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//! Example of set reconciliation that uses "bisection" approach when number of differences
//! between two sets is exceeding an estimate and simple reconciliation fails.
//!
//! Bisection leverages the "divide-and-conquer" approach. It is possible thanks to the linearity of
//! the set sketches.
//!
//! In following example Bob wants to reconcile his set with Alice:
//!
//! ```notrust
//! +-------+ +-------+
//! | Bob | | Alice |
//! +-------+ +-------+
//! | |
//! | Sketch from a set [0..8] | Sketch from a set [0..32]
//! |------------------------------- |-------------------------------
//! | | | |
//! |<------------------------------ |<------------------------------
//! | |
//! | Serialized sketch (B) |
//! |---------------------------------->|
//! | |
//! | | Deserialize sketch
//! | |-------------------
//! | | |
//! | |<------------------
//! | |
//! | | reconcile(A, B)
//! | |-------------------------------
//! | | | failed!
//! | |<------------------------------
//! | |
//! | Ask for B/2 (bisect request) |
//! |<----------------------------------|
//! | |
//! | Sketch from B/2 [0, 2, 4, 6] |
//! |----------------------------- |
//! | | |
//! |<---------------------------- |
//! | |
//! | Serialized sketch (B/2) |
//! |---------------------------------->|
//! | |
//! | | Deserialize sketch
//! | |-------------------
//! | | |
//! | |<------------------
//! | |
//! | | Compute: A/2, reconcile(A, A/2), reconcile(B, B/2)
//! | |---------------------------------------------------
//! | | |
//! | |<--------------------------------------------------
//! | |
//! | | Perform bisection:
//! | | diff1 = reconcile(A/2, B/2)
//! | | diff2 = reconcile(A - A/2, B - B/2)
//! | | bob_missing = diff1 ∪ diff2
//! | |-------------------------------------
//! | | |
//! | |<------------------------------------
//! | |
//! | |
//! | Send bob_missing |
//! |<----------------------------------|
//! | |
//! ```
//!
//! ```
//! use minisketch_rs::Minisketch;
//!
//! /// Extracts remainder sketch from a difference of two sketches
//! fn sub_sketches(s1: &[u8], s2: &[u8], d: usize, seed: Option<u64>) -> Vec<u8> {
//! let mut a = create_minisketch(d, seed);
//! if let Some(seed) = seed {
//! a.set_seed(seed);
//! }
//! a.deserialize(s1);
//!
//! let mut b = create_minisketch(d, seed);
//! if let Some(seed) = seed {
//! b.set_seed(seed);
//! }
//! b.deserialize(s2);
//!
//! a.merge(&b).expect("Sketch sub merge");
//!
//! let mut sketch = vec![0u8; a.serialized_size()];
//! a.serialize(&mut sketch).expect("Serialize sketch sub");
//!
//! sketch
//! }
//!
//! /// Creates a_whole set from a_whole range of elements
//! fn sketch_from_range(
//! range: impl IntoIterator<Item = u64>,
//! capacity: usize,
//! seed: Option<u64>,
//! ) -> Minisketch {
//! let mut sketch = create_minisketch(capacity, seed);
//! for i in range {
//! sketch.add(i);
//! }
//! sketch
//! }
//!
//! /// Creates `Minisketch` for given `capacity` and optional `seed`.
//! fn create_minisketch(capacity: usize, seed: Option<u64>) -> Minisketch {
//! let mut minisketch = Minisketch::try_new(64, 0, capacity).unwrap();
//!
//! if let Some(seed) = seed {
//! minisketch.set_seed(seed);
//! }
//!
//! minisketch
//! }
//!
//! /// Creates serialized sketch.
//! fn serialize_sketch(sketch: Minisketch) -> Vec<u8> {
//! let mut buf = vec![0u8; sketch.serialized_size()];
//! sketch.serialize(&mut buf).expect("Minisketch serialize");
//!
//! buf
//! }
//!
//! /// Does set reconciliation from two sets.
//! fn reconcile(
//! sketch_a: &[u8],
//! sketch_b: &[u8],
//! capacity: usize,
//! seed: Option<u64>,
//! ) -> Result<Vec<u64>, ()> {
//! let mut a = create_minisketch(capacity, seed);
//! a.deserialize(sketch_a);
//!
//! let mut b = create_minisketch(capacity, seed);
//! b.deserialize(sketch_b);
//!
//! a.merge(&b).expect("Minisketch merge");
//!
//! let mut diffs = vec![0u64; capacity];
//! let num_diffs = a.decode(&mut diffs).map_err(|_| ())?;
//!
//! Ok(diffs.into_iter().take(num_diffs).collect())
//! }
//!
//! fn example(capacity: usize) -> Result<Vec<u64>, ()> {
//! let seed = None;
//!
//! // There is exactly 24 differences, but since capacity = 16, simple set reconciliation will fail
//! let a = 0..32;
//! let b = 0..8;
//!
//! // Count difference between two sets
//! let set_diff = a.clone().into_iter().filter(|e| !b.contains(e)).count();
//!
//! println!(
//! "Alice's set: {:?}",
//! a.clone().into_iter().collect::<Vec<_>>()
//! );
//! println!("Bob's set: {:?}", b.clone().into_iter().collect::<Vec<_>>());
//!
//! // To increase chance of bisect success, take only even elements of the set,
//! // so they're distributed uniformly.
//! let b_half = b
//! .clone()
//! .into_iter()
//! .enumerate()
//! .filter(|(i, _)| *i % 2 == 0)
//! .map(|(_, n)| n)
//! .collect::<Vec<_>>();
//! let a_half = a
//! .clone()
//! .into_iter()
//! .enumerate()
//! .filter(|(i, _)| *i % 2 == 0)
//! .map(|(_, n)| n)
//! .collect::<Vec<_>>();
//!
//! let alice_set_full = sketch_from_range(a, capacity, seed);
//! let a_whole = serialize_sketch(alice_set_full);
//! let a_half = serialize_sketch(sketch_from_range(a_half, capacity, seed));
//!
//! let bob_set_full = sketch_from_range(b, capacity, seed);
//! let b_whole = serialize_sketch(bob_set_full);
//! let b_half = serialize_sketch(sketch_from_range(b_half, capacity, seed));
//!
//! println!("Trying simple reconciliation");
//! let simple = reconcile(&a_whole, &b_whole, capacity, seed);
//! if let Err(()) = simple {
//! println!(
//! "Error. Difference exceeds sketch capacity: {} > {}",
//! set_diff, capacity
//! );
//! println!("Trying bisection");
//!
//! let a_minus_a_2 = sub_sketches(&a_whole, &a_half, capacity, seed);
//! let b_minus_b_2 = sub_sketches(&b_whole, &b_half, capacity, seed);
//!
//! let res_1 = reconcile(&a_half, &b_half, capacity, seed);
//! let res_2 = reconcile(&a_minus_a_2, &b_minus_b_2, capacity, seed);
//!
//! let res = res_1.and_then(|diffs1| {
//! res_2.and_then(|diffs2| {
//! Ok(diffs1
//! .into_iter()
//! .chain(diffs2.into_iter())
//! .collect::<Vec<_>>())
//! })
//! });
//!
//! res
//! } else {
//! Ok(simple.unwrap())
//! }
//! }
//!
//! pub fn main() {
//! let capacity = 16; // Try to change it to 24 and compare results
//!
//! match example(capacity) {
//! Ok(mut diffs) => {
//! // Sort differences for result readability (not required)
//! diffs.sort();
//!
//! println!("Success!");
//! println!("Differences: {:?}", diffs);
//! }
//!
//! Err(()) => println!("Example failed"),
//! }
//! }
//! ```
// Auto-generated. Do not modify.