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<title>Apache Portable Runtime: Reader/Writer Lock Routines</title>
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<h1>Reader/Writer Lock Routines<br>
<small>
[<a class="el" href="group__APR.html">Apache Portability Runtime library</a>]</small>
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<tr><td colspan="2"><br><h2>Typedefs</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">typedef <a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a></td></tr>
<tr><td colspan="2"><br><h2>Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga1">apr_thread_rwlock_create</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> **rwlock, <a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> *pool)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga2">apr_thread_rwlock_rdlock</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga3">apr_thread_rwlock_tryrdlock</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga4">apr_thread_rwlock_wrlock</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga5">apr_thread_rwlock_trywrlock</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga6">apr_thread_rwlock_unlock</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga7">apr_thread_rwlock_destroy</a> (<a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *rwlock)</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> * </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__thread__rwlock.html#ga8">apr_thread_rwlock_pool_get</a> (const <a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> *thethread_rwlock)</td></tr>
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<hr><h2>Typedef Documentation</h2>
<a class="anchor" name="ga0" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_t"></a><p>
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<td class="md" nowrap valign="top">typedef struct <a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> <a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> </td>
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<p>
Opaque read-write thread-safe lock. </td>
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<hr><h2>Function Documentation</h2>
<a class="anchor" name="ga1" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_create"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> apr_thread_rwlock_create </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> ** </td>
<td class="mdname" nowrap> <em>rwlock</em>, </td>
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<td class="md"></td>
<td class="md" nowrap><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> * </td>
<td class="mdname" nowrap> <em>pool</em></td>
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Create and initialize a read-write lock that can be used to synchronize threads. <dl compact><dt><b>Parameters:</b></dt><dd>
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<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the memory address where the newly created readwrite lock will be stored. </td></tr>
<tr><td valign="top"></td><td valign="top"><em>pool</em> </td><td>the pool from which to allocate the mutex. </td></tr>
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<a class="anchor" name="ga7" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_destroy"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> apr_thread_rwlock_destroy </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Destroy the read-write lock and free the associated memory. <dl compact><dt><b>Parameters:</b></dt><dd>
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<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the rwlock to destroy. </td></tr>
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<a class="anchor" name="ga8" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_pool_get"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a>* apr_thread_rwlock_pool_get </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top">const <a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>thethread_rwlock</em> </td>
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Get the pool used by this thread_rwlock. <dl compact><dt><b>Returns:</b></dt><dd>apr_pool_t the pool </dd></dl>
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<a class="anchor" name="ga2" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_rdlock"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> apr_thread_rwlock_rdlock </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Acquire a shared-read lock on the given read-write lock. This will allow multiple threads to enter the same critical section while they have acquired the read lock. <dl compact><dt><b>Parameters:</b></dt><dd>
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<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the read-write lock on which to acquire the shared read. </td></tr>
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<a class="anchor" name="ga3" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_tryrdlock"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> apr_thread_rwlock_tryrdlock </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Attempt to acquire the shared-read lock on the given read-write lock. This is the same as <a class="el" href="group__apr__thread__rwlock.html#ga2">apr_thread_rwlock_rdlock()</a>, only that the function fails if there is another thread holding the write lock, or if there are any write threads blocking on the lock. If the function fails for this case, APR_EBUSY will be returned. Note: it is important that the <a class="el" href="group__APR__STATUS__IS.html#ga44">APR_STATUS_IS_EBUSY(s)</a> macro be used to determine if the return value was APR_EBUSY, for portability reasons. <dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the rwlock on which to attempt the shared read. </td></tr>
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<a class="anchor" name="ga5" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_trywrlock"></a><p>
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<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Attempt to acquire the exclusive-write lock on the given read-write lock. This is the same as <a class="el" href="group__apr__thread__rwlock.html#ga4">apr_thread_rwlock_wrlock()</a>, only that the function fails if there is any other thread holding the lock (for reading or writing), in which case the function will return APR_EBUSY. Note: it is important that the <a class="el" href="group__APR__STATUS__IS.html#ga44">APR_STATUS_IS_EBUSY(s)</a> macro be used to determine if the return value was APR_EBUSY, for portability reasons. <dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the rwlock on which to attempt the exclusive write. </td></tr>
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<a class="anchor" name="ga6" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_unlock"></a><p>
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<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Release either the read or write lock currently held by the calling thread associated with the given read-write lock. <dl compact><dt><b>Parameters:</b></dt><dd>
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<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the read-write lock to be released (unlocked). </td></tr>
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<a class="anchor" name="ga4" doxytag="apr_thread_rwlock.h::apr_thread_rwlock_wrlock"></a><p>
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<td class="md" nowrap valign="top"><a class="el" href="group__apr__errno.html#ga0">apr_status_t</a> apr_thread_rwlock_wrlock </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group__apr__thread__rwlock.html#ga0">apr_thread_rwlock_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>rwlock</em> </td>
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Acquire an exclusive-write lock on the given read-write lock. This will allow only one single thread to enter the critical sections. If there are any threads currently holding the read-lock, this thread is put to sleep until it can have exclusive access to the lock. <dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>rwlock</em> </td><td>the read-write lock on which to acquire the exclusive write. </td></tr>
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