1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
<! "@(#)stat.so 10.11 (Sleepycat) 10/26/98">
<!Copyright 1997, 1998 by Sleepycat Software, Inc. All rights reserved.>
<html>
<body bgcolor=white>
<head>
<title>Berkeley DB: memp_stat</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>memp_stat</h1>
<hr size=1 noshade>
<tt>
<h3>
<pre>
#include <db.h>
<p>
int
memp_stat(DB_MPOOL *mp, DB_MPOOL_STAT **gsp,
DB_MPOOL_FSTAT *(*fsp)[], void *(*db_malloc)(size_t));
</pre>
</h3>
<h1>Description</h1>
<p>
The memp_stat function method creates statistical structures and copies
pointers to them into user-specified memory locations. The statistics
include the number of files participating in the pool, the active pages
in the pool, and information as to how effective the cache has been.
<p>
Statistical structures are created in allocated memory.
If
<b>db_malloc</b> is non-NULL, it is called to allocate the memory,
otherwise, the library function <b>malloc</b>(3)) is used.
The function <b>db_malloc</b> must match the calling conventions of
the <b>malloc</b>(3)) library routine.
Regardless, the caller is responsible for deallocating the returned
memory.
To deallocate the returned memory, free each returned memory pointer;
pointers inside the memory do not need to be individually freed.
<p>
If <b>gsp</b> is non-NULL, the global statistics for the memory pool
<b>mp</b> are copied into the memory location it references. The
global statistics are stored in a structure of type DB_MPOOL_STAT.
<p>
The following DB_MPOOL_STAT fields will be filled in:
<dl compact>
<dt>u_int32_t st_refcnt;<dd>The number of references to the region.
<dt>u_int32_t st_regsize;<dd>The size of the region.
<dt>size_t st_cachesize;<dd>Cache size in bytes.
<dt>u_int32_t st_cache_hit;<dd>Requested pages found in the cache.
<dt>u_int32_t st_cache_miss;<dd>Requested pages not found in the cache.
<dt>u_int32_t st_map;<dd>Requested pages mapped into the process' address space (there is no
available information as to whether or not this request caused disk I/O,
although examining the application page fault rate may be helpful).
<dt>u_int32_t st_page_create;<dd>Pages created in the cache.
<dt>u_int32_t st_page_in;<dd>Pages read into the cache.
<dt>u_int32_t st_page_out;<dd>Pages written from the cache to the backing file.
<dt>u_int32_t st_ro_evict;<dd>Clean pages forced from the cache.
<dt>u_int32_t st_rw_evict;<dd>Dirty pages forced from the cache.
<dt>u_int32_t st_hash_buckets;<dd>Number of hash buckets in buffer hash table.
<dt>u_int32_t st_hash_searches;<dd>Total number of buffer hash table lookups.
<dt>u_int32_t st_hash_longest;<dd>The longest chain ever encountered in buffer hash table lookups.
<dt>u_int32_t st_hash_examined;<dd>Total number of hash elements traversed during hash table lookups.
<dt>u_int32_t st_page_clean;<dd>Clean pages currently in the cache.
<dt>u_int32_t st_page_dirty;<dd>Dirty pages currently in the cache.
<dt>u_int32_t st_page_trickle;<dd>Dirty pages written using the <a href="../../api_c/DbMpool/trickle.html">memp_trickle</a> interface.
<dt>u_int32_t st_region_wait;<dd>The number of times that a thread of control was forced to wait before
obtaining the region lock.
<dt>u_int32_t st_region_nowait;<dd>The number of times that a thread of control was able to obtain
the region lock without waiting.
</dl>
If <b>fsp</b> is non-NULL, a pointer to a NULL-terminated variable
length array of statistics for individual files, in the memory pool <b>mp</b>,
is copied into the memory location it references. If no individual files
currently exist in the memory pool, <b>fsp</b> will be set to NULL.
<p>
The per-file statistics are stored in structures of type DB_MPOOL_FSTAT.
The following DB_MPOOL_FSTAT fields will be filled in for each file in
the pool, i.e., each element of the array:
<dl compact>
<dt>char *file_name;<dd>The name of the file.
<dt>size_t st_pagesize;<dd>Page size in bytes.
<dt>u_int32_t st_cache_hit;<dd>Requested pages found in the cache.
<dt>u_int32_t st_cache_miss;<dd>Requested pages not found in the cache.
<dt>u_int32_t st_map;<dd>Requested pages mapped into the process' address space.
<dt>u_int32_t st_page_create;<dd>Pages created in the cache.
<dt>u_int32_t st_page_in;<dd>Pages read into the cache.
<dt>u_int32_t st_page_out;<dd>Pages written from the cache to the backing file.
</dl>
<p>
The memp_stat
function returns the value of <b>errno</b> on failure, and 0 on success.
<p>
<h1>Errors</h1>
If a fatal error occurs in Berkeley DB, the memp_stat function may fail and return
DB_RUNRECOVERY, at which point all subsequent database calls will also
return DB_RUNRECOVERY.
<p>
The memp_stat
function may fail and return <b>errno</b>
for any of the errors specified for the following Berkeley DB and C library
functions:
abort(3),
fcntl(3),
fprintf(3),
getpid(3),
malloc(3),
memcpy(3),
memset(3),
and
strlen(3).
In addition, the memp_stat
function may fail and return <b>errno</b>
for the following conditions:
<dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>
</dl>
<p>
<h1>See Also</h1>
<a href="../../api_c/DbMpool/close.html">memp_close</a>,
<a href="../../api_c/DbMpoolFile/close.html">memp_fclose</a>,
<a href="../../api_c/DbMpoolFile/get.html">memp_fget</a>,
<a href="../../api_c/DbMpoolFile/open.html">memp_fopen</a>,
<a href="../../api_c/DbMpoolFile/put.html">memp_fput</a>,
<a href="../../api_c/DbMpoolFile/set.html">memp_fset</a>,
<a href="../../api_c/DbMpoolFile/sync.html">memp_fsync</a>,
<a href="../../api_c/DbMpool/open.html">memp_open</a>,
<a href="../../api_c/DbMpool/db_register.html">memp_register</a>,
memp_stat,
memp_stat,
<a href="../../api_c/DbMpool/sync.html">memp_sync</a>,
<a href="../../api_c/DbMpool/trickle.html">memp_trickle</a>
and
<a href="../../api_c/DbMpool/unlink.html">memp_unlink</a>.
</tt>
</body>
</html>
|
