Introducing the most important speed-up to date 🚀

Hey folks,

Before I start the note on the new release, I'll just introduce what roaring-rs is. It is a Rust idiomatic port of the Roaring Bitmap data structure introduced by Daniel Lemire, G. Ssi-Yan-Kai and O. Kaser. The data structure simply defines better-compressed sets of bits, faster and memory-efficient data structures for performing operations on sets, i.e. intersections, unions... and so on.

So, about this new version of roaring-rs, it is a bit special because it's the version that introduces the most performance improvements in a while and on the most topics. Most of this amazing work was done by @saik0, a new contributor to the crate 🎉. @schmidek implemented DoubleEndedIterator on the bitmap iterators 💪

Breaking changes

• Removed deprecated set ops such as union_with. Use the corresponding operators |=.
• Minimum supported Rust version (MSRV) increased to 1.56.
• deserialize_from validates inputs. In some cases, it can be 4x slower. For workloads that are heavy in deserialization from trusted sources migrate to deserialize_unchecked_from.

Performance optimizations

• from_sorted_iter and append are exponentially faster. They should be preferred over collect and extend whenever adding monotonically increasing integers to the set as it's about 2-2.5x faster.
• Other performance optimizations.

  	Min	Mean	Max
  Iteration	6%	57%	125%
  And	0%	7%	22%
  Or	0%	10%	33%
  Sub	0%	9%	39%
  Xor	4%	90%	209%

New features

• rank Returns the number of integers that are lower or equal to a given value. rank(u64::MAX) == len().
• select Returns the nth integer in the set or None if n >= len().
• union_len, intersection_len ... and so on. Compute the cardinality of a set operation without materializing it. Usually about twice as fast as materializing the bitmap.
• implemented DoubleEndedIterator.
• implemented ExactSizeIterator (on 64 bit targets only).
• EXPERIMENTAL SIMD feature (requires rust nightly).

  	Min	Mean	Max
  And	0%	34%	141%
  Or	2%	45%	145%
  Sub	0%	51%	168%
  Xor	0%	130%	437%

Other

• Added proper testing suite for set operations.
• Added many benchmarks and real world datasets.

Perf numbers are for pairwise operations on collections of bitmaps from real datasets.
Pairwise as in: B₁ ∩ B₂, B₂ ∩ B₃, ... B_N-1 ∩ B_N