Allow to auto-stop after N hashes generated

[BenBE]

A small (and likely easy to implement) idea I was recently missing was a command line flag where I can tell n3map to generate at most a given number of hashes (like 2^30) and terminate at the time latest even if the zone hasn't been fully enumerated yet.

This feature can be interesting if you are enumerating several zones in a batch run and want a somewhat "guaranteed" runtime for each zone.

[anonion0]

Agreed. I wanted to add something along these lines at some point.

Similar options could be:

• Abort after N hashes tested w/o finding an uncovered one
• Abort at a certain hash coverage (bonus if it could estimate how long it would take to find another uncovered hash)

[BenBE]

Given that finding a hash inside a certain range is proportional to that range's size, you can estimate the number of (random) guesses by 2^-log(1-coverage). So if a quarter is currently still uncovered, you will likely be a random guess for that uncovered range in the next for guesses (not guaranteed, but with high probability).

This even could be used as a further termination option: Terminate if log(1 - coverage) / log(coverage / #RR) > X with X > 2 (i.e. if the remaining gap in the coverage is significantly smaller than the average gap covered by each found RR so far).

[anonion0]

I decided to add an option --hashlimit=N to limit the # of hashes checked as you originally described. I may add more sophisticated termination options at some point, but I think for most scenarios this is probably sufficient.