tornado-packages/ethers.js
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Fix median calculation for large block number deltas across FallbackProvider backends.

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This commit is contained in:
Richard Moore 2020-04-23 08:15:46 -04:00
parent 8cf4b3cf45
commit fca5ccbc20
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GPG Key ID: 665176BE8E9DC651
1 changed files with 22 additions and 11 deletions
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33
packages/providers/src.ts/fallback-provider.ts
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@ -40,18 +40,23 @@ function checkNetworks(networks: Array<Network>): Network {
return result; return result;
} }
function median(values: Array<number>): number { function median(values: Array<number>, maxDelta?: number): number {
values = values.slice().sort(); values = values.slice().sort();
const middle = Math.floor(values.length / 2); const middle = Math.floor(values.length / 2);
// Odd length; take the middle // Odd length; take the middle
if (values.length % 2) { if (values.length % 2) {
return values[middle]; return values[middle];
} }
// Even length; take the average of the two middle // Even length; take the average of the two middle
const a = values[middle - 1], b = values[middle]; const a = values[middle - 1], b = values[middle];
return (a + b) / 2;
if (maxDelta != null && Math.abs(a - b) > maxDelta) {
return null;
}
return (a + b) / 2;
} }
function serialize(value: any): string { function serialize(value: any): string {
@ -178,7 +183,10 @@ function getProcessFunc(provider: FallbackProvider, method: string, params: { [
const values = configs.map((c) => c.result); const values = configs.map((c) => c.result);
// Get the median block number // Get the median block number
let blockNumber = Math.ceil(median(configs.map((c) => c.result))); let blockNumber = median(configs.map((c) => c.result), 2);
if (blockNumber == null) { return undefined; }
blockNumber = Math.ceil(blockNumber);
// If the next block height is present, its prolly safe to use // If the next block height is present, its prolly safe to use
if (values.indexOf(blockNumber + 1) >= 0) { blockNumber++; } if (values.indexOf(blockNumber + 1) >= 0) { blockNumber++; }
@ -391,6 +399,7 @@ export class FallbackProvider extends BaseProvider {
configs.sort((a, b) => (a.priority - b.priority)); configs.sort((a, b) => (a.priority - b.priority));
let i = 0; let i = 0;
let first = true;
while (true) { while (true) {
const t0 = now(); const t0 = now();
@ -470,6 +479,8 @@ export class FallbackProvider extends BaseProvider {
if (results.length >= this.quorum) { if (results.length >= this.quorum) {
const result = processFunc(results); const result = processFunc(results);
if (result !== undefined) { return result; } if (result !== undefined) { return result; }
if (!first) { await stall(100); }
first = false;
} }
// All configs have run to completion; we will never get more data // All configs have run to completion; we will never get more data