Function loadAppendOnlyFile

src/aof.cpp:840–1070

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. */

 * 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");
    struct redis_stat sb;
    int old_aof_state = g_pserver->aof_state;
    long loops = 0;
    off_t valid_up_to = 0; /* Offset of latest well-formed command loaded. */
    off_t valid_before_multi = 0; /* Offset before MULTI command loaded. */
    serverAssert(serverTL != NULL); // This happens early in boot, ensure serverTL was setup

    if (fp == NULL) {
        serverLog(LL_WARNING,"Fatal error: can't open the append log file for reading: %s",strerror(errno));
        exit(1);
    }

    /* Handle a zero-length AOF file as a special case. An empty AOF file
     * is a valid AOF because an empty server with AOF enabled will create
     * a zero length file at startup, that will remain like that if no write
     * operation is received. */
    if (fp && redis_fstat(fileno(fp),&sb) != -1 && sb.st_size == 0) {
        g_pserver->aof_current_size = 0;
        g_pserver->aof_fsync_offset = g_pserver->aof_current_size;
        fclose(fp);
        return C_ERR;
    }

    /* Temporarily disable AOF, to prevent EXEC from feeding a MULTI
     * to the same file we're about to read. */
    g_pserver->aof_state = AOF_OFF;

    fakeClient = createAOFClient();
    startLoadingFile(fp, filename, RDBFLAGS_AOF_PREAMBLE);

    for (int idb = 0; idb < cserver.dbnum; ++idb)
    {
        g_pserver->db[idb]->trackChanges(true);
    }

    /* 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;
        rdbSaveInfo rsi;

        serverLog(LL_NOTICE,"Reading RDB preamble from AOF file...");
        if (fseek(fp,0,SEEK_SET) == -1) goto readerr;
        rioInitWithFile(&rdb,fp);
        if (rdbLoadRio(&rdb,RDBFLAGS_AOF_PREAMBLE,&rsi) != C_OK) {
            serverLog(LL_WARNING,"Error reading the RDB preamble of the AOF file, AOF loading aborted");
            goto readerr;
        } else {
            serverLog(LL_NOTICE,"Reading the remaining AOF tail...");
        }