<a class="indexterm" name="id2883636"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a>            (*GThreadFunc)                      (<a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> data);</pre>
<p>
Specifies the type of the <em class="parameter"><code>func</code></em> functions passed to
<a class="link" href="glib-Threads.html#g-thread-create"><code class="function">g_thread_create()</code></a> or <a class="link" href="glib-Threads.html#g-thread-create-full"><code class="function">g_thread_create_full()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">