libmemcached初探

     最近要使用memcacheq作为消息队列，想找下memcacheq的c的客户端库，后来一想，既然memcacheq本身是支持memcache协议的，使用memcached的客户端的库应该就可以了。

     惭愧的是，真没用编写过c对memcached的操作，以前只是简简单单的使用下ruby程序对客户端操作而已，不过ruby下的memcache客户端实在是简介，昨天很快就用ruby实现了我的应用的初级模型，可惜后台开发，效率还是很重要的。接下来昨天到今天上午一直再看libmemcached的库写了几个小程序。话说ruby，python和perl，php也是使用该库编写的memcached客户端程序的。

     发现libmemcached本身支持 memcached的分布式应用。

   

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <libmemcached/memcached.h>
 int fun(memcached_server_st *servers)
 {
     //return servers[0].count;
 }
 int main(int argc, char *argv[])
 {
     memcached_st *memc;
     memcached_return rc;
     memcached_server_st *servers;
     char value[8191];
     //connect multi server
     memc = memcached_create(NULL);
     // memcached_behavior_set(memc, MEMCACHED_BEHAVIOR_SORT_HOSTS, 1);
    memcached_behavior_set(memc,MEMCACHED_BEHAVIOR_DISTRIBUTION,MEMCACHED_DISTRIBUTION_CONSISTENT);
     servers = memcached_server_list_append(NULL, "localhost", 21202, &rc);
   //  servers = memcached_server_list_append(servers, "localhost", 21201, &rc);
     servers = memcached_server_list_append(servers, "localhost", 11217, &rc);
  //   servers = memcached_server_list_append(servers, "localhost",11216,&rc);
     rc = memcached_server_push(memc, servers);
 //    int count = memcached_server_list_count(servers);
     int  count2 = memcached_server_count(memc);


     fprintf(stdout, "server count is%d/n",memc->number_of_hosts);
     memcached_server_free(servers);
     //Save multi data
     size_t i;
     const char const *keys[]= {"key1", "key2", "key3","key4"};
    const  size_t key_length[]= {4, 4, 4, 4};
     char *values[] = {"This is c first value", "This is c second value", "This is c third value"," this is c forth value"};
     size_t val_length[]= {21, 22, 21, 21};
     for (i=0; i < 4; i++) {
     rc = memcached_set(memc, keys[i], key_length[i], values[i], val_length[i], (time_t)180,(uint32_t)0);
     if (rc == MEMCACHED_SUCCESS) {
         printf("Save key:%s data:/"%s/" success./n", keys[i], values[i]);
     }
     }
     //Fetch multi data
     char return_key[MEMCACHED_MAX_KEY];
     size_t return_key_length;
     char *return_value;
     size_t return_value_length;
     uint32_t flags;
     rc = memcached_mget(memc, keys, key_length, 4);
     while ((return_value = memcached_fetch(memc, return_key, &return_key_length, &return_value_length, &flags, &rc))) {
     if (rc == MEMCACHED_SUCCESS) {
         printf("Fetch key:%s data:%s/n", return_key, return_value);
     }
     }

     //Delete multi data
     for (i=0; i <4; i++) {
     rc = memcached_set(memc, keys[i], key_length[i], values[i], val_length[i], (time_t)180, (uint32_t)0);
     rc = memcached_delete(memc, keys[i], key_length[i], (time_t)0);
     if (rc == MEMCACHED_SUCCESS) {
         printf("Delete %s success/n", keys[i], values[i]);
     }
     }
     //free
     memcached_free(memc);
     return 0;
 }

 

另外还支持连接池的管理：

 

 

 #include <assert.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <signal.h>
 #include <unistd.h>
 #include <time.h>
 #include <libmemcached/memcached.h>
 #include <libmemcached/memcached_util.h>
 int main(void)
 {
     memcached_return_t rc;
     memcached_st *memc;
     memc = memcached_create(NULL);
     const char *keys[] = {"foo", "foo2"};
     size_t lengths[] = {3,4};
     const char *values[]= { "fjord", "41" };
     memcached_server_st *servers;
     //servers= memcached_server_list_append(NULL, "localhost", 21201, &rc);
     servers = memcached_server_list_append_with_weight(NULL,"localhost",21201,0,&rc);
     assert (servers != NULL);
     memcached_server_push(memc,servers);
     memcached_pool_st *pool = memcached_pool_create(memc,5,10);


   // Set foo and foo2
     int i;
   for ( i= 0; i < 2; i++)
   {
     rc= memcached_set(memc, keys[i], lengths[i], values[i], strlen(values[i]),
               (time_t)0, (uint32_t)0);
     assert(rc == MEMCACHED_SUCCESS);
   }
   char *string;
   size_t string_length;
   uint32_t flags;
   // retrieve both via mget
   rc= memcached_mget(memc, keys, lengths, 2);
   assert(rc == MEMCACHED_SUCCESS);
   char key[MEMCACHED_MAX_KEY];
   size_t key_length;
   // this should get both
   for ( i = 0; i < 2; i++)
   {
     string= memcached_fetch(memc, key, &key_length, &string_length,
                             &flags, &rc);
     assert(rc == MEMCACHED_SUCCESS);
     int val = 0;
     if (key_length == 4)
       val= 1;
     assert(string_length == strlen(values[val]));
     assert(strncmp(values[val], string, string_length) == 0);
     free(string);
   }
   // this should indicate end
   string= memcached_fetch(memc, key, &key_length, &string_length, &flags, &rc);
   assert(rc == MEMCACHED_END);
   // now get just one
   rc= memcached_mget(memc, keys, lengths, 1);
   assert(rc == MEMCACHED_SUCCESS);
   string= memcached_fetch(memc, key, &key_length, &string_length, &flags, &rc);
   assert(key_length == lengths[0]);
   assert(strncmp(keys[0], key, key_length) == 0);
   assert(string_length == strlen(values[0]));
   assert(strncmp(values[0], string, string_length) == 0);
   assert(rc == MEMCACHED_SUCCESS);
   free(string);
   // this should indicate end
   string= memcached_fetch(memc, key, &key_length, &string_length, &flags, &rc);
   assert(rc == MEMCACHED_END);

   memcached_free(memc);
   return 1;
 }

 

    基本的api，libmemcached给出的examples比较少，建议看下他自带的tests目录下的测试函数，比较有帮助，libmemcached-api基本操作差不多了，下面估计要研究的是如何将memcacheq实现分布。初步是简单的通过一致性hash算法，将消息分布到不同的memcacheq中去。

  接着需要研究下redis，等下周就开始动手上路了。

原文地址：http://blog.csdn.net/saint1126/article/details/6080146