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<h2 class="title" style="clear: both"><a id="lockstat"></a>DbEnv::lock_stat()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::lock_stat(DB_LOCK_STAT **statp, u_int32_t flags); </pre>
<p>
The <code class="methodname">DbEnv::lock_stat()</code> method returns the locking subsystem
statistics.
</p>
<p>
The <code class="methodname">DbEnv::lock_stat()</code> 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 class="xref" href="envset_alloc.html" title="DbEnv::set_alloc()">DbEnv::set_alloc()</a>
for more information), they are used to allocate the memory;
otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(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>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="bold"><strong>u_int32_t st_cur_maxid;</strong></span>
</p>
<p>
The current maximum unused locker ID.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_hash_len;</strong></span>
</p>
<p>
Maximum length of a lock hash bucket.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_id;</strong></span>
</p>
<p>
The last allocated locker ID.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_initlocks;</strong></span>
</p>
<p>
The initial number of locks allocated in the lock
table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_initlockers;</strong></span>
</p>
<p>
The initial number of lockers allocated in the lock
table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_initobjects;</strong></span>
</p>
<p>
The initial number of lock objects allocated in the lock
table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_lock_nowait;</strong></span>
</p>
<p>
The number of lock requests not immediately available due to
conflicts, for which the thread of control did not wait.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_lock_wait;</strong></span>
</p>
<p>
The number of lock requests not immediately available due to
conflicts, for which the thread of control waited.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_lockers_nowait;</strong></span>
</p>
<p>
The number of requests to allocate or deallocate a locker for which
the thread of control did not wait.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_lockers_wait;</strong></span>
</p>
<p>
The number of requests to allocate or deallocate a locker for which
the thread of control waited.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_lockers;</strong></span>
</p>
<p>
The current number of lockers allocated in the lock table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_locks;</strong></span>
</p>
<p>
The current number of locks allocated in the lock table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_locksteals;</strong></span>
</p>
<p>
The maximum number of locks stolen by an empty partition.
</p>
</li>
<li>
<p>
<span class="bold"><strong>db_timeout_t st_locktimeout;</strong></span>
</p>
<p>
Lock timeout value.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxhlocks;</strong></span>
</p>
<p>
The maximum number of locks in any hash bucket at any one time.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxhobjects;</strong></span>
</p>
<p>
The maximum number of objects in any hash bucket at any one time.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxlockers;</strong></span>
</p>
<p>
The maximum number of lockers possible.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxlocks;</strong></span>
</p>
<p>
The maximum number of locks possible.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_maxlsteals;</strong></span>
</p>
<p>
The maximum number of lock steals for any one partition.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxnlockers;</strong></span>
</p>
<p>
The maximum number of lockers at any one time.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxnobjects;</strong></span>
</p>
<p>
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.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxnlocks;</strong></span>
</p>
<p>
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.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxobjects;</strong></span>
</p>
<p>
The maximum number of lock objects possible.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_maxosteals;</strong></span>
</p>
<p>
The maximum number of object steals for any one partition.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_ndeadlocks;</strong></span>
</p>
<p>
The number of deadlocks.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_ndowngrade;</strong></span>
</p>
<p>
The total number of locks downgraded.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nlockers;</strong></span>
</p>
<p>
The number of current lockers.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nlocks;</strong></span>
</p>
<p>
The number of current locks.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_nlocktimeouts;</strong></span>
</p>
<p>
The number of lock requests that have timed out.
</p>
</li>
<li>
<p>
<span class="bold"><strong>int st_nmodes;</strong></span>
</p>
<p>
The number of lock modes.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nobjects;</strong></span>
</p>
<p>
The number of current lock objects.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_nreleases;</strong></span>
</p>
<p>
The total number of locks released.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_nrequests;</strong></span>
</p>
<p>
The total number of locks requested.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_ntxntimeouts;</strong></span>
</p>
<p>
The number of transactions that have timed out. This value is also a
component of <span class="bold"><strong>st_ndeadlocks</strong></span>, the total
number of deadlocks detected.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_nupgrade;</strong></span>
</p>
<p>
The total number of locks upgraded.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_objects;</strong></span>
</p>
<p>
The current number of lock objects allocated in the lock
table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_objectsteals;</strong></span>
</p>
<p>
The maximum number of objects stolen by an empty partition.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_objs_nowait;</strong></span>
</p>
<p>
The number of requests to allocate or deallocate an object for which
the thread of control did not wait.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_objs_wait;</strong></span>
</p>
<p>
The number of requests to allocate or deallocate an object for which
the thread of control waited.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_part_max_nowait;</strong></span>
</p>
<p>
The number of times that a thread of control was able to obtain any
one lock partition mutex without waiting.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_part_max_wait;</strong></span>
</p>
<p>
The maximum number of times that a thread of control was forced to
wait before obtaining any one lock partition mutex.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_part_nowait;</strong></span>
</p>
<p>
The number of times that a thread of control was able to obtain the
lock partition mutex without waiting.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_part_wait;</strong></span>
</p>
<p>
The number of times that a thread of control was forced to wait before
obtaining the lock partition mutex.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_partitions;</strong></span>
</p>
<p>
The number of lock table partitions.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_region_nowait;</strong></span>
</p>
<p>
The number of times that a thread of control was able to obtain the
lock region mutex without waiting.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_region_wait;</strong></span>
</p>
<p>
The number of times that a thread of control was forced to wait before
obtaining the lock region mutex.
</p>
</li>
<li>
<p>
<span class="bold"><strong>roff_t st_regsize;</strong></span>
</p>
<p>
The region size, in bytes.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_tablesize;</strong></span>
</p>
<p>
The size of the object hash table.
</p>
</li>
<li>
<p>
<span class="bold"><strong>db_timeout_t st_txntimeout;</strong></span>
</p>
<p>
Transaction timeout value.
</p>
</li>
</ul>
</div>
<p>
The <code class="methodname">DbEnv::lock_stat()</code> method may not be called before the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method is called.
</p>
<p>
The <code class="methodname">DbEnv::lock_stat()</code> method returns a non-zero error value on
failure and 0 on success.
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp2749904"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp2790912"></a>statp</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>statp</strong></span> parameter references memory
into which a pointer to the allocated statistics structure is copied.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp2779272"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or the following value:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="stat_DB_STAT_CLEAR"></a>
<code class="literal">DB_STAT_CLEAR</code>
</p>
<p>
Reset statistics after returning their values.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp2799376"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::lock_stat()</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="idp2806632"></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="idp2805336"></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="lock.html" title="Chapter 7. The DbLock Handle">DbLock</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp2807928"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="lock.html#locklist" title="Locking Subsystem and Related Methods">Locking Subsystem and Related Methods</a>
</p>
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