Merge pull request #1950 from carver/transaction-apply-hook

Call a new hook when a transaction is applied

Author: carver

eth/abc.py

@@ -2666,6 +2666,25 @@ def get_block(self) -> BlockAPI:
         """
         ...
 
+    #
+    # Hooks
+    #
+
+    def transaction_applied_hook(
+            self,
+            transaction_index: int,
+            transactions: Sequence[SignedTransactionAPI],
+            base_header: BlockHeaderAPI,
+            partial_header: BlockHeaderAPI,
+            computation: ComputationAPI,
+            receipt: ReceiptAPI) -> None:
+        """
+        A hook for a subclass to use as a way to note that a transaction was applied.
+        This only gets triggered as part of `apply_all_transactions`, which is called
+        by `block_import`.
+        """
+        pass
+
     #
     # Execution
     #

eth/chains/base.py

@@ -468,7 +468,10 @@ def import_block(self,
             )
 
         base_header_for_import = self.create_header_from_parent(parent_header)
-        block_result = self.get_vm(base_header_for_import).import_block(block)
+        # Make a copy of the empty header, adding in the expected amount of gas used. This
+        #   allows for richer logging in the VM.
+        annotated_header = base_header_for_import.copy(gas_used=block.header.gas_used)
+        block_result = self.get_vm(annotated_header).import_block(block)
         imported_block = block_result.block
 
         # Validate the imported block.

eth/vm/base.py

@@ -227,7 +227,8 @@ def apply_all_transactions(
         transactions: Sequence[SignedTransactionAPI],
         base_header: BlockHeaderAPI
     ) -> Tuple[BlockHeaderAPI, Tuple[ReceiptAPI, ...], Tuple[ComputationAPI, ...]]:
-        if base_header.block_number != self.get_header().block_number:
+        vm_header = self.get_header()
+        if base_header.block_number != vm_header.block_number:
             raise ValidationError(
                 f"This VM instance must only work on block #{self.get_header().block_number}, "
                 f"but the target header has block #{base_header.block_number}"
@@ -238,7 +239,7 @@ def apply_all_transactions(
         previous_header = base_header
         result_header = base_header
 
-        for transaction in transactions:
+        for transaction_index, transaction in enumerate(transactions):
             try:
                 snapshot = self.state.snapshot()
                 receipt, computation = self.apply_transaction(
@@ -254,6 +255,15 @@ def apply_all_transactions(
             receipts.append(receipt)
             computations.append(computation)
 
+            self.transaction_applied_hook(
+                transaction_index,
+                transactions,
+                vm_header,
+                result_header,
+                computation,
+                receipt,
+            )
+
         receipts_tuple = tuple(receipts)
         computations_tuple = tuple(computations)
 
@@ -286,7 +296,9 @@ def import_block(self, block: BlockAPI) -> BlockAndMetaWitness:
         execution_context = self.create_execution_context(
             block.header, self.previous_hashes, self.chain_context)
 
-        header = self.get_header()
+        # Zero out the gas_used before applying transactions. Each applied transaction will
+        #   increase the gas used in the final new_header.
+        header = self.get_header().copy(gas_used=0)
         # we need to re-initialize the `state` to update the execution context.
         self._state = self.get_state_class()(self.chaindb.db, execution_context, header.state_root)
 

newsfragments/1950.feature.rst

@@ -0,0 +1,3 @@
+Add a new hook :meth:`eth.abc.VirtualMachineAPI.transaction_applied_hook` which is triggered after
+each transaction in ``apply_all_transactions``, which is called by ``import_block``. The first use
+case is reporting progress in the middle of Beam Sync.