optimize Params<C>::read()

halo2_proofs/src/arithmetic.rs

@@ -1,6 +1,8 @@
 //! This module provides common utilities, traits and structures for group,
 //! field and polynomial arithmetic.
 
+use std::io;
+
 use super::multicore;
 pub use ff::Field;
 use group::{
@@ -352,6 +354,42 @@ pub fn parallelize<T: Send, F: Fn(&mut [T], usize) + Send + Sync + Clone>(v: &mu
     });
 }
 
+/// This simple utility function will parallelize an operation returning `io::Result` that is to be
+/// performed over a mutable slice.
+pub fn parallelize_is_ok<
+    T: Send,
+    F: Fn(&mut [T], usize) -> io::Result<()> + Send + Sync + Clone,
+>(
+    v: &mut [T],
+    f: F,
+) -> io::Result<()> {
+    let n = v.len();
+    let num_threads = multicore::current_num_threads();
+    let mut chunk = (n as usize) / num_threads;
+    if chunk < num_threads {
+        chunk = n as usize;
+    }
+
+    let mut is_ok = true;
+    multicore::scope(|scope| {
+        for (chunk_num, v) in v.chunks_mut(chunk).enumerate() {
+            let f = f.clone();
+            scope.spawn(move |_| {
+                let start = chunk_num * chunk;
+                is_ok = is_ok && f(v, start).is_ok();
+            });
+        }
+    });
+
+    match is_ok {
+        true => Ok(()),
+        false => Err(io::Error::new(
+            io::ErrorKind::Other,
+            "invalid point encoding in proof",
+        )),
+    }
+}
+
 fn log2_floor(num: usize) -> u32 {
     assert!(num > 0);
 

halo2_proofs/src/helpers.rs

@@ -11,6 +11,11 @@ pub(crate) trait CurveRead: CurveAffine {
         Option::from(Self::from_bytes(&compressed))
             .ok_or_else(|| io::Error::new(io::ErrorKind::Other, "invalid point encoding in proof"))
     }
+
+    fn convert_from_bytes(compressed: Self::Repr) -> io::Result<Self> {
+        Option::from(Self::from_bytes(&compressed))
+            .ok_or_else(|| io::Error::new(io::ErrorKind::Other, "invalid point encoding in proof"))
+    }
 }
 
 impl<C: CurveAffine> CurveRead for C {}

halo2_proofs/src/poly/commitment.rs

@@ -5,7 +5,8 @@
 
 use super::{Coeff, LagrangeCoeff, Polynomial, MSM};
 use crate::arithmetic::{
-    best_fft, best_multiexp, parallelize, CurveAffine, CurveExt, Engine, FieldExt, Group,
+    best_fft, best_multiexp, parallelize, parallelize_is_ok, CurveAffine, CurveExt, Engine,
+    FieldExt, Group,
 };
 use crate::helpers::CurveRead;
 
@@ -177,12 +178,45 @@ impl<C: CurveAffine> Params<C> {
         let k = u32::from_le_bytes(k);
         let n = 1 << k;
 
-        let g: Vec<C> = (0..n)
-            .map(|_| C::read(&mut reader))
-            .collect::<Result<_, _>>()?;
-        let g_lagrange: Vec<C> = (0..n)
-            .map(|_| C::read(&mut reader))
-            .collect::<Result<_, _>>()?;
+        let mut g_compressed: Vec<C::Repr> = vec![C::Repr::default(); n];
+        for i in 0..n {
+            reader.read_exact(g_compressed[i].as_mut())?;
+        }
+
+        let mut g_lagrange_compressed: Vec<C::Repr> = vec![C::Repr::default(); n];
+        for i in 0..n {
+            reader.read_exact(g_lagrange_compressed[i].as_mut())?;
+        }
+
+        let g: Vec<C> = {
+            let mut g = vec![C::default(); n];
+            parallelize_is_ok(&mut g, |g, chunks| {
+                for (i, g) in g.iter_mut().enumerate() {
+                    let tmp = C::convert_from_bytes(g_compressed[chunks + i]);
+                    *g = match tmp {
+                        Ok(ele) => ele,
+                        Err(e) => return Err(e),
+                    }
+                }
+                Ok(())
+            })?;
+            g
+        };
+
+        let g_lagrange: Vec<C> = {
+            let mut g_lagrange = vec![C::default(); n];
+            parallelize_is_ok(&mut g_lagrange, |g_lagrange, chunks| {
+                for (i, g_lagrange) in g_lagrange.iter_mut().enumerate() {
+                    let tmp = C::convert_from_bytes(g_lagrange_compressed[chunks + i]);
+                    *g_lagrange = match tmp {
+                        Ok(ele) => ele,
+                        Err(e) => return Err(e),
+                    }
+                }
+                Ok(())
+            })?;
+            g_lagrange
+        };
 
         let mut additional_data_len = [0u8; 4];
         reader.read_exact(&mut additional_data_len[..])?;
@@ -193,7 +227,7 @@ impl<C: CurveAffine> Params<C> {
 
         Ok(Params {
             k,
-            n,
+            n: n as u64,
             g,
             g_lagrange,
             additional_data,