use bit_vec::{self, BitVec};
use ff::{Field, PrimeField, PrimeFieldRepr, ScalarEngine};
use futures::Future;
use groupy::{CurveAffine, CurveProjective};
use log::{info, warn};
use std::io;
use std::iter;
use std::sync::Arc;
use super::multicore::Worker;
use super::SynthesisError;
use crate::gpu;
pub trait SourceBuilder<G: CurveAffine>: Send + Sync + 'static + Clone {
type Source: Source<G>;
fn new(self) -> Self::Source;
fn get(self) -> (Arc<Vec<G>>, usize);
}
pub trait Source<G: CurveAffine> {
fn add_assign_mixed(
&mut self,
to: &mut <G as CurveAffine>::Projective,
) -> Result<(), SynthesisError>;
fn skip(&mut self, amt: usize) -> Result<(), SynthesisError>;
}
impl<G: CurveAffine> SourceBuilder<G> for (Arc<Vec<G>>, usize) {
type Source = (Arc<Vec<G>>, usize);
fn new(self) -> (Arc<Vec<G>>, usize) {
(self.0.clone(), self.1)
}
fn get(self) -> (Arc<Vec<G>>, usize) {
(self.0.clone(), self.1)
}
}
impl<G: CurveAffine> Source<G> for (Arc<Vec<G>>, usize) {
fn add_assign_mixed(
&mut self,
to: &mut <G as CurveAffine>::Projective,
) -> Result<(), SynthesisError> {
if self.0.len() <= self.1 {
return Err(io::Error::new(
io::ErrorKind::UnexpectedEof,
"expected more bases from source",
)
.into());
}
if self.0[self.1].is_zero() {
return Err(SynthesisError::UnexpectedIdentity);
}
to.add_assign_mixed(&self.0[self.1]);
self.1 += 1;
Ok(())
}
fn skip(&mut self, amt: usize) -> Result<(), SynthesisError> {
if self.0.len() <= self.1 {
return Err(io::Error::new(
io::ErrorKind::UnexpectedEof,
"expected more bases from source",
)
.into());
}
self.1 += amt;
Ok(())
}
}
pub trait QueryDensity {
type Iter: Iterator<Item = bool>;
fn iter(self) -> Self::Iter;
fn get_query_size(self) -> Option<usize>;
}
#[derive(Clone)]
pub struct FullDensity;
impl AsRef<FullDensity> for FullDensity {
fn as_ref(&self) -> &FullDensity {
self
}
}
impl<'a> QueryDensity for &'a FullDensity {
type Iter = iter::Repeat<bool>;
fn iter(self) -> Self::Iter {
iter::repeat(true)
}
fn get_query_size(self) -> Option<usize> {
None
}
}
pub struct DensityTracker {
bv: BitVec,
total_density: usize,
}
impl<'a> QueryDensity for &'a DensityTracker {
type Iter = bit_vec::Iter<'a>;
fn iter(self) -> Self::Iter {
self.bv.iter()
}
fn get_query_size(self) -> Option<usize> {
Some(self.bv.len())
}
}
impl DensityTracker {
pub fn new() -> DensityTracker {
DensityTracker {
bv: BitVec::new(),
total_density: 0,
}
}
pub fn add_element(&mut self) {
self.bv.push(false);
}
pub fn inc(&mut self, idx: usize) {
if !self.bv.get(idx).unwrap() {
self.bv.set(idx, true);
self.total_density += 1;
}
}
pub fn get_total_density(&self) -> usize {
self.total_density
}
}
fn multiexp_inner<Q, D, G, S>(
pool: &Worker,
bases: S,
density_map: D,
exponents: Arc<Vec<<<G::Engine as ScalarEngine>::Fr as PrimeField>::Repr>>,
mut skip: u32,
c: u32,
handle_trivial: bool,
) -> Box<dyn Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
where
for<'a> &'a Q: QueryDensity,
D: Send + Sync + 'static + Clone + AsRef<Q>,
G: CurveAffine,
S: SourceBuilder<G>,
{
let this = {
let bases = bases.clone();
let exponents = exponents.clone();
let density_map = density_map.clone();
pool.compute(move || {
let mut acc = G::Projective::zero();
let mut bases = bases.new();
let mut buckets = vec![<G as CurveAffine>::Projective::zero(); (1 << c) - 1];
let zero = <G::Engine as ScalarEngine>::Fr::zero().into_repr();
let one = <G::Engine as ScalarEngine>::Fr::one().into_repr();
for (&exp, density) in exponents.iter().zip(density_map.as_ref().iter()) {
if density {
if exp == zero {
bases.skip(1)?;
} else if exp == one {
if handle_trivial {
bases.add_assign_mixed(&mut acc)?;
} else {
bases.skip(1)?;
}
} else {
let mut exp = exp;
exp.shr(skip);
let exp = exp.as_ref()[0] % (1 << c);
if exp != 0 {
bases.add_assign_mixed(&mut buckets[(exp - 1) as usize])?;
} else {
bases.skip(1)?;
}
}
}
}
let mut running_sum = G::Projective::zero();
for exp in buckets.into_iter().rev() {
running_sum.add_assign(&exp);
acc.add_assign(&running_sum);
}
Ok(acc)
})
};
skip += c;
if skip >= <G::Engine as ScalarEngine>::Fr::NUM_BITS {
Box::new(this)
} else {
Box::new(
this.join(multiexp_inner(
pool,
bases,
density_map,
exponents,
skip,
c,
false,
))
.map(move |(this, mut higher)| {
for _ in 0..c {
higher.double();
}
higher.add_assign(&this);
higher
}),
)
}
}
pub fn multiexp<Q, D, G, S>(
pool: &Worker,
bases: S,
density_map: D,
exponents: Arc<Vec<<<G::Engine as ScalarEngine>::Fr as PrimeField>::Repr>>,
kern: &mut Option<gpu::LockedMultiexpKernel<G::Engine>>,
) -> Box<dyn Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
where
for<'a> &'a Q: QueryDensity,
D: Send + Sync + 'static + Clone + AsRef<Q>,
G: CurveAffine,
G::Engine: paired::Engine,
S: SourceBuilder<G>,
{
if let Some(ref mut kern) = kern {
if let Ok(p) = kern.with(|k: &mut gpu::MultiexpKernel<G::Engine>| {
let mut exps = vec![exponents[0]; exponents.len()];
let mut n = 0;
for (&e, d) in exponents.iter().zip(density_map.as_ref().iter()) {
if d {
exps[n] = e;
n += 1;
}
}
let (bss, skip) = bases.clone().get();
k.multiexp(pool, bss, Arc::new(exps.clone()), skip, n)
}) {
return Box::new(pool.compute(move || Ok(p)));
}
}
let c = if exponents.len() < 32 {
3u32
} else {
(f64::from(exponents.len() as u32)).ln().ceil() as u32
};
if let Some(query_size) = density_map.as_ref().get_query_size() {
assert!(query_size == exponents.len());
}
let future = multiexp_inner(pool, bases, density_map, exponents, 0, c, true);
#[cfg(feature = "gpu")]
{
let result = future.wait();
Box::new(pool.compute(move || result))
}
#[cfg(not(feature = "gpu"))]
future
}
#[cfg(feature = "pairing")]
#[test]
fn test_with_bls12() {
fn naive_multiexp<G: CurveAffine>(
bases: Arc<Vec<G>>,
exponents: Arc<Vec<<G::Scalar as PrimeField>::Repr>>,
) -> G::Projective {
assert_eq!(bases.len(), exponents.len());
let mut acc = G::Projective::zero();
for (base, exp) in bases.iter().zip(exponents.iter()) {
acc.add_assign(&base.mul(*exp));
}
acc
}
use paired::{bls12_381::Bls12, Engine};
use rand;
const SAMPLES: usize = 1 << 14;
let rng = &mut rand::thread_rng();
let v = Arc::new(
(0..SAMPLES)
.map(|_| <Bls12 as ScalarEngine>::Fr::random(rng).into_repr())
.collect::<Vec<_>>(),
);
let g = Arc::new(
(0..SAMPLES)
.map(|_| <Bls12 as Engine>::G1::random(rng).into_affine())
.collect::<Vec<_>>(),
);
let naive = naive_multiexp(g.clone(), v.clone());
let pool = Worker::new();
let fast = multiexp(&pool, (g, 0), FullDensity, v).wait().unwrap();
assert_eq!(naive, fast);
}
pub fn create_multiexp_kernel<E>(_log_d: usize, priority: bool) -> Option<gpu::MultiexpKernel<E>>
where
E: paired::Engine,
{
match gpu::MultiexpKernel::<E>::create(priority) {
Ok(k) => {
info!("GPU Multiexp kernel instantiated!");
Some(k)
}
Err(e) => {
warn!("Cannot instantiate GPU Multiexp kernel! Error: {}", e);
None
}
}
}
#[cfg(feature = "gpu")]
#[test]
pub fn gpu_multiexp_consistency() {
use paired::bls12_381::Bls12;
use std::time::Instant;
const MAX_LOG_D: usize = 20;
const START_LOG_D: usize = 10;
let mut kern = Some(gpu::LockedMultiexpKernel::<Bls12>::new(MAX_LOG_D, false));
let pool = Worker::new();
let rng = &mut rand::thread_rng();
let mut bases = (0..(1 << 10))
.map(|_| <Bls12 as paired::Engine>::G1::random(rng).into_affine())
.collect::<Vec<_>>();
for _ in 10..START_LOG_D {
bases = [bases.clone(), bases.clone()].concat();
}
for log_d in START_LOG_D..(MAX_LOG_D + 1) {
let g = Arc::new(bases.clone());
let samples = 1 << log_d;
println!("Testing Multiexp for {} elements...", samples);
let v = Arc::new(
(0..samples)
.map(|_| <Bls12 as ScalarEngine>::Fr::random(rng).into_repr())
.collect::<Vec<_>>(),
);
let mut now = Instant::now();
let gpu = multiexp(&pool, (g.clone(), 0), FullDensity, v.clone(), &mut kern)
.wait()
.unwrap();
let gpu_dur = now.elapsed().as_secs() * 1000 as u64 + now.elapsed().subsec_millis() as u64;
println!("GPU took {}ms.", gpu_dur);
now = Instant::now();
let cpu = multiexp(&pool, (g.clone(), 0), FullDensity, v.clone(), &mut None)
.wait()
.unwrap();
let cpu_dur = now.elapsed().as_secs() * 1000 as u64 + now.elapsed().subsec_millis() as u64;
println!("CPU took {}ms.", cpu_dur);
println!("Speedup: x{}", cpu_dur as f32 / gpu_dur as f32);
assert_eq!(cpu, gpu);
println!("============================");
bases = [bases.clone(), bases.clone()].concat();
}
}