初始化:
1、open文件
2、write 1M空数据到文件
3、mmap文件,ptr作为写指针
4、关闭文件
#include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <string.h> #include <sys/syscall.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <sys/mman.h> #define XLOG_MAX_FILE_SIZE 32*1024 char *xlog_write_ptr = NULL; int xlog_write_size = 0; int xlog_fd = -1; int inner_id = 0; char xlog_path_name[128] = "/home/derek"; int xlog_set_path_name(char *path_name) { if(strlen(path_name) > 64 || path_name == NULL) return 1; sprintf(xlog_path_name, "%s", path_name); return 0; } int xlog_file_restore(int mid) { int fd; char file_name[128]; char *temp_buff; //flush to file if ( xlog_write_ptr != NULL) munmap(xlog_write_ptr, XLOG_MAX_FILE_SIZE); sprintf(file_name, "%s/xlog%d.%d.txt", xlog_path_name, mid, inner_id++); fd = open(file_name, O_RDWR|O_CREAT); if(fd < 0) { printf("open: %s ", strerror(errno)); return 1; } temp_buff = malloc(XLOG_MAX_FILE_SIZE); if (temp_buff == NULL) { printf("malloc: %s ", strerror(errno)); return 1; } memset(temp_buff, 0, XLOG_MAX_FILE_SIZE); write(fd, temp_buff, XLOG_MAX_FILE_SIZE); free(temp_buff); xlog_write_ptr = mmap(0, XLOG_MAX_FILE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (xlog_write_ptr == (char *)-1) { printf("mmap: %s ", strerror(errno)); return 1; } printf("xlog_write_ptr=0x%x ", xlog_write_ptr); xlog_write_size = 0; close(fd); return 0; } int xlog_buffer(int mid, char *buffer) { char log_info[128]; int str_len = strlen(buffer); if ( (xlog_write_size + str_len > XLOG_MAX_FILE_SIZE) || (xlog_write_ptr == 0) ) { if ( xlog_file_restore(mid) < 0) return 1; } // write to buffer sprintf(xlog_write_ptr + xlog_write_size, "%s", buffer); xlog_write_size += str_len; return 0; } int main() { int i; char log_info[128]; for(i = 0; i < 100000; i++) { sprintf(log_info, "hello, %d ", i); xlog_buffer(1, log_info); //sleep(1); } return 0; }