wsConnectorPool.ts

import { Mutex } from "async-mutex";
import { WebSocketConnector } from "./wsConnector";
import { ErrorCode, TDWebSocketClientError } from "../common/wsError";
import logger from "../common/log";
import { w3cwebsocket } from "websocket";

const mutex = new Mutex();

export class WebSocketConnectionPool {
    private static _instance?: WebSocketConnectionPool;
    private pool: Map<string, WebSocketConnector[]> = new Map();
    private readonly _maxConnections: number;
    private static sharedBuffer: SharedArrayBuffer;
    private static sharedArray: Int32Array;

    private constructor(maxConnections: number = -1) {
        this._maxConnections = maxConnections;
        WebSocketConnectionPool.sharedBuffer = new SharedArrayBuffer(4);
        WebSocketConnectionPool.sharedArray = new Int32Array(
            WebSocketConnectionPool.sharedBuffer
        );
        Atomics.store(WebSocketConnectionPool.sharedArray, 0, 0);
    }

    public static instance(
        maxConnections: number = -1
    ): WebSocketConnectionPool {
        if (!WebSocketConnectionPool._instance) {
            WebSocketConnectionPool._instance = new WebSocketConnectionPool(
                maxConnections
            );
        }
        return WebSocketConnectionPool._instance;
    }

    async getConnection(
        url: URL,
        timeout: number | undefined | null
    ): Promise<WebSocketConnector> {
        let connectAddr = url.origin.concat(url.pathname).concat(url.search);
        let connector: WebSocketConnector | undefined;
        const unlock = await mutex.acquire();
        try {
            if (this.pool.has(connectAddr)) {
                const connectors = this.pool.get(connectAddr);
                while (connectors && connectors.length > 0) {
                    const candidate = connectors.pop();
                    if (!candidate) {
                        continue;
                    }
                    if (
                        candidate &&
                        candidate.readyState() === w3cwebsocket.OPEN
                    ) {
                        connector = candidate;
                        break;
                    } else if (candidate) {
                        Atomics.add(WebSocketConnectionPool.sharedArray, 0, -1);
                        candidate.close();
                        logger.error(
                            `getConnection, current connection status fail, url: ${connectAddr}`
                        );
                    }
                }
            }

            if (connector) {
                logger.debug(
                    "get connection success:" +
                    Atomics.load(WebSocketConnectionPool.sharedArray, 0)
                );
                return connector;
            }

            if (
                this._maxConnections != -1 &&
                Atomics.load(WebSocketConnectionPool.sharedArray, 0) >
                this._maxConnections
            ) {
                throw new TDWebSocketClientError(
                    ErrorCode.ERR_WEBSOCKET_CONNECTION_ARRIVED_LIMIT,
                    "websocket connect arrived limited:" +
                    Atomics.load(WebSocketConnectionPool.sharedArray, 0)
                );
            }
            Atomics.add(WebSocketConnectionPool.sharedArray, 0, 1);
            logger.info(
                "getConnection, new connection count:" +
                Atomics.load(WebSocketConnectionPool.sharedArray, 0) +
                ", connectAddr:" +
                connectAddr
            );
            return new WebSocketConnector(url, timeout);
        } finally {
            unlock();
        }
    }

    async releaseConnection(connector: WebSocketConnector): Promise<void> {
        if (connector) {
            const unlock = await mutex.acquire();
            try {
                if (connector.readyState() === w3cwebsocket.OPEN) {
                    let url = connector.getWsURL();
                    let connectAddr = url.origin
                        .concat(url.pathname)
                        .concat(url.search);
                    let connectors = this.pool.get(connectAddr);
                    if (!connectors) {
                        connectors = new Array();
                        connectors.push(connector);
                        this.pool.set(connectAddr, connectors);
                    } else {
                        connectors.push(connector);
                    }
                    logger.info(
                        "releaseConnection, current connection count:" +
                        connectors.length
                    );
                } else {
                    Atomics.add(WebSocketConnectionPool.sharedArray, 0, -1);
                    connector.close();
                    logger.info(
                        "releaseConnection, current connection status fail:" +
                        Atomics.load(WebSocketConnectionPool.sharedArray, 0)
                    );
                }
            } finally {
                unlock();
            }
        }
    }

    destroyed() {
        let num = 0;
        if (this.pool) {
            for (let values of this.pool.values()) {
                for (let i in values) {
                    num++;
                    values[i].close();
                }
            }
        }
        logger.info(
            "destroyed connect:" +
            Atomics.load(WebSocketConnectionPool.sharedArray, 0) +
            " current count:" +
            num
        );
        Atomics.store(WebSocketConnectionPool.sharedArray, 0, 0);
        this.pool = new Map();
    }
}

process.on("exit", (code) => {
    logger.info("begin destroy connect");
    WebSocketConnectionPool.instance().destroyed();
    process.exit();
});

process.on("SIGINT", () => {
    logger.info("Received SIGINT. Press Control-D to exit, begin destroy connect...");
    WebSocketConnectionPool.instance().destroyed();
    process.exit();
});

process.on("SIGTERM", () => {
    logger.info("Received SIGINT. Press Control-D to exit, begin destroy connect");
    WebSocketConnectionPool.instance().destroyed();
    process.exit();
});