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<! "@(#)detect.so 10.8 (Sleepycat) 9/29/98">
<!Copyright 1997, 1998 by Sleepycat Software, Inc. All rights reserved.>
<html>
<body bgcolor=white>
<head>
<title>Berkeley DB: DbLockTab::detect</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btr
ee,hash,hashing,transaction,transactions,locking,logging,access method,access me
thods,java,C,C++">
</head>
<h1>DbLockTab::detect</h1>
<hr size=1 noshade>
<tt>
<h3>
<pre>
#include <db_cxx.h>
<p>
int
DbLockTab::detect(u_int32_t flags, u_int32_t atype);
</pre>
</h3>
<h1>Description</h1>
<p>
The DbLockTab::detect method runs one iteration of the deadlock detector.
The deadlock detector traverses the lock table, and for each deadlock
it finds, marks one of the participating transactions for abort.
<p>
The <b>flags</b> value is specified by logically <b>OR</b>'ing together one or more of the
following values:
<dl compact>
<a name="DB_LOCK_CONFLICT">
<p><dt>DB_LOCK_CONFLICT<dd>Only run the deadlock detector if a lock conflict has occurred since
the last time that the deadlock detector was run.
</dl>
<p>
The <b>atype</b> parameter specifies which transaction to abort in the
case of deadlock.
It must be set to one of values described for the <b>lk_detect</b> field
of the
<a href="../../api_cxx/DbEnv/class.html">DbEnv</a> object.
<p>
The DbLockTab::detect method is the underlying method used by the <a href="../../utility/db_deadlock.html">db_deadlock</a> utility.
See the <a href="../../utility/db_deadlock.html">db_deadlock</a> utility source code for an example of using DbLockTab::detect
in a POSIX 1003.1 environment.
<p>
The DbLockTab::detect
method either returns <b>errno</b> or throws an exception that
encapsulates an <b>errno</b> on failure, and 0 on success.
<p>
<h1>Errors</h1>
If a fatal error occurs in Berkeley DB, the DbLockTab::detect method may fail and either
return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY,
at which point all subsequent database calls will also fail in the same
way. Methods marked as returning <b>errno</b> will, by default, throw
an exception that encapsulates the error information. The default error
behavior can be changed, see <a href="../../api_cxx/DbException/class.html">DbException</a>.
<p>
The DbLockTab::detect
method may fail and throw an exception
for any of the errors specified for the following Berkeley DB and C library
functions:
abort(3),
fcntl(3),
fflush(3),
fprintf(3),
free(3),
fsync(3),
getpid(3),
lseek(3),
malloc(3),
memcpy(3),
memset(3),
mmap(3),
munmap(3),
shmat(3),
shmdt(3),
sprintf(3),
strerror(3),
vfprintf(3),
vsnprintf(3),
and
write(3).
<p>
<h1>Class</h1>
<a href="../../api_cxx/DbLockTab/class.html">DbLockTab</a>
<p>
<h1>See Also</h1>
<a href="../../api_cxx/DbLockTab/close.html">DbLockTab::close</a>,
DbLockTab::detect,
<a href="../../api_cxx/DbLockTab/get.html">DbLockTab::get</a>,
<a href="../../api_cxx/DbLockTab/id.html">DbLockTab::id</a>,
<a href="../../api_cxx/DbLockTab/open.html">DbLockTab::open</a>,
<a href="../../api_cxx/DbLockTab/stat.html">DbLockTab::stat</a>
<a href="../../api_cxx/DbLockTab/unlink.html">DbLockTab::unlink</a>
and
<a href="../../api_cxx/DbLockTab/vec.html">DbLockTab::vec</a>.
</tt>
</body>
</html>
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