Function trimStringObjectIfNeeded

src/object.cpp:467–473

Optimize the SDS string inside the string object to require little space, * in case there is more than 10% of free space at the end of the SDS * string. This happens because SDS strings tend to overallocate to avoid * wasting too much time in allocations when appending to the string. */

 * string. This happens because SDS strings tend to overallocate to avoid
 * wasting too much time in allocations when appending to the string. */
void trimStringObjectIfNeeded(robj *o) {
    if (o->encoding == OBJ_ENCODING_RAW &&
        sdsavail(szFromObj(o)) > sdslen(szFromObj(o))/10)
    {
        o->m_ptr = sdsRemoveFreeSpace(szFromObj(o));
    }
}

/* Try to encode a string object in order to save space */
robj *tryObjectEncoding(robj *o) {