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/*
* Copyright (C) 2005-2016 Christoph Rupp (chris@crupp.de).
* All Rights Reserved.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* See the file COPYING for License information.
*/
/**
* This example demonstrates a more complex UQI queries which applies a
* user-supplied predicate function to filter data
*/
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h> /* for exit() */
#include <ups/upscaledb.h>
#include <ups/upscaledb_uqi.h>
#define DATABASE_NAME 1
void
error(const char *foo, ups_status_t st)
{
printf("%s() returned error %d: %s\n", foo, st, ups_strerror(st));
exit(-1);
}
/*
* Aggregation plugin: initialization
* Allocates storage for the aggregated counter.
*/
static void *
mycount_init(int flags, int key_type, uint32_t key_size,
int record_type, uint32_t record_size, const char *reserved)
{
uint64_t *count = (uint64_t *)malloc(sizeof(uint64_t));
*count = 0;
return count;
}
/*
* Aggregation plugin: de-initialization.
* Releases the storage which was allocated in mycount_init
*/
static void
mycount_cleanup(void *state)
{
free(state);
}
/*
* Aggregation plugin: aggregates a single value
* Here we simply increment the counter
*/
static void
mycount_single(void *state, const void *key_data, uint32_t key_size,
const void *record_data, uint32_t record_size)
{
*(uint64_t *)state += 1;
}
/*
* Aggregation plugin: aggregates a list of values
* Here we simply increase the counter by the number of elements in the list.
* This function is called for fixed-length data, but never for
* variable-length data.
*/
static void
mycount_many(void *state, const void *key_data_list,
const void *record_data_list, size_t list_length)
{
uint64_t *pcount = (uint64_t *)state;
*pcount += list_length;
}
/*
* Aggregation plugin: returns the results
*/
static void
mycount_results(void *state, uqi_result_t *result)
{
uint64_t *pcount = (uint64_t *)state;
uqi_result_add_row(result, 0, 0, pcount, sizeof(*pcount));
}
/*
* Predicate plugin: checks if the record is 10
*/
static int
equals10_predicate(void *state, const void *key_data, uint32_t key_size,
const void *record_data, uint32_t record_size)
{
assert(record_size == sizeof(uint32_t));
return *(uint32_t *)record_data == 10;
}
int
main(int argc, char **argv)
{
ups_status_t st; /* status variable */
ups_env_t *env; /* upscaledb environment object */
ups_db_t *db; /* upscaledb database object */
ups_parameter_t params[] = { /* parameters for ups_env_create_db */
{UPS_PARAM_KEY_TYPE, UPS_TYPE_UINT32},
{UPS_PARAM_RECORD_TYPE, UPS_TYPE_UINT32},
{0, 0}
};
/* First create a new upscaledb Environment */
st = ups_env_create(&env, "test.db", 0, 0664, 0);
if (st != UPS_SUCCESS)
error("ups_env_create", st);
/* And in this Environment we create a new Database for uint32-keys
* and uint32-records. */
st = ups_env_create_db(env, &db, DATABASE_NAME, UPS_RECORD_NUMBER32,
&params[0]);
if (st != UPS_SUCCESS)
error("ups_env_create_db", st);
/*
* now insert a bunch of key/value pairs. The IDs are automatically
* assigned, the record is a pseudo-random value
*/
for (int i = 0; i < 10000; i++) {
uint32_t value = 1 + i % 30;
ups_key_t key = {0};
ups_record_t record = ups_make_record(&value, sizeof(value));
st = ups_db_insert(db, 0, &key, &record, 0);
if (st != UPS_SUCCESS)
error("ups_db_insert", st);
}
uqi_result_t *result;
ups_record_t record = {0};
/* Our query will count all database entries with a record value of 10.
* For demonstration purposes we will use our own COUNT function (instead
* of the built-in "COUNT". */
/* The first plugin will perform the aggregation. */
uqi_plugin_t agg;
memset(&agg, 0, sizeof(agg));
agg.name = "mycount";
agg.type = UQI_PLUGIN_AGGREGATE;
agg.init = mycount_init;
agg.cleanup = mycount_cleanup;
agg.agg_single = mycount_single;
agg.agg_many = mycount_many;
agg.results = mycount_results;
st = uqi_register_plugin(&agg);
if (st != UPS_SUCCESS)
error("uqi_register_plugin", st);
/* Our second plugin will filter the data: all values != 10 are discarded.
* This plugin does not keep any state and therefore does not require an
* init or cleanup function. */
uqi_plugin_t pred;
memset(&pred, 0, sizeof(pred));
pred.type = UQI_PLUGIN_PREDICATE;
pred.name = "equals10";
pred.pred = equals10_predicate;
st = uqi_register_plugin(&pred);
if (st != UPS_SUCCESS)
error("uqi_register_plugin", st);
/* Now run the query */
st = uqi_select(env, "mycount($record) FROM DATABASE 1 "
"WHERE equals10($record)", &result);
if (st != UPS_SUCCESS)
error("uqi_select", st);
/* Our aggregation plugin stores the result as a 64bit variable in the
* result's record (see mycount_results()) */
uqi_result_get_record(result, 0, &record);
printf("mycount($record): %lu\n", *(uint64_t *)record.data);
uqi_result_close(result);
/* we're done! close the handles. UPS_AUTO_CLEANUP will also close the
* 'db' handle */
st = ups_env_close(env, UPS_AUTO_CLEANUP);
if (st != UPS_SUCCESS)
error("ups_env_close", st);
printf("success!\n");
return 0;
}