skgangaEkam/node_modules/piscina/dist/src/worker.js

"use strict";
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    if (k2 === undefined) k2 = k;
    Object.defineProperty(o, k2, { enumerable: true, get: function() { return m[k]; } });
}) : (function(o, m, k, k2) {
    if (k2 === undefined) k2 = k;
    o[k2] = m[k];
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    Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
    o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
    if (mod && mod.__esModule) return mod;
    var result = {};
    if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
    __setModuleDefault(result, mod);
    return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
const worker_threads_1 = require("worker_threads");
const url_1 = require("url");
const common_1 = require("./common");
common_1.commonState.isWorkerThread = true;
common_1.commonState.workerData = worker_threads_1.workerData;
const handlerCache = new Map();
let useAtomics = true;
// Get `import(x)` as a function that isn't transpiled to `require(x)` by
// TypeScript for dual ESM/CJS support.
// Load this lazily, so that there is no warning about the ESM loader being
// experimental (on Node v12.x) until we actually try to use it.
let importESMCached;
function getImportESM() {
    if (importESMCached === undefined) {
        // eslint-disable-next-line no-eval
        importESMCached = eval('(specifier) => import(specifier)');
    }
    return importESMCached;
}
// Look up the handler function that we call when a task is posted.
// This is either going to be "the" export from a file, or the default export.
async function getHandler(filename, name) {
    let handler = handlerCache.get(`${filename}/${name}`);
    if (handler !== undefined) {
        return handler;
    }
    try {
        // With our current set of TypeScript options, this is transpiled to
        // `require(filename)`.
        handler = await Promise.resolve().then(() => __importStar(require(filename)));
        if (typeof handler !== 'function') {
            handler = await (handler[name]);
        }
    }
    catch { }
    if (typeof handler !== 'function') {
        handler = await getImportESM()(url_1.pathToFileURL(filename).href);
        if (typeof handler !== 'function') {
            handler = await (handler[name]);
        }
    }
    if (typeof handler !== 'function') {
        return null;
    }
    // Limit the handler cache size. This should not usually be an issue and is
    // only provided for pathological cases.
    if (handlerCache.size > 1000) {
        const [[key]] = handlerCache;
        handlerCache.delete(key);
    }
    handlerCache.set(`${filename}/${name}`, handler);
    return handler;
}
// We should only receive this message once, when the Worker starts. It gives
// us the MessagePort used for receiving tasks, a SharedArrayBuffer for fast
// communication using Atomics, and the name of the default filename for tasks
// (so we can pre-load and cache the handler).
worker_threads_1.parentPort.on('message', (message) => {
    useAtomics = message.useAtomics;
    const { port, sharedBuffer, filename, name, niceIncrement } = message;
    (async function () {
        try {
            if (niceIncrement !== 0 && process.platform === 'linux') {
                // ts-ignore because the dependency is not installed on Windows.
                // @ts-ignore
                (await Promise.resolve().then(() => __importStar(require('nice-napi')))).default(niceIncrement);
            }
        }
        catch { }
        if (filename !== null) {
            await getHandler(filename, name);
        }
        const readyMessage = { ready: true };
        worker_threads_1.parentPort.postMessage(readyMessage);
        port.on('message', onMessage.bind(null, port, sharedBuffer));
        atomicsWaitLoop(port, sharedBuffer);
    })().catch(throwInNextTick);
});
let currentTasks = 0;
let lastSeenRequestCount = 0;
function atomicsWaitLoop(port, sharedBuffer) {
    if (!useAtomics)
        return;
    // This function is entered either after receiving the startup message, or
    // when we are done with a task. In those situations, the *only* thing we
    // expect to happen next is a 'message' on `port`.
    // That call would come with the overhead of a C++ → JS boundary crossing,
    // including async tracking. So, instead, if there is no task currently
    // running, we wait for a signal from the parent thread using Atomics.wait(),
    // and read the message from the port instead of generating an event,
    // in order to avoid that overhead.
    // The one catch is that this stops asynchronous operations that are still
    // running from proceeding. Generally, tasks should not spawn asynchronous
    // operations without waiting for them to finish, though.
    while (currentTasks === 0) {
        // Check whether there are new messages by testing whether the current
        // number of requests posted by the parent thread matches the number of
        // requests received.
        Atomics.wait(sharedBuffer, common_1.kRequestCountField, lastSeenRequestCount);
        lastSeenRequestCount = Atomics.load(sharedBuffer, common_1.kRequestCountField);
        // We have to read messages *after* updating lastSeenRequestCount in order
        // to avoid race conditions.
        let entry;
        while ((entry = worker_threads_1.receiveMessageOnPort(port)) !== undefined) {
            onMessage(port, sharedBuffer, entry.message);
        }
    }
}
function onMessage(port, sharedBuffer, message) {
    currentTasks++;
    const { taskId, task, filename, name } = message;
    (async function () {
        let response;
        const transferList = [];
        try {
            const handler = await getHandler(filename, name);
            if (handler === null) {
                throw new Error(`No handler function exported from ${filename}`);
            }
            let result = await handler(task);
            if (common_1.isMovable(result)) {
                transferList.concat(result[common_1.kTransferable]);
                result = result[common_1.kValue];
            }
            response = {
                taskId,
                result: result,
                error: null
            };
            // If the task used e.g. console.log(), wait for the stream to drain
            // before potentially entering the `Atomics.wait()` loop, and before
            // returning the result so that messages will always be printed even
            // if the process would otherwise be ready to exit.
            if (process.stdout.writableLength > 0) {
                await new Promise((resolve) => process.stdout.write('', resolve));
            }
            if (process.stderr.writableLength > 0) {
                await new Promise((resolve) => process.stderr.write('', resolve));
            }
        }
        catch (error) {
            response = {
                taskId,
                result: null,
                // It may be worth taking a look at the error cloning algorithm we
                // use in Node.js core here, it's quite a bit more flexible
                error
            };
        }
        currentTasks--;
        // Post the response to the parent thread, and let it know that we have
        // an additional message available. If possible, use Atomics.wait()
        // to wait for the next message.
        port.postMessage(response, transferList);
        Atomics.add(sharedBuffer, common_1.kResponseCountField, 1);
        atomicsWaitLoop(port, sharedBuffer);
    })().catch(throwInNextTick);
}
function throwInNextTick(error) {
    process.nextTick(() => { throw error; });
}
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