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<!--$Id: lock_stat.so,v 10.65 2005/07/20 16:26:38 bostic Exp $-->
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<title>Berkeley DB: DB_ENV->lock_stat</title>
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<h3>DB_ENV->lock_stat</h3>
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<tt>
<h3><pre>
#include <db.h>
<p>
int
DB_ENV->lock_stat(DB_ENV *env, DB_LOCK_STAT **statp, u_int32_t flags);
<p>
int
DB_ENV->lock_stat_print(DB_ENV *env, u_int32_t flags);
</pre></h3>
<hr size=1 noshade>
<h3>Description: DB_ENV->lock_stat</h3>
<p>The DB_ENV->lock_stat method returns the locking subsystem statistics.</p>
<p>The DB_ENV->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_c/env_set_alloc.html">DB_ENV->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>
<dl compact>
<dt>u_int32_t st_id;<dd>The last allocated locker ID.
<dt>u_int32_t st_cur_maxid;<dd>The current maximum unused locker ID.
<dt>u_int32_t st_nmodes;<dd>The number of lock modes.
<dt>u_int32_t st_maxlocks;<dd>The maximum number of locks possible.
<dt>u_int32_t st_maxlockers;<dd>The maximum number of lockers possible.
<dt>u_int32_t st_maxobjects;<dd>The maximum number of lock objects possible.
<dt>u_int32_t st_nlocks;<dd>The number of current locks.
<dt>u_int32_t st_maxnlocks;<dd>The maximum number of locks at any one time.
<dt>u_int32_t st_nlockers;<dd>The number of current lockers.
<dt>u_int32_t st_maxnlockers;<dd>The maximum number of lockers at any one time.
<dt>u_int32_t st_nobjects;<dd>The number of current lock objects.
<dt>u_int32_t st_maxnobjects;<dd>The maximum number of lock objects at any one time.
<dt>u_int32_t st_nrequests;<dd>The total number of locks requested.
<dt>u_int32_t st_nreleases;<dd>The total number of locks released.
<dt>u_int32_t st_nupgrade;<dd>The total number of locks upgraded.
<dt>u_int32_t st_ndowngrade;<dd>The total number of locks downgraded.
<dt>u_int32_t st_lock_wait;<dd>The number of lock requests not immediately available due to conflicts,
for which the thread of control waited.
<dt>u_int32_t st_lock_nowait;<dd>The number of lock requests not immediately available due to conflicts,
for which the thread of control did not wait.
<dt>u_int32_t st_ndeadlocks;<dd>The number of deadlocks.
<dt>u_int32_t st_locktimeout;<dd>Lock timeout value.
<dt>u_int32_t st_nlocktimeouts;<dd>The number of lock requests that have timed out.
<dt>u_int32_t st_txntimeout;<dd>Transaction timeout value.
<dt>u_int32_t st_ntxntimeouts;<dd>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.
<dt>roff_t st_regsize;<dd>The size of the lock region, in bytes.
<dt>u_int32_t st_region_wait;<dd>The number of times that a thread of control was forced to wait before
obtaining the lock region mutex.
<dt>u_int32_t st_region_nowait;<dd>The number of times that a thread of control was able to obtain
the lock region mutex without waiting.
</dl>
<p>The DB_ENV->lock_stat method
returns a non-zero error value on failure
and 0 on success.
</p>
<h3>Parameters</h3>
<dl compact>
<dt><b>flags</b><dd>The <b>flags</b> parameter must be set to 0 or
the following value:
<dl compact>
<dt><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a><dd>Reset statistics after returning their values.
</dl>
<dt><b>statp</b><dd>The <b>statp</b> parameter references memory into which
a pointer to the allocated statistics structure is copied.
</dl>
<h3>Errors</h3>
<p>The DB_ENV->lock_stat method
may fail and return one of the following non-zero errors:</p>
<dl compact>
<dt>EINVAL<dd>An
invalid flag value or parameter was specified.
</dl>
<hr size=1 noshade>
<h3>Description: DB_ENV->lock_stat_print</h3>
<p>The DB_ENV->lock_stat_print method prints diagnostic information to the output
channel described by the <a href="../api_c/env_set_msgfile.html">DB_ENV->set_msgfile</a> method.</p>
<p>The DB_ENV->lock_stat_print method may not be called before the <a href="../api_c/env_open.html">DB_ENV->open</a> method has
been called.</p>
<p>The DB_ENV->lock_stat_print method
returns a non-zero error value on failure
and 0 on success.
</p>
<h3>Parameters</h3>
<dl compact>
<dt><b>flags</b><dd>The <b>flags</b> parameter must be set by bitwise inclusively <b>OR</b>'ing together one or more
of the following values:
<dl compact>
<dt><a name="DB_STAT_ALL">DB_STAT_ALL</a><dd>Display all available information.
<dt><a name="DB_STAT_LOCK_CONF">DB_STAT_LOCK_CONF</a><dd>Display the lock conflict matrix.
<dt><a name="DB_STAT_LOCK_LOCKERS">DB_STAT_LOCK_LOCKERS</a><dd>Display the lockers within hash chains.
<dt><a name="DB_STAT_LOCK_OBJECTS">DB_STAT_LOCK_OBJECTS</a><dd>Display the lock objects within hash chains.
<dt><a name="DB_STAT_LOCK_PARAMS">DB_STAT_LOCK_PARAMS</a><dd>Display the locking subsystem parameters.
</dl>
</dl>
<hr size=1 noshade>
<h3>Class</h3>
<a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/lock_class.html">DB_LOCK</a>
<h3>See Also</h3>
<a href="../api_c/lock_list.html">Locking Subsystem and Related Methods</a>
</tt>
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