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>DbEnv::txn_recover()</title> 7 <link rel="stylesheet" href="apiReference.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 C++ API Reference" /> 10 <link rel="up" href="txn.html" title="Chapter 13. The DbTxn Handle" /> 11 <link rel="prev" href="txnprepare.html" title="DbTxn::prepare()" /> 12 <link rel="next" href="txnset_name.html" title="DbTxn::set_name()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DbEnv::txn_recover()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="txnprepare.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 13. 23 The DbTxn Handle 24 </th> 25 <td width="20%" align="right"> <a accesskey="n" href="txnset_name.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="txnrecover"></a>DbEnv::txn_recover()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db_cxx.h> 39 40int 41DbEnv::txn_recover(DB_PREPLIST preplist[], 42 long count, long *retp, u_int32_t flags);</pre> 43 <p> 44 Database environment recovery restores transactions that were 45 prepared, but not yet resolved at the time of the system shut down or 46 crash, to their state prior to the shut down or crash, including any 47 locks previously held. The <code class="methodname">DbEnv::txn_recover()</code> method returns a 48 list of those prepared transactions. 49 </p> 50 <p> 51 The <code class="methodname">DbEnv::txn_recover()</code> method should only be called after the 52 environment has been recovered. 53 </p> 54 <p> 55 Multiple threads of control may call <code class="methodname">DbEnv::txn_recover()</code>, but only 56 one thread of control may resolve each returned transaction, that is, 57 only one thread of control may call <a class="xref" href="txncommit.html" title="DbTxn::commit()">DbTxn::commit()</a> 58 or <a class="xref" href="txnabort.html" title="DbTxn::abort()">DbTxn::abort()</a> on each 59 returned transaction. Callers of <code class="methodname">DbEnv::txn_recover()</code> must call 60 <a class="xref" href="txndiscard.html" title="DbTxn::discard()">DbTxn::discard()</a> to 61 discard each transaction they do not resolve. 62 </p> 63 <p> 64 On return from <code class="methodname">DbEnv::txn_recover()</code>, the <span class="bold"><strong>preplist</strong></span> parameter will be filled in with a list of transactions 65 that must be resolved by the application (committed, aborted or discarded). The <span class="bold"><strong>preplist</strong></span> parameter is a structure of type 66 <code class="literal">DB_PREPLIST</code>; the following <code class="literal">DB_PREPLIST</code> fields will be 67 filled in: 68 </p> 69 <div class="itemizedlist"> 70 <ul type="disc"> 71 <li> 72 <p> 73 <span class="bold"><strong>DB_TXN * txn;</strong></span> 74 </p> 75 <p> 76 The transaction handle for the transaction. 77 </p> 78 </li> 79 <li> 80 <p> 81 <span class="bold"><strong>u_int8_t gid[DB_XIDDATASIZE];</strong></span> 82 </p> 83 <p> 84 The global transaction ID for the transaction. The global transaction 85 ID is the one specified when the transaction was prepared. The 86 application is responsible for ensuring uniqueness among global 87 transaction IDs. 88 </p> 89 </li> 90 </ul> 91 </div> 92 <p> 93 The <code class="methodname">DbEnv::txn_recover()</code> <span> 94 95 <span> 96 method either returns a non-zero error value or throws an 97 exception that encapsulates a non-zero error value on 98 failure, and returns 0 on success. 99 </span> 100 </span> 101 </p> 102 <div class="sect2" lang="en" xml:lang="en"> 103 <div class="titlepage"> 104 <div> 105 <div> 106 <h3 class="title"><a id="id1714886"></a>Parameters</h3> 107 </div> 108 </div> 109 </div> 110 <div class="sect3" lang="en" xml:lang="en"> 111 <div class="titlepage"> 112 <div> 113 <div> 114 <h4 class="title"><a id="id1714945"></a>count</h4> 115 </div> 116 </div> 117 </div> 118 <p> 119 The <span class="bold"><strong>count</strong></span> parameter specifies the 120 number of available entries in the passed-in <span class="bold"><strong>preplist</strong></span> array. The <span class="bold"><strong>retp</strong></span> parameter returns the number of entries 121 <code class="methodname">DbEnv::txn_recover()</code> has filled in, in the array. 122 </p> 123 </div> 124 <div class="sect3" lang="en" xml:lang="en"> 125 <div class="titlepage"> 126 <div> 127 <div> 128 <h4 class="title"><a id="id1715316"></a>flags</h4> 129 </div> 130 </div> 131 </div> 132 <p> 133 The <span class="bold"><strong>flags</strong></span> parameter must be set to 134 one of the following values: 135 </p> 136 <div class="itemizedlist"> 137 <ul type="disc"> 138 <li> 139 <p> 140 <code class="literal">DB_FIRST</code> 141 </p> 142 <p> 143 Begin returning a list of prepared, but not yet resolved transactions. 144 Specifying this flag begins a new pass over all prepared, but not yet 145 completed transactions, regardless of whether they have already been 146 returned in previous calls to <code class="methodname">DbEnv::txn_recover.()</code> Calls to 147 <code class="methodname">DbEnv::txn_recover()</code> from different threads of control should not be 148 intermixed in the same environment. 149 </p> 150 </li> 151 <li> 152 <p> 153 <code class="literal">DB_NEXT</code> 154 </p> 155 <p> 156 Continue returning a list of prepared, but not yet resolved 157 transactions, starting where the last call to 158 <code class="methodname">DbEnv::txn_recover()</code> 159 left off. 160 </p> 161 </li> 162 </ul> 163 </div> 164 </div> 165 <div class="sect3" lang="en" xml:lang="en"> 166 <div class="titlepage"> 167 <div> 168 <div> 169 <h4 class="title"><a id="id1715111"></a>preplist</h4> 170 </div> 171 </div> 172 </div> 173 <p> 174 The <span class="bold"><strong>preplist</strong></span> parameter references 175 memory into which the list of transactions to be resolved by the 176 application is copied. 177 </p> 178 </div> 179 </div> 180 <div class="sect2" lang="en" xml:lang="en"> 181 <div class="titlepage"> 182 <div> 183 <div> 184 <h3 class="title"><a id="id1715360"></a>Class</h3> 185 </div> 186 </div> 187 </div> 188 <p> 189 <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, <a class="link" href="txn.html" title="Chapter 13. The DbTxn Handle">DbTxn</a> 190 </p> 191 </div> 192 <div class="sect2" lang="en" xml:lang="en"> 193 <div class="titlepage"> 194 <div> 195 <div> 196 <h3 class="title"><a id="id1715527"></a>See Also</h3> 197 </div> 198 </div> 199 </div> 200 <p> 201 <a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a> 202 </p> 203 </div> 204 </div> 205 <div class="navfooter"> 206 <hr /> 207 <table width="100%" summary="Navigation footer"> 208 <tr> 209 <td width="40%" align="left"><a accesskey="p" href="txnprepare.html">Prev</a> </td> 210 <td width="20%" align="center"> 211 <a accesskey="u" href="txn.html">Up</a> 212 </td> 213 <td width="40%" align="right"> <a accesskey="n" href="txnset_name.html">Next</a></td> 214 </tr> 215 <tr> 216 <td width="40%" align="left" valign="top">DbTxn::prepare() </td> 217 <td width="20%" align="center"> 218 <a accesskey="h" href="index.html">Home</a> 219 </td> 220 <td width="40%" align="right" valign="top"> DbTxn::set_name()</td> 221 </tr> 222 </table> 223 </div> 224 </body> 225</html> 226