1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>Using transactions in dbstl</title> 7 <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" /> 10 <link rel="up" href="stl.html" title="Chapter��7.��Standard Template Library API" /> 11 <link rel="prev" href="stl_db_advanced_usage.html" title="Using advanced Berkeley DB features with dbstl" /> 12 <link rel="next" href="stl_mt_usage.html" title="Using dbstl in multithreaded applications" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">Using transactions in dbstl</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="stl_db_advanced_usage.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��7.��Standard Template Library API</th> 23 <td width="20%" align="right">��<a accesskey="n" href="stl_mt_usage.html">Next</a></td> 24 </tr> 25 </table> 26 <hr /> 27 </div> 28 <div class="sect1" lang="en" xml:lang="en"> 29 <div class="titlepage"> 30 <div> 31 <div> 32 <h2 class="title" style="clear: both"><a id="stl_txn_usage"></a>Using transactions in dbstl</h2> 33 </div> 34 </div> 35 </div> 36 <p> 37 When using transactions with dbstl, you must call the dbstl transaction 38 functions instead of the corresponding methods from the Berkeley DB C 39 or C++ transaction API. That is, you must use 40 <code class="methodname">dbstl::begin_txn()</code>, 41 <code class="methodname">dbstl::commit_txn()</code> and 42 <code class="methodname">dbstl::abort_txn()</code> in order to 43 begin/commit/abort transactions. 44</p> 45 <p> 46 A container can be configured to use auto commit by setting the 47 <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 handle is 48 opened. In this case, any container method that supports auto commit 49 will automatically form an independent transaction if the method 50 is not in an external transactional context; Otherwise, 51 the operation will become part of that transaction. 52 53</p> 54 <p> 55 You can configure the flags used internally by dbstl when it is 56 creating and committing these independent transactions required by auto 57 commit. To do so, use the 58 <code class="methodname">db_container::set_txn_begin_flags()</code> and/or 59 <code class="methodname">db_container::set_commit_flags()</code> methods. 60</p> 61 <p> 62 When a transaction is committed or aborted, dbstl will automatically 63 close any cursors opened for use by the transaction. For this reason, 64 any iterators opened within the transaction context should not be used 65 after the transaction commits or aborts. 66</p> 67 <p> 68 You can use nested transactions explicitly and externally, by calling 69 <code class="methodname">dbstl::begin_txn()</code> in a context already 70 operating under the protection of a transaction. But you can not 71 designate which transaction is the parent transaction. The parent 72 transaction is automatically the most recently created and unresolved 73 transaction in current thread. 74</p> 75 <p> 76 It is also acceptable to use explicit transactions in a container 77 configured for auto commit. The operation performed by the method will 78 become part of the provided external transaction. 79</p> 80 <p> 81 Finally, transactions and iterators cannot be shared among multiple 82 threads. That is, they are not free-threaded, or thread-safe. 83</p> 84 </div> 85 <div class="navfooter"> 86 <hr /> 87 <table width="100%" summary="Navigation footer"> 88 <tr> 89 <td width="40%" align="left"><a accesskey="p" href="stl_db_advanced_usage.html">Prev</a>��</td> 90 <td width="20%" align="center"> 91 <a accesskey="u" href="stl.html">Up</a> 92 </td> 93 <td width="40%" align="right">��<a accesskey="n" href="stl_mt_usage.html">Next</a></td> 94 </tr> 95 <tr> 96 <td width="40%" align="left" valign="top">Using advanced Berkeley DB features with dbstl��</td> 97 <td width="20%" align="center"> 98 <a accesskey="h" href="index.html">Home</a> 99 </td> 100 <td width="40%" align="right" valign="top">��Using dbstl in multithreaded applications</td> 101 </tr> 102 </table> 103 </div> 104 </body> 105</html> 106