tor/changes/ticket30307

  o Major features (performance):
    - Update our node selection algorithm to exclude nodes in linear time.
      Previously, the algorithm was quadratic, which could slow down heavily
      used onion services.  Closes ticket 30307.
Use a linear algorithm to subtract two nodelists. The nodelist_idx for each node_t serves as a unique identifier for the node, so we can use a bitarray to hold all the excluded nodes, and then remove them from the smartlist. Previously use used smartlist_subtract(sl, excluded), which is O(len(sl)*len(excluded)). We can use this function in other places too, but this is the one that showed up on the profiles of 30291. Closes ticket 30307. 2019-04-26 17:03:22 +02:00			`o Major features (performance):`
			`- Update our node selection algorithm to exclude nodes in linear time.`
			`Previously, the algorithm was quadratic, which could slow down heavily`
			`used onion services. Closes ticket 30307.`