feat: add query param to add a tip, partialFee, and priority field to each extrinsic for /node/transaction-pool

docs/src/openapi-v1.yaml

@@ -584,6 +584,14 @@ paths:
       description: Returns the extrinsics that the node knows of that have not
         been included in a block.
       operationId: getNodeTransactionPool
+      paramaters:
+      - name: includeFee
+        in: query
+        description: Boolean representing whether or not to include tips, partialFee, and priority in each extrinsic.
+        required: false
+        schema:
+          type: boolean
+          default: false
       responses:
         "200":
           description: successful operation
@@ -2765,6 +2773,18 @@ components:
                   type: string
                   format: hex
                   description: Scale encoded extrinsic.
+                tip:
+                  type: string
+                  format: unsignedInteger
+                  description: The tip included in the extrinsic. Only included if the query param `includeFee` is set to true.
+                priority:
+                  type: string
+                  format: unsignedInteger
+                  description: Computed priority of an extrinsic. Only included if the query param `includeFee` is set to true.
+                partialFee:
+                  type: string
+                  format: unsignedInteger
+                  description: Provided `partialFee` of an extrinsic. Only included if the query param `includeFee` is set to true.
     TransactionSuccess:
       type: object
       properties:

src/controllers/node/NodeTransactionPoolController.ts

@@ -27,6 +27,7 @@ import AbstractController from '../AbstractController';
  * - `pool`: array of
  * 		- `hash`: H256 hash of the extrinsic.
  * 		- `encodedExtrinsic`: Scale encoded extrinsic.
+ * 		- `tip`: Tip included into the extrinsic. Available when the `tip` query param is set to true.
  */
 export default class NodeTransactionPoolController extends AbstractController<NodeTransactionPoolService> {
 	constructor(api: ApiPromise) {
@@ -39,18 +40,20 @@ export default class NodeTransactionPoolController extends AbstractController<No
 	}
 
 	/**
-	 ** GET pending extrinsics from the Substrate node.
+	 * GET pending extrinsics from the Substrate node.
 	 *
-	 * @param _req Express Request
+	 * @param req Express Request, accepts the query param `tip`
 	 * @param res Express Response
 	 */
 	private getNodeTransactionPool: RequestHandler = async (
-		_req,
+		{ query: { includeFee } },
 		res
 	): Promise<void> => {
+		const shouldIncludeFee = includeFee === 'true';
+
 		NodeTransactionPoolController.sanitizedSend(
 			res,
-			await this.service.fetchTransactionPool()
+			await this.service.fetchTransactionPool(shouldIncludeFee)
 		);
 	};
 }

src/services/node/NodeTransactionPoolService.spec.ts

@@ -17,12 +17,17 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/no-unsafe-member-access */
 import { sanitizeNumbers } from '../../sanitize/sanitizeNumbers';
+import { polkadotRegistryV9190 } from '../../test-helpers/registries';
 import {
 	// blockHash789629,
 	defaultMockApi,
 	pendingExtrinsics,
+	queryInfoBalancesTransfer,
+	queryInfoCouncilVote,
 } from '../test-helpers/mock';
 import transactionPoolResponse from '../test-helpers/responses/node/transactionPool.json';
+import transactionPoolWithTipResponse from '../test-helpers/responses/node/transactionPoolWithTip.json';
+import transactionPoolWithTipOperationalResponse from '../test-helpers/responses/node/transactionPoolWithTipOperational.json';
 import { NodeTransactionPoolService } from '.';
 
 const nodeTranstionPoolService = new NodeTransactionPoolService(defaultMockApi);
@@ -32,10 +37,10 @@ describe('NodeTransactionPoolService', () => {
 		it('works when ApiPromiseWorks (no txs)', async () => {
 			expect(
 				sanitizeNumbers(
-					await nodeTranstionPoolService
-						.fetchTransactionPool
+					await nodeTranstionPoolService.fetchTransactionPool(
 						// blockHash789629
-						()
+						false
+					)
 				)
 			).toStrictEqual({ pool: [] });
 		});
@@ -52,14 +57,58 @@ describe('NodeTransactionPoolService', () => {
 
 			expect(
 				sanitizeNumbers(
-					await nodeTranstionPoolService
-						.fetchTransactionPool
+					await nodeTranstionPoolService.fetchTransactionPool(
 						// blockHash789629
-						()
+						false
+					)
 				)
 			).toStrictEqual(transactionPoolResponse);
 
 			(defaultMockApi.rpc.author as any).pendingExtrinsics = pendingExtrinsics;
 		});
+
+		it('works when query param `includeFee` is set to true for normal extrinsics', async () => {
+			// This test does not use the same metadata in defaultMockApi. It changes it to v9190,
+			// and sets it back to the default value after.
+			const normalExt = polkadotRegistryV9190.createType(
+				'Extrinsic',
+				'0x4d028400d43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d0196a6cd1652fc83c449884f67e8f444587b69c5874512f1d746ff6f062a097b2acedfe8d2e07915b4c93cc1c3b48a16ebccc1db8eb810146373ba53c9f42ab48e4500000284d717050300e281b7ec09fb8420ca7ba3fbd627fbe203ff04b2ba0777ae1d8a6942257af0230700e8764817'
+			);
+			const pool = polkadotRegistryV9190.createType('Vec<Extrinsic>', [
+				normalExt,
+			]);
+			(defaultMockApi.rpc.author as any).pendingExtrinsics = () =>
+				Promise.resolve().then(() => pool);
+
+			expect(
+				sanitizeNumbers(
+					await nodeTranstionPoolService.fetchTransactionPool(true)
+				)
+			).toStrictEqual(transactionPoolWithTipResponse);
+
+			(defaultMockApi.rpc.author as any).pendingExtrinsics = pendingExtrinsics;
+		});
+
+		it('works when query param `includeFee` is set to true for operational extrinsics', async () => {
+			const operationalExt = polkadotRegistryV9190.createType(
+				'Extrinsic',
+				'0x350284004adf51a47b72795366d52285e329229c836ea7bbfe139dbe8fa0700c4f86fc5601fc44dcd1994c111671b3577b02e391be8aff10f7ccf766f3189859ea343db041779a67f9357cba0ba051f83d63e45e7a88b5e2ca642181592052acd9f4ccc8821501c107000f03f2af187bbc8a4a2b5a28c2a3c2d85bf7e5b1700cbf1207a8e4c1eb7d8e7e4037350301'
+			);
+			const pool = polkadotRegistryV9190.createType('Vec<Extrinsic>', [
+				operationalExt,
+			]);
+			(defaultMockApi.rpc.author as any).pendingExtrinsics = () =>
+				Promise.resolve().then(() => pool);
+			(defaultMockApi.rpc.payment as any).queryInfo = queryInfoCouncilVote;
+
+			expect(
+				sanitizeNumbers(
+					await nodeTranstionPoolService.fetchTransactionPool(true)
+				)
+			).toStrictEqual(transactionPoolWithTipOperationalResponse);
+
+			(defaultMockApi.rpc.author as any).pendingExtrinsics = pendingExtrinsics;
+			(defaultMockApi.rpc.payment as any).queryInfo = queryInfoBalancesTransfer;
+		});
 	});
 });

src/services/node/NodeTransactionPoolService.ts

@@ -14,24 +14,172 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import { DispatchClass, Extrinsic, Weight } from '@polkadot/types/interfaces';
+import { u32 } from '@polkadot/types-codec';
+import BN from 'bn.js';
+
 import { INodeTransactionPool } from '../../types/responses';
 import { AbstractService } from '../AbstractService';
 
 export class NodeTransactionPoolService extends AbstractService {
-	async fetchTransactionPool(): Promise<INodeTransactionPool> {
+	/**
+	 * Fetch the transaction pool, and provide relevant extrinsic information.
+	 *
+	 * @param includeFee Whether or not to include the fee's and priority of a extrinsic
+	 * in the transaction pool.
+	 */
+	public async fetchTransactionPool(
+		includeFee: boolean
+	): Promise<INodeTransactionPool> {
 		const { api } = this;
-
 		const extrinsics = await api.rpc.author.pendingExtrinsics();
 
-		const pool = extrinsics.map((ext) => {
+		if (includeFee) {
+			const pool = await Promise.all(
+				extrinsics.map((ext) => this.extractExtrinsicInfo(ext))
+			);
+
 			return {
-				hash: ext.hash.toHex(),
-				encodedExtrinsic: ext.toHex(),
+				pool,
 			};
-		});
+		} else {
+			return {
+				pool: extrinsics.map((ext) => {
+					return {
+						hash: ext.hash.toHex(),
+						encodedExtrinsic: ext.toHex(),
+					};
+				}),
+			};
+		}
+	}
+
+	/**
+	 * Extract all information related to the extrinsic, and compute it's
+	 * priority in the transaction pool.
+	 *
+	 * @param ext Extrinsic we want to provide all the information for.
+	 */
+	private async extractExtrinsicInfo(ext: Extrinsic) {
+		const { api } = this;
+		const { hash, tip } = ext;
+		const {
+			class: c,
+			partialFee,
+			weight,
+		} = await api.rpc.payment.queryInfo(ext.toHex());
+		const priority = await this.computeExtPriority(ext, c, weight);
 
 		return {
-			pool,
+			hash: hash.toHex(),
+			encodedExtrinsic: ext.toHex(),
+			tip: tip.toString(),
+			priority: priority,
+			partialFee: partialFee,
 		};
 	}
+
+	/**
+	 * We calculate the priority of an extrinsic in the transaction pool depending
+	 * on its dispatch class, ie. 'normal', 'operational', 'mandatory'.
+	 *
+	 * The following formula can summarize the below logic.
+	 * tip * (max_block_{weight|length} / bounded_{weight|length})
+	 *
+	 * Please reference this link for more information
+	 * ref: https://github.com/paritytech/substrate/blob/fe5bf49290d166b9552f65e751d46ec592173ebd/frame/transaction-payment/src/lib.rs#L610
+	 *
+	 * @param ext
+	 * @param c
+	 * @param weight
+	 */
+	private async computeExtPriority(
+		ext: Extrinsic,
+		dispatchClass: DispatchClass,
+		weight: Weight
+	): Promise<string> {
+		const { api } = this;
+		const { tip, encodedLength: len } = ext;
+		const BN_ONE = new BN(1);
+		const sanitizedClass = this.defineDispatchClassType(dispatchClass);
+
+		const { maxBlock } = this.api.consts.system.blockWeights;
+		const maxLength: u32 =
+			this.api.consts.system.blockLength.max[sanitizedClass];
+		const boundedWeight = BN.min(BN.max(weight.toBn(), BN_ONE), maxBlock);
+		const boundedLength = BN.min(BN.max(new BN(len), BN_ONE), maxLength);
+		const maxTxPerBlockWeight = maxBlock.div(boundedWeight);
+		const maxTxPerBlockLength = maxLength.div(boundedLength);
+
+		const maxTxPerBlock = BN.min(maxTxPerBlockWeight, maxTxPerBlockLength);
+		const saturatedTip = tip.toBn().add(BN_ONE);
+		const scaledTip = this.maxReward(saturatedTip, maxTxPerBlock);
+
+		let priority: string;
+		switch (sanitizedClass) {
+			case 'normal': {
+				priority = scaledTip.toString();
+				break;
+			}
+			case 'mandatory': {
+				priority = scaledTip.toString();
+				break;
+			}
+			case 'operational': {
+				const { inclusionFee } = await api.rpc.payment.queryFeeDetails(
+					ext.toHex()
+				);
+				const { operationalFeeMultiplier } = this.api.consts.transactionPayment;
+
+				if (inclusionFee.isNone) {
+					// This is an unsigned_extrinsic, and does not have priority
+					priority = '0';
+					break;
+				}
+
+				const { baseFee, lenFee, adjustedWeightFee } = inclusionFee.unwrap();
+				const computedInclusionFee = baseFee.add(lenFee).add(adjustedWeightFee);
+				const finalFee = computedInclusionFee.add(tip.toBn());
+				const virtualTip = finalFee.mul(operationalFeeMultiplier);
+				const scaledVirtualTip = this.maxReward(virtualTip, maxTxPerBlock);
+
+				priority = scaledTip.add(scaledVirtualTip).toString();
+				break;
+			}
+			default: {
+				priority = '0';
+				break;
+			}
+		}
+
+		return priority;
+	}
+
+	/**
+	 * Explicitly define the type of class an extrinsic is.
+	 *
+	 * @param c DispatchClass of an extrinsic
+	 */
+	private defineDispatchClassType(
+		c: DispatchClass
+	): 'normal' | 'mandatory' | 'operational' {
+		const cString = c.type.toLowerCase();
+		if (cString === 'normal') return 'normal';
+		if (cString === 'mandatory') return 'mandatory';
+		if (cString === 'operational') return 'operational';
+
+		// This will never be reached, but is here to satisfy the TS compiler.
+		return 'normal';
+	}
+
+	/**
+	 * Multiply a value (tip) by its maxTxPerBlock multiplier.
+	 * ref: https://github.com/paritytech/substrate/blob/fe5bf49290d166b9552f65e751d46ec592173ebd/frame/transaction-payment/src/lib.rs#L633
+	 *
+	 * @param val Value to be multiplied by the maxTxPerBlock. Usually a tip.
+	 * @param maxTxPerBlock The minimum value between maxTxPerBlockWeight and maxTxPerBlockLength
+	 */
+	private maxReward(val: BN, maxTxPerBlock: BN): BN {
+		return val.mul(maxTxPerBlock);
+	}
 }