199 lines
7.0 KiB
Rust
199 lines
7.0 KiB
Rust
//! Async RedJubjub batch verifier service
|
|
|
|
use std::{
|
|
future::Future,
|
|
mem,
|
|
pin::Pin,
|
|
task::{Context, Poll},
|
|
};
|
|
|
|
use futures::{future::BoxFuture, FutureExt};
|
|
use once_cell::sync::Lazy;
|
|
use rand::thread_rng;
|
|
|
|
use tokio::sync::watch;
|
|
use tower::{util::ServiceFn, Service};
|
|
use tower_batch_control::{Batch, BatchControl};
|
|
use tower_fallback::Fallback;
|
|
|
|
use zebra_chain::primitives::redjubjub::*;
|
|
|
|
use crate::BoxError;
|
|
|
|
use super::{spawn_fifo, spawn_fifo_and_convert};
|
|
|
|
#[cfg(test)]
|
|
mod tests;
|
|
|
|
/// The type of the batch verifier.
|
|
type BatchVerifier = batch::Verifier;
|
|
|
|
/// The type of verification results.
|
|
type VerifyResult = Result<(), Error>;
|
|
|
|
/// The type of the batch sender channel.
|
|
type Sender = watch::Sender<Option<VerifyResult>>;
|
|
|
|
/// The type of the batch item.
|
|
/// This is a `RedJubjubItem`.
|
|
pub type Item = batch::Item;
|
|
|
|
/// Global batch verification context for RedJubjub signatures.
|
|
///
|
|
/// This service transparently batches contemporaneous signature verifications,
|
|
/// handling batch failures by falling back to individual verification.
|
|
///
|
|
/// Note that making a `Service` call requires mutable access to the service, so
|
|
/// you should call `.clone()` on the global handle to create a local, mutable
|
|
/// handle.
|
|
pub static VERIFIER: Lazy<
|
|
Fallback<
|
|
Batch<Verifier, Item>,
|
|
ServiceFn<fn(Item) -> BoxFuture<'static, Result<(), BoxError>>>,
|
|
>,
|
|
> = Lazy::new(|| {
|
|
Fallback::new(
|
|
Batch::new(
|
|
Verifier::default(),
|
|
super::MAX_BATCH_SIZE,
|
|
None,
|
|
super::MAX_BATCH_LATENCY,
|
|
),
|
|
// We want to fallback to individual verification if batch verification fails,
|
|
// so we need a Service to use.
|
|
//
|
|
// Because we have to specify the type of a static, we need to be able to
|
|
// write the type of the closure and its return value. But both closures and
|
|
// async blocks have unnameable types. So instead we cast the closure to a function
|
|
// (which is possible because it doesn't capture any state), and use a BoxFuture
|
|
// to erase the result type.
|
|
// (We can't use BoxCloneService to erase the service type, because it is !Sync.)
|
|
tower::service_fn(
|
|
(|item: Item| Verifier::verify_single_spawning(item).boxed()) as fn(_) -> _,
|
|
),
|
|
)
|
|
});
|
|
|
|
/// RedJubjub signature verifier service
|
|
pub struct Verifier {
|
|
/// A batch verifier for RedJubjub signatures.
|
|
batch: BatchVerifier,
|
|
|
|
/// A channel for broadcasting the result of a batch to the futures for each batch item.
|
|
///
|
|
/// Each batch gets a newly created channel, so there is only ever one result sent per channel.
|
|
/// Tokio doesn't have a oneshot multi-consumer channel, so we use a watch channel.
|
|
tx: Sender,
|
|
}
|
|
|
|
impl Default for Verifier {
|
|
fn default() -> Self {
|
|
let batch = BatchVerifier::default();
|
|
let (tx, _) = watch::channel(None);
|
|
Self { batch, tx }
|
|
}
|
|
}
|
|
|
|
impl Verifier {
|
|
/// Returns the batch verifier and channel sender from `self`,
|
|
/// replacing them with a new empty batch.
|
|
fn take(&mut self) -> (BatchVerifier, Sender) {
|
|
// Use a new verifier and channel for each batch.
|
|
let batch = mem::take(&mut self.batch);
|
|
|
|
let (tx, _) = watch::channel(None);
|
|
let tx = mem::replace(&mut self.tx, tx);
|
|
|
|
(batch, tx)
|
|
}
|
|
|
|
/// Synchronously process the batch, and send the result using the channel sender.
|
|
/// This function blocks until the batch is completed.
|
|
fn verify(batch: BatchVerifier, tx: Sender) {
|
|
let result = batch.verify(thread_rng());
|
|
let _ = tx.send(Some(result));
|
|
}
|
|
|
|
/// Flush the batch using a thread pool, and return the result via the channel.
|
|
/// This returns immediately, usually before the batch is completed.
|
|
fn flush_blocking(&mut self) {
|
|
let (batch, tx) = self.take();
|
|
|
|
// Correctness: Do CPU-intensive work on a dedicated thread, to avoid blocking other futures.
|
|
//
|
|
// We don't care about execution order here, because this method is only called on drop.
|
|
tokio::task::block_in_place(|| rayon::spawn_fifo(|| Self::verify(batch, tx)));
|
|
}
|
|
|
|
/// Flush the batch using a thread pool, and return the result via the channel.
|
|
/// This function returns a future that becomes ready when the batch is completed.
|
|
async fn flush_spawning(batch: BatchVerifier, tx: Sender) {
|
|
// Correctness: Do CPU-intensive work on a dedicated thread, to avoid blocking other futures.
|
|
let _ = tx.send(spawn_fifo(move || batch.verify(thread_rng())).await.ok());
|
|
}
|
|
|
|
/// Verify a single item using a thread pool, and return the result.
|
|
async fn verify_single_spawning(item: Item) -> Result<(), BoxError> {
|
|
// Correctness: Do CPU-intensive work on a dedicated thread, to avoid blocking other futures.
|
|
spawn_fifo_and_convert(move || item.verify_single()).await
|
|
}
|
|
}
|
|
|
|
impl Service<BatchControl<Item>> for Verifier {
|
|
type Response = ();
|
|
type Error = BoxError;
|
|
type Future = Pin<Box<dyn Future<Output = Result<(), BoxError>> + Send + 'static>>;
|
|
|
|
fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
|
|
Poll::Ready(Ok(()))
|
|
}
|
|
|
|
fn call(&mut self, req: BatchControl<Item>) -> Self::Future {
|
|
match req {
|
|
BatchControl::Item(item) => {
|
|
tracing::trace!("got item");
|
|
self.batch.queue(item);
|
|
let mut rx = self.tx.subscribe();
|
|
|
|
Box::pin(async move {
|
|
match rx.changed().await {
|
|
Ok(()) => {
|
|
// We use a new channel for each batch,
|
|
// so we always get the correct batch result here.
|
|
let result = rx.borrow()
|
|
.ok_or("threadpool unexpectedly dropped response channel sender. Is Zebra shutting down?")?;
|
|
|
|
if result.is_ok() {
|
|
tracing::trace!(?result, "validated redjubjub signature");
|
|
metrics::counter!("signatures.redjubjub.validated").increment(1);
|
|
} else {
|
|
tracing::trace!(?result, "invalid redjubjub signature");
|
|
metrics::counter!("signatures.redjubjub.invalid").increment(1);
|
|
}
|
|
|
|
result.map_err(BoxError::from)
|
|
}
|
|
Err(_recv_error) => panic!("verifier was dropped without flushing"),
|
|
}
|
|
})
|
|
}
|
|
|
|
BatchControl::Flush => {
|
|
tracing::trace!("got redjubjub flush command");
|
|
|
|
let (batch, tx) = self.take();
|
|
|
|
Box::pin(Self::flush_spawning(batch, tx).map(Ok))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Drop for Verifier {
|
|
fn drop(&mut self) {
|
|
// We need to flush the current batch in case there are still any pending futures.
|
|
// This returns immediately, usually before the batch is completed.
|
|
self.flush_blocking();
|
|
}
|
|
}
|