least-connected-load-balancing-strategy.js•4.04 kB
"use strict";
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (Object.prototype.hasOwnProperty.call(b, p)) d[p] = b[p]; };
return extendStatics(d, b);
};
return function (d, b) {
if (typeof b !== "function" && b !== null)
throw new TypeError("Class extends value " + String(b) + " is not a constructor or null");
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
/**
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.com]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var round_robin_array_index_1 = __importDefault(require("./round-robin-array-index"));
var load_balancing_strategy_1 = __importDefault(require("./load-balancing-strategy"));
var LeastConnectedLoadBalancingStrategy = /** @class */ (function (_super) {
__extends(LeastConnectedLoadBalancingStrategy, _super);
/**
* @constructor
* @param {Pool} connectionPool the connection pool of this driver.
*/
function LeastConnectedLoadBalancingStrategy(connectionPool) {
var _this = _super.call(this) || this;
_this._readersIndex = new round_robin_array_index_1.default();
_this._writersIndex = new round_robin_array_index_1.default();
_this._connectionPool = connectionPool;
return _this;
}
/**
* @inheritDoc
*/
LeastConnectedLoadBalancingStrategy.prototype.selectReader = function (knownReaders) {
return this._select(knownReaders, this._readersIndex);
};
/**
* @inheritDoc
*/
LeastConnectedLoadBalancingStrategy.prototype.selectWriter = function (knownWriters) {
return this._select(knownWriters, this._writersIndex);
};
LeastConnectedLoadBalancingStrategy.prototype._select = function (addresses, roundRobinIndex) {
var length = addresses.length;
if (length === 0) {
return null;
}
// choose start index for iteration in round-robin fashion
var startIndex = roundRobinIndex.next(length);
var index = startIndex;
var leastConnectedAddress = null;
var leastActiveConnections = Number.MAX_SAFE_INTEGER;
// iterate over the array to find least connected address
do {
var address = addresses[index];
var activeConnections = this._connectionPool.activeResourceCount(address);
if (activeConnections < leastActiveConnections) {
leastConnectedAddress = address;
leastActiveConnections = activeConnections;
}
// loop over to the start of the array when end is reached
if (index === length - 1) {
index = 0;
}
else {
index++;
}
} while (index !== startIndex);
return leastConnectedAddress;
};
return LeastConnectedLoadBalancingStrategy;
}(load_balancing_strategy_1.default));
exports.default = LeastConnectedLoadBalancingStrategy;