1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>DbTxn::prepare()</title>
<link rel="stylesheet" href="apiReference.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB C++ API Reference" />
<link rel="up" href="txn.html" title="Chapter 13. The DbTxn Handle" />
<link rel="prev" href="txnid.html" title="DbTxn::id()" />
<link rel="next" href="txnrecover.html" title="DbEnv::txn_recover()" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DbTxn::prepare()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="txnid.html">Prev</a> </td>
<th width="60%" align="center">Chapter 13.
The DbTxn Handle
</th>
<td width="20%" align="right"> <a accesskey="n" href="txnrecover.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="txnprepare"></a>DbTxn::prepare()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbTxn::prepare(u_int8_t gid[DB_XIDDATASIZE]);</pre>
<p>
The <code class="methodname">DbTxn::prepare()</code> method initiates the beginning of a two-phase
commit.
</p>
<p>
In a distributed transaction environment, Berkeley DB can be used as a
local transaction manager. In this case, the distributed transaction
manager must send <span class="emphasis"><em>prepare</em></span> messages to each local
manager. The local manager must then issue a <code class="methodname">DbTxn::prepare()</code> and
await its successful return before responding to the distributed
transaction manager. Only after the distributed transaction manager
receives successful responses from all of its
<span class="emphasis"><em>prepare</em></span> messages should it issue any
<span class="emphasis"><em>commit</em></span> messages.
</p>
<p>
In the case of nested transactions, preparing the parent causes all
unresolved children of the parent transaction to be committed. Child
transactions should never be explicitly prepared. Their fate will be
resolved along with their parent's during global recovery.
</p>
<p>
The <code class="methodname">DbTxn::prepare()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1714462"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1714940"></a>gid</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>gid</strong></span> parameter specifies the
global transaction ID by which this transaction will be known. This
global transaction ID will be returned in calls
to <a class="xref" href="txnrecover.html" title="DbEnv::txn_recover()">DbEnv::txn_recover()</a>
telling the application which global transactions must be resolved.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1714463"></a>Class</h3>
</div>
</div>
</div>
<p>
<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>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1714988"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a>
</p>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="txnid.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="txn.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="txnrecover.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">DbTxn::id() </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> DbEnv::txn_recover()</td>
</tr>
</table>
</div>
</body>
</html>
|
