Function geodistCommand

app/redis-6.2.6/src/geo.c:966–998

GEODIST key ele1 ele2 [unit] * * Return the distance, in meters by default, otherwise according to "unit", * between points ele1 and ele2. If one or more elements are missing NULL * is returned. */

 * between points ele1 and ele2. If one or more elements are missing NULL
 * is returned. */
void geodistCommand(client *c) {
    double to_meter = 1;

    /* Check if there is the unit to extract, otherwise assume meters. */
    if (c->argc == 5) {
        to_meter = extractUnitOrReply(c,c->argv[4]);
        if (to_meter < 0) return;
    } else if (c->argc > 5) {
        addReplyErrorObject(c,shared.syntaxerr);
        return;
    }

    /* Look up the requested zset */
    robj *zobj = NULL;
    if ((zobj = lookupKeyReadOrReply(c, c->argv[1], shared.null[c->resp]))
        == NULL || checkType(c, zobj, OBJ_ZSET)) return;

    /* Get the scores. We need both otherwise NULL is returned. */
    double score1, score2, xyxy[4];
    if (zsetScore(zobj, c->argv[2]->ptr, &score1) == C_ERR ||
        zsetScore(zobj, c->argv[3]->ptr, &score2) == C_ERR)
    {
        addReplyNull(c);
        return;
    }

    /* Decode & compute the distance. */
    if (!decodeGeohash(score1,xyxy) || !decodeGeohash(score2,xyxy+2))
        addReplyNull(c);
    else
        addReplyDoubleDistance(c,
            geohashGetDistance(xyxy[0],xyxy[1],xyxy[2],xyxy[3]) / to_meter);
}