task-farmer
Version:
A simple multi-core task scheduler that works well with promises. Great for doing parallel data processing.
220 lines • 8.43 kB
JavaScript
;
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
var __generator = (this && this.__generator) || function (thisArg, body) {
var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
function verb(n) { return function (v) { return step([n, v]); }; }
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while (_) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, t.value];
switch (op[0]) {
case 0: case 1: t = op; break;
case 4: _.label++; return { value: op[1], done: false };
case 5: _.label++; y = op[1]; op = [0]; continue;
case 7: op = _.ops.pop(); _.trys.pop(); continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
if (t[2]) _.ops.pop();
_.trys.pop(); continue;
}
op = body.call(thisArg, _);
} catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
}
};
Object.defineProperty(exports, "__esModule", { value: true });
var uuid_1 = require("uuid");
//
// Defines a parallelizable asynchronous task.
//
var TaskDef = /** @class */ (function () {
function TaskDef(taskName, taskFn) {
this.taskName = taskName;
this.taskFn = taskFn;
}
//
// Retreive the user-defined name of the task.
//
TaskDef.prototype.getTaskName = function () {
return this.taskName;
};
//
// Get the function that is invoked to perform the task.
//
TaskDef.prototype.getTaskFn = function () {
return this.taskFn;
};
//
// Instantiate a task from the definition.
//
TaskDef.prototype.create = function () {
var inputs = [];
for (var _i = 0; _i < arguments.length; _i++) {
inputs[_i] = arguments[_i];
}
var wrappedTasks = inputs.map(this.wrapTask); // Wrap direct inputs as tasks.
return new Task(wrappedTasks, this);
};
//
// Wrap direct values in tasks where necessary.
//
TaskDef.prototype.wrapTask = function (input) {
if (typeof (input.run) === "function") {
// It's a task.
return input;
}
else {
// It's a direct value, so wrap it in a task.
return new WrappedValue(input);
}
};
return TaskDef;
}());
//
// Interface to a parallelizable asynchronous task.
//
var Task = /** @class */ (function () {
function Task(inputTasks, taskDef) {
this.taskId = uuid_1.v4();
this.inputTasks = inputTasks;
this.taskDef = taskDef;
}
//
// Register a task.
//
Task.register = function (taskName, taskFn) {
var taskDef = new TaskDef(taskName, taskFn);
Task.taskDefs[taskDef.getTaskName()] = taskDef;
return taskDef;
};
//
// Look up a task.
//
Task.lookup = function (taskDefId) {
return Task.taskDefs[taskDefId];
};
//
// Run multiple tasks in parallel and collect their results as an array.
//
Task.all = function (inputTasks) {
return new AllTask(inputTasks);
};
//
// Retreive the unique ID for the task.
//
Task.prototype.getTaskId = function () {
return this.taskId;
};
//
// Retreive the task definition.
//
Task.prototype.getTaskDef = function () {
return this.taskDef;
};
//
// Run a task and all it's input tasks as soon as workers are available.
// Returns a promise that is resolved when the task and its inputs have completed successfully.
// Rejects the promise if the task or any input throws an error.
//
Task.prototype.run = function (scheduler) {
return __awaiter(this, void 0, void 0, function () {
var inputs;
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /*yield*/, Promise.all(this.inputTasks.map(function (inputTask) { return inputTask.run(scheduler); }))];
case 1:
inputs = _a.sent();
return [4 /*yield*/, scheduler.runTask(inputs, this)];
case 2: return [2 /*return*/, _a.sent()];
}
});
});
};
//
// Lookup table for tasks.
// Allows task to be found by name when request to run in a worker process.
//
Task.taskDefs = {};
return Task;
}());
exports.Task = Task;
//
// A task that wraps up a direct value.
//
var WrappedValue = /** @class */ (function () {
function WrappedValue(value) {
this.value = value;
}
//
// Retreive the unique ID for the task.
//
WrappedValue.prototype.getTaskId = function () {
return "wrapped"; // This doesn't need a distinct ID because it's not to be transmitted to a worker process.
};
//
// Retreive the task definition.
//
WrappedValue.prototype.getTaskDef = function () {
var _this = this;
return new TaskDef("wrapped", function () { return __awaiter(_this, void 0, void 0, function () { return __generator(this, function (_a) {
return [2 /*return*/];
}); }); });
};
//
// Simply returns the wrapped value.
//
WrappedValue.prototype.run = function (scheduler) {
return this.value;
};
return WrappedValue;
}());
//
// A task that aggregates a list of tasks.
//
var AllTask = /** @class */ (function () {
function AllTask(inputTasks) {
this.inputTasks = inputTasks;
}
//
// Retreive the unique ID for the task.
//
AllTask.prototype.getTaskId = function () {
return "all"; // This doesn't need a distinct ID because it's not to be transmitted to a worker process.
};
//
// Retreive the task definition.
//
AllTask.prototype.getTaskDef = function () {
var _this = this;
return new TaskDef("all", function () { return __awaiter(_this, void 0, void 0, function () { return __generator(this, function (_a) {
return [2 /*return*/];
}); }); }); //TODO: Is there a better design that doesn't need these fake implementations?
};
//
// Simply returns the wrapped value.
//
AllTask.prototype.run = function (scheduler) {
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /*yield*/, Promise.all(this.inputTasks.map(function (inputTask) { return inputTask.run(scheduler); }))];
case 1: return [2 /*return*/, _a.sent()];
}
});
});
};
return AllTask;
}());
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