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32 .\" @(#)mpool.3 8.1 (Berkeley) 6/4/93
34 .TH MPOOL 3 1993-06-04 "" "Linux Programmer's Manual"
37 mpool \- shared memory buffer pool
43 .BI "MPOOL *mpool_open(DBT *" key ", int " fd ", pgno_t " pagesize \
44 ", pgno_t " maxcache );
46 .BI "void mpool_filter(MPOOL *" mp ", void (*pgin)(void *, pgno_t, void *),"
47 .BI " void (*" pgout ")(void *, pgno_t, void *),"
48 .BI " void *" pgcookie );
50 .BI "void *mpool_new(MPOOL *" mp ", pgno_t *" pgnoaddr );
52 .BI "void *mpool_get(MPOOL *" mp ", pgno_t " pgno ", unsigned int " flags );
54 .BI "int mpool_put(MPOOL *" mp ", void *" pgaddr ", unsigned int " flags );
56 .BI "int mpool_sync(MPOOL *" mp );
58 .BI "int mpool_close(MPOOL *" mp );
62 is the library interface intended to provide page oriented buffer management
64 The buffers may be shared between processes.
68 initializes a memory pool.
71 argument is the byte string used to negotiate between multiple
72 processes wishing to share buffers.
73 If the file buffers are mapped in shared memory, all processes using
74 the same key will share the buffers.
77 is NULL, the buffers are mapped into private memory.
80 argument is a file descriptor for the underlying file, which must be seekable.
83 is non-NULL and matches a file already being mapped, the
89 argument is the size, in bytes, of the pages into which the file is broken up.
92 argument is the maximum number of pages from the underlying file to cache
94 This value is not relative to the number of processes which share a file's
95 buffers, but will be the largest value specified by any of the processes
100 function is intended to make transparent input and output processing of the
104 function is specified, it is called each time a buffer is read into the memory
105 pool from the backing file.
108 function is specified, it is called each time a buffer is written into the
110 Both functions are called with the
112 pointer, the page number and a pointer to the page to being read or written.
118 pointer and an address as arguments.
119 If a new page can be allocated, a pointer to the page is returned and
120 the page number is stored into the
123 Otherwise, NULL is returned and
131 pointer and a page number as arguments.
132 If the page exists, a pointer to the page is returned.
133 Otherwise, NULL is returned and
138 argument is not currently used.
142 unpins the page referenced by
145 must be an address previously returned by
149 The flag value is specified by ORing
150 any of the following values:
153 The page has been modified and needs to be written to the backing file.
156 returns 0 on success and \-1 if an error occurs.
160 writes all modified pages associated with the
165 returns 0 on success and \-1 if an error occurs.
169 function free's up any allocated memory associated with the memory pool
173 written to the backing file.
175 returns 0 on success and \-1 if an error occurs.
179 function may fail and set
181 for any of the errors specified for the library routine
186 function may fail and set
191 The requested record doesn't exist.
197 functions may fail and set
199 for any of the errors specified for the library routines
207 function may fail and set
209 for any of the errors specified for the library routine
214 function may fail and set
216 for any of the errors specified for the library routine