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<!--$Id: lock_stat.so,v 10.71 2008/03/21 18:20:27 ubell Exp $-->
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<title>Berkeley DB: DbEnv::lock_stat</title>
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<td>
<b>DbEnv::lock_stat</b>
</td>
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<tt>
<b><pre>
#include <db_cxx.h>
<p>
int
DbEnv::lock_stat(DB_LOCK_STAT **statp, u_int32_t flags);
<p>
int
DbEnv::lock_stat_print(u_int32_t flags);
</pre></b>
<hr size=1 noshade>
<b>Description: DbEnv::lock_stat</b>
<p>The DbEnv::lock_stat method returns the locking subsystem statistics.</p>
<p>The DbEnv::lock_stat method creates a statistical structure of type
DB_LOCK_STAT and copies a pointer to it into a user-specified memory
location.</p>
<p>Statistical structures are stored in allocated memory. If application-specific allocation
routines have been declared (see <a href="../api_cxx/env_set_alloc.html">DbEnv::set_alloc</a> for more
information), they are used to allocate the memory; otherwise, the
standard C library <b>malloc</b>(3) is used. The caller is
responsible for deallocating the memory. To deallocate the memory, free
the memory reference; references inside the returned memory need not be
individually freed.</p>
<p>The following DB_LOCK_STAT fields will be filled in:</p>
<br>
<b>u_int32_t st_id;</b><ul compact><li>The last allocated locker ID.</ul>
<b>u_int32_t st_cur_maxid;</b><ul compact><li>The current maximum unused locker ID.</ul>
<b>u_int32_t st_nmodes;</b><ul compact><li>The number of lock modes.</ul>
<b>u_int32_t st_maxlocks;</b><ul compact><li>The maximum number of locks possible.</ul>
<b>u_int32_t st_maxlockers;</b><ul compact><li>The maximum number of lockers possible.</ul>
<b>u_int32_t st_maxobjects;</b><ul compact><li>The maximum number of lock objects possible.</ul>
<b>u_int32_t st_partitions;</b><ul compact><li>The number of lock table partitions.</ul>
<b>u_int32_t st_nlocks;</b><ul compact><li>The number of current locks.</ul>
<b>u_int32_t st_maxnlocks;</b><ul compact><li>The maximum number of locks at any one time. Note that if there is more
than one partition, this is the sum of the maximum across all partitions.</ul>
<b>u_int32_t st_maxhlocks;</b><ul compact><li>The maximum number of locks in any hash bucket at any one time.</ul>
<b>u_int32_t st_locksteals;</b><ul compact><li>The maximum number of locks stolen by for an empty partition.</ul>
<b>u_int32_t st_maxlsteals;</b><ul compact><li>The maximum number of lock steals for any one partition.</ul>
<b>u_int32_t st_nlockers;</b><ul compact><li>The number of current lockers.</ul>
<b>u_int32_t st_maxnlockers;</b><ul compact><li>The maximum number of lockers at any one time.</ul>
<b>u_int32_t st_nobjects;</b><ul compact><li>The number of current lock objects.</ul>
<b>u_int32_t st_maxnobjects;</b><ul compact><li>The maximum number of lock objects at any one time. Note that if there is more
than one partition this is the sum of the maximum across all partitions.</ul>
<b>u_int32_t st_maxhobjects;</b><ul compact><li>The maximum number of objects in any hash bucket at any one time.</ul>
<b>u_int32_t st_objectsteals;</b><ul compact><li>The maximum number of objects stolen by for an empty partition.</ul>
<b>u_int32_t st_maxosteals;</b><ul compact><li>The maximum number of object steals for any one partition.</ul>
<b>u_int32_t st_nrequests;</b><ul compact><li>The total number of locks requested.</ul>
<b>u_int32_t st_nreleases;</b><ul compact><li>The total number of locks released.</ul>
<b>u_int32_t st_nupgrade;</b><ul compact><li>The total number of locks upgraded.</ul>
<b>u_int32_t st_ndowngrade;</b><ul compact><li>The total number of locks downgraded.</ul>
<b>u_int32_t st_lock_wait;</b><ul compact><li>The number of lock requests not immediately available due to conflicts,
for which the thread of control waited.</ul>
<b>u_int32_t st_lock_nowait;</b><ul compact><li>The number of lock requests not immediately available due to conflicts,
for which the thread of control did not wait.</ul>
<b>u_int32_t st_ndeadlocks;</b><ul compact><li>The number of deadlocks.</ul>
<b>u_int32_t st_locktimeout;</b><ul compact><li>Lock timeout value.</ul>
<b>u_int32_t st_nlocktimeouts;</b><ul compact><li>The number of lock requests that have timed out.</ul>
<b>u_int32_t st_txntimeout;</b><ul compact><li>Transaction timeout value.</ul>
<b>u_int32_t st_ntxntimeouts;</b><ul compact><li>The number of transactions that have timed out. This value is also a
component of <b>st_ndeadlocks</b>, the total number of deadlocks
detected.</ul>
<b>u_int32_t st_objs_wait;</b><ul compact><li>The number of requests to allocate or deallocate an object
for which the thread of control waited.</ul>
<b>u_int32_t st_objs_nowait;</b><ul compact><li>The number of requests to allocate or deallocate an object
for which the thread of control did not wait.</ul>
<b>u_int32_t st_lockers_wait;</b><ul compact><li>The number of requests to allocate or deallocate a locker
for which the thread of control waited.</ul>
<b>u_int32_t st_lockers_nowait;</b><ul compact><li>The number of requests to allocate or deallocate a locker
for which the thread of control did not wait.</ul>
<b>u_int32_t st_hash_len;</b><ul compact><li>Maximum length of a lock hash bucket.</ul>
<b>roff_t st_regsize;</b><ul compact><li>The size of the lock region, in bytes.</ul>
<b>u_int32_t st_part_wait;</b><ul compact><li>The number of times that a thread of control was forced to wait before
obtaining the lock partition mutex.</ul>
<b>u_int32_t st_part_nowait;</b><ul compact><li>The number of times that a thread of control was able to obtain
the lock partition mutex without waiting.</ul>
<b>u_int32_t st_part_max_wait;</b><ul compact><li>The maximum number of times that a thread of control was forced to wait before
obtaining any one lock partition mutex.</ul>
<b>u_int32_t st_part_max_nowait;</b><ul compact><li>The number of times that a thread of control was able to obtain
any one lock partition mutex without waiting.</ul>
<b>u_int32_t st_region_wait;</b><ul compact><li>The number of times that a thread of control was forced to wait before
obtaining the lock region mutex.</ul>
<b>u_int32_t st_region_nowait;</b><ul compact><li>The number of times that a thread of control was able to obtain
the lock region mutex without waiting.</ul>
<br>
<p>The DbEnv::lock_stat method may not be called before the <a href="../api_cxx/env_open.html">DbEnv::open</a> method is called.</p>
<p>The DbEnv::lock_stat 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.
</p>
<b>Parameters</b> <br>
<b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or
the following value:
<br>
<b><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a></b><ul compact><li>Reset statistics after returning their values.</ul>
<br></ul>
<b>statp</b><ul compact><li>The <b>statp</b> parameter references memory into which
a pointer to the allocated statistics structure is copied.</ul>
<br>
<br><b>Errors</b>
<p>The DbEnv::lock_stat method
may fail and throw
<a href="../api_cxx/except_class.html">DbException</a>,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:</p>
<br>
<b>EINVAL</b><ul compact><li>An
invalid flag value or parameter was specified.</ul>
<br>
<hr size=1 noshade>
<b>Description: DbEnv::lock_stat_print</b>
<p>The DbEnv::lock_stat_print method displays the
locking subsystem statistical information, as described for the DbEnv::lock_stat method.
The information is printed to a specified output channel (see the
<a href="../api_cxx/env_set_msgfile.html">DbEnv::set_msgfile</a> method for more information), or passed to an
application callback function (see the <a href="../api_cxx/env_set_msgcall.html">DbEnv::set_msgcall</a> method for
more information).</p>
<p>The DbEnv::lock_stat_print method may not be called before the <a href="../api_cxx/env_open.html">DbEnv::open</a> method is called.</p>
<p>The DbEnv::lock_stat_print 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.
</p>
<b>Parameters</b> <br>
<b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one
or more of the following values:
<br>
<b><a name="DB_STAT_ALL">DB_STAT_ALL</a></b><ul compact><li>Display all available information.</ul>
<b><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a></b><ul compact><li>Reset statistics after displaying their values.</ul>
<b><a name="DB_STAT_LOCK_CONF">DB_STAT_LOCK_CONF</a></b><ul compact><li>Display the lock conflict matrix.</ul>
<b><a name="DB_STAT_LOCK_LOCKERS">DB_STAT_LOCK_LOCKERS</a></b><ul compact><li>Display the lockers within hash chains.</ul>
<b><a name="DB_STAT_LOCK_OBJECTS">DB_STAT_LOCK_OBJECTS</a></b><ul compact><li>Display the lock objects within hash chains.</ul>
<b><a name="DB_STAT_LOCK_PARAMS">DB_STAT_LOCK_PARAMS</a></b><ul compact><li>Display the locking subsystem parameters.</ul>
<br></ul>
<br>
<hr size=1 noshade>
<br><b>Class</b>
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/lock_class.html">DbLock</a>
<br><b>See Also</b>
<a href="../api_cxx/lock_list.html">Locking Subsystem and Related Methods</a>
</tt>
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