Remove the distribution cache

It's a notable bandwidth/performance improvement, yet it's not ready. We need a
dedicated Distribution struct which is managed by the wallet and passed in.
While we can do that now, it's not currently worth the effort.

Cargo.lock

@@ -4768,7 +4768,6 @@ dependencies = [
 name = "monero-serai"
 version = "0.1.4-alpha"
 dependencies = [
- "async-lock",
  "async-trait",
  "base58-monero",
  "curve25519-dalek",

coins/monero/Cargo.toml

@@ -47,8 +47,6 @@ frost = { package = "modular-frost", path = "../../crypto/frost", version = "0.8
 
 monero-generators = { path = "generators", version = "0.4", default-features = false }
 
-async-lock = { version = "3", default-features = false, optional = true }
-
 hex-literal = "0.4"
 hex = { version = "0.4", default-features = false, features = ["alloc"] }
 serde = { version = "1", default-features = false, features = ["derive", "alloc"] }
@@ -93,8 +91,6 @@ std = [
 
   "monero-generators/std",
 
-  "async-lock?/std",
-
   "hex/std",
   "serde/std",
   "serde_json/std",
@@ -102,7 +98,6 @@ std = [
   "base58-monero/std",
 ]
 
-cache-distribution = ["async-lock"]
 http-rpc = ["digest_auth", "simple-request", "tokio"]
 multisig = ["transcript", "frost", "std"]
 binaries = ["tokio/rt-multi-thread", "tokio/macros", "http-rpc"]

coins/monero/src/wallet/decoys.rs

@@ -1,13 +1,5 @@
 use std_shims::{vec::Vec, collections::HashSet};
 
-#[cfg(feature = "cache-distribution")]
-use std_shims::sync::OnceLock;
-
-#[cfg(all(feature = "cache-distribution", not(feature = "std")))]
-use std_shims::sync::Mutex;
-#[cfg(all(feature = "cache-distribution", feature = "std"))]
-use async_lock::Mutex;
-
 use zeroize::{Zeroize, ZeroizeOnDrop};
 
 use rand_core::{RngCore, CryptoRng};
@@ -29,16 +21,6 @@ const BLOCKS_PER_YEAR: usize = 365 * 24 * 60 * 60 / BLOCK_TIME;
 #[allow(clippy::cast_precision_loss)]
 const TIP_APPLICATION: f64 = (DEFAULT_LOCK_WINDOW * BLOCK_TIME) as f64;
 
-// TODO: Resolve safety of this in case a reorg occurs/the network changes
-// TODO: Update this when scanning a block, as possible
-#[cfg(feature = "cache-distribution")]
-static DISTRIBUTION_CELL: OnceLock<Mutex<Vec<u64>>> = OnceLock::new();
-#[cfg(feature = "cache-distribution")]
-#[allow(non_snake_case)]
-fn DISTRIBUTION() -> &'static Mutex<Vec<u64>> {
-  DISTRIBUTION_CELL.get_or_init(|| Mutex::new(Vec::with_capacity(3000000)))
-}
-
 #[allow(clippy::too_many_arguments)]
 async fn select_n<'a, R: RngCore + CryptoRng, RPC: RpcConnection>(
   rng: &mut R,
@@ -158,14 +140,6 @@ async fn select_decoys<R: RngCore + CryptoRng, RPC: RpcConnection>(
   inputs: &[SpendableOutput],
   fingerprintable_canonical: bool,
 ) -> Result<Vec<Decoys>, RpcError> {
-  #[cfg(feature = "cache-distribution")]
-  #[cfg(not(feature = "std"))]
-  let mut distribution = DISTRIBUTION().lock();
-  #[cfg(feature = "cache-distribution")]
-  #[cfg(feature = "std")]
-  let mut distribution = DISTRIBUTION().lock().await;
-
-  #[cfg(not(feature = "cache-distribution"))]
   let mut distribution = vec![];
 
   let decoy_count = ring_len - 1;

tests/no-std/Cargo.toml

@@ -36,4 +36,4 @@ dkg = { path = "../../crypto/dkg", default-features = false }
 bitcoin-serai = { path = "../../coins/bitcoin", default-features = false, features = ["hazmat"] }
 
 monero-generators = { path = "../../coins/monero/generators", default-features = false }
-monero-serai = { path = "../../coins/monero", default-features = false, features = ["cache-distribution"] }
+monero-serai = { path = "../../coins/monero", default-features = false }