chore: add compile time flags to disable rayon (#240)

* maybe-rayon package

* refactor code

* remove rayon from dep

* fix features

* remove default

* conditionally compile the DasContext constructor

* use multithread and singlethreaded

* turn on multithreading for c_kzg

* add feature flags

Cargo.toml

@@ -7,6 +7,7 @@ members = [
     "bindings/nim/rust_code",
     "bindings/csharp/rust_code",
     "eip7594",
+    "maybe_rayon",
     "cryptography/bls12_381",
     "cryptography/kzg_multi_open",
     "cryptography/polynomial",
@@ -31,6 +32,7 @@ bls12_381 = { package = "crate_crypto_internal_eth_kzg_bls12_381", version = "0.
 polynomial = { package = "crate_crypto_internal_eth_kzg_polynomial", version = "0.4.1", path = "cryptography/polynomial" }
 erasure_codes = { package = "crate_crypto_internal_eth_kzg_erasure_codes", version = "0.4.1", path = "cryptography/erasure_codes" }
 rust_eth_kzg = { version = "0.4.1", path = "eip7594" }
+maybe_rayon = { package = "crate_crypto_internal_eth_kzg_maybe_rayon", version = "0.4.1", path = "maybe_rayon" }
 kzg_multi_open = { package = "crate_crypto_kzg_multi_open_fk20", version = "0.4.1", path = "cryptography/kzg_multi_open" }
 c_eth_kzg = { version = "0.4.1", path = "bindings/c" }
 hex = "0.4.3"

bindings/c/Cargo.toml

@@ -13,7 +13,7 @@ crate-type = ["staticlib", "cdylib", "rlib"]
 
 [dependencies]
 libc = "0.2.2"
-rust_eth_kzg = { workspace = true }
+rust_eth_kzg = { workspace = true, features = ["multithreaded"] }
 
 [build-dependencies]
 cbindgen = "0.26.0"

bindings/node/Cargo.toml

@@ -17,7 +17,7 @@ napi = { version = "2.12.2", default-features = false, features = [
     "async",
 ] }
 napi-derive = "2.12.2"
-rust_eth_kzg = { workspace = true }
+rust_eth_kzg = { workspace = true, features = ["multithreaded"] }
 
 [build-dependencies]
 napi-build = "2.0.1"

cryptography/bls12_381/Cargo.toml

@@ -31,6 +31,9 @@ subtle = { version = ">=2.5.0, <3.0" }
 criterion = "0.5.1"
 rand = "0.8.4"
 
+[features]
+blst-no-threads = ["blst/no-threads"]
+
 [[bench]]
 name = "benchmark"
 harness = false

cryptography/kzg_multi_open/Cargo.toml

@@ -13,14 +13,18 @@ repository = { workspace = true }
 [dependencies]
 bls12_381 = { workspace = true }
 polynomial = { workspace = true }
+maybe_rayon = { workspace = true }
 hex = { workspace = true }
-rayon = { workspace = true }
 sha2 = "0.10.8"
 
 [dev-dependencies]
 criterion = "0.5.1"
 rand = "0.8.4"
 
+[features]
+singlethreaded = ["bls12_381/blst-no-threads"]
+multithreaded = ["maybe_rayon/multithreaded"]
+
 [[bench]]
 name = "benchmark"
 harness = false

cryptography/kzg_multi_open/src/fk20/batch_toeplitz.rs

@@ -3,8 +3,8 @@ use bls12_381::{
     fixed_base_msm::{FixedBaseMSM, UsePrecomp},
     g1_batch_normalize, G1Point, G1Projective,
 };
+use maybe_rayon::prelude::*;
 use polynomial::domain::Domain;
-use rayon::prelude::*;
 
 /// BatchToeplitzMatrixVecMul allows one to compute multiple matrix vector multiplications
 /// and sum them together.
@@ -43,7 +43,7 @@ impl BatchToeplitzMatrixVecMul {
 
         // Precompute the FFT of the vectors, since they do not change per matrix-vector multiplication
         let vectors: Vec<Vec<G1Point>> = vectors
-            .into_par_iter()
+            .maybe_par_iter()
             .map(|vector| {
                 let vector_projective = vector
                     .iter()
@@ -61,7 +61,7 @@ impl BatchToeplitzMatrixVecMul {
         //
         // This is a trade-off between storage and computation, where storage grows exponentially.
         let precomputed_table: Vec<_> = transposed_msm_vectors
-            .into_par_iter()
+            .maybe_into_par_iter()
             .map(|v| FixedBaseMSM::new(v, use_precomp))
             .collect();
 
@@ -87,22 +87,23 @@ impl BatchToeplitzMatrixVecMul {
         );
 
         // Embed Toeplitz matrices into circulant matrices
-        let circulant_matrices = matrices.into_iter().map(CirculantMatrix::from_toeplitz);
+        let circulant_matrices = matrices
+            .maybe_into_par_iter()
+            .map(CirculantMatrix::from_toeplitz);
 
         // Perform circulant matrix-vector multiplication between all of the matrices and vectors
         // and sum them together.
         //
         // Transpose the circulant matrices so that we convert a group of hadamard products into a group of
         // inner products.
         let col_ffts: Vec<_> = circulant_matrices
-            .into_iter()
+            .maybe_into_par_iter()
             .map(|matrix| self.circulant_domain.fft_scalars(matrix.row))
             .collect();
         let msm_scalars = transpose(col_ffts);
 
-        let result: Vec<_> = self
-            .precomputed_fft_vectors
-            .iter()
+        let result: Vec<_> = (&self.precomputed_fft_vectors)
+            .maybe_par_iter()
             .zip(msm_scalars)
             .map(|(points, scalars)| points.msm(scalars))
             .collect();

eip7594/Cargo.toml

@@ -13,10 +13,14 @@ kzg_multi_open = { workspace = true }
 bls12_381 = { workspace = true }
 hex = { workspace = true }
 erasure_codes = { workspace = true }
-rayon = { workspace = true }
+rayon = { workspace = true, optional = true }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 
+[features]
+singlethreaded = ["rayon", "kzg_multi_open/singlethreaded"]
+multithreaded = ["rayon", "kzg_multi_open/multithreaded"]
+
 [dev-dependencies]
 criterion = "0.5.1"
 rand = "0.8.4"
@@ -28,3 +32,4 @@ serde_yaml = "0.9.34"
 [[bench]]
 name = "benchmark"
 harness = false
+# required-features = ["multithreaded"]

eip7594/src/lib.rs

@@ -1,9 +1,14 @@
+#[cfg(all(feature = "singlethreaded", feature = "multithreaded"))]
+compile_error!("feature_a and feature_b cannot be enabled simultaneously");
+
 pub mod constants;
 mod errors;
 mod prover;
 mod serialization;
 mod trusted_setup;
 mod verifier;
+#[macro_use]
+pub(crate) mod macros;
 
 pub use bls12_381::fixed_base_msm::UsePrecomp;
 // Exported types
@@ -54,9 +59,12 @@ pub type CellIndex = kzg_multi_open::CosetIndex;
 
 use constants::{BYTES_PER_BLOB, BYTES_PER_CELL, BYTES_PER_COMMITMENT};
 use prover::ProverContext;
+use verifier::VerifierContext;
+
+#[cfg(feature = "multithreaded")]
 use rayon::ThreadPool;
+#[cfg(feature = "multithreaded")]
 use std::sync::Arc;
-use verifier::VerifierContext;
 
 /// ThreadCount indicates whether we want to use a single thread or multiple threads
 #[derive(Debug, Copy, Clone)]
@@ -65,19 +73,23 @@ pub enum ThreadCount {
     Single,
     /// Initializes the threadpool with the number of threads
     /// denoted by this enum variant.
+    #[cfg(feature = "multithreaded")]
     Multi(usize),
     /// Initializes the threadpool with a sensible default number of
     /// threads. This is currently set to `RAYON_NUM_THREADS`.
+    #[cfg(feature = "multithreaded")]
     SensibleDefault,
 }
 
 impl From<ThreadCount> for usize {
     fn from(value: ThreadCount) -> Self {
         match value {
             ThreadCount::Single => 1,
+            #[cfg(feature = "multithreaded")]
             ThreadCount::Multi(num_threads) => num_threads,
             // Setting this to `0` will tell ThreadPool to use
             // `RAYON_NUM_THREADS`.
+            #[cfg(feature = "multithreaded")]
             ThreadCount::SensibleDefault => 0,
         }
     }
@@ -86,29 +98,37 @@ impl From<ThreadCount> for usize {
 /// The context that will be used to create and verify opening proofs.
 #[derive(Debug)]
 pub struct DASContext {
+    #[cfg(feature = "multithreaded")]
     thread_pool: Arc<ThreadPool>,
     pub prover_ctx: ProverContext,
     pub verifier_ctx: VerifierContext,
 }
 
+#[cfg(feature = "multithreaded")]
 impl Default for DASContext {
     fn default() -> Self {
         let trusted_setup = TrustedSetup::default();
         const DEFAULT_NUM_THREADS: ThreadCount = ThreadCount::Single;
         DASContext::with_threads(&trusted_setup, DEFAULT_NUM_THREADS, UsePrecomp::No)
     }
 }
+#[cfg(not(feature = "multithreaded"))]
+impl Default for DASContext {
+    fn default() -> Self {
+        let trusted_setup = TrustedSetup::default();
+
+        DASContext::new(&trusted_setup, UsePrecomp::No)
+    }
+}
 
 impl DASContext {
+    #[cfg(feature = "multithreaded")]
     pub fn with_threads(
         trusted_setup: &TrustedSetup,
         num_threads: ThreadCount,
-        // This parameter indicates whether we should allocate memory
-        // in order to speed up proof creation. Heuristics show that
-        // if pre-computations are desired, one should set the
-        // width value to `8` for optimal storage and performance tradeoffs.
         use_precomp: UsePrecomp,
     ) -> Self {
+        #[cfg(feature = "multithreaded")]
         let thread_pool = std::sync::Arc::new(
             rayon::ThreadPoolBuilder::new()
                 .num_threads(num_threads.into())
@@ -117,12 +137,28 @@ impl DASContext {
         );
 
         DASContext {
+            #[cfg(feature = "multithreaded")]
             thread_pool,
             prover_ctx: ProverContext::new(trusted_setup, use_precomp),
             verifier_ctx: VerifierContext::new(trusted_setup),
         }
     }
 
+    #[cfg(not(feature = "multithreaded"))]
+    pub fn new(
+        trusted_setup: &TrustedSetup,
+        // This parameter indicates whether we should allocate memory
+        // in order to speed up proof creation. Heuristics show that
+        // if pre-computations are desired, one should set the
+        // width value to `8` for optimal storage and performance tradeoffs.
+        use_precomp: UsePrecomp,
+    ) -> Self {
+        DASContext {
+            prover_ctx: ProverContext::new(trusted_setup, use_precomp),
+            verifier_ctx: VerifierContext::new(trusted_setup),
+        }
+    }
+
     pub fn prover_ctx(&self) -> &ProverContext {
         &self.prover_ctx
     }

eip7594/src/macros.rs

@@ -0,0 +1,13 @@
+#[macro_export]
+macro_rules! with_optional_threadpool {
+    ($self:expr, $body:expr) => {{
+        #[cfg(feature = "multithreaded")]
+        {
+            $self.thread_pool.install(|| $body)
+        }
+        #[cfg(not(feature = "multithreaded"))]
+        {
+            $body
+        }
+    }};
+}

eip7594/src/prover.rs

@@ -14,7 +14,8 @@ use crate::{
         deserialize_blob_to_scalars, serialize_cells_and_proofs, serialize_g1_compressed,
     },
     trusted_setup::TrustedSetup,
-    BlobRef, Cell, CellIndex, CellRef, DASContext, KZGCommitment, KZGProof,
+    with_optional_threadpool, BlobRef, Cell, CellIndex, CellRef, DASContext, KZGCommitment,
+    KZGProof,
 };
 
 /// Context object that is used to call functions in the prover API.
@@ -64,7 +65,7 @@ impl DASContext {
     ///
     /// The matching function in the specs is: https://github.com/ethereum/consensus-specs/blob/13ac373a2c284dc66b48ddd2ef0a10537e4e0de6/specs/deneb/polynomial-commitments.md#blob_to_kzg_commitment
     pub fn blob_to_kzg_commitment(&self, blob: BlobRef) -> Result<KZGCommitment, Error> {
-        self.thread_pool.install(|| {
+        with_optional_threadpool!(self, {
             // Deserialize the blob into scalars.
             let scalars = deserialize_blob_to_scalars(blob)?;
 
@@ -86,7 +87,7 @@ impl DASContext {
         &self,
         blob: BlobRef,
     ) -> Result<([Cell; CELLS_PER_EXT_BLOB], [KZGProof; CELLS_PER_EXT_BLOB]), Error> {
-        self.thread_pool.install(|| {
+        with_optional_threadpool!(self, {
             // Deserialization
             //
             let scalars = deserialize_blob_to_scalars(blob)?;
@@ -116,7 +117,7 @@ impl DASContext {
         cell_indices: Vec<CellIndex>,
         cells: Vec<CellRef>,
     ) -> Result<([Cell; CELLS_PER_EXT_BLOB], [KZGProof; CELLS_PER_EXT_BLOB]), Error> {
-        self.thread_pool.install(|| {
+        with_optional_threadpool!(self, {
             // Recover polynomial
             //
             let poly_coeff = self.recover_polynomial_coeff(cell_indices, cells)?;

eip7594/src/verifier.rs

@@ -9,7 +9,7 @@ use crate::{
     errors::Error,
     serialization::{deserialize_cells, deserialize_compressed_g1_points},
     trusted_setup::TrustedSetup,
-    Bytes48Ref, CellIndex, CellRef, DASContext,
+    with_optional_threadpool, Bytes48Ref, CellIndex, CellRef, DASContext,
 };
 use bls12_381::Scalar;
 use erasure_codes::{BlockErasureIndices, ReedSolomon};
@@ -103,7 +103,7 @@ impl DASContext {
         cells: Vec<CellRef>,
         proofs_bytes: Vec<Bytes48Ref>,
     ) -> Result<(), Error> {
-        self.thread_pool.install(|| {
+        with_optional_threadpool!(self, {
             let (deduplicated_commitments, row_indices) = deduplicate_with_indices(commitments);
             // Validation
             //

maybe_rayon/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "crate_crypto_internal_eth_kzg_maybe_rayon"
+description = "This crate provides an implementation of a wrapper around the rayon crate"
+version = { workspace = true }
+authors = { workspace = true }
+edition = { workspace = true }
+license = { workspace = true }
+rust-version = { workspace = true }
+repository = { workspace = true }
+
+[dependencies]
+rayon = { workspace = true, optional = true }
+
+[features]
+multithreaded = ["rayon"]

maybe_rayon/src/lib.rs

@@ -0,0 +1,17 @@
+#[cfg(feature = "multithreaded")]
+mod multi_threaded;
+#[cfg(not(feature = "multithreaded"))]
+mod single_threaded;
+
+#[cfg(feature = "multithreaded")]
+pub use multi_threaded::*;
+#[cfg(not(feature = "multithreaded"))]
+pub use single_threaded::*;
+
+pub mod prelude {
+    pub use crate::MaybeParallelRefExt;
+    pub use crate::MaybeParallelRefMutExt;
+    pub use crate::*;
+    #[cfg(feature = "multithreaded")]
+    pub use rayon::prelude::*;
+}

maybe_rayon/src/multi_threaded.rs

@@ -0,0 +1,29 @@
+pub use rayon::iter::IntoParallelIterator;
+pub use rayon::iter::IntoParallelRefIterator;
+pub use rayon::iter::IntoParallelRefMutIterator;
+pub use rayon::iter::ParallelIterator;
+
+pub trait MaybeParallelExt: IntoParallelIterator {
+    fn maybe_into_par_iter(self) -> <Self as IntoParallelIterator>::Iter
+    where
+        Self: Sized,
+    {
+        self.into_par_iter()
+    }
+}
+
+pub trait MaybeParallelRefExt: for<'a> IntoParallelRefIterator<'a> {
+    fn maybe_par_iter(&self) -> <Self as IntoParallelRefIterator>::Iter {
+        self.par_iter()
+    }
+}
+
+pub trait MaybeParallelRefMutExt: for<'a> IntoParallelRefMutIterator<'a> {
+    fn maybe_par_iter_mut(&mut self) -> <Self as IntoParallelRefMutIterator>::Iter {
+        self.par_iter_mut()
+    }
+}
+
+impl<T: IntoParallelIterator> MaybeParallelExt for T {}
+impl<T: for<'a> IntoParallelRefIterator<'a>> MaybeParallelRefExt for T {}
+impl<T: for<'a> IntoParallelRefMutIterator<'a>> MaybeParallelRefMutExt for T {}