Version 3.1.1
ex_extending.c

Shows how to extend WiredTiger with application-specific collations, extractors and cursor types.

/*-
* Public Domain 2014-2018 MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ex_extending.c
* This is an example demonstrating ways to extend WiredTiger with
* extractors, collators and loadable modules.
*/
#include <test_util.h>
static const char *home;
/* A simple case insensitive comparator. */
static int
__compare_nocase(WT_COLLATOR *collator, WT_SESSION *session,
const WT_ITEM *v1, const WT_ITEM *v2, int *cmp)
{
const char *s1 = (const char *)v1->data;
const char *s2 = (const char *)v2->data;
(void)session; /* unused variable */
(void)collator; /* unused variable */
*cmp = strcasecmp(s1, s2);
return (0);
}
static WT_COLLATOR nocasecoll = { __compare_nocase, NULL, NULL };
/*
* Comparator that only compares the first N prefix characters of the string.
* This has associated data, so we need to extend WT_COLLATOR.
*/
typedef struct {
WT_COLLATOR iface;
uint32_t maxlen;
} PREFIX_COLLATOR;
static int
__compare_prefixes(WT_COLLATOR *collator, WT_SESSION *session,
const WT_ITEM *v1, const WT_ITEM *v2, int *cmp)
{
PREFIX_COLLATOR *pcoll = (PREFIX_COLLATOR *)collator;
const char *s1 = (const char *)v1->data;
const char *s2 = (const char *)v2->data;
(void)session; /* unused */
*cmp = strncmp(s1, s2, pcoll->maxlen);
return (0);
}
static PREFIX_COLLATOR pcoll10 = { {__compare_prefixes, NULL, NULL}, 10 };
int
main(int argc, char *argv[])
{
WT_SESSION *session;
home = example_setup(argc, argv);
/* Open a connection to the database, creating it if necessary. */
error_check(wiredtiger_open(home, NULL, "create", &conn));
error_check(conn->add_collator(conn, "nocase", &nocasecoll, NULL));
error_check(conn->add_collator(conn, "prefix10", &pcoll10.iface, NULL));
/* Open a session for the current thread's work. */
error_check(conn->open_session(conn, NULL, NULL, &session));
/* Do some work... */
error_check(conn->close(conn, NULL));
return (EXIT_SUCCESS);
}