Redis流行的原因( 四 ) 1.Redis是什么Redis官方这样解释Redisi

判断是否开启了AOF

是：则通过loadAppendOnlyFile() 加载AOF文件
否：通过rdbLoad() 加载RDB文件

loadAppendOnlyFile()

/* Replay the append log file. On success C_OK is returned. On non fatal * error (the append only file is zero-length) C_ERR is returned. On * fatal error an error message is logged and the program exists. */int loadAppendOnlyFile(char *filename) {struct client *fakeClient;FILE *fp = fopen(filename,"r");....../* Check if this AOF file has an RDB preamble. In that case we need to* load the RDB file and later continue loading the AOF tail. */char sig[5]; /* "REDIS" */if (fread(sig,1,5,fp) != 5 || memcmp(sig,"REDIS",5) != 0) {/* No RDB preamble, seek back at 0 offset. */if (fseek(fp,0,SEEK_SET) == -1) goto readerr;} else {/* RDB preamble. Pass loading the RDB functions. */rio rdb;serverLog(LL_NOTICE,"Reading RDB preamble from AOF file...");if (fseek(fp,0,SEEK_SET) == -1) goto readerr;rioInitWithFile(if (rdbLoadRio(goto readerr;} else {serverLog(LL_NOTICE,"Reading the remaining AOF tail...");}}/* Read the actual AOF file, in REPL format, command by command. */while(1) {int argc, j;unsigned long len;robj **argv;char buf[128];sds argsds;struct redisCommand *cmd;/* Serve the clients from time to time */if (!(loops++ % 1000)) {loadingProgress(ftello(fp));processEventsWhileBlocked();}if (fgets(buf,sizeof(buf),fp) == NULL) {if (feof(fp))break;elsegoto readerr;}......}......}

通过读取AOF文件的前5个字符来判断是否是RDB+AOF混合模式