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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
<?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>DbEnv::failchk()</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="env.html" title="Chapter 5. The DbEnv Handle" />
<link rel="prev" href="enverr.html" title="DbEnv::err()" />
<link rel="next" href="envfileid_reset.html" title="DbEnv::fileid_reset()" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DbEnv::failchk()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="enverr.html">Prev</a> </td>
<th width="60%" align="center">Chapter 5.
The DbEnv Handle
</th>
<td width="20%" align="right"> <a accesskey="n" href="envfileid_reset.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="envfailchk"></a>DbEnv::failchk()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::failchk(u_int32_t flags);</pre>
<p>
The <code class="methodname">DbEnv::failchk()</code> method checks for threads of control (either a
true thread or a process) that have exited while manipulating Berkeley
DB library data structures, while holding a logical database lock, or
with an unresolved transaction (that is, a transaction that was never
aborted or committed). For more information, see
<a href="../../programmer_reference/cam_app.html" class="olink">Architecting Data Store and
Concurrent Data Store applications</a>, and
<a href="../../programmer_reference/transapp_app.html" class="olink">Architecting Transactional
Data Store applications</a>, both in the
<em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
The <code class="methodname">DbEnv::failchk()</code> method is based on the <code class="literal">thread_id</code> and
<code class="literal">is_alive</code> functions specified to the
<a class="xref" href="envset_thread_id.html" title="DbEnv::set_thread_id()">DbEnv::set_thread_id()</a>
and
<a class="xref" href="envset_isalive.html" title="DbEnv::set_isalive()">DbEnv::set_isalive()</a>
methods. Applications calling the <code class="methodname">DbEnv::failchk()</code> method must have
already called the <a class="xref" href="envset_isalive.html" title="DbEnv::set_isalive()">DbEnv::set_isalive()</a>
method, on the same <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, and must have configured
their database environment using the
<a class="xref" href="envset_thread_count.html" title="DbEnv::set_thread_count()">DbEnv::set_thread_count()</a>
method.
</p>
<p>
If <code class="methodname">DbEnv::failchk()</code> determines a thread of control exited while
holding database read locks, it will release those locks. If
<code class="methodname">DbEnv::failchk()</code> determines a thread of control exited with an
unresolved transaction, the transaction will be aborted. In either of
these cases, <code class="methodname">DbEnv::failchk()</code> will return 0 and the application may
continue to use the database environment.
</p>
<p>
In either of these cases, the <code class="methodname">DbEnv::failchk()</code> method will also
report the process and thread IDs associated with any released locks
or aborted transactions. The information is printed to a specified
output channel (see the
<a class="xref" href="envset_msgfile.html" title="DbEnv::set_msgfile()">DbEnv::set_msgfile()</a>
method for more information), or passed to an application callback
function (see the
<a class="xref" href="envset_msgcall.html" title="DbEnv::set_msgcall()">DbEnv::set_msgcall()</a>
method for more information).
</p>
<p>
If <code class="methodname">DbEnv::failchk()</code> determines a thread of control has exited such
that database environment recovery is required, it will return
<a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">DB_RUNRECOVERY</a>.
In this case, the application should not continue to use the database
environment. For a further description as to the actions the
application should take when this failure occurs, see
<a href="../../programmer_reference/cam_fail.html" class="olink">Handling failure in Data Store and
Concurrent Data Store applications</a>, and
<a href="../../programmer_reference/transapp_fail.html" class="olink">Handling failure in Transactional Data
Store applications</a>, both in the
<em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
In multiprocess applications, it is recommended that the <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle
used to invoke the <code class="methodname">DbEnv::failchk()</code> method not be shared and therefore
not <span class="emphasis"><em>free-threaded</em></span>.
</p>
<p>
The <code class="methodname">DbEnv::failchk()</code> method may not be called by the
application before the <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
method is called.
</p>
<p>
The <code class="methodname">DbEnv::failchk()</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="id1664521"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1664711"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter is currently
unused, and must be set to 0.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1664866"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::failchk()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1664694"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
An invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1664798"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1664629"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments 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="enverr.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="env.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="envfileid_reset.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">DbEnv::err() </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> DbEnv::fileid_reset()</td>
</tr>
</table>
</div>
</body>
</html>
|
