Update function docs to detail shallow copy behavior (#2855)

ethereumjs · Jul 4, 2023 · d7131f5 · d7131f5
1 parent 629c80f
commit d7131f5
Show file tree

Hide file tree

Showing 5 changed files with 22 additions and 1 deletion.
diff --git a/packages/blockchain/src/types.ts b/packages/blockchain/src/types.ts
@@ -44,7 +44,7 @@ export interface BlockchainInterface {
   ): Promise<number>
 
   /**
-   * Returns a copy of the blockchain
+   * Returns a shallow copy of the blockchain that may share state with the original
    */
   shallowCopy(): BlockchainInterface
 

diff --git a/packages/evm/src/evm.ts b/packages/evm/src/evm.ts
@@ -1018,6 +1018,15 @@ export class EVM implements EVMInterface {
     if (this._common.isActivatedEIP(1153)) this._transientStorage.clear()
   }
 
+  /**
+   * This method copies the EVM, current HF and EIP settings
+   * and returns a new EVM instance.
+   *
+   * Note: this is only a shallow copy and both EVM instances
+   * will point to the same underlying state DB.
+   *
+   * @returns EVMInterface
+   */
   public shallowCopy(): EVMInterface {
     const common = this._common.copy()
     common.setHardfork(this._common.hardfork())

diff --git a/packages/statemanager/src/ethersStateManager.ts b/packages/statemanager/src/ethersStateManager.ts
@@ -51,6 +51,11 @@ export class EthersStateManager implements EVMStateManagerInterface {
     this.originalStorageCache = new OriginalStorageCache(this.getContractStorage.bind(this))
   }
 
+  /**
+   * Note that the returned statemanager will share the same JsonRpcProvider as the original
+   *
+   * @returns EthersStateManager
+   */
   shallowCopy(): EthersStateManager {
     const newState = new EthersStateManager({
       provider: this.provider,

diff --git a/packages/util/src/mapDB.ts b/packages/util/src/mapDB.ts
@@ -40,6 +40,11 @@ export class MapDB<
     }
   }
 
+  /**
+   * Note that the returned shallow copy will share the underlying database with the original
+   *
+   * @returns DB
+   */
   shallowCopy(): DB<TKey, TValue> {
     return new MapDB<TKey, TValue>(this._database)
   }

diff --git a/packages/vm/src/vm.ts b/packages/vm/src/vm.ts
@@ -218,6 +218,8 @@ export class VM {
 
   /**
    * Returns a copy of the {@link VM} instance.
+   *
+   * Note that the returned copy will share the same db as the original for the blockchain and the statemanager
    */
   async shallowCopy(): Promise<VM> {
     const common = this._common.copy()