漫话Redis源码之三十二

关于report相关的函数，非核心逻辑。我一般是直接忽略，不纠结。这样对理解整个代码也有好处，该忽略就忽略，该屏蔽就屏蔽：

#ifdef __GNUC__
void rdbReportError(int corruption_error, int linenum, char *reason, ...) __attribute__ ((format (printf, 3, 4)));
#endif
void rdbReportError(int corruption_error, int linenum, char *reason, ...) {
    va_list ap;
    char msg[1024];
    int len;
 
    len = snprintf(msg,sizeof(msg),
        "Internal error in RDB reading offset %llu, function at rdb.c:%d -> ",
        (unsigned long long)server.loading_loaded_bytes, linenum);
    va_start(ap,reason);
    vsnprintf(msg+len,sizeof(msg)-len,reason,ap);
    va_end(ap);
 
    if (!server.loading) {
        /* If we're in the context of a RESTORE command, just propagate the error. */
        /* log in VERBOSE, and return (don't exit). */
        serverLog(LL_VERBOSE, "%s", msg);
        return;
    } else if (rdbCheckMode) {
        /* If we're inside the rdb checker, let it handle the error. */
        rdbCheckError("%s",msg);
    } else if (rdbFileBeingLoaded) {
        /* If we're loading an rdb file form disk, run rdb check (and exit) */
        serverLog(LL_WARNING, "%s", msg);
        char *argv[2] = {"",rdbFileBeingLoaded};
        redis_check_rdb_main(2,argv,NULL);
    } else if (corruption_error) {
        /* In diskless loading, in case of corrupt file, log and exit. */
        serverLog(LL_WARNING, "%s. Failure loading rdb format", msg);
    } else {
        /* In diskless loading, in case of a short read (not a corrupt
         * file), log and proceed (don't exit). */
        serverLog(LL_WARNING, "%s. Failure loading rdb format from socket, assuming connection error, resuming operation.", msg);
        return;
    }
    serverLog(LL_WARNING, "Terminating server after rdb file reading failure.");
    exit(1);
}
 
static ssize_t rdbWriteRaw(rio *rdb, void *p, size_t len) {
    if (rdb && rioWrite(rdb,p,len) == 0)
        return -1;
    return len;
}
 
int rdbSaveType(rio *rdb, unsigned char type) {
    return rdbWriteRaw(rdb,&type,1);
}
 
/* Load a "type" in RDB format, that is a one byte unsigned integer.
 * This function is not only used to load object types, but also special
 * "types" like the end-of-file type, the EXPIRE type, and so forth. */
int rdbLoadType(rio *rdb) {
    unsigned char type;
    if (rioRead(rdb,&type,1) == 0) return -1;
    return type;
}
 
/* This is only used to load old databases stored with the RDB_OPCODE_EXPIRETIME
 * opcode. New versions of Redis store using the RDB_OPCODE_EXPIRETIME_MS
 * opcode. On error -1 is returned, however this could be a valid time, so
 * to check for loading errors the caller should call rioGetReadError() after
 * calling this function. */
time_t rdbLoadTime(rio *rdb) {
    int32_t t32;
    if (rioRead(rdb,&t32,4) == 0) return -1;
    return (time_t)t32;
}
 
int rdbSaveMillisecondTime(rio *rdb, long long t) {
    int64_t t64 = (int64_t) t;
    memrev64ifbe(&t64); /* Store in little endian. */
    return rdbWriteRaw(rdb,&t64,8);
}
 
/* This function loads a time from the RDB file. It gets the version of the
 * RDB because, unfortunately, before Redis 5 (RDB version 9), the function
 * failed to convert data to/from little endian, so RDB files with keys having
 * expires could not be shared between big endian and little endian systems
 * (because the expire time will be totally wrong). The fix for this is just
 * to call memrev64ifbe(), however if we fix this for all the RDB versions,
 * this call will introduce an incompatibility for big endian systems:
 * after upgrading to Redis version 5 they will no longer be able to load their
 * own old RDB files. Because of that, we instead fix the function only for new
 * RDB versions, and load older RDB versions as we used to do in the past,
 * allowing big endian systems to load their own old RDB files.
 *
 * On I/O error the function returns LLONG_MAX, however if this is also a
 * valid stored value, the caller should use rioGetReadError() to check for
 * errors after calling this function. */
long long rdbLoadMillisecondTime(rio *rdb, int rdbver) {
    int64_t t64;
    if (rioRead(rdb,&t64,8) == 0) return LLONG_MAX;
    if (rdbver >= 9) /* Check the top comment of this function. */
        memrev64ifbe(&t64); /* Convert in big endian if the system is BE. */
    return (long long)t64;
}