chore: Removed cache of pending transactions

We currently cache all pending transactions when they are read from the tx poo database. This causes significant memory usage however and is unnecessary. This PR removes this cache.

Co-authored-by: Phil Windle <[email protected]>

Author: PhilWindle

yarn-project/p2p/src/mem_pools/tx_pool/aztec_kv_tx_pool.ts

@@ -57,9 +57,6 @@ export class AztecKVTxPool
 
   #feePayerToTxHash: AztecAsyncMultiMap<string, string>;
 
-  /** In-memory mapping of pending tx hashes to the hydrated pending tx in the pool. */
-  #pendingTxs: Map<string, Tx>;
-
   /** In-memory set of txs that should not be evicted from the pool. */
   #nonEvictableTxs: Set<string>;
 
@@ -124,7 +121,6 @@ export class AztecKVTxPool
     this.#historicalHeaderToTxHash = store.openMultiMap('historicalHeaderToPendingTxHash');
     this.#feePayerToTxHash = store.openMultiMap('feePayerToPendingTxHash');
 
-    this.#pendingTxs = new Map<string, Tx>();
     this.#nonEvictableTxs = new Set<string>();
 
     this.#archivedTxs = archive.openMap('archivedTxs');
@@ -576,20 +572,12 @@ export class AztecKVTxPool
    * @returns The transaction, if found, 'undefined' otherwise.
    */
   private async getPendingTxByHash(txHash: TxHash | string): Promise<Tx | undefined> {
-    let key;
     if (typeof txHash === 'string') {
-      key = txHash;
       txHash = TxHash.fromString(txHash);
-    } else {
-      key = txHash.toString();
     }
 
-    if (this.#pendingTxs.has(key)) {
-      return this.#pendingTxs.get(key);
-    }
     const tx = await this.getTxByHash(txHash);
     if (tx) {
-      this.#pendingTxs.set(key, tx);
       return tx;
     }
     return undefined;
@@ -664,7 +652,6 @@ export class AztecKVTxPool
   // Assumes being called within a DB transaction
   private async removePendingTxIndicesInDbTx(tx: Tx, txHash: string): Promise<void> {
     await this.#pendingTxPriorityToHash.deleteValue(getPendingTxPriority(tx), txHash);
-    this.#pendingTxs.delete(txHash);
     await this.#historicalHeaderToTxHash.deleteValue(
       (await tx.data.constants.anchorBlockHeader.hash()).toString(),
       txHash,