Function pfdebugCommand

app/redis-6.2.6/src/hyperloglog.c:1493–1594

PFDEBUG ... args ... * Different debugging related operations about the HLL implementation. */

/* PFDEBUG <subcommand> <key> ... args ...
 * Different debugging related operations about the HLL implementation. */
void pfdebugCommand(client *c) {
    char *cmd = c->argv[1]->ptr;
    struct hllhdr *hdr;
    robj *o;
    int j;

    o = lookupKeyWrite(c->db,c->argv[2]);
    if (o == NULL) {
        addReplyError(c,"The specified key does not exist");
        return;
    }
    if (isHLLObjectOrReply(c,o) != C_OK) return;
    o = dbUnshareStringValue(c->db,c->argv[2],o);
    hdr = o->ptr;

    /* PFDEBUG GETREG <key> */
    if (!strcasecmp(cmd,"getreg")) {
        if (c->argc != 3) goto arityerr;

        if (hdr->encoding == HLL_SPARSE) {
            if (hllSparseToDense(o) == C_ERR) {
                addReplyError(c,invalid_hll_err);
                return;
            }
            server.dirty++; /* Force propagation on encoding change. */
        }

        hdr = o->ptr;
        addReplyArrayLen(c,HLL_REGISTERS);
        for (j = 0; j < HLL_REGISTERS; j++) {
            uint8_t val;

            HLL_DENSE_GET_REGISTER(val,hdr->registers,j);
            addReplyLongLong(c,val);
        }
    }
    /* PFDEBUG DECODE <key> */
    else if (!strcasecmp(cmd,"decode")) {
        if (c->argc != 3) goto arityerr;

        uint8_t *p = o->ptr, *end = p+sdslen(o->ptr);
        sds decoded = sdsempty();

        if (hdr->encoding != HLL_SPARSE) {
            sdsfree(decoded);
            addReplyError(c,"HLL encoding is not sparse");
            return;
        }

        p += HLL_HDR_SIZE;
        while(p < end) {
            int runlen, regval;

            if (HLL_SPARSE_IS_ZERO(p)) {
                runlen = HLL_SPARSE_ZERO_LEN(p);
                p++;
                decoded = sdscatprintf(decoded,"z:%d ",runlen);
            } else if (HLL_SPARSE_IS_XZERO(p)) {