eth-block-tracker
Version:
A block tracker for the Ethereum blockchain. Keeps track of the latest block.
276 lines (217 loc) • 10 kB
JavaScript
;
var _regenerator = _interopRequireDefault(require("@babel/runtime/regenerator"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }
function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }
function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { Promise.resolve(value).then(_next, _throw); } }
function _asyncToGenerator(fn) { return function () { var self = this, args = arguments; return new Promise(function (resolve, reject) { var gen = fn.apply(self, args); function _next(value) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value); } function _throw(err) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err); } _next(undefined); }); }; }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }
function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }
function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } return _assertThisInitialized(self); }
function _assertThisInitialized(self) { if (self === void 0) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
function _getPrototypeOf(o) { _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) { return o.__proto__ || Object.getPrototypeOf(o); }; return _getPrototypeOf(o); }
function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, writable: true, configurable: true } }); if (superClass) _setPrototypeOf(subClass, superClass); }
function _setPrototypeOf(o, p) { _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) { o.__proto__ = p; return o; }; return _setPrototypeOf(o, p); }
var pify = require('pify');
var BaseBlockTracker = require('./base');
var sec = 1000;
var PollingBlockTracker =
/*#__PURE__*/
function (_BaseBlockTracker) {
_inherits(PollingBlockTracker, _BaseBlockTracker);
function PollingBlockTracker() {
var _this;
var opts = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
_classCallCheck(this, PollingBlockTracker);
// parse + validate args
if (!opts.provider) throw new Error('PollingBlockTracker - no provider specified.');
var pollingInterval = opts.pollingInterval || 20 * sec;
var retryTimeout = opts.retryTimeout || pollingInterval / 10;
var keepEventLoopActive = opts.keepEventLoopActive !== undefined ? opts.keepEventLoopActive : true;
var setSkipCacheFlag = opts.setSkipCacheFlag || false; // BaseBlockTracker constructor
_this = _possibleConstructorReturn(this, _getPrototypeOf(PollingBlockTracker).call(this, Object.assign({
blockResetDuration: pollingInterval
}, opts))); // config
_this._provider = opts.provider;
_this._pollingInterval = pollingInterval;
_this._retryTimeout = retryTimeout;
_this._keepEventLoopActive = keepEventLoopActive;
_this._setSkipCacheFlag = setSkipCacheFlag;
return _this;
} //
// public
//
// trigger block polling
_createClass(PollingBlockTracker, [{
key: "checkForLatestBlock",
value: function () {
var _checkForLatestBlock = _asyncToGenerator(
/*#__PURE__*/
_regenerator["default"].mark(function _callee() {
return _regenerator["default"].wrap(function _callee$(_context) {
while (1) {
switch (_context.prev = _context.next) {
case 0:
_context.next = 2;
return this._updateLatestBlock();
case 2:
_context.next = 4;
return this.getLatestBlock();
case 4:
return _context.abrupt("return", _context.sent);
case 5:
case "end":
return _context.stop();
}
}
}, _callee, this);
}));
function checkForLatestBlock() {
return _checkForLatestBlock.apply(this, arguments);
}
return checkForLatestBlock;
}() //
// private
//
}, {
key: "_start",
value: function _start() {
var _this2 = this;
this._performSync()["catch"](function (err) {
return _this2.emit('error', err);
});
}
}, {
key: "_performSync",
value: function () {
var _performSync2 = _asyncToGenerator(
/*#__PURE__*/
_regenerator["default"].mark(function _callee2() {
var newErr;
return _regenerator["default"].wrap(function _callee2$(_context2) {
while (1) {
switch (_context2.prev = _context2.next) {
case 0:
if (!this._isRunning) {
_context2.next = 16;
break;
}
_context2.prev = 1;
_context2.next = 4;
return this._updateLatestBlock();
case 4:
_context2.next = 6;
return timeout(this._pollingInterval, !this._keepEventLoopActive);
case 6:
_context2.next = 14;
break;
case 8:
_context2.prev = 8;
_context2.t0 = _context2["catch"](1);
newErr = new Error("PollingBlockTracker - encountered an error while attempting to update latest block:\n".concat(_context2.t0.stack));
try {
this.emit('error', newErr);
} catch (emitErr) {
console.error(newErr);
}
_context2.next = 14;
return timeout(this._retryTimeout, !this._keepEventLoopActive);
case 14:
_context2.next = 0;
break;
case 16:
case "end":
return _context2.stop();
}
}
}, _callee2, this, [[1, 8]]);
}));
function _performSync() {
return _performSync2.apply(this, arguments);
}
return _performSync;
}()
}, {
key: "_updateLatestBlock",
value: function () {
var _updateLatestBlock2 = _asyncToGenerator(
/*#__PURE__*/
_regenerator["default"].mark(function _callee3() {
var latestBlock;
return _regenerator["default"].wrap(function _callee3$(_context3) {
while (1) {
switch (_context3.prev = _context3.next) {
case 0:
_context3.next = 2;
return this._fetchLatestBlock();
case 2:
latestBlock = _context3.sent;
this._newPotentialLatest(latestBlock);
case 4:
case "end":
return _context3.stop();
}
}
}, _callee3, this);
}));
function _updateLatestBlock() {
return _updateLatestBlock2.apply(this, arguments);
}
return _updateLatestBlock;
}()
}, {
key: "_fetchLatestBlock",
value: function () {
var _fetchLatestBlock2 = _asyncToGenerator(
/*#__PURE__*/
_regenerator["default"].mark(function _callee4() {
var _this3 = this;
var req, res;
return _regenerator["default"].wrap(function _callee4$(_context4) {
while (1) {
switch (_context4.prev = _context4.next) {
case 0:
req = {
jsonrpc: "2.0",
id: 1,
method: 'eth_blockNumber',
params: []
};
if (this._setSkipCacheFlag) req.skipCache = true;
_context4.next = 4;
return pify(function (cb) {
return _this3._provider.sendAsync(req, cb);
})();
case 4:
res = _context4.sent;
if (!res.error) {
_context4.next = 7;
break;
}
throw new Error("PollingBlockTracker - encountered error fetching block:\n".concat(res.error));
case 7:
return _context4.abrupt("return", res.result);
case 8:
case "end":
return _context4.stop();
}
}
}, _callee4, this);
}));
function _fetchLatestBlock() {
return _fetchLatestBlock2.apply(this, arguments);
}
return _fetchLatestBlock;
}()
}]);
return PollingBlockTracker;
}(BaseBlockTracker);
module.exports = PollingBlockTracker;
function timeout(duration, unref) {
return new Promise(function (resolve) {
var timoutRef = setTimeout(resolve, duration); // don't keep process open
if (timoutRef.unref && unref) {
timoutRef.unref();
}
});
}