Couchbase C Client  2.9.0
Asynchronous C Client for Couchbase
example/libeventdirect/main.c

Shows how to integrate the library with an external event loop

/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright 2012 Couchbase, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libcouchbase/api3.h>
#include <event2/event.h>
const char key[] = "foo";
lcb_SIZE nkey = sizeof(key);
const char val[] = "{\"answer\":42}";
lcb_SIZE nval = sizeof(val);
int nreq = 1;
int nresp = 1;
int interval = 0;
struct event *timer = NULL;
static void bootstrap_callback(lcb_t instance, lcb_error_t err)
{
lcb_CMDSTORE cmd = {0};
if (err != LCB_SUCCESS) {
fprintf(stderr, "ERROR: %s\n", lcb_strerror(instance, err));
exit(EXIT_FAILURE);
}
printf("successfully bootstrapped\n");
fflush(stdout);
/* Since we've got our configuration, let's go ahead and store a value */
LCB_CMD_SET_KEY(&cmd, key, nkey);
LCB_CMD_SET_VALUE(&cmd, val, nval);
err = lcb_store3(instance, NULL, &cmd);
if (err != LCB_SUCCESS) {
fprintf(stderr, "Failed to set up store request: %s\n", lcb_strerror(instance, err));
exit(EXIT_FAILURE);
}
}
static void get_callback(lcb_t instance, int cbtype, const lcb_RESPBASE *rb)
{
const lcb_RESPGET *rg = (const lcb_RESPGET *)rb;
if (rg->rc != LCB_SUCCESS) {
fprintf(stderr, "Failed to get key: %s\n", lcb_strerror(instance, rg->rc));
exit(EXIT_FAILURE);
}
printf("%d. retrieved the key 'foo', value: %.*s\n", nresp, (int)rg->nvalue, rg->value);
fflush(stdout);
nresp--;
if (nresp == 0) {
printf("stopping the loop\n");
event_base_loopbreak((void *)lcb_get_cookie(instance));
}
(void)cbtype;
}
static void schedule_timer();
static void timer_callback(int fd, short event, void *arg)
{
lcb_t instance = arg;
lcb_CMDGET gcmd = {0};
LCB_CMD_SET_KEY(&gcmd, key, nkey);
rc = lcb_get3(instance, NULL, &gcmd);
if (rc != LCB_SUCCESS) {
fprintf(stderr, "Failed to schedule get request: %s\n", lcb_strerror(NULL, rc));
exit(EXIT_FAILURE);
}
(void)fd;
(void)event;
schedule_timer();
}
static void schedule_timer()
{
struct timeval tv;
if (!nreq) {
return;
}
tv.tv_sec = interval;
tv.tv_usec = 0;
evtimer_add(timer, &tv);
nreq--;
}
static void store_callback(lcb_t instance, int cbtype, const lcb_RESPBASE *rb)
{
if (rb->rc != LCB_SUCCESS) {
fprintf(stderr, "Failed to store key: %s\n", lcb_strerror(instance, rb->rc));
exit(EXIT_FAILURE);
}
printf("stored key 'foo'\n");
fflush(stdout);
{
struct event_base *evbase = (struct event_base *)lcb_get_cookie(instance);
printf("try to get value %d times with %dsec interval\n", nreq, interval);
timer = evtimer_new(evbase, timer_callback, instance);
schedule_timer();
}
(void)cbtype;
}
static lcb_io_opt_t create_libevent_io_ops(struct event_base *evbase)
{
struct lcb_create_io_ops_st ciops;
lcb_io_opt_t ioops;
lcb_error_t error;
memset(&ciops, 0, sizeof(ciops));
ciops.v.v0.type = LCB_IO_OPS_LIBEVENT;
ciops.v.v0.cookie = evbase;
error = lcb_create_io_ops(&ioops, &ciops);
if (error != LCB_SUCCESS) {
fprintf(stderr, "Failed to create an IOOPS structure for libevent: %s\n", lcb_strerror(NULL, error));
exit(EXIT_FAILURE);
}
return ioops;
}
static lcb_t create_libcouchbase_handle(lcb_io_opt_t ioops, int argc, char **argv)
{
lcb_t instance;
lcb_error_t error;
struct lcb_create_st copts;
memset(&copts, 0, sizeof(copts));
/* If NULL, will default to localhost */
copts.version = 3;
if (argc > 1) {
copts.v.v3.connstr = argv[1];
}
if (argc > 2) {
copts.v.v3.passwd = argv[2];
}
if (argc > 3) {
copts.v.v3.username = argv[3];
}
copts.v.v3.io = ioops;
error = lcb_create(&instance, &copts);
if (error != LCB_SUCCESS) {
fprintf(stderr, "Failed to create a libcouchbase instance: %s\n", lcb_strerror(NULL, error));
exit(EXIT_FAILURE);
}
/* Set up the callbacks */
lcb_set_bootstrap_callback(instance, bootstrap_callback);
lcb_install_callback3(instance, LCB_CALLBACK_GET, get_callback);
lcb_install_callback3(instance, LCB_CALLBACK_STORE, store_callback);
if ((error = lcb_connect(instance)) != LCB_SUCCESS) {
fprintf(stderr, "Failed to connect libcouchbase instance: %s\n", lcb_strerror(NULL, error));
lcb_destroy(instance);
exit(EXIT_FAILURE);
}
return instance;
}
/* This example shows how we can hook ourself into an external event loop.
* You may find more information in the blogpost: http://goo.gl/fCTrX */
int main(int argc, char **argv)
{
struct event_base *evbase = event_base_new();
lcb_io_opt_t ioops = create_libevent_io_ops(evbase);
lcb_t instance = create_libcouchbase_handle(ioops, argc, argv);
if (argc > 4) {
nreq = nresp = atoi(argv[4]);
}
if (argc > 5) {
interval = atoi(argv[4]);
}
/*Store the event base as the user cookie in our instance so that
* we may terminate the program when we're done */
lcb_set_cookie(instance, evbase);
/* Run the event loop */
event_base_loop(evbase, 0);
/* Cleanup */
lcb_destroy(instance);
if (timer) {
evtimer_del(timer);
}
event_base_free(evbase);
return EXIT_SUCCESS;
}