91 lines
4.6 KiB
HTML
91 lines
4.6 KiB
HTML
<!--$Id: set_func_region_map.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<!--See the file LICENSE for redistribution information.-->
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<html>
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<head>
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<title>Berkeley DB: db_env_set_func_region_map</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b>db_env_set_func_region_map</b>
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</td>
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<td align=right>
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<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>
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#include <db.h>
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<p>
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int
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db_env_set_func_region_map(int (*func_region_map)(DB_ENV *dbenv, char *path, size_t len, int *is_create, void **addr),
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int (*func_region_unmap)(DB_ENV *dbenv, void *addr));
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</pre></b>
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<hr size=1 noshade>
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<b>Description: db_env_set_func_region_map</b>
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<p>The Berkeley DB library optionally uses the ability to create shared memory
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regions (which may or may not be backed by physical files). The memory
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will be used as a shared memory region for synchronization between Berkeley DB
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threads/processes; while the returned memory may be of any kind (for
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example, anonymous memory), it must be able to support semaphores.</p>
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<p>The db_env_set_func_region_map method configures all operations performed by a process and
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all of its threads of control, not operations confined to a single
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database environment.</p>
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<p>Although the db_env_set_func_region_map method may be called at any time during the life of
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the application, it should normally be called before making calls to the
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<a href="../api_c/env_class.html">db_env_create</a> or <a href="../api_c/db_class.html">db_create</a> methods.</p>
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<p>The db_env_set_func_region_map method
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returns a non-zero error value on failure
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and 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>func_region_map</b><ul compact><li>The <b>func_region_map</b> parameter is the function which creates
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shared memory regions. The function takes 5 parameters:
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<br>
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<b><b>dbenv</b></b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment
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handle. This handle is provided to uniquely identify a shared memory
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region: the <b>dbenv</b> parameter and the path are a unique identifier
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pair for mapping any new region, and the <b>dbenv</b> parameter and the
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address are a unique identifier pair for unmapping any region.</ul>
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<b><b>path</b></b><ul compact><li>The <b>path</b> parameter is the name of the region. Repeated requests
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for the shared regions of the same name, in the same database
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environment, should return a reference to the same memory.</ul>
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<b><b>len</b></b><ul compact><li>The <b>len</b> parameter is the length, in bytes, needed for the
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region.</ul>
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<b><b>is_create</b></b><ul compact><li>The memory referenced by the <b>is_create</b> parameter will be
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non-zero if flags to Berkeley DB allowed creation of the mapped region; the
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memory referenced by the <b>is_create</b> parameter must be set to
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non-zero if the region is created by the <b>func_region_map</b> function, and
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set to zero if the region is not created by the function. This returned
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information will determine if the region is subsequently initialized by
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Berkeley DB.</ul>
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<b><b>addr</b></b><ul compact><li>The <b>addr</b> parameter is the memory location into which a pointer
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to the region or mapped file is returned.</ul>
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<br>
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<p>The <b>func_region_map</b> function must return the value of <b>errno</b> on
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failure and 0 on success.</p></ul>
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<b>func_region_unmap</b><ul compact><li>The <b>func_region_unmap</b> parameter is the function which unmaps a
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shared memory region. The function takes 2 parameters:
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<br>
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<b><b>dbenv</b></b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment handle.</ul>
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<b><b>addr</b></b><ul compact><li>The <b>addr</b> parameter is the value returned by the
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<b>func_region_map</b> function when the region was mapped into
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memory.</ul>
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<br>
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<p>The <b>func_region_unmap</b> function must return the value of <b>errno</b> on
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failure and 0 on success.</p></ul>
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<br>
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<br><b>See Also</b>
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<a href="../ref/program/runtime.html">Run-time configuration</a>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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