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Текущая директория: /var/www/bitcardoApp/node_modules/ethers/src.ts/providers
Просмотр файла: provider-fallback.ts
/**
* A **FallbackProvider** provides resilience, security and performance
* in a way that is customizable and configurable.
*
* @_section: api/providers/fallback-provider:Fallback Provider [about-fallback-provider]
*/
import {
assert, assertArgument, getBigInt, getNumber, isError
} from "../utils/index.js";
import { AbstractProvider } from "./abstract-provider.js";
import { Network } from "./network.js"
import type { PerformActionRequest } from "./abstract-provider.js";
import type { Networkish } from "./network.js"
const BN_1 = BigInt("1");
const BN_2 = BigInt("2");
function shuffle<T = any>(array: Array<T>): void {
for (let i = array.length - 1; i > 0; i--) {
const j = Math.floor(Math.random() * (i + 1));
const tmp = array[i];
array[i] = array[j];
array[j] = tmp;
}
}
function stall(duration: number): Promise<void> {
return new Promise((resolve) => { setTimeout(resolve, duration); });
}
function getTime(): number { return (new Date()).getTime(); }
function stringify(value: any): string {
return JSON.stringify(value, (key, value) => {
if (typeof(value) === "bigint") {
return { type: "bigint", value: value.toString() };
}
return value;
});
}
/**
* A configuration entry for how to use a [[Provider]].
*/
export interface FallbackProviderConfig {
/**
* The provider.
*/
provider: AbstractProvider;
/**
* The amount of time to wait before kicking off the next provider.
*
* Any providers that have not responded can still respond and be
* counted, but this ensures new providers start.
*/
stallTimeout?: number;
/**
* The priority. Lower priority providers are dispatched first.
*/
priority?: number;
/**
* The amount of weight a provider is given against the quorum.
*/
weight?: number;
};
const defaultConfig = { stallTimeout: 400, priority: 1, weight: 1 };
// We track a bunch of extra stuff that might help debug problems or
// optimize infrastructure later on.
/**
* The statistics and state maintained for a [[Provider]].
*/
export interface FallbackProviderState extends Required<FallbackProviderConfig> {
/**
* The most recent blockNumber this provider has reported (-2 if none).
*/
blockNumber: number;
/**
* The number of total requests ever sent to this provider.
*/
requests: number;
/**
* The number of responses that errored.
*/
errorResponses: number;
/**
* The number of responses that occured after the result resolved.
*/
lateResponses: number;
/**
* How many times syncing was required to catch up the expected block.
*/
outOfSync: number;
/**
* The number of requests which reported unsupported operation.
*/
unsupportedEvents: number;
/**
* A rolling average (5% current duration) for response time.
*/
rollingDuration: number;
/**
* The ratio of quorum-agreed results to total.
*/
score: number;
}
interface Config extends FallbackProviderState {
_updateNumber: null | Promise<any>;
_network: null | Network;
_totalTime: number;
_lastFatalError: null | Error;
_lastFatalErrorTimestamp: number;
}
const defaultState = {
blockNumber: -2, requests: 0, lateResponses: 0, errorResponses: 0,
outOfSync: -1, unsupportedEvents: 0, rollingDuration: 0, score: 0,
_network: null, _updateNumber: null, _totalTime: 0,
_lastFatalError: null, _lastFatalErrorTimestamp: 0
};
async function waitForSync(config: Config, blockNumber: number): Promise<void> {
while (config.blockNumber < 0 || config.blockNumber < blockNumber) {
if (!config._updateNumber) {
config._updateNumber = (async () => {
try {
const blockNumber = await config.provider.getBlockNumber();
if (blockNumber > config.blockNumber) {
config.blockNumber = blockNumber;
}
} catch (error: any) {
config.blockNumber = -2;
config._lastFatalError = error;
config._lastFatalErrorTimestamp = getTime();
}
config._updateNumber = null;
})();
}
await config._updateNumber;
config.outOfSync++;
if (config._lastFatalError) { break; }
}
}
/**
* Additional options to configure a [[FallbackProvider]].
*/
export type FallbackProviderOptions = {
// How many providers must agree on a value before reporting
// back the response
quorum?: number;
// How many providers must have reported the same event
// for it to be emitted (currently unimplmented)
eventQuorum?: number;
// How many providers to dispatch each event to simultaneously.
// Set this to 0 to use getLog polling, which implies eventQuorum
// is equal to quorum. (currently unimplemented)
eventWorkers?: number;
cacheTimeout?: number;
pollingInterval?: number;
};
type RunnerResult = { result: any } | { error: Error };
type RunnerState = {
config: Config;
staller: null | Promise<void>;
didBump: boolean;
perform: null | Promise<any>;
result: null | RunnerResult;
}
function _normalize(value: any): string {
if (value == null) { return "null"; }
if (Array.isArray(value)) {
return "[" + (value.map(_normalize)).join(",") + "]";
}
if (typeof(value) === "object" && typeof(value.toJSON) === "function") {
return _normalize(value.toJSON());
}
switch (typeof(value)) {
case "boolean": case "symbol":
return value.toString();
case "bigint": case "number":
return BigInt(value).toString();
case "string":
return JSON.stringify(value);
case "object": {
const keys = Object.keys(value);
keys.sort();
return "{" + keys.map((k) => `${ JSON.stringify(k) }:${ _normalize(value[k]) }`).join(",") + "}";
}
}
console.log("Could not serialize", value);
throw new Error("Hmm...");
}
function normalizeResult(value: RunnerResult): { tag: string, value: any } {
if ("error" in value) {
const error = value.error;
return { tag: _normalize(error), value: error };
}
const result = value.result;
return { tag: _normalize(result), value: result };
}
type TallyResult = {
tag: string;
value: any;
weight: number;
};
// This strategy picks the highest weight result, as long as the weight is
// equal to or greater than quorum
function checkQuorum(quorum: number, results: Array<TallyResult>): any | Error {
const tally: Map<string, { value: any, weight: number }> = new Map();
for (const { value, tag, weight } of results) {
const t = tally.get(tag) || { value, weight: 0 };
t.weight += weight;
tally.set(tag, t);
}
let best: null | { value: any, weight: number } = null;
for (const r of tally.values()) {
if (r.weight >= quorum && (!best || r.weight > best.weight)) {
best = r;
}
}
if (best) { return best.value; }
return undefined;
}
function getMedian(quorum: number, results: Array<TallyResult>): undefined | bigint | Error {
let resultWeight = 0;
const errorMap: Map<string, { weight: number, value: Error }> = new Map();
let bestError: null | { weight: number, value: Error } = null;
const values: Array<bigint> = [ ];
for (const { value, tag, weight } of results) {
if (value instanceof Error) {
const e = errorMap.get(tag) || { value, weight: 0 };
e.weight += weight;
errorMap.set(tag, e);
if (bestError == null || e.weight > bestError.weight) { bestError = e; }
} else {
values.push(BigInt(value));
resultWeight += weight;
}
}
if (resultWeight < quorum) {
// We have quorum for an error
if (bestError && bestError.weight >= quorum) { return bestError.value; }
// We do not have quorum for a result
return undefined;
}
// Get the sorted values
values.sort((a, b) => ((a < b) ? -1: (b > a) ? 1: 0));
const mid = Math.floor(values.length / 2);
// Odd-length; take the middle value
if (values.length % 2) { return values[mid]; }
// Even length; take the ceiling of the mean of the center two values
return (values[mid - 1] + values[mid] + BN_1) / BN_2;
}
function getAnyResult(quorum: number, results: Array<TallyResult>): undefined | any | Error {
// If any value or error meets quorum, that is our preferred result
const result = checkQuorum(quorum, results);
if (result !== undefined) { return result; }
// Otherwise, do we have any result?
for (const r of results) {
if (r.value) { return r.value; }
}
// Nope!
return undefined;
}
function getFuzzyMode(quorum: number, results: Array<TallyResult>): undefined | number {
if (quorum === 1) { return getNumber(<bigint>getMedian(quorum, results), "%internal"); }
const tally: Map<number, { result: number, weight: number }> = new Map();
const add = (result: number, weight: number) => {
const t = tally.get(result) || { result, weight: 0 };
t.weight += weight;
tally.set(result, t);
};
for (const { weight, value } of results) {
const r = getNumber(value);
add(r - 1, weight);
add(r, weight);
add(r + 1, weight);
}
let bestWeight = 0;
let bestResult: undefined | number = undefined;
for (const { weight, result } of tally.values()) {
// Use this result, if this result meets quorum and has either:
// - a better weight
// - or equal weight, but the result is larger
if (weight >= quorum && (weight > bestWeight || (bestResult != null && weight === bestWeight && result > bestResult))) {
bestWeight = weight;
bestResult = result;
}
}
return bestResult;
}
/**
* A **FallbackProvider** manages several [[Providers]] providing
* resilience by switching between slow or misbehaving nodes, security
* by requiring multiple backends to aggree and performance by allowing
* faster backends to respond earlier.
*
*/
export class FallbackProvider extends AbstractProvider {
/**
* The number of backends that must agree on a value before it is
* accpeted.
*/
readonly quorum: number;
/**
* @_ignore:
*/
readonly eventQuorum: number;
/**
* @_ignore:
*/
readonly eventWorkers: number;
readonly #configs: Array<Config>;
#height: number;
#initialSyncPromise: null | Promise<void>;
/**
* Creates a new **FallbackProvider** with %%providers%% connected to
* %%network%%.
*
* If a [[Provider]] is included in %%providers%%, defaults are used
* for the configuration.
*/
constructor(providers: Array<AbstractProvider | FallbackProviderConfig>, network?: Networkish, options?: FallbackProviderOptions) {
super(network, options);
this.#configs = providers.map((p) => {
if (p instanceof AbstractProvider) {
return Object.assign({ provider: p }, defaultConfig, defaultState );
} else {
return Object.assign({ }, defaultConfig, p, defaultState );
}
});
this.#height = -2;
this.#initialSyncPromise = null;
if (options && options.quorum != null) {
this.quorum = options.quorum;
} else {
this.quorum = Math.ceil(this.#configs.reduce((accum, config) => {
accum += config.weight;
return accum;
}, 0) / 2);
}
this.eventQuorum = 1;
this.eventWorkers = 1;
assertArgument(this.quorum <= this.#configs.reduce((a, c) => (a + c.weight), 0),
"quorum exceed provider weight", "quorum", this.quorum);
}
get providerConfigs(): Array<FallbackProviderState> {
return this.#configs.map((c) => {
const result: any = Object.assign({ }, c);
for (const key in result) {
if (key[0] === "_") { delete result[key]; }
}
return result;
});
}
async _detectNetwork(): Promise<Network> {
return Network.from(getBigInt(await this._perform({ method: "chainId" })));
}
// @TODO: Add support to select providers to be the event subscriber
//_getSubscriber(sub: Subscription): Subscriber {
// throw new Error("@TODO");
//}
/**
* Transforms a %%req%% into the correct method call on %%provider%%.
*/
async _translatePerform(provider: AbstractProvider, req: PerformActionRequest): Promise<any> {
switch (req.method) {
case "broadcastTransaction":
return await provider.broadcastTransaction(req.signedTransaction);
case "call":
return await provider.call(Object.assign({ }, req.transaction, { blockTag: req.blockTag }));
case "chainId":
return (await provider.getNetwork()).chainId;
case "estimateGas":
return await provider.estimateGas(req.transaction);
case "getBalance":
return await provider.getBalance(req.address, req.blockTag);
case "getBlock": {
const block = ("blockHash" in req) ? req.blockHash: req.blockTag;
return await provider.getBlock(block, req.includeTransactions);
}
case "getBlockNumber":
return await provider.getBlockNumber();
case "getCode":
return await provider.getCode(req.address, req.blockTag);
case "getGasPrice":
return (await provider.getFeeData()).gasPrice;
case "getPriorityFee":
return (await provider.getFeeData()).maxPriorityFeePerGas;
case "getLogs":
return await provider.getLogs(req.filter);
case "getStorage":
return await provider.getStorage(req.address, req.position, req.blockTag);
case "getTransaction":
return await provider.getTransaction(req.hash);
case "getTransactionCount":
return await provider.getTransactionCount(req.address, req.blockTag);
case "getTransactionReceipt":
return await provider.getTransactionReceipt(req.hash);
case "getTransactionResult":
return await provider.getTransactionResult(req.hash);
}
}
// Grab the next (random) config that is not already part of
// the running set
#getNextConfig(running: Set<RunnerState>): null | Config {
// @TODO: Maybe do a check here to favour (heavily) providers that
// do not require waitForSync and disfavour providers that
// seem down-ish or are behaving slowly
const configs = Array.from(running).map((r) => r.config)
// Shuffle the states, sorted by priority
const allConfigs = this.#configs.slice();
shuffle(allConfigs);
allConfigs.sort((a, b) => (a.priority - b.priority));
for (const config of allConfigs) {
if (config._lastFatalError) { continue; }
if (configs.indexOf(config) === -1) { return config; }
}
return null;
}
// Adds a new runner (if available) to running.
#addRunner(running: Set<RunnerState>, req: PerformActionRequest): null | RunnerState {
const config = this.#getNextConfig(running);
// No runners available
if (config == null) { return null; }
// Create a new runner
const runner: RunnerState = {
config, result: null, didBump: false,
perform: null, staller: null
};
const now = getTime();
// Start performing this operation
runner.perform = (async () => {
try {
config.requests++;
const result = await this._translatePerform(config.provider, req);
runner.result = { result };
} catch (error: any) {
config.errorResponses++;
runner.result = { error };
}
const dt = (getTime() - now);
config._totalTime += dt;
config.rollingDuration = 0.95 * config.rollingDuration + 0.05 * dt;
runner.perform = null;
})();
// Start a staller; when this times out, it's time to force
// kicking off another runner because we are taking too long
runner.staller = (async () => {
await stall(config.stallTimeout);
runner.staller = null;
})();
running.add(runner);
return runner;
}
// Initializes the blockNumber and network for each runner and
// blocks until initialized
async #initialSync(): Promise<void> {
let initialSync = this.#initialSyncPromise;
if (!initialSync) {
const promises: Array<Promise<any>> = [ ];
this.#configs.forEach((config) => {
promises.push((async () => {
await waitForSync(config, 0);
if (!config._lastFatalError) {
config._network = await config.provider.getNetwork();
}
})());
});
this.#initialSyncPromise = initialSync = (async () => {
// Wait for all providers to have a block number and network
await Promise.all(promises);
// Check all the networks match
let chainId: null | bigint = null;
for (const config of this.#configs) {
if (config._lastFatalError) { continue; }
const network = <Network>(config._network);
if (chainId == null) {
chainId = network.chainId;
} else if (network.chainId !== chainId) {
assert(false, "cannot mix providers on different networks", "UNSUPPORTED_OPERATION", {
operation: "new FallbackProvider"
});
}
}
})();
}
await initialSync
}
async #checkQuorum(running: Set<RunnerState>, req: PerformActionRequest): Promise<any> {
// Get all the result objects
const results: Array<TallyResult> = [ ];
for (const runner of running) {
if (runner.result != null) {
const { tag, value } = normalizeResult(runner.result);
results.push({ tag, value, weight: runner.config.weight });
}
}
// Are there enough results to event meet quorum?
if (results.reduce((a, r) => (a + r.weight), 0) < this.quorum) {
return undefined;
}
switch (req.method) {
case "getBlockNumber": {
// We need to get the bootstrap block height
if (this.#height === -2) {
this.#height = Math.ceil(getNumber(<bigint>getMedian(this.quorum, this.#configs.filter((c) => (!c._lastFatalError)).map((c) => ({
value: c.blockNumber,
tag: getNumber(c.blockNumber).toString(),
weight: c.weight
})))));
}
// Find the mode across all the providers, allowing for
// a little drift between block heights
const mode = getFuzzyMode(this.quorum, results);
if (mode === undefined) { return undefined; }
if (mode > this.#height) { this.#height = mode; }
return this.#height;
}
case "getGasPrice":
case "getPriorityFee":
case "estimateGas":
return getMedian(this.quorum, results);
case "getBlock":
// Pending blocks are in the mempool and already
// quite untrustworthy; just grab anything
if ("blockTag" in req && req.blockTag === "pending") {
return getAnyResult(this.quorum, results);
}
return checkQuorum(this.quorum, results);
case "call":
case "chainId":
case "getBalance":
case "getTransactionCount":
case "getCode":
case "getStorage":
case "getTransaction":
case "getTransactionReceipt":
case "getLogs":
return checkQuorum(this.quorum, results);
case "broadcastTransaction":
return getAnyResult(this.quorum, results);
}
assert(false, "unsupported method", "UNSUPPORTED_OPERATION", {
operation: `_perform(${ stringify((<any>req).method) })`
});
}
async #waitForQuorum(running: Set<RunnerState>, req: PerformActionRequest): Promise<any> {
if (running.size === 0) { throw new Error("no runners?!"); }
// Any promises that are interesting to watch for; an expired stall
// or a successful perform
const interesting: Array<Promise<void>> = [ ];
let newRunners = 0;
for (const runner of running) {
// No responses, yet; keep an eye on it
if (runner.perform) {
interesting.push(runner.perform);
}
// Still stalling...
if (runner.staller) {
interesting.push(runner.staller);
continue;
}
// This runner has already triggered another runner
if (runner.didBump) { continue; }
// Got a response (result or error) or stalled; kick off another runner
runner.didBump = true;
newRunners++;
}
// Check if we have reached quorum on a result (or error)
const value = await this.#checkQuorum(running, req);
if (value !== undefined) {
if (value instanceof Error) { throw value; }
return value;
}
// Add any new runners, because a staller timed out or a result
// or error response came in.
for (let i = 0; i < newRunners; i++) {
this.#addRunner(running, req);
}
// All providers have returned, and we have no result
assert(interesting.length > 0, "quorum not met", "SERVER_ERROR", {
request: "%sub-requests",
info: { request: req, results: Array.from(running).map((r) => stringify(r.result)) }
});
// Wait for someone to either complete its perform or stall out
await Promise.race(interesting);
// This is recursive, but at worst case the depth is 2x the
// number of providers (each has a perform and a staller)
return await this.#waitForQuorum(running, req);
}
async _perform<T = any>(req: PerformActionRequest): Promise<T> {
// Broadcasting a transaction is rare (ish) and already incurs
// a cost on the user, so spamming is safe-ish. Just send it to
// every backend.
if (req.method === "broadcastTransaction") {
// Once any broadcast provides a positive result, use it. No
// need to wait for anyone else
const results: Array<null | TallyResult> = this.#configs.map((c) => null);
const broadcasts = this.#configs.map(async ({ provider, weight }, index) => {
try {
const result = await provider._perform(req);
results[index] = Object.assign(normalizeResult({ result }), { weight });
} catch (error: any) {
results[index] = Object.assign(normalizeResult({ error }), { weight });
}
});
// As each promise finishes...
while (true) {
// Check for a valid broadcast result
const done = <Array<any>>results.filter((r) => (r != null));
for (const { value } of done) {
if (!(value instanceof Error)) { return value; }
}
// Check for a legit broadcast error (one which we cannot
// recover from; some nodes may return the following red
// herring events:
// - alredy seend (UNKNOWN_ERROR)
// - NONCE_EXPIRED
// - REPLACEMENT_UNDERPRICED
const result = checkQuorum(this.quorum, <Array<any>>results.filter((r) => (r != null)));
if (isError(result, "INSUFFICIENT_FUNDS")) {
throw result;
}
// Kick off the next provider (if any)
const waiting = broadcasts.filter((b, i) => (results[i] == null));
if (waiting.length === 0) { break; }
await Promise.race(waiting);
}
// Use standard quorum results; any result was returned above,
// so this will find any error that met quorum if any
const result = getAnyResult(this.quorum, <Array<any>>results);
assert(result !== undefined, "problem multi-broadcasting", "SERVER_ERROR", {
request: "%sub-requests",
info: { request: req, results: results.map(stringify) }
})
if (result instanceof Error) { throw result; }
return result;
}
await this.#initialSync();
// Bootstrap enough runners to meet quorum
const running: Set<RunnerState> = new Set();
let inflightQuorum = 0;
while (true) {
const runner = this.#addRunner(running, req);
if (runner == null) { break; }
inflightQuorum += runner.config.weight;
if (inflightQuorum >= this.quorum) { break; }
}
const result = await this.#waitForQuorum(running, req);
// Track requests sent to a provider that are still
// outstanding after quorum has been otherwise found
for (const runner of running) {
if (runner.perform && runner.result == null) {
runner.config.lateResponses++;
}
}
return result;
}
async destroy(): Promise<void> {
for (const { provider } of this.#configs) {
provider.destroy();
}
super.destroy();
}
}
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