ts-safe-redis-leader
Version:
Redis leader election implementation that does not have any race conditions in Typescript
216 lines (215 loc) • 10.2 kB
JavaScript
"use strict";
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
var __generator = (this && this.__generator) || function (thisArg, body) {
var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
function verb(n) { return function (v) { return step([n, v]); }; }
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while (_) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, t.value];
switch (op[0]) {
case 0: case 1: t = op; break;
case 4: _.label++; return { value: op[1], done: false };
case 5: _.label++; y = op[1]; op = [0]; continue;
case 7: op = _.ops.pop(); _.trys.pop(); continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
if (t[2]) _.ops.pop();
_.trys.pop(); continue;
}
op = body.call(thisArg, _);
} catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
}
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.SafeRedisLeader = exports.EmitterEnum = void 0;
var crypto_1 = require("crypto");
var atomicGetIsEqualDelete_1 = require("./atomicGetIsEqualDelete");
var atomicGetIsEqualSetPExpire_1 = require("./atomicGetIsEqualSetPExpire");
var emitter_1 = require("./emitter");
var EmitterEnum;
(function (EmitterEnum) {
EmitterEnum["NOT_ELECTED"] = "notElected";
EmitterEnum["ELECTED"] = "elected";
EmitterEnum["DEMOTED"] = "demoted";
EmitterEnum["ERROR"] = "error";
EmitterEnum["RENEW"] = "renew";
})(EmitterEnum = exports.EmitterEnum || (exports.EmitterEnum = {}));
var hashKey = function (key) { return "leader: " + crypto_1.createHash("sha1").update(key).digest("hex"); };
var random = function () { return crypto_1.randomBytes(32).toString("base64"); };
var SafeRedisLeader = /** @class */ (function () {
function SafeRedisLeader(asyncRedis, ttl, wait, key) {
this.isStarted = false;
this.wasLeading = false;
this.canLead = false;
this.emitter = new emitter_1.MainEmitter();
this.id = hashKey(random());
this.asyncRedis = asyncRedis;
this.ttl = ttl;
this.wait = wait;
this.key = hashKey(key || random());
}
SafeRedisLeader.prototype.renew = function () {
return __awaiter(this, void 0, void 0, function () {
var isLeading, err_1;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
_a.trys.push([0, 2, , 3]);
return [4 /*yield*/, atomicGetIsEqualSetPExpire_1.atomicGetIsEqualSetPExpire(this.asyncRedis, this.key, this.id, this.ttl)];
case 1:
isLeading = _a.sent();
if (isLeading) {
this.wasLeading = true;
this.renewTimeoutId = setTimeout(this.renew.bind(this), this.ttl / 2);
this.emitter.emit(EmitterEnum.RENEW);
}
else {
if (this.wasLeading) {
this.wasLeading = false;
this.emitter.emit(EmitterEnum.DEMOTED);
}
clearTimeout(this.renewTimeoutId);
this.electTimeoutId = setTimeout(this.runElection.bind(this), this.wait);
}
return [3 /*break*/, 3];
case 2:
err_1 = _a.sent();
if (this.isStarted) {
this.emitter.emit(EmitterEnum.ERROR, err_1);
}
return [3 /*break*/, 3];
case 3: return [2 /*return*/];
}
});
});
};
SafeRedisLeader.prototype.runElection = function () {
return __awaiter(this, void 0, void 0, function () {
var res, err_2;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
_a.trys.push([0, 2, , 3]);
return [4 /*yield*/, this.asyncRedis.set(this.key, this.id, "PX", this.ttl, "NX")];
case 1:
res = _a.sent();
if (res) {
this.emitter.emit(EmitterEnum.ELECTED);
this.wasLeading = true;
if (!this.canLead) {
return [2 /*return*/, this.stop()];
}
this.renewTimeoutId = setTimeout(this.renew.bind(this), this.ttl / 2);
}
else {
this.emitter.emit(EmitterEnum.NOT_ELECTED);
this.electTimeoutId = setTimeout(this.runElection.bind(this), this.wait);
}
return [3 /*break*/, 3];
case 2:
err_2 = _a.sent();
if (this.isStarted) {
this.emitter.emit(EmitterEnum.ERROR, err_2);
}
return [3 /*break*/, 3];
case 3: return [2 /*return*/];
}
});
});
};
SafeRedisLeader.prototype.elect = function () {
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
this.isStarted = true;
this.canLead = true;
return [4 /*yield*/, this.runElection()];
case 1:
_a.sent();
return [2 /*return*/];
}
});
});
};
SafeRedisLeader.prototype.isLeader = function () {
return __awaiter(this, void 0, void 0, function () {
var curId;
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /*yield*/, this.asyncRedis.get(this.key)];
case 1:
curId = _a.sent();
return [2 /*return*/, this.id === curId];
}
});
});
};
SafeRedisLeader.prototype.stop = function () {
return __awaiter(this, void 0, void 0, function () {
var res;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
this.canLead = false;
this.renewTimeoutId && clearTimeout(this.renewTimeoutId);
this.electTimeoutId && clearTimeout(this.electTimeoutId);
return [4 /*yield*/, atomicGetIsEqualDelete_1.atomicGetIsEqualDelete(this.asyncRedis, this.key, this.id)];
case 1:
res = _a.sent();
if (res) {
this.emitter.emit(EmitterEnum.DEMOTED);
}
this.wasLeading = false;
return [2 /*return*/];
}
});
});
};
SafeRedisLeader.prototype.on = function (name, fn) {
this.emitter.on(name, fn);
};
SafeRedisLeader.prototype.off = function (name, fn) {
this.emitter.off(name, fn);
};
SafeRedisLeader.prototype.once = function (name, fn) {
this.emitter.once(name, fn);
};
SafeRedisLeader.prototype.removeAllListeners = function () {
this.emitter.removeAllListeners();
};
SafeRedisLeader.prototype.shutdown = function () {
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
this.isStarted = false;
this.canLead = false;
this.renewTimeoutId && clearTimeout(this.renewTimeoutId);
this.electTimeoutId && clearTimeout(this.electTimeoutId);
return [4 /*yield*/, this.stop()];
case 1:
_a.sent();
return [2 /*return*/];
}
});
});
};
return SafeRedisLeader;
}());
exports.SafeRedisLeader = SafeRedisLeader;