avoid memory allocation during and_provides

Signed-off-by: Uncle Stinky <uncle.stinky@ghostchain.io>

README.md

@@ -346,7 +346,7 @@ sha256sum /etc/ghost/casper.json
 
 You should see:
 ```
-4645c7d39a64424d823f659d408070f8c90426117e7af147b0360697b2db7f4f  /etc/ghost/casper.json
+74f5a6df5e33dac94a8852ddfb73e472283bba0b30e260ca581919eb50c734db  /etc/ghost/casper.json
 ```
 
 Create running `ghost-node` service that starts on system boot using `--unit-file` flag.

pallets/weaver/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ghost-weaver"
-version = "0.0.14"
+version = "0.0.17"
 description = "Weaving a secure cryptographic tapestry across different external chains."
 license.workspace = true
 authors.workspace = true

pallets/weaver/src/lib.rs

@@ -616,6 +616,21 @@ pub mod pallet {
                         .propagate(true)
                         .build()
                 }
+                Call::pull_thread {
+                    network_id,
+                    session,
+                    thread_proof,
+                } => {
+                    let thread_context =
+                        Self::validate_thread(network_id, session, thread_proof)?;
+
+                    ValidTransaction::with_tag_prefix("WeaverThread")
+                        .priority(T::UnsignedPriority::get())
+                        .and_provides(thread_context.to_fixed_bytes())
+                        .longevity(LOCK_BLOCK_EXPIRATION)
+                        .propagate(true)
+                        .build()
+                }
                 _ => InvalidTransaction::Call.into(),
             }
         }
@@ -623,6 +638,31 @@ pub mod pallet {
 }
 
 impl<T: Config> Pallet<T> {
+    fn validate_thread(
+        network_id: &NetworkIdOf<T>,
+        session: &WeavingSession,
+        thread_proof: &ThreadProof<BalanceOf<T>>,
+    ) -> Result<H256, InvalidTransaction> {
+        let network_data = T::NetworkDataHandler::get(&network_id)
+            .ok_or(InvalidTransaction::BadProof)?;
+
+        let root_hash = LoomStates::<T>::get(&network_id, &session);
+        if root_hash == Default::default() {
+            return Err(InvalidTransaction::BadProof);
+        }
+
+        thread_proof
+            .verify_thread_proof(root_hash, *network_id, &network_data.gatekeeper)
+            .ok_or(InvalidTransaction::BadProof)?;
+
+        let pulled_thread_key = thread_proof.get_unique_key(*session, *network_id);
+        if PulledThreads::<T>::contains_key(&pulled_thread_key) {
+            return Err(InvalidTransaction::Stale);
+        }
+
+        Ok(pulled_thread_key)
+    }
+
     fn validate_attestation_signature<A>(
         attestation: &A,
         signature: &<T::AuthorityId as RuntimeAppPublic>::Signature,

pallets/weaver/src/types.rs

@@ -14,7 +14,6 @@ use ghost_helpers::{
     merkle_tree::verify_tree_proof,
     SubstrateBlake2Hasher, SubstrateKeccakHasher, UtxoSha2Hasher,
 };
-use ghost_traits::hashing::GhostHasher;
 
 use crate::{ExternalBlockNumber, ThreadId, WeavingSession};
 
@@ -350,8 +349,10 @@ where
 	{
         if EVM_MERKLE_DEPTH as usize != self.proof.len() { return None; }
 
+        let preimage_hash = self.get_preimage_hash(network_id)?;
+
         let proof_valid = verify_tree_proof::<SubstrateKeccakHasher, _>(
-            &self.get_preimage_slice(network_id).to_fixed_bytes(),
+            &preimage_hash.to_fixed_bytes(),
             self.proof.as_ref(),
             root_hash,
             self.proof_index,
@@ -362,22 +363,17 @@ where
         Some((self.receiver.clone(), self.amount))
     }
 
-    fn get_preimage_slice<NetworkId>(&self, network_id: NetworkId) -> H256
+    fn get_preimage_hash<NetworkId>(&self, network_id: NetworkId) -> Option<H256>
 	where
 		NetworkId: Copy + Clone + Eq + PartialEq + UniqueSaturatedInto<u64>,
 	{
         let slot_index_usize: usize = self.slot_index.unique_saturated_into();
-        let mut slot_values: Vec<H256> = self.slots.to_vec();
 
-        match slot_values.get_mut(slot_index_usize) {
-            Some(slot) => {
-                *slot = self.compute_arguments_hash(network_id);
-                cumulative_hash::<SubstrateKeccakHasher, _>(slot_values)
-            }
-            None => {
-                SubstrateKeccakHasher::empty()
-            }
-        }
+        self.slots.get(slot_index_usize)
+            .filter(|&&provided_hash| {
+                provided_hash == self.compute_arguments_hash(network_id)
+            })
+            .map(|_| cumulative_hash::<SubstrateKeccakHasher, _>(self.slots.iter()))
     }
 
     pub fn get_unique_key<NetworkId>(