revset: improve roots revset performance Previously we would iterate over every item in the subset, checking if it was in the provided args. This often meant iterating over every rev in the repo. Now we iterate over the args provided, checking if they exist in the subset. On a large repo this brings setting phase boundaries (which use this revset roots(X:: - X::Y)) down from 0.8 seconds to 0.4 seconds. The "roots((tip~100::) - (tip~100::tip))" revset in revsetbenchmarks shows it going from 0.12s to 0.10s, so we should be able to catch regressions here in the future. This actually introduces a regression in 'roots(all())' (0.2s to 0.26s) since we're now using spansets, which are slightly slower to do containment checks on. I believe this trade off is worth it, since it makes the revset O(number of args) instead of O(size of repo).

revset: improve _descendants performance Previously revset._descendants would iterate over the entire subset (which is often the entire repo) and test if each rev was in the descendants list. This is really slow on large repos (3+ seconds). Now we iterate over the descendants and test if they're in the subset. This affects advancing and retracting the phase boundary (3.5 seconds down to 0.8 seconds, which is even faster than it was in 2.9). Also affects commands that move the phase boundary (commit and rebase, presumably). The new revsetbenchmark indicates an improvement from 0.2 to 0.12 seconds. So future revset changes should be able to notice regressions. I removed a bad test. It was recently added and tested '1:: and reverse(all())', which has an amibiguous output direction. Previously it printed in reverse order, because we iterated over the subset (the reverse part). Now it prints in normal order because we iterate over the 1:: . Since the revset itself doesn't imply an order, I removed the test.