<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"> <title>Apache Portable Runtime: Pool Debugging functions.</title> <link href="doxygen.css" rel="stylesheet" type="text/css"> </head><body> <!-- Generated by Doxygen 1.3.9.1 --> <div class="qindex"><a class="qindex" href="index.html">Main Page</a> | <a class="qindex" href="modules.html">Modules</a> | <a class="qindex" href="annotated.html">Data Structures</a> | <a class="qindex" href="files.html">File List</a> | <a class="qindex" href="functions.html">Data Fields</a> | <a class="qindex" href="globals.html">Globals</a> | <a class="qindex" href="pages.html">Related Pages</a></div> <h1>Pool Debugging functions.<br> <small> [<a class="el" href="group__apr__pools.html">Memory Pool Functions</a>]</small> </h1><table border="0" cellpadding="0" cellspacing="0"> <tr><td></td></tr> <tr><td colspan="2"><br><h2>Functions</h2></td></tr> <tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__PoolDebug.html#ga0">apr_pool_join</a> (<a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> *p, <a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> *sub)</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__PoolDebug.html#ga1">apr_pool_find</a> (const void *mem)</td></tr> <tr><td class="memItemLeft" nowrap align="right" valign="top">apr_size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__PoolDebug.html#ga2">apr_pool_num_bytes</a> (<a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> *p, int recurse)</td></tr> <tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__PoolDebug.html#ga3">apr_pool_lock</a> (<a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> *pool, int flag)</td></tr> </table> <hr><a name="_details"></a><h2>Detailed Description</h2> pools have nested lifetimes -- sub_pools are destroyed when the parent pool is cleared. We allow certain liberties with operations on things such as tables (and on other structures in a more general sense) where we allow the caller to insert values into a table which were not allocated from the table's pool. The table's data will remain valid as long as all the pools from which its values are allocated remain valid.<p> For example, if B is a sub pool of A, and you build a table T in pool B, then it's safe to insert data allocated in A or B into T (because B lives at most as long as A does, and T is destroyed when B is cleared/destroyed). On the other hand, if S is a table in pool A, it is safe to insert data allocated in A into S, but it is *not safe* to insert data allocated from B into S... because B can be cleared/destroyed before A is (which would leave dangling pointers in T's data structures).<p> In general we say that it is safe to insert data into a table T if the data is allocated in any ancestor of T's pool. This is the basis on which the APR_POOL_DEBUG code works -- it tests these ancestor relationships for all data inserted into tables. APR_POOL_DEBUG also provides tools (apr_pool_find, and apr_pool_is_ancestor) for other folks to implement similar restrictions for their own data structures.<p> However, sometimes this ancestor requirement is inconvenient -- sometimes we're forced to create a sub pool (such as through apr_sub_req_lookup_uri), and the sub pool is guaranteed to have the same lifetime as the parent pool. This is a guarantee implemented by the *caller*, not by the pool code. That is, the caller guarantees they won't destroy the sub pool individually prior to destroying the parent pool.<p> In this case the caller must call <a class="el" href="group__PoolDebug.html#ga0">apr_pool_join()</a> to indicate this guarantee to the APR_POOL_DEBUG code. There are a few examples spread through the standard modules.<p> These functions are only implemented when <a class="el" href="group__apr__pools.html#ga32">APR_POOL_DEBUG</a> is set. <hr><h2>Function Documentation</h2> <a class="anchor" name="ga1" doxytag="apr_pools.h::apr_pool_find"></a><p> <table class="mdTable" width="100%" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a>* apr_pool_find </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top">const void * </td> <td class="mdname1" valign="top" nowrap> <em>mem</em> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap></td> </tr> </table> </td> </tr> </table> <table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td> <p> Find a pool from something allocated in it. <dl compact><dt><b>Parameters:</b></dt><dd> <table border="0" cellspacing="2" cellpadding="0"> <tr><td valign="top"></td><td valign="top"><em>mem</em> </td><td>The thing allocated in the pool </td></tr> </table> </dl> <dl compact><dt><b>Returns:</b></dt><dd>The pool it is allocated in </dd></dl> </td> </tr> </table> <a class="anchor" name="ga0" doxytag="apr_pools.h::apr_pool_join"></a><p> <table class="mdTable" width="100%" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">void apr_pool_join </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> * </td> <td class="mdname" nowrap> <em>p</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <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>sub</em></td> </tr> <tr> <td class="md"></td> <td class="md">) </td> <td class="md" colspan="2"></td> </tr> </table> </td> </tr> </table> <table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td> <p> Guarantee that a subpool has the same lifetime as the parent. <dl compact><dt><b>Parameters:</b></dt><dd> <table border="0" cellspacing="2" cellpadding="0"> <tr><td valign="top"></td><td valign="top"><em>p</em> </td><td>The parent pool </td></tr> <tr><td valign="top"></td><td valign="top"><em>sub</em> </td><td>The subpool </td></tr> </table> </dl> </td> </tr> </table> <a class="anchor" name="ga3" doxytag="apr_pools.h::apr_pool_lock"></a><p> <table class="mdTable" width="100%" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">void apr_pool_lock </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> * </td> <td class="mdname" nowrap> <em>pool</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int </td> <td class="mdname" nowrap> <em>flag</em></td> </tr> <tr> <td class="md"></td> <td class="md">) </td> <td class="md" colspan="2"></td> </tr> </table> </td> </tr> </table> <table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td> <p> Lock a pool <dl compact><dt><b>Parameters:</b></dt><dd> <table border="0" cellspacing="2" cellpadding="0"> <tr><td valign="top"></td><td valign="top"><em>pool</em> </td><td>The pool to lock </td></tr> <tr><td valign="top"></td><td valign="top"><em>flag</em> </td><td>The flag </td></tr> </table> </dl> </td> </tr> </table> <a class="anchor" name="ga2" doxytag="apr_pools.h::apr_pool_num_bytes"></a><p> <table class="mdTable" width="100%" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">apr_size_t apr_pool_num_bytes </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top"><a class="el" href="group__apr__pools.html#ga0">apr_pool_t</a> * </td> <td class="mdname" nowrap> <em>p</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int </td> <td class="mdname" nowrap> <em>recurse</em></td> </tr> <tr> <td class="md"></td> <td class="md">) </td> <td class="md" colspan="2"></td> </tr> </table> </td> </tr> </table> <table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td> <p> Report the number of bytes currently in the pool <dl compact><dt><b>Parameters:</b></dt><dd> <table border="0" cellspacing="2" cellpadding="0"> <tr><td valign="top"></td><td valign="top"><em>p</em> </td><td>The pool to inspect </td></tr> <tr><td valign="top"></td><td valign="top"><em>recurse</em> </td><td>Recurse/include the subpools' sizes </td></tr> </table> </dl> <dl compact><dt><b>Returns:</b></dt><dd>The number of bytes </dd></dl> </td> </tr> </table> <hr size="1"><address style="align: right;"><small>Generated on Sun Mar 20 19:52:27 2005 for Apache Portable Runtime by <a href="http://www.doxygen.org/index.html"> <img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.3.9.1 </small></address> </body> </html>