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6.4 KiB
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<!--$Id: memp_stat.so,v 10.28 2000/05/25 13:47:08 dda Exp $-->
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<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.-->
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<!--All rights reserved.-->
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<html>
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<head>
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<title>Berkeley DB: memp_stat</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
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</head>
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<body bgcolor=white>
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<a name="2"><!--meow--></a>
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<table><tr valign=top>
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<td>
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<h1>memp_stat</h1>
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</td>
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<td width="1%">
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<a href="../api_c/c_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<hr size=1 noshade>
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<tt>
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<h3><pre>
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#include <db.h>
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<p>
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int
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memp_stat(DB_ENV *env, DB_MPOOL_STAT **gsp,
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DB_MPOOL_FSTAT *(*fsp)[], void *(*db_malloc)(size_t));
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</pre></h3>
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<h1>Description</h1>
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<p>The memp_stat function method creates statistical structures and copies
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pointers to them into user-specified memory locations. The statistics
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include the number of files participating in the pool, the active pages
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in the pool, and information as to how effective the cache has been.
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<p>Statistical structures are created in allocated memory. If <b>db_malloc</b> is non-NULL, it
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is called to allocate the memory, otherwise, the library function
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<b>malloc</b>(3) is used. The function <b>db_malloc</b> must match
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the calling conventions of the <b>malloc</b>(3) library routine.
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Regardless, the caller is responsible for deallocating the returned
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memory. To deallocate returned memory, free the returned memory
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reference, references inside the returned memory do not need to be
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individually freed.
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<p>If <b>gsp</b> is non-NULL, the global statistics for the memory pool
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<b>mp</b> are copied into the memory location it references. The
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global statistics are stored in a structure of type DB_MPOOL_STAT.
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<p>The following DB_MPOOL_STAT fields will be filled in:
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<p><dl compact>
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<dt>size_t st_gbytes;<dd>Gigabytes of cache (total cache size is st_gbytes + st_bytes)
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<dt>size_t st_bytes;<dd>Bytes of cache (total cache size is st_gbytes + st_bytes)
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<dt>u_int32_t st_ncache;<dd>Number of caches.
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<dt>u_int32_t st_regsize;<dd>Individual cache size.
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<dt>u_int32_t st_cache_hit;<dd>Requested pages found in the cache.
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<dt>u_int32_t st_cache_miss;<dd>Requested pages not found in the cache.
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<dt>u_int32_t st_map;<dd>Requested pages mapped into the process' address space (there is no
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available information as to whether or not this request caused disk I/O,
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although examining the application page fault rate may be helpful).
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<dt>u_int32_t st_page_create;<dd>Pages created in the cache.
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<dt>u_int32_t st_page_in;<dd>Pages read into the cache.
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<dt>u_int32_t st_page_out;<dd>Pages written from the cache to the backing file.
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<dt>u_int32_t st_ro_evict;<dd>Clean pages forced from the cache.
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<dt>u_int32_t st_rw_evict;<dd>Dirty pages forced from the cache.
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<dt>u_int32_t st_hash_buckets;<dd>Number of hash buckets in buffer hash table.
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<dt>u_int32_t st_hash_searches;<dd>Total number of buffer hash table lookups.
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<dt>u_int32_t st_hash_longest;<dd>The longest chain ever encountered in buffer hash table lookups.
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<dt>u_int32_t st_hash_examined;<dd>Total number of hash elements traversed during hash table lookups.
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<dt>u_int32_t st_page_clean;<dd>Clean pages currently in the cache.
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<dt>u_int32_t st_page_dirty;<dd>Dirty pages currently in the cache.
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<dt>u_int32_t st_page_trickle;<dd>Dirty pages written using the <a href="../api_c/memp_trickle.html">memp_trickle</a> interface.
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<dt>u_int32_t st_region_wait;<dd>The number of times that a thread of control was forced to wait before
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obtaining the region lock.
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<dt>u_int32_t st_region_nowait;<dd>The number of times that a thread of control was able to obtain
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the region lock without waiting.
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</dl>
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<p>If <b>fsp</b> is non-NULL, a pointer to a NULL-terminated variable
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length array of statistics for individual files, in the memory pool <b>mp</b>,
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is copied into the memory location it references. If no individual files
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currently exist in the memory pool, <b>fsp</b> will be set to NULL.
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<p>The per-file statistics are stored in structures of type DB_MPOOL_FSTAT.
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The following DB_MPOOL_FSTAT fields will be filled in for each file in
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the pool, i.e., each element of the array:
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<p><dl compact>
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<dt>char *file_name;<dd>The name of the file.
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<dt>size_t st_pagesize;<dd>Page size in bytes.
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<dt>u_int32_t st_cache_hit;<dd>Requested pages found in the cache.
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<dt>u_int32_t st_cache_miss;<dd>Requested pages not found in the cache.
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<dt>u_int32_t st_map;<dd>Requested pages mapped into the process' address space.
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<dt>u_int32_t st_page_create;<dd>Pages created in the cache.
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<dt>u_int32_t st_page_in;<dd>Pages read into the cache.
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<dt>u_int32_t st_page_out;<dd>Pages written from the cache to the backing file.
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</dl>
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<p>The memp_stat function returns a non-zero error value on failure and 0 on success.
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<h1>Errors</h1>
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<p>The memp_stat function may fail and return a non-zero error for the following conditions:
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<p><dl compact>
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<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
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</dl>
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<p>The memp_stat function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
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If a catastrophic error has occurred, the memp_stat function may fail and return
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<a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>, in which case all subsequent Berkeley DB calls will fail
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in the same way.
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<h1>See Also</h1>
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<a href="../api_c/env_set_mp_mmapsize.html">DBENV->set_mp_mmapsize</a>,
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<a href="../api_c/memp_fclose.html">memp_fclose</a>,
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<a href="../api_c/memp_fget.html">memp_fget</a>,
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<a href="../api_c/memp_fopen.html">memp_fopen</a>,
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<a href="../api_c/memp_fput.html">memp_fput</a>,
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<a href="../api_c/memp_fset.html">memp_fset</a>,
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<a href="../api_c/memp_fsync.html">memp_fsync</a>,
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<a href="../api_c/memp_register.html">memp_register</a>,
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<a href="../api_c/memp_stat.html">memp_stat</a>,
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<a href="../api_c/memp_sync.html">memp_sync</a>
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and
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<a href="../api_c/memp_trickle.html">memp_trickle</a>.
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</tt>
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<table><tr><td><br></td><td width="1%">
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<a href="../api_c/c_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
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