find_nonce() + add_aux_pow async wrapper

binaries/cuprated/src/rpc/json.rs

@@ -1009,8 +1009,16 @@ async fn flush_cache(
     })
 }
 
-/// <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server.cpp#L2072-L2207>
+/// An async-friendly wrapper for [`add_aux_pow_inner`].
 async fn add_aux_pow(
+    state: CupratedRpcHandler,
+    request: AddAuxPowRequest,
+) -> Result<AddAuxPowResponse, Error> {
+    tokio::task::spawn_blocking(|| add_aux_pow_inner(state, request)).await?
+}
+
+/// <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server.cpp#L2072-L2207>
+fn add_aux_pow_inner(
     mut state: CupratedRpcHandler,
     request: AddAuxPowRequest,
 ) -> Result<AddAuxPowResponse, Error> {
@@ -1046,48 +1054,36 @@ async fn add_aux_pow(
         path_domain += 1;
     }
 
-    let mut nonce = 0_u32;
+    fn find_nonce(aux_pow_len: usize) -> Result<(u32, Box<[u32]>), Error> {
-    let mut collision = true;
+        // INVARIANT: this must be the same `.len()` as `aux_pow`
-    let mut slots: Box<[u32]> = vec![0; len].into_boxed_slice(); // INVARIANT: this must be the same `.len()` as `aux_pow`
+        let mut slots: Box<[u32]> = vec![u32::MAX; aux_pow_len].into_boxed_slice();
-
+        let mut slot_seen: Box<[bool]> = vec![false; aux_pow_len].into_boxed_slice();
-    for n in 0..u32::MAX {
-        nonce = n;
-
-        let slot_seen: Vec<bool> = vec![false; len];
-
-        collision = false;
-
-        slots.fill(u32::MAX);
 
+        for nonce in 0..u32::MAX {
             for i in &mut slots {
                 let slot_u32: u32 = todo!("const uint32_t slot = cryptonote::get_aux_slot(aux_pow[idx].first, nonce, aux_pow.size());");
                 let slot = u32_to_usize(slot_u32);
 
-            if slot >= len {
+                if slot >= aux_pow_len {
                     return Err(anyhow!("Computed slot is out of range"));
                 }
 
                 if slot_seen[slot] {
-                collision = true;
+                    return Ok((nonce, slots));
-                break;
                 }
 
                 slot_seen[slot] = true;
                 *i = slot_u32;
             }
 
-        if !collision {
+            slots.fill(u32::MAX);
-            break;
-        }
         }
 
-    let nonce = nonce;
+        Err(anyhow!("Failed to find a suitable nonce"))
-    let slots = slots;
-
-    if collision {
-        return Err(anyhow!("Failed to find a suitable nonce"));
     }
 
+    let (nonce, slots) = find_nonce(len)?;
+
     // FIXME: use iterator version.
     let (aux_pow_id_raw, aux_pow_raw) = {
         let mut aux_pow_id_raw = Vec::<[u8; 32]>::with_capacity(len);