主从同步，实现新的更改应用到slave上，实现同步slave未上线时间的更改。

kvs_slave.c

@@ -0,0 +1,70 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/epoll.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "server.h"
+
+static int kvs_write_u8(uint8_t **pp, uint8_t v) {
+	uint8_t *p = *pp;
+	*p = v;
+	*pp = p + 1;
+	return 0;
+}
+
+static int kvs_write_u32(uint8_t **pp, uint32_t v) {
+	uint8_t *p = *pp;
+	uint32_t be = htonl(v);
+	memcpy(p, &be, 4);
+	*pp = p + 4;
+	return 0;
+}
+
+
+int try_connect_master(char *ip, int port){
+    
+    struct sockaddr_in addr;
+    memset(&addr, 0, sizeof(struct sockaddr));
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(port);
+    addr.sin_addr.s_addr = inet_addr(ip);
+
+    int rt = 1;
+    while(1){
+        int fd = socket(AF_INET, SOCK_STREAM, 0);
+        if(fd < 0){
+            continue;
+        }
+        
+        if(0 == connect(fd, (struct sockaddr*)&addr, sizeof(struct sockaddr_in))){
+            // [OP KVS_CMD_PSYNC=15][ARGC 1][ARGLEN 4][ARG offset]
+
+            char buf[100];
+            char *p = buf;
+
+            kvs_write_u8((uint8_t**)&p, 15);
+            kvs_write_u8((uint8_t**)&p, 1);
+
+            uint64_t len = sizeof(uint64_t);
+            kvs_write_u32((uint8_t**)&p, len);
+
+            uint64_t offset = 0;            
+            memcpy(p, (void*)&offset, len);
+            
+            p += len;
+
+            send(fd, buf, p-buf, 0);
+            recv(fd, buf, 100, 0);
+            return fd;
+        }
+        
+        close(fd);
+    }
+
+	return -1;
+}