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Yasuhiro KIMURA
117 lines
5.1 KiB
HTML
117 lines
5.1 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Using transactions in dbstl</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="stl.html" title="Chapter 7. Standard Template Library API" />
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<link rel="prev" href="stl_db_advanced_usage.html" title="Using advanced Berkeley DB features with dbstl" />
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<link rel="next" href="stl_mt_usage.html" title="Using dbstl in multithreaded applications" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Using transactions in dbstl</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="stl_db_advanced_usage.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 7. Standard Template Library API</th>
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<td width="20%" align="right"> <a accesskey="n" href="stl_mt_usage.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="stl_txn_usage"></a>Using transactions in dbstl</h2>
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</div>
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</div>
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</div>
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<p>
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When using transactions with dbstl, you must call the dbstl
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transaction functions instead of the corresponding methods
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from the Berkeley DB C or C++ transaction API. That is, you
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must use <code class="methodname">dbstl::begin_txn()</code>,
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<code class="methodname">dbstl::commit_txn()</code> and
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<code class="methodname">dbstl::abort_txn()</code> in order to
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begin/commit/abort transactions.
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</p>
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<p>
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A container can be configured to use auto commit by setting
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the <a href="../api_reference/C/envset_flags.html#envset_flags_DB_AUTO_COMMIT" class="olink">DB_AUTO_COMMIT</a> flag when the environment or database
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handle is opened. In this case, any container method that
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supports auto commit will automatically form an independent
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transaction if the method is not in an external transactional
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context; Otherwise, the operation will become part of that
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transaction.
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</p>
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<p>
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You can configure the flags used internally by dbstl when
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it is creating and committing these independent transactions
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required by auto commit. To do so, use the
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<code class="methodname">db_container::set_txn_begin_flags()</code>
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and/or
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<code class="methodname">db_container::set_commit_flags()</code>
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methods.
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</p>
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<p>
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When a transaction is committed or aborted, dbstl will
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automatically close any cursors opened for use by the
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transaction. For this reason, any iterators opened within the
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transaction context should not be used after the transaction
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commits or aborts.
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</p>
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<p>
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You can use nested transactions explicitly and externally,
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by calling <code class="methodname">dbstl::begin_txn()</code> in a
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context already operating under the protection of a
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transaction. But you can not designate which transaction is
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the parent transaction. The parent transaction is
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automatically the most recently created and unresolved
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transaction in current thread.
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</p>
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<p>
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It is also acceptable to use explicit transactions in a
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container configured for auto commit. The operation performed
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by the method will become part of the provided external
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transaction.
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</p>
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<p>
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Finally, transactions and iterators cannot be shared among
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multiple threads. That is, they are not free-threaded, or
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thread-safe.
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</p>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="stl_db_advanced_usage.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="stl.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="stl_mt_usage.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Using advanced Berkeley DB
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features with dbstl </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Using dbstl in multithreaded
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applications</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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