ex_extending.c

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

/*-
 * 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 <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <wiredtiger.h>

#ifdef _WIN32
#define strcasecmp stricmp
#endif

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 */
        (void)collator; /* unused */

        *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(void)
{
        int ret;
        WT_CONNECTION *conn;
        WT_SESSION *session;

        /*
         * Create a clean test directory for this run of the test program if the
         * environment variable isn't already set (as is done by make check).
         */
        if (getenv("WIREDTIGER_HOME") == NULL) {
                home = "WT_HOME";
                ret = system("rm -rf WT_HOME && mkdir WT_HOME");
        } else
                home = NULL;

        /* Open a connection to the database, creating it if necessary. */
        if ((ret = wiredtiger_open(home, NULL, "create", &conn)) != 0)
                fprintf(stderr, "Error connecting to %s: %s\n",
                    home, wiredtiger_strerror(ret));

        ret = conn->add_collator(conn, "nocase", &nocasecoll, NULL);
        ret = conn->add_collator(conn, "prefix10", &pcoll10.iface, NULL);

        /* Open a session for the current thread's work. */
        if ((ret = conn->open_session(conn, NULL, NULL, &session)) != 0)
                fprintf(stderr, "Error opening a session on %s: %s\n",
                    home, wiredtiger_strerror(ret));

        /* XXX Do some work... */

        /* Note: closing the connection implicitly closes open session(s). */
        if ((ret = conn->close(conn, NULL)) != 0)
                fprintf(stderr, "Error connecting to %s: %s\n",
                    home, wiredtiger_strerror(ret));

        return (ret);
}