Add database_extra module to ethcore-blockchain

ethcore/blockchain/src/database_extras.rs

@@ -0,0 +1,53 @@
+// Copyright 2015-2019 Parity Technologies (UK) Ltd.
+// This file is part of Parity Ethereum.
+
+// Parity Ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Provides a `DatabaseExtras` trait that defines an interface to query for block data not
+//! contained in a TraceDB.
+
+use common_types::BlockNumber;
+use ethereum_types::H256;
+use ethcore_db::keys::TransactionAddress;
+
+use crate::blockchain::{BlockProvider, BlockChain};
+
+/// `DatabaseExtras` provides an interface to query extra data which is not stored in TraceDB,
+/// but necessary to work correctly.
+pub trait DatabaseExtras {
+	/// Returns hash of given block number.
+	fn block_hash(&self, block_number: BlockNumber) -> Option<H256>;
+
+	/// Returns hash of transaction at given position.
+	fn transaction_hash(&self, block_number: BlockNumber, tx_position: usize) -> Option<H256>;
+}
+
+/// Bridge between TraceDB and Blockchain.
+impl DatabaseExtras for BlockChain {
+	fn block_hash(&self, block_number: BlockNumber) -> Option<H256> {
+		(self as &dyn BlockProvider).block_hash(block_number)
+	}
+
+	fn transaction_hash(&self, block_number: BlockNumber, tx_position: usize) -> Option<H256> {
+		(self as &dyn BlockProvider).block_hash(block_number)
+			.and_then(|block_hash| {
+				let tx_address = TransactionAddress {
+					block_hash,
+					index: tx_position
+				};
+				self.transaction(&tx_address)
+			})
+			.map(|tx| tx.hash())
+	}
+}