gistfile1.c

#include <stdio.h>
#include <pthread.h>
#include "config.h"
#include "memcached.h"

void make_thread_local_connection_key();
void memcached_destroy(void *connection);
void make_prototypical_connection();
void initialize_process();
    
static memcached_st *prototypical_connection = NULL;
static pthread_key_t thread_local_connection_key;
static pthread_once_t is_initialized = PTHREAD_ONCE_INIT;

memcached_st *twitter_connect() {
    int return_code;
    
    pthread_once(&is_initialized, initialize_process);
    memcached_st *connection = (memcached_st *)pthread_getspecific(thread_local_connection_key);
    
    if (!connection) {
        connection = memcached_clone(NULL, prototypical_connection);
        if (return_code = pthread_setspecific(thread_local_connection_key, (void *)connection)) {
            fprintf(stderr, "failed to set thread specific key: %i.\n", return_code);
            exit(1);        
        }    
    }
    return connection;
}

void memcached_destroy(void *connection) {
    memcached_free((memcached_st *)connection);
}

void initialize_process() {
    make_thread_local_connection_key();
    make_prototypical_connection();
}

void make_thread_local_connection_key() {
    int return_code;

    if (return_code = pthread_key_create(&thread_local_connection_key, memcached_destroy)) {
        fprintf(stderr, "failed to create thread local key: %i.\n", return_code);
        exit(1);
    }
}

void make_prototypical_connection() {
    memcached_server_st *servers = NULL;
    memcached_return return_code;
    struct memcached_config *config = read_memcached_config("/usr/local/etc/varnish/memcached.yml");

    prototypical_connection = memcached_create(NULL);
    if (prototypical_connection == NULL) {
        fprintf(stderr, "failed to allocate memcache object.\n");
        exit(1);
    }

    if (memcached_behavior_set(prototypical_connection, MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED, 1) != MEMCACHED_SUCCESS) {
        fprintf(stderr, "failed to set ketama behavior.\n");
        exit(1);
    }
    if (memcached_behavior_set(prototypical_connection, MEMCACHED_BEHAVIOR_KETAMA_HASH, MEMCACHED_HASH_MD5) != MEMCACHED_SUCCESS) {
        fprintf(stderr, "failed to set md5 key hashing.\n");
        exit(1);
    }
    if (memcached_behavior_set(prototypical_connection, MEMCACHED_BEHAVIOR_HASH_WITH_PREFIX_KEY, 1) != MEMCACHED_SUCCESS) {
        fprintf(stderr, "failed to set always-prefix.\n");
        exit(1);
    }
    if (memcached_callback_set(prototypical_connection, MEMCACHED_CALLBACK_PREFIX_KEY, config->prefix) != MEMCACHED_SUCCESS) {
        fprintf(stderr, "failed to set key prefix.\n");
        exit(1);
    }
    
    return_code = memcached_server_push(prototypical_connection, memcached_servers_parse(config->server_list));

    if (return_code == MEMCACHED_SUCCESS) {
        fprintf(stderr, "Added servers (%s) successfully\n", config->server_list);
    } else {
        fprintf(stderr, "Couldn't add server: %s\n", memcached_strerror(prototypical_connection, return_code));
    }
    memcached_config_free(config);
    
}