diff --git a/beacon_chain/types/src/attestation_record.rs b/beacon_chain/types/src/attestation_record.rs index 15b1a2e71..569cfa2dc 100644 --- a/beacon_chain/types/src/attestation_record.rs +++ b/beacon_chain/types/src/attestation_record.rs @@ -31,7 +31,7 @@ impl Encodable for AttestationRecord { s.append(&self.shard_id); s.append_vec(&self.oblique_parent_hashes); s.append(&self.shard_block_hash); - s.append_vec(&self.attester_bitfield.to_be_vec()); + s.append_vec(&self.attester_bitfield.to_bytes()); s.append(&self.justified_slot); s.append(&self.justified_block_hash); s.append_vec(&self.aggregate_sig.as_bytes()); diff --git a/beacon_chain/utils/boolean-bitfield/Cargo.toml b/beacon_chain/utils/boolean-bitfield/Cargo.toml index feacb844a..b93e88f23 100644 --- a/beacon_chain/utils/boolean-bitfield/Cargo.toml +++ b/beacon_chain/utils/boolean-bitfield/Cargo.toml @@ -5,3 +5,7 @@ authors = ["Paul Hauner "] [dependencies] ssz = { path = "../ssz" } +bit-vec = "0.5.0" + +[dev-dependencies] +rand = "0.5.5" \ No newline at end of file diff --git a/beacon_chain/utils/boolean-bitfield/README.md b/beacon_chain/utils/boolean-bitfield/README.md index 749ccdb51..adf83f6f8 100644 --- a/beacon_chain/utils/boolean-bitfield/README.md +++ b/beacon_chain/utils/boolean-bitfield/README.md @@ -1,7 +1,3 @@ # Boolean Bitfield -A work-in-progress implementation of an unbounded boolean bitfield. - -Based upon a `Vec` - -Documentation TBC... +Implements a set of boolean as a tightly-packed vector of bits. diff --git a/beacon_chain/utils/boolean-bitfield/src/lib.rs b/beacon_chain/utils/boolean-bitfield/src/lib.rs index db3d4f99f..4d562d95b 100644 --- a/beacon_chain/utils/boolean-bitfield/src/lib.rs +++ b/beacon_chain/utils/boolean-bitfield/src/lib.rs @@ -1,161 +1,74 @@ -/* - * Implemenation of a bitfield as a vec. Only - * supports bytes (Vec) as the underlying - * storage. - * - * A future implementation should be more efficient, - * this is just to get the job done for now. - */ +extern crate bit_vec; extern crate ssz; -use std::cmp::max; +#[cfg(test)] +extern crate rand; -#[derive(Eq, Clone, Default, Debug)] -pub struct BooleanBitfield { - len: usize, - vec: Vec, +use bit_vec::BitVec; + +/// A BooleanBitfield represents a set of booleans compactly stored as a vector of bits. +#[derive(Debug, Clone, PartialEq)] +pub struct BooleanBitfield(BitVec); + +/// Error represents some reason a request against a bitfield was not satisfied +#[derive(Debug)] +pub enum Error { + /// OutOfBounds refers to indexing into a bitfield where no bits exist; returns the illegal index and the current size of the bitfield, respectively + OutOfBounds(usize, usize), } impl BooleanBitfield { /// Create a new bitfield with a length of zero. pub fn new() -> Self { - Self { - len: 0, - vec: vec![0], - } + Self { 0: BitVec::new() } } - /// Create a new bitfield of a certain capacity - pub fn with_capacity(capacity: usize) -> Self { - let mut vec = Vec::with_capacity(capacity / 8 + 1); - vec.push(0); - Self { len: 0, vec } + /// Create a new bitfield using the supplied `bytes` as input + pub fn from_bytes(bytes: &[u8]) -> Self { + Self { + 0: BitVec::from_bytes(bytes), + } } /// Read the value of a bit. /// - /// Will return `true` if the bit has been set to `true` - /// without then being set to `False`. - pub fn get_bit(&self, i: usize) -> bool { - let bit = |i: usize| i % 8; - let byte = |i: usize| i / 8; - - if byte(i) >= self.vec.len() { - false - } else { - self.vec[byte(i)] & (1 << (bit(i) as u8)) != 0 + /// If the index is in bounds, then result is Ok(value) where value is `true` if the bit is 1 and `false` if the bit is 0. + /// If the index is out of bounds, we return an error to that extent. + pub fn get(&self, i: usize) -> Result { + match self.0.get(i) { + Some(value) => Ok(value), + None => Err(Error::OutOfBounds(i, self.0.len())), } } /// Set the value of a bit. /// - /// If this bit is larger than the length of the underlying byte - /// array it will be extended. - pub fn set_bit(&mut self, i: usize, to: bool) { - let bit = |i: usize| i % 8; - let byte = |i: usize| i / 8; - - self.len = max(self.len, i + 1); - - if byte(i) >= self.vec.len() { - self.vec.resize(byte(i) + 1, 0); - } - if to { - self.vec[byte(i)] = self.vec[byte(i)] | (1 << (bit(i) as u8)) - } else { - self.vec[byte(i)] = self.vec[byte(i)] & !(1 << (bit(i) as u8)) - } + /// Returns the previous value if successful. + /// If the index is out of bounds, we return an error to that extent. + pub fn set(&mut self, i: usize, value: bool) -> Result { + let previous = self.get(i)?; + self.0.set(i, value); + Ok(previous) } - /// Return the "length" of this bitfield. Length is defined as - /// the highest bit that has been set. - /// - /// Note: this is distinct from the length of the underlying - /// vector. + /// Returns the index of the highest set bit. Some(n) if some bit is set, None otherwise. + pub fn highest_set_bit(&self) -> Option { + self.0.iter().rposition(|bit| bit) + } + + /// Returns the number of bits in this bitfield. pub fn len(&self) -> usize { - self.len + self.0.len() } - /// True if no bits have ever been set. A bit that is set and then - /// unset will still count to the length of the bitfield. - /// - /// Note: this is distinct from the length of the underlying - /// vector. - pub fn is_empty(&self) -> bool { - self.len == 0 + /// Returns the number of `1` bits in the bitfield + pub fn num_set_bits(&self) -> usize { + self.0.iter().filter(|&bit| bit).count() } - /// The number of bytes required to represent the bitfield. - pub fn num_bytes(&self) -> usize { - self.vec.len() - } - - /// Iterate through the underlying vector and count the number of - /// true bits. - pub fn num_true_bits(&self) -> u64 { - let mut count: u64 = 0; - for byte in &self.vec { - for bit in 0..8 { - if byte & (1 << (bit as u8)) != 0 { - count += 1; - } - } - } - count - } - - /// Iterate through the underlying vector and find the highest - /// set bit. Useful for instantiating a new instance from - /// some set of bytes. - pub fn compute_length(bytes: &[u8]) -> usize { - for byte in (0..bytes.len()).rev() { - for bit in (0..8).rev() { - if bytes[byte] & (1 << (bit as u8)) != 0 { - return (byte * 8) + bit + 1; - } - } - } - 0 - } - - /// Get the byte at a position, assuming big-endian encoding. - pub fn get_byte(&self, n: usize) -> Option<&u8> { - self.vec.get(n) - } - - /// Clone and return the underlying byte array (`Vec`). - pub fn to_vec(&self) -> Vec { - self.vec.clone() - } - - /// Clone and return the underlying byte array (`Vec`) in big-endinan format. - pub fn to_be_vec(&self) -> Vec { - let mut o = self.vec.clone(); - o.reverse(); - o - } -} - -impl<'a> From<&'a [u8]> for BooleanBitfield { - fn from(input: &[u8]) -> Self { - let mut vec = input.to_vec(); - vec.reverse(); - BooleanBitfield { - vec, - len: BooleanBitfield::compute_length(input), - } - } -} - -impl PartialEq for BooleanBitfield { - fn eq(&self, other: &BooleanBitfield) -> bool { - (self.vec == other.vec) & (self.len == other.len) - } -} - -impl ssz::Encodable for BooleanBitfield { - fn ssz_append(&self, s: &mut ssz::SszStream) { - s.append_vec(&self.to_vec()); + /// Returns a vector of bytes representing the bitfield + pub fn to_bytes(&self) -> Vec { + self.0.to_bytes() } } @@ -165,12 +78,13 @@ impl ssz::Decodable for BooleanBitfield { if (ssz::LENGTH_BYTES + len) > bytes.len() { return Err(ssz::DecodeError::TooShort); } + if len == 0 { Ok((BooleanBitfield::new(), index + ssz::LENGTH_BYTES)) } else { - let b = BooleanBitfield::from(&bytes[(index + 4)..(index + len + 4)]); + let field = BooleanBitfield::from_bytes(&bytes[(index + 4)..(index + len + 4)]); let index = index + ssz::LENGTH_BYTES + len; - Ok((b, index)) + Ok((field, index)) } } } @@ -178,149 +92,77 @@ impl ssz::Decodable for BooleanBitfield { #[cfg(test)] mod tests { use super::*; - use ssz::Decodable; #[test] - fn test_new_from_slice() { - let s = [0]; - let b = BooleanBitfield::from(&s[..]); - assert_eq!(b.len, 0); + fn test_empty_bitfield() { + let mut field = BooleanBitfield::new(); - let s = [255]; - let b = BooleanBitfield::from(&s[..]); - assert_eq!(b.len, 8); - - let s = [0, 1]; - let b = BooleanBitfield::from(&s[..]); - assert_eq!(b.len, 9); - - let s = [31]; - let b = BooleanBitfield::from(&s[..]); - assert_eq!(b.len, 5); - } - - #[test] - fn test_ssz_encoding() { - let mut b = BooleanBitfield::new(); - b.set_bit(8, true); - - let mut stream = ssz::SszStream::new(); - stream.append(&b); - - assert_eq!(stream.drain(), vec![0, 0, 0, 2, 0, 1]); - } - - /* - #[test] - fn test_ssz_decoding() { - /* - * Correct input - */ - let input = vec![0, 0, 0, 2, 0, 1]; - let (b, i) = BooleanBitfield::ssz_decode(&input, 0).unwrap(); - assert_eq!(i, 6); - assert_eq!(b.num_true_bits(), 1); - assert_eq!(b.get_bit(8), true); - - /* - * Input too long - */ - let mut input = vec![0, 0, 0, 2, 0, 1]; - input.push(42); - let (b, i) = BooleanBitfield::ssz_decode(&input, 0).unwrap(); - assert_eq!(i, 6); - assert_eq!(b.num_true_bits(), 1); - assert_eq!(b.get_bit(8), true); - - /* - * Input too short - */ - let input = vec![0, 0, 0, 2, 1]; - let res = BooleanBitfield::ssz_decode(&input, 0); - assert_eq!(res, Err(ssz::DecodeError::TooShort)); - } - */ - - #[test] - fn test_new_bitfield_len() { - let b = BooleanBitfield::new(); - assert_eq!(b.len(), 0); - assert_eq!(b.to_be_vec(), vec![0]); - - let b = BooleanBitfield::with_capacity(100); - assert_eq!(b.len(), 0); - assert_eq!(b.to_be_vec(), vec![0]); - } - - #[test] - fn test_bitfield_set() { - let mut b = BooleanBitfield::new(); - b.set_bit(0, false); - assert_eq!(b.to_be_vec(), [0]); - - b = BooleanBitfield::new(); - b.set_bit(7, true); - assert_eq!(b.to_be_vec(), [128]); - b.set_bit(7, false); - assert_eq!(b.to_be_vec(), [0]); - assert_eq!(b.len(), 8); - - b = BooleanBitfield::new(); - b.set_bit(7, true); - b.set_bit(0, true); - assert_eq!(b.to_be_vec(), [129]); - b.set_bit(7, false); - assert_eq!(b.to_be_vec(), [1]); - assert_eq!(b.len(), 8); - - b = BooleanBitfield::new(); - b.set_bit(8, true); - assert_eq!(b.to_be_vec(), [1, 0]); - assert_eq!(b.len(), 9); - b.set_bit(8, false); - assert_eq!(b.to_be_vec(), [0, 0]); - assert_eq!(b.len(), 9); - - b = BooleanBitfield::new(); - b.set_bit(15, true); - assert_eq!(b.to_be_vec(), [128, 0]); - b.set_bit(15, false); - assert_eq!(b.to_be_vec(), [0, 0]); - assert_eq!(b.len(), 16); - - b = BooleanBitfield::new(); - b.set_bit(8, true); - b.set_bit(15, true); - assert_eq!(b.to_be_vec(), [129, 0]); - b.set_bit(15, false); - assert_eq!(b.to_be_vec(), [1, 0]); - assert_eq!(b.len(), 16); - } - - #[test] - fn test_bitfield_get() { - let test_nums = vec![0, 8, 15, 42, 1337]; - for i in test_nums { - let mut b = BooleanBitfield::new(); - assert_eq!(b.get_bit(i), false); - b.set_bit(i, true); - assert_eq!(b.get_bit(i), true); - b.set_bit(i, true); + for _ in 0..100 { + let index: usize = rand::random(); + assert!(field.get(index).is_err()); + assert!(field.set(index, rand::random()).is_err()) } } + const INPUT: &[u8] = &[0b0000_0010, 0b0000_0010]; + #[test] - fn test_bitfield_num_true_bits() { - let mut b = BooleanBitfield::new(); - assert_eq!(b.num_true_bits(), 0); - b.set_bit(15, true); - assert_eq!(b.num_true_bits(), 1); - b.set_bit(15, false); - assert_eq!(b.num_true_bits(), 0); - b.set_bit(0, true); - b.set_bit(7, true); - b.set_bit(8, true); - b.set_bit(1337, true); - assert_eq!(b.num_true_bits(), 4); + fn test_get_from_bitfield() { + let field = BooleanBitfield::from_bytes(INPUT); + let unset = field.get(0).unwrap(); + assert!(!unset); + let set = field.get(6).unwrap(); + assert!(set); + let set = field.get(14).unwrap(); + assert!(set); + } + + #[test] + fn test_set_for_bitfield() { + let mut field = BooleanBitfield::from_bytes(INPUT); + let previous = field.set(10, true).unwrap(); + assert!(!previous); + let previous = field.get(10).unwrap(); + assert!(previous); + let previous = field.set(6, false).unwrap(); + assert!(previous); + let previous = field.get(6).unwrap(); + assert!(!previous); + } + + #[test] + fn test_highest_set_bit() { + let field = BooleanBitfield::from_bytes(INPUT); + assert_eq!(field.highest_set_bit().unwrap(), 14); + + let field = BooleanBitfield::new(); + assert_eq!(field.highest_set_bit(), None); + } + + #[test] + fn test_len() { + let field = BooleanBitfield::from_bytes(INPUT); + assert_eq!(field.len(), 16); + + let field = BooleanBitfield::new(); + assert_eq!(field.len(), 0); + } + + #[test] + fn test_num_set_bits() { + let field = BooleanBitfield::from_bytes(INPUT); + assert_eq!(field.num_set_bits(), 2); + + let field = BooleanBitfield::new(); + assert_eq!(field.num_set_bits(), 0); + } + + #[test] + fn test_to_bytes() { + let field = BooleanBitfield::from_bytes(INPUT); + assert_eq!(field.to_bytes(), INPUT); + + let field = BooleanBitfield::new(); + assert_eq!(field.to_bytes(), vec![]); } }