@pdftron/webviewer-react-toolkit/dist/esm/work/GlobalQueue.js

A React component library for integrating with PDFTron WebViewer API.

import { __awaiter, __generator } from "tslib";
import { getId } from '../utils';
var MAX_ACTIVE_UNITS = 1;
var QueueItem = /** @class */ (function () {
    function QueueItem(id, unit) {
        this.cancelled = false;
        this.id = id;
        this.unit = unit;
    }
    QueueItem.prototype.process = function () {
        return this.unit();
    };
    QueueItem.prototype.cancel = function () {
        this.cancelled = true;
    };
    return QueueItem;
}());
var GlobalQueue = /** @class */ (function () {
    function GlobalQueue() {
        this.queue = [];
        this.queueRefs = new Map();
        this._listeners = new Map();
        this._queueLength = 0;
        this._activeUnits = 0;
    }
    GlobalQueue.prototype.process = function (unit) {
        var _this = this;
        var id = getId();
        var item = new QueueItem(id, unit);
        this.queue.push(item);
        this.queueRefs.set(id, item);
        var p = new Promise(function (resolve, reject) {
            _this._listeners.set(id, function (result) {
                if (result instanceof Error) {
                    return reject(result);
                }
                resolve(result);
            });
        });
        this._queueLength++;
        this.flush();
        return [p, function () { return _this.cancel(id); }];
    };
    // Marks a unit of work as cancelled.
    // The unit will not be processed and will be removed
    // from the queue when no other work is going on
    GlobalQueue.prototype.cancel = function (id) {
        var ref = this.queueRefs.get(id);
        ref === null || ref === void 0 ? void 0 : ref.cancel();
        this.flush();
    };
    GlobalQueue.prototype.cleanup = function () {
        var _this = this;
        this.queue = this.queue.filter(function (item) {
            var cancelled = item.cancelled, id = item.id;
            if (cancelled) {
                _this.queueRefs.delete(id);
                return false;
            }
            return true;
        });
        this._queueLength = this.queue.length;
    };
    GlobalQueue.prototype.flush = function () {
        return __awaiter(this, void 0, void 0, function () {
            var item, result, e_1, id, callback;
            return __generator(this, function (_a) {
                switch (_a.label) {
                    case 0:
                        if (this._activeUnits === MAX_ACTIVE_UNITS)
                            return [2 /*return*/];
                        if (this._queueLength === 0) {
                            this.cleanup();
                            return [2 /*return*/];
                        }
                        item = this.queue.shift();
                        if (item === null || item === void 0 ? void 0 : item.cancelled) {
                            this._queueLength--;
                            this.flush();
                            return [2 /*return*/];
                        }
                        // If no items left, return
                        if (!item) {
                            this.cleanup();
                            return [2 /*return*/];
                        }
                        this._activeUnits++;
                        _a.label = 1;
                    case 1:
                        _a.trys.push([1, 3, , 4]);
                        return [4 /*yield*/, (item === null || item === void 0 ? void 0 : item.process())];
                    case 2:
                        result = _a.sent();
                        return [3 /*break*/, 4];
                    case 3:
                        e_1 = _a.sent();
                        result = new Error(e_1);
                        return [3 /*break*/, 4];
                    case 4:
                        id = item === null || item === void 0 ? void 0 : item.id;
                        callback = this._listeners.get(id);
                        callback === null || callback === void 0 ? void 0 : callback(result);
                        this.queueRefs.delete(id);
                        this._activeUnits--;
                        this._queueLength--;
                        this.flush();
                        return [2 /*return*/];
                }
            });
        });
    };
    return GlobalQueue;
}());
// Singleton
export default new GlobalQueue();