Function streamRadixTreeMemoryUsage

src/object.cpp:878–885

This is an helper function with the goal of estimating the memory * size of a radix tree that is used to store Stream IDs. * * Note: to guess the size of the radix tree is not trivial, so we * approximate it considering 16 bytes of data overhead for each * key (the ID), and then adding the number of bare nodes, plus some * overhead due by the data and child pointers. This secret recipe * wa

 * on the insertion speed and thus the ability of the radix tree
 * to compress prefixes. */
size_t streamRadixTreeMemoryUsage(rax *rax) {
    size_t size;
    size = rax->numele * sizeof(streamID);
    size += rax->numnodes * sizeof(raxNode);
    /* Add a fixed overhead due to the aux data pointer, children, ... */
    size += rax->numnodes * sizeof(long)*30;
    return size;
}

/* Returns the size in bytes consumed by the key's value in RAM.
 * Note that the returned value is just an approximation, especially in the