Initial implementation (#1)

* Port most code to library

* Add deploy script

* Seperate from MyCrypto provider

* Add multi provider support

* Clean up types

* Actually export code

* Use eth-scan for multi provider support

* Remove eslint boolean rule

* Bump eth-scan

* Use native bigint

* Remove unnecesary comments

* Use generic parameter for reduce

Author: FrederikBolding

.eslintrc.json

@@ -74,8 +74,7 @@
             "ignoreRestSiblings": true,
             "argsIgnorePattern": "^_"
           }
-        ],
-        "@typescript-eslint/strict-boolean-expressions": ["error", { "allowNullableBoolean": true }]
+        ]
       },
       "parserOptions": {
         "project": ["./tsconfig.json"],

.github/workflows/deploy.yml

@@ -0,0 +1,55 @@
+name: Deploy
+
+on:
+  push:
+    branches:
+      - 'master'
+
+jobs:
+  deploy:
+    name: Deploy
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version:
+          - 12
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/[email protected]
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Cache Dependencies
+        uses: actions/[email protected]
+        with:
+          path: node_modules
+          key: yarn-${{ hashFiles('yarn.lock') }}
+
+      - name: Install Dependencies
+        run: yarn install --frozen-lockfile --ignore-scripts
+
+      - uses: JS-DevTools/npm-publish@v1
+        id: publish
+        with:
+          token: ${{ secrets.NPM_TOKEN }}
+
+      - name: Push tag
+        if: steps.publish.outputs.type != 'none'
+        id: tag_version
+        uses: mathieudutour/[email protected]
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          custom_tag: ${{ steps.publish.outputs.version }}
+
+      - name: Create a GitHub release
+        if: steps.publish.outputs.type != 'none'
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: ${{ steps.tag_version.outputs.new_tag }}
+          release_name: Release ${{ steps.tag_version.outputs.new_tag }}
+          body: ${{ steps.tag_version.outputs.changelog }}

package.json

@@ -29,7 +29,9 @@
     "prepare": "simple-git-hooks",
     "prepack": "yarn build"
   },
-  "dependencies": {},
+  "dependencies": {
+    "@mycrypto/eth-scan": "3.5.1"
+  },
   "devDependencies": {
     "@babel/cli": "^7.13.14",
     "@babel/core": "^7.13.14",

src/eip1559.test.ts

@@ -0,0 +1,163 @@
+import { estimateFees, FALLBACK_ESTIMATE } from './eip1559';
+
+const block = {
+  hash: '0x38b34c2313e148a0916406a204536c03e5bf77312c558d25d3b63d8a4e30af47',
+  parentHash: '0xc33eb2f6795e58cb9ad800bfeed0463a14c8a94a9e621de14fd05a782f1ffbd4',
+  number: 5219914,
+  timestamp: 1627469703,
+  nonce: '0x0000000000000000',
+  difficulty: 1,
+  gasLimit: 0x01c9c380,
+  gasUsed: 0x26aee4,
+  miner: '0x0000000000000000000000000000000000000000',
+  extraData:
+    '0xd883010a05846765746888676f312e31362e35856c696e757800000000000000a866c8e4b72c133037132849cf9419f32126bf93dfb5a42b092828fd4bfa5e8e2ce59121cb2516740c03af11225e5b6a2d9dad29cf4fe77a70af26c4ce30236601',
+  transactions: [],
+  baseFeePerGas: '0x2540be400'
+};
+
+const feeHistory = {
+  oldestBlock: '0x4fa645',
+  reward: [['0x0'], ['0x3b9aca00'], ['0x12a05f1f9'], ['0x3b9aca00'], ['0x12a05f1f9']],
+  baseFeePerGas: ['0x7', '0x7', '0x7', '0x7', '0x7', '0x7'],
+  gasUsedRatio: [0, 0.10772606666666666, 0.0084, 0.12964573239101315, 0.06693689580776942]
+};
+
+describe('estimateFees', () => {
+  afterEach(() => {
+    jest.resetAllMocks();
+  });
+  const mockProvider = {
+    send: jest.fn()
+  };
+  it('estimates without using priority fees', () => {
+    mockProvider.send.mockResolvedValueOnce(block);
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 10000000000n,
+      maxFeePerGas: 20000000000n,
+      maxPriorityFeePerGas: 3000000000n
+    });
+  });
+
+  it('estimates priority fees', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x174876e800' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 100000000000n,
+      maxFeePerGas: 160000000000n,
+      maxPriorityFeePerGas: 5000000000n
+    });
+  });
+
+  it('estimates priority fees removing low outliers', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return {
+          ...feeHistory,
+          reward: [
+            ['0x1'],
+            ['0x1'],
+            ['0x1'],
+            ['0x1'],
+            ['0x1'],
+            ['0x1a13b8600'],
+            ['0x12a05f1f9'],
+            ['0x3b9aca00'],
+            ['0x1a13b8600']
+          ]
+        };
+      }
+      return { ...block, baseFeePerGas: '0x174876e800' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 100000000000n,
+      maxFeePerGas: 160000000000n,
+      maxPriorityFeePerGas: 5000000000n
+    });
+  });
+
+  it('uses 1.6 multiplier for base if above 40 gwei', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x11766ffa76' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 75001494134n,
+      maxFeePerGas: 120000000000n,
+      maxPriorityFeePerGas: 3000000000n
+    });
+  });
+
+  it('uses 1.4 multiplier for base if above 100 gwei', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x2e90edd000' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 200000000000n,
+      maxFeePerGas: 280000000000n,
+      maxPriorityFeePerGas: 5000000000n
+    });
+  });
+
+  it('uses 1.2 multiplier for base if above 200 gwei', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x45d964b800' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 300000000000n,
+      maxFeePerGas: 360000000000n,
+      maxPriorityFeePerGas: 5000000000n
+    });
+  });
+
+  it('handles baseFee being smaller than priorityFee', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x7' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual({
+      baseFee: 7n,
+      maxFeePerGas: 3000000000n,
+      maxPriorityFeePerGas: 3000000000n
+    });
+  });
+
+  it('falls back if no baseFeePerGas on block', async () => {
+    mockProvider.send.mockResolvedValueOnce({ ...block, baseFeePerGas: undefined });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual(FALLBACK_ESTIMATE);
+  });
+
+  it('falls back if priority fetching fails', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return { ...feeHistory, reward: undefined };
+      }
+      return { ...block, baseFeePerGas: '0x45d964b800' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual(FALLBACK_ESTIMATE);
+  });
+
+  it('falls back if gas is VERY high', async () => {
+    mockProvider.send.mockImplementation((method) => {
+      if (method === 'eth_feeHistory') {
+        return feeHistory;
+      }
+      return { ...block, baseFeePerGas: '0x91812d7d600' };
+    });
+    return expect(estimateFees(mockProvider)).resolves.toStrictEqual(FALLBACK_ESTIMATE);
+  });
+});

src/eip1559.ts

@@ -0,0 +1,127 @@
+import type { ProviderLike } from '@mycrypto/eth-scan';
+
+import { getFeeHistory, getLatestBlock } from './provider';
+import type { EstimationResult } from './types';
+import { gwei, hexlify, max, roundToWholeGwei } from './utils';
+
+const MAX_GAS_FAST = gwei(1500n);
+
+// How many blocks to consider for priority fee estimation
+const FEE_HISTORY_BLOCKS = 10;
+// Which percentile of effective priority fees to include
+const FEE_HISTORY_PERCENTILE = 5;
+// Which base fee to trigger priority fee estimation at
+const PRIORITY_FEE_ESTIMATION_TRIGGER = gwei(100n);
+// Returned if above trigger is not met
+const DEFAULT_PRIORITY_FEE = gwei(3n);
+// In case something goes wrong fall back to this estimate
+export const FALLBACK_ESTIMATE = {
+  maxFeePerGas: gwei(20n),
+  maxPriorityFeePerGas: DEFAULT_PRIORITY_FEE,
+  baseFee: undefined
+};
+const PRIORITY_FEE_INCREASE_BOUNDARY = 200; // %
+
+// Returns base fee multiplier percentage
+const getBaseFeeMultiplier = (baseFee: bigint) => {
+  if (baseFee <= gwei(40n)) {
+    return 200n;
+  } else if (baseFee <= gwei(100n)) {
+    return 160n;
+  } else if (baseFee <= gwei(200n)) {
+    return 140n;
+  } else {
+    return 120n;
+  }
+};
+
+const estimatePriorityFee = async (
+  provider: ProviderLike,
+  baseFee: bigint,
+  blockNumber: bigint
+) => {
+  if (baseFee < PRIORITY_FEE_ESTIMATION_TRIGGER) {
+    return DEFAULT_PRIORITY_FEE;
+  }
+  const feeHistory = await getFeeHistory(
+    provider,
+    hexlify(FEE_HISTORY_BLOCKS),
+    hexlify(blockNumber),
+    [FEE_HISTORY_PERCENTILE]
+  );
+
+  const rewards = feeHistory.reward
+    ?.map((r) => BigInt(r[0]))
+    .filter((r) => r > 0n)
+    .sort();
+
+  if (!rewards) {
+    return null;
+  }
+
+  // Calculate percentage increases from between ordered list of fees
+  const percentageIncreases = rewards.reduce<bigint[]>((acc, cur, i, arr) => {
+    if (i === arr.length - 1) {
+      return acc;
+    }
+    const next = arr[i + 1];
+    const p = ((next - cur) / cur) * 100n;
+    return [...acc, p];
+  }, []);
+  const highestIncrease = max(percentageIncreases);
+  const highestIncreaseIndex = percentageIncreases.findIndex((p) => p === highestIncrease);
+
+  // If we have big increase in value, we could be considering "outliers" in our estimate
+  // Skip the low elements and take a new median
+  const values =
+    highestIncrease >= PRIORITY_FEE_INCREASE_BOUNDARY &&
+    highestIncreaseIndex >= Math.floor(rewards.length / 2)
+      ? rewards.slice(highestIncreaseIndex)
+      : rewards;
+
+  return values[Math.floor(values.length / 2)];
+};
+
+export const estimateFees = async (provider: ProviderLike): Promise<EstimationResult> => {
+  try {
+    const latestBlock = await getLatestBlock(provider);
+
+    if (!latestBlock.baseFeePerGas) {
+      throw new Error('An error occurred while fetching current base fee, falling back');
+    }
+
+    const baseFee = BigInt(latestBlock.baseFeePerGas);
+
+    const blockNumber = BigInt(latestBlock.number);
+
+    const estimatedPriorityFee = await estimatePriorityFee(provider, baseFee, blockNumber);
+
+    if (estimatedPriorityFee === null) {
+      throw new Error('An error occurred while estimating priority fee, falling back');
+    }
+
+    const maxPriorityFeePerGas = max([estimatedPriorityFee, DEFAULT_PRIORITY_FEE]);
+
+    const multiplier = getBaseFeeMultiplier(baseFee);
+
+    const potentialMaxFee = (baseFee * multiplier) / 100n;
+    const maxFeePerGas =
+      maxPriorityFeePerGas > potentialMaxFee
+        ? potentialMaxFee + maxPriorityFeePerGas
+        : potentialMaxFee;
+
+    if (maxFeePerGas >= MAX_GAS_FAST || maxPriorityFeePerGas >= MAX_GAS_FAST) {
+      throw new Error('Estimated gas fee was much higher than expected, erroring');
+    }
+
+    return {
+      maxFeePerGas: roundToWholeGwei(maxFeePerGas),
+      maxPriorityFeePerGas: roundToWholeGwei(maxPriorityFeePerGas),
+      baseFee
+    };
+  } catch (err) {
+    // eslint-disable-next-line no-console
+    console.error(err);
+    return FALLBACK_ESTIMATE;
+  }
+};

src/index.ts

@@ -1 +1,2 @@
-// @todo
+export * from './eip1559';
+export * from './types';

src/provider.ts

@@ -0,0 +1,18 @@
+import type { ProviderLike } from '@mycrypto/eth-scan';
+import { send } from '@mycrypto/eth-scan';
+
+import type { Block, FeeHistory } from './types';
+
+export const getBlock = (provider: ProviderLike, blockNumber: string | number): Promise<Block> =>
+  send<Block>(provider, 'eth_getBlockByNumber', [blockNumber, false]);
+
+export const getLatestBlock = (provider: ProviderLike): Promise<Block> =>
+  getBlock(provider, 'latest');
+
+export const getFeeHistory = (
+  provider: ProviderLike,
+  blockCount: string,
+  newestBlock: string,
+  rewardPercentiles?: number[]
+): Promise<FeeHistory> =>
+  send<FeeHistory>(provider, 'eth_feeHistory', [blockCount, newestBlock, rewardPercentiles ?? []]);