cjdns/tools/lib/Semaphore.js

/*@flow*/
/*::
export type Saferphore_ReturnAfter_t = ((...any)=>void)=>(...any)=>void;
export type Saferphore_t = {
    take: ((Saferphore_ReturnAfter_t)=>void)=>void,
};
*/
;(function () {
    "use strict";
    var create = function (resourceCount /*:number*/) /*:Saferphore_t*/ {
        var queue = [];
        var check;
        var mkRa = function () /*:Saferphore_ReturnAfter_t*/ {
            var outerCalled = 0;
            return function (func) {
                if (outerCalled++) { throw new Error("returnAfter() called multiple times"); }
                var called = 0;
                return function () {
                    if (called++) {
                        throw new Error("returnAfter wrapped callback called multiple times");
                    }
                    if (func) { func.apply(null, arguments); }
                    resourceCount++;
                    check();
                };
            };
        };
        check = function () {
            if (resourceCount < 0) { throw new Error("(resourceCount < 0) should never happen"); }
            if (resourceCount === 0 || queue.length === 0) { return; }
            resourceCount--;
            queue.shift()(mkRa());
        };
        return {
            take: function (func) {
                queue.push(func);
                check();
            }
        };
    };
    if (typeof(window) === 'object') {
        if (window.define && window.define.amd) {
            window.define({ create: create });
        } else {
            window.Saferphore = { create: create };
        }
    } else if (typeof(module) === 'object' && module.exports) {
        module.exports.create = create;
    }
    }());