Add safe and finalized block tags support (#853)

* Add `safe` and `finalized` block tags support

* prettier

client/rpc-core/src/types/block_number.rs

@@ -41,6 +41,12 @@ pub enum BlockNumber {
 	Earliest,
 	/// Pending block (being mined)
 	Pending,
+	/// The most recent crypto-economically secure block.
+	/// There is no difference between Ethereum's `safe` and `finalized`
+	/// in Substrate finality gadget.
+	Safe,
+	/// The most recent crypto-economically secure block.
+	Finalized,
 }
 
 impl Default for BlockNumber {
@@ -86,6 +92,8 @@ impl Serialize for BlockNumber {
 			BlockNumber::Latest => serializer.serialize_str("latest"),
 			BlockNumber::Earliest => serializer.serialize_str("earliest"),
 			BlockNumber::Pending => serializer.serialize_str("pending"),
+			BlockNumber::Safe => serializer.serialize_str("safe"),
+			BlockNumber::Finalized => serializer.serialize_str("finalized"),
 		}
 	}
 }
@@ -98,7 +106,7 @@ impl<'a> Visitor<'a> for BlockNumberVisitor {
 	fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
 		write!(
 			formatter,
-			"a block number or 'latest', 'earliest' or 'pending'"
+			"a block number or 'latest', 'safe', 'finalized', 'earliest' or 'pending'"
 		)
 	}
 
@@ -163,6 +171,8 @@ impl<'a> Visitor<'a> for BlockNumberVisitor {
 			"latest" => Ok(BlockNumber::Latest),
 			"earliest" => Ok(BlockNumber::Earliest),
 			"pending" => Ok(BlockNumber::Pending),
+			"safe" => Ok(BlockNumber::Safe),
+			"finalized" => Ok(BlockNumber::Finalized),
 			_ if value.starts_with("0x") => u64::from_str_radix(&value[2..], 16)
 				.map(BlockNumber::Num)
 				.map_err(|e| Error::custom(format!("Invalid block number: {}", e))),
@@ -196,6 +206,8 @@ mod tests {
 			BlockNumber::Num(number) => Some(number),
 			BlockNumber::Earliest => Some(0),
 			BlockNumber::Latest => Some(1000),
+			BlockNumber::Safe => Some(999),
+			BlockNumber::Finalized => Some(999),
 			BlockNumber::Pending => Some(1001),
 			_ => None,
 		}
@@ -208,13 +220,17 @@ mod tests {
 		let bn_u64: BlockNumber = serde_json::from_str(r#"420"#).unwrap();
 		let bn_tag_earliest: BlockNumber = serde_json::from_str(r#""earliest""#).unwrap();
 		let bn_tag_latest: BlockNumber = serde_json::from_str(r#""latest""#).unwrap();
+		let bn_tag_safe: BlockNumber = serde_json::from_str(r#""safe""#).unwrap();
+		let bn_tag_finalized: BlockNumber = serde_json::from_str(r#""finalized""#).unwrap();
 		let bn_tag_pending: BlockNumber = serde_json::from_str(r#""pending""#).unwrap();
 
 		assert_eq!(match_block_number(bn_dec).unwrap(), 42);
 		assert_eq!(match_block_number(bn_hex).unwrap(), 69);
 		assert_eq!(match_block_number(bn_u64).unwrap(), 420);
 		assert_eq!(match_block_number(bn_tag_earliest).unwrap(), 0);
 		assert_eq!(match_block_number(bn_tag_latest).unwrap(), 1000);
+		assert_eq!(match_block_number(bn_tag_safe).unwrap(), 999);
+		assert_eq!(match_block_number(bn_tag_finalized).unwrap(), 999);
 		assert_eq!(match_block_number(bn_tag_pending).unwrap(), 1001);
 	}
 }

client/rpc/src/lib.rs

@@ -81,6 +81,8 @@ pub mod frontier_backend_client {
 			BlockNumber::Latest => Some(BlockId::Hash(client.info().best_hash)),
 			BlockNumber::Earliest => Some(BlockId::Number(Zero::zero())),
 			BlockNumber::Pending => None,
+			BlockNumber::Safe => Some(BlockId::Hash(client.info().finalized_hash)),
+			BlockNumber::Finalized => Some(BlockId::Hash(client.info().finalized_hash)),
 		})
 	}
 

ts-tests/package.json

@@ -23,7 +23,7 @@
     "truffle": "^5.1.62",
     "ts-node": "^8.10.2",
     "typescript": "^3.9.6",
-    "web3": "^1.3.4"
+    "web3": "^1.8.0-rc.0"
   },
   "devDependencies": {
     "@types/chai-as-promised": "^7.1.5",

ts-tests/tests/test-block-tags.ts

@@ -0,0 +1,30 @@
+import { expect } from "chai";
+import { step } from "mocha-steps";
+
+import { GENESIS_ACCOUNT, GENESIS_ACCOUNT_PRIVATE_KEY, GENESIS_ACCOUNT_BALANCE, EXISTENTIAL_DEPOSIT } from "./config";
+import { createAndFinalizeBlock, describeWithFrontier, customRequest } from "./util";
+
+describeWithFrontier("Frontier RPC (BlockNumber tags)", (context) => {
+	before("Send some transactions across blocks", async function () {
+		// block #1 finalized
+		await createAndFinalizeBlock(context.web3);
+		// block #2 not finalized
+		await createAndFinalizeBlock(context.web3, false);
+	});
+
+	step("`earliest` returns genesis", async function () {
+		expect((await context.web3.eth.getBlock("earliest")).number).to.equal(0);
+	});
+
+	step("`latest` returns `BlockchainInfo::best_hash` number", async function () {
+		expect((await context.web3.eth.getBlock("latest")).number).to.equal(2);
+	});
+
+	step("`finalized` uses `BlockchainInfo::finalized_hash`  number", async function () {
+		expect((await context.web3.eth.getBlock("finalized")).number).to.equal(1);
+	});
+
+	step("`safe` is an alias for `finalized` in Polkadot", async function () {
+		expect((await context.web3.eth.getBlock("safe")).number).to.equal(1);
+	});
+});

ts-tests/tests/util.ts

@@ -41,8 +41,8 @@ export async function customRequest(web3: Web3, method: string, params: any[]) {
 
 // Create a block and finalize it.
 // It will include all previously executed transactions since the last finalized block.
-export async function createAndFinalizeBlock(web3: Web3) {
-	const response = await customRequest(web3, "engine_createBlock", [true, true, null]);
+export async function createAndFinalizeBlock(web3: Web3, finalize: boolean = true) {
+	const response = await customRequest(web3, "engine_createBlock", [true, finalize, null]);
 	if (!response.result) {
 		throw new Error(`Unexpected result: ${JSON.stringify(response)}`);
 	}