C++实现zookeeper主从切换
1.下载zk
2.配置zk
查看有无java环境。
java -version
安装java环境。
yum list java* 查看yum源的java包。
yum -y install java-1.8.0-openjdk 安装java包。
在/usr/local/zookeeper下解压压缩包，解压后的文件夹重命名为zookeeper-3.5.5，进入zookeeper-3.5.5/conf目录，重命名zoo_sample.cfg为zoo.cfg，打开zoo.cfg，修改红色部分为dataDir=/usr/local/zookeeper/ zookeeper-3.5.5/data，并增加灰色底色部分。
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/tmp/zookeeper
dataLogDir=/usr/local/zookeeper/zookeeper-3.5.5/logs
将 zookeeper 的根目录设置到系统环境变量 PATH 中：
sudo vi /etc/profile
在打开的 profile 文件末尾追加如下配置：
export ZOOKEEPER_HOME=/usr/local/zookeeper/zookeeper-3.5.5
export PATH=$ZOOKEEPER_HOME/bin:$PATH
export PATH
保存并退出 vi；
刷新 profile 文件使之立即生效：
source /etc/profile
3.启动zk
进入apache-zookeeper-3.5.5-bin/bin目录，执行：
sh ./zkServer.sh start
4.C++包含的头文件和库
- 下载
- 解压后进入目录：apache-zookeeper-3.5.5/zookeeper-client/zookeeper-client-c
- 执行命令：
autoreconf -if
./configure --disable-shared --without-cppunit
make
make install
编译C lib库
- 编译后头文件为：/usr/local/include/zookeeper/zookeeper.h
- 编译后静态库文件为：/usr/local/lib/libzookeeper_mt.a
- 程序makefile需要引用zookeeper.h, libzookeeper_mt.a才能编译通过。
-bash: autoreconf:未找到命令：
yum -y install install autoconf automake libtool
server.h
#include
#include
#include
#include
#include
using namespace std;
class Server
{
public:
Server(string path, string data, int timeout);
~Server();
int connect_zk(const char *host);
int create_zk_nodes();
void start_work();
private:
void work();
void run_for_master();
void regist_master();
static void zk_watcher(zhandle_t *zh, int type, int state, const char *path,void *watcherCtx);
static void node_watcher(zhandle_t *zh, int type, int state, const char *path,void *watcherCtx);
private:
string m_strNodePath;
string m_strNodeData;
int m_iRecvTimeout;
zhandle_t *m_zkHandle;
struct String_vector m_path_info;
volatile bool m_connect;
volatile bool m_run;
}; server.cpp
#include "server.h"
Server::Server(string path, string data, int timeout)
{
m_strNodePath = path;
m_strNodeData = data;
m_iRecvTimeout = timeout;
m_run = false;
m_connect = false;
m_zkHandle = NULL;
}
Server::~Server()
{
if(NULL != m_zkHandle)
{
zookeeper_close(m_zkHandle);
}
}
int Server::connect_zk(const char *host)
{
m_zkHandle = zookeeper_init(host, zk_watcher, m_iRecvTimeout, 0, this, 0);
while(!m_connect)
{
sleep(1);
}
if (NULL == m_zkHandle)
{
cout << "zookeeper_init(): function return NULL!" << endl;
return -1;
}
else
{
return 0;
}
}
int Server::create_zk_nodes()
{
char buf[256] = {0};
int errcode = zoo_create(m_zkHandle, m_strNodePath.c_str(),
m_strNodeData.c_str(), static_cast(m_strNodeData.size()),
&ZOO_OPEN_ACL_UNSAFE, ZOO_EPHEMERAL|ZOO_SEQUENCE, buf, 256);
if (errcode != ZOK)
{
cout << "create_zk_nodes():Failed to create zk node!" << endl;
return -1;
}
else
{
m_strNodePath = string(buf);
return 0;
}
}
void Server::zk_watcher(zhandle_t *zh, int type, int state, const char *path,void *watcherCtx)
{
Server *pthis = (Server*)watcherCtx;
if (type == ZOO_SESSION_EVENT)
{
if (state == ZOO_CONNECTED_STATE)
{
pthis->m_connect = true;
cout << "Connected to zookeeper service successfully!" << endl;
}
}
}
void Server::start_work()
{
run_for_master();
if (!m_run)
{
cout << "become slave" << endl;
}
int ret = zoo_wget_children(m_zkHandle, "/", node_watcher, this, &m_path_info);
if (ret != 0)
{
cout << "get nodelist failed!" << endl;
}
while (!m_run)
{
sleep(1);
}
deallocate_String_vector(&m_path_info);
cout << "become master" << endl;
work();
}
void Server:: node_watcher(zhandle_t *zh, int type, int state, const char *path,void *watcherCtx)
{
sleep(3);
Server *pthis = (Server*)watcherCtx;
if (type == ZOO_CHILD_EVENT)
{
pthis->run_for_master();
}
}
void Server::run_for_master()
{
int ret = zoo_wget_children(m_zkHandle, "/", node_watcher, this, &m_path_info);
if (0 != ret)
{
cout << "node_watcher(): update path error!" << endl;
}
string pathstr;
pathstr.assign(m_strNodePath, 1, 15);
char *minstr = new char[16];
char *p = minstr;
strcpy(minstr,pathstr.c_str());
for (int i=0, len=m_path_info.count; i 0
&& strcmp("master",*(m_path_info.data + i)) != 0)
{
minstr = *(m_path_info.data + i);
}
}
if (strcmp(minstr,pathstr.c_str()) == 0
&& zoo_wexists(m_zkHandle, "/master", zk_watcher, NULL, NULL) == ZNONODE)
{
regist_master();
}
deallocate_String_vector(&m_path_info);
delete []p;
p = NULL;
}
void Server::regist_master()
{
int errorcode = zoo_create(m_zkHandle, "/master", NULL, 0,
&ZOO_OPEN_ACL_UNSAFE, ZOO_EPHEMERAL, NULL, 0);
if (ZOK == errorcode)
{
m_run = true;
}
else if (ZNODEEXISTS == errorcode)
{
cout << "regist_master():master is exist!" << endl;
}
else
{
cout << "regist_master():other error!" << endl;
}
}
void Server:: work()
{
while (1)
{
cout << "hello" << endl;
sleep(2);
}
}
main.cpp
#include "server.h"
int main(int argc, char *argv[])
{
zoo_set_debug_level( ZOO_LOG_LEVEL_ERROR );
const char *host = "127.0.0.1:2181";
string path = "/nodes";
string data = "nothing";
int timeout = 10000;
Server server(path, data, timeout);
if (-1 == server.connect_zk(host))
{
return -1;
}
if (-1 == server.create_zk_nodes())
{
return -1;
}
server.start_work();
getchar();
return 0;
}makefile
FLAGS = -g -I/user/local/include/zookeeper
CLIBS = -lzookeeper_mt -DTHREADED -lpthread
result: server.o main.o
g++ $(FLAGS) server.o main.o -o result $(CLIBS)
main.o:main.cpp server.h
g++ -g -c main.cpp
server.o:server.cpp server.h
g++ -g -c server.cpp $(CLIBS)
clean:
rm *.o