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<th colspan="3" align="center">DB->set_alloc()</th>
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<h2 class="title" style="clear: both"><a id="dbset_alloc"></a>DB->set_alloc()</h2>
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<pre class="programlisting">#include <db.h>
int
DB->set_alloc(DB *db,
void *(*app_malloc)(size_t),
void *(*app_realloc)(void *, size_t),
void (*app_free)(void *)); </pre>
<p>
Set the allocation functions used by the
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> and
<a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a> methods to allocate or free
memory owned by the application.
</p>
<p>
There are a number of interfaces in Berkeley DB where memory is
allocated by the library and then given to the application. For
example, the <a class="link" href="dbt.html#dbt_DB_DBT_MALLOC">DB_DBT_MALLOC</a>
flag, when specified in the <a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>
object, will cause the <a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a> methods to allocate and
reallocate memory which then becomes the responsibility of the calling
application. (See <a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>
for more information.) Other examples are the Berkeley DB interfaces
which return statistical information to the application:
<a class="xref" href="dbstat.html" title="DB->stat()">DB->stat()</a>,
<a class="xref" href="lockstat.html" title="DB_ENV->lock_stat()">DB_ENV->lock_stat()</a>,
<a class="xref" href="logarchive.html" title="DB_ENV->log_archive()">DB_ENV->log_archive()</a>,
<a class="xref" href="logstat.html" title="DB_ENV->log_stat()">DB_ENV->log_stat()</a>,
<a class="xref" href="mempstat.html" title="DB_ENV->memp_stat()">DB_ENV->memp_stat()</a>,
and <a class="xref" href="txnstat.html" title="DB_ENV->txn_stat()">DB_ENV->txn_stat()</a>. There is
one method in Berkeley DB where memory is allocated by the application
and then given to the library: <a class="xref" href="dbassociate.html" title="DB->associate()">DB->associate()</a>.
</p>
<p>
On systems in which there may be multiple library versions of the
standard allocation routines (notably Windows NT), transferring memory
between the library and the application will fail because the Berkeley
DB library allocates memory from a different heap than the application
uses to free it. To avoid this problem, the
<a class="xref" href="envset_alloc.html" title="DB_ENV->set_alloc()">DB_ENV->set_alloc()</a> and
<code class="methodname">DB->set_alloc()</code> methods can be used to pass Berkeley DB references to
the application's allocation routines.
</p>
<p>
It is not an error to specify only one or two of the possible
allocation function parameters to these interfaces; however, in that
case the specified interfaces must be compatible with the standard
library interfaces, as they will be used together. The functions
specified must match the calling conventions of the ANSI C X3.159-1989
(ANSI C) library routines of the same name.
</p>
<p>
Because databases opened within Berkeley DB environments use the
allocation interfaces specified to the environment, it is an error to
attempt to set those interfaces in a database created within an
environment.
</p>
<p>
The <code class="methodname">DB->set_alloc()</code> method may not be called after the
<a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> method is called.
</p>
<p>
The <code class="methodname">DB->set_alloc()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h3 class="title"><a id="id1642170"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DB->set_alloc()</code> <span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h4 class="title"><a id="id1642303"></a>EINVAL</h4>
</div>
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<p>
If called in a database environment, or called after
<a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> was called; or if an
invalid flag value or parameter was specified.
</p>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h3 class="title"><a id="id1642314"></a>Class</h3>
</div>
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<p>
<a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a>
</p>
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<div class="sect2" lang="en" xml:lang="en">
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<h3 class="title"><a id="id1642211"></a>See Also</h3>
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<p>
<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
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