eth-json-rpc-middleware
Version:
Ethereum-related json-rpc-engine middleware.
101 lines • 4.65 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.createRetryOnEmptyMiddleware = void 0;
const clone_1 = __importDefault(require("clone"));
const json_rpc_engine_1 = require("json-rpc-engine");
const pify_1 = __importDefault(require("pify"));
const logging_utils_1 = require("./logging-utils");
const cache_1 = require("./utils/cache");
//
// RetryOnEmptyMiddleware will retry any request with an empty response that has
// a numbered block reference at or lower than the blockTracker's latest block.
// Its useful for dealing with load-balanced ethereum JSON RPC
// nodes that are not always in sync with each other.
//
const log = logging_utils_1.createModuleLogger(logging_utils_1.projectLogger, 'retry-on-empty');
// empty values used to determine if a request should be retried
// `<nil>` comes from https://github.com/ethereum/go-ethereum/issues/16925
const emptyValues = [
undefined,
null,
'\u003cnil\u003e',
];
function createRetryOnEmptyMiddleware({ provider, blockTracker, } = {}) {
if (!provider) {
throw Error('RetryOnEmptyMiddleware - mandatory "provider" option is missing.');
}
if (!blockTracker) {
throw Error('RetryOnEmptyMiddleware - mandatory "blockTracker" option is missing.');
}
return json_rpc_engine_1.createAsyncMiddleware(async (req, res, next) => {
var _a;
const blockRefIndex = cache_1.blockTagParamIndex(req);
// skip if method does not include blockRef
if (blockRefIndex === undefined) {
return next();
}
// skip if not exact block references
let blockRef = (_a = req.params) === null || _a === void 0 ? void 0 : _a[blockRefIndex];
// omitted blockRef implies "latest"
if (blockRef === undefined) {
blockRef = 'latest';
}
// skip if non-number block reference
if (['latest', 'pending'].includes(blockRef)) {
return next();
}
// skip if block refernce is not a valid number
const blockRefNumber = Number.parseInt(blockRef.slice(2), 16);
if (Number.isNaN(blockRefNumber)) {
return next();
}
// lookup latest block
const latestBlockNumberHex = await blockTracker.getLatestBlock();
const latestBlockNumber = Number.parseInt(latestBlockNumberHex.slice(2), 16);
// skip if request block number is higher than current
if (blockRefNumber > latestBlockNumber) {
log('Requested block number %o is higher than latest block number %o, falling through to original request', blockRefNumber, latestBlockNumber);
return next();
}
log('Requested block number %o is not higher than latest block number %o, trying request until non-empty response is received', blockRefNumber, latestBlockNumber);
// create child request with specific block-ref
const childRequest = clone_1.default(req);
// attempt child request until non-empty response is received
const childResponse = await retry(10, async () => {
log('Performing request %o', childRequest);
const attemptResponse = await pify_1.default(provider.sendAsync).call(provider, childRequest);
log('Response is %o', attemptResponse);
// verify result
if (emptyValues.includes(attemptResponse.result)) {
throw new Error(`RetryOnEmptyMiddleware - empty response "${JSON.stringify(attemptResponse)}" for request "${JSON.stringify(childRequest)}"`);
}
return attemptResponse;
});
log('Copying result %o and error %o', childResponse.result, childResponse.error);
// copy child response onto original response
res.result = childResponse.result;
res.error = childResponse.error;
return undefined;
});
}
exports.createRetryOnEmptyMiddleware = createRetryOnEmptyMiddleware;
async function retry(maxRetries, asyncFn) {
for (let index = 0; index < maxRetries; index++) {
try {
return await asyncFn();
}
catch (err) {
log('(call %i) Request failed, waiting 1s to retry again...', index + 1);
await timeout(1000);
}
}
log('Retries exhausted');
throw new Error('RetryOnEmptyMiddleware - retries exhausted');
}
function timeout(duration) {
return new Promise((resolve) => setTimeout(resolve, duration));
}
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