import Scheduler from './scheduler/scheduler';
import UnboundedSchedulerPolicy from './scheduler/policies/unbounded-policy';
import EnqueueSchedulerPolicy from './scheduler/policies/enqueued-policy';
import DropSchedulerPolicy from './scheduler/policies/drop-policy';
import KeepLatestSchedulerPolicy from './scheduler/policies/keep-latest-policy';
import RestartableSchedulerPolicy from './scheduler/policies/restartable-policy';
import { Task } from './task/task';
import { TaskGroup } from './task/task-group';
function assertModifiersNotMixedWithGroup(obj) {
if (obj._hasSetConcurrencyConstraint && obj._taskGroupPath) {
throw new Error(
`Cannot use both 'group' and other concurrency-constraining task modifiers (e.g. 'drop', 'enqueue', 'restartable')`
);
}
}
function assertUnsetBufferPolicy(obj) {
if (obj._hasSetBufferPolicy) {
throw new Error(
`Cannot set multiple buffer policies on a task or task group. ${obj._schedulerPolicyClass} has already been set for task or task group '${obj.name}'`
);
}
}
const MODIFIER_REGISTRY = {
enqueue: (factory, value) =>
value && factory.setBufferPolicy(EnqueueSchedulerPolicy),
evented: (factory, value) => value && factory.setEvented(value),
debug: (factory, value) => value && factory.setDebug(value),
drop: (factory, value) =>
value && factory.setBufferPolicy(DropSchedulerPolicy),
group: (factory, groupName) => factory.setGroup(groupName),
keepLatest: (factory, value) =>
value && factory.setBufferPolicy(KeepLatestSchedulerPolicy),
maxConcurrency: (factory, maxConcurrency) =>
factory.setMaxConcurrency(maxConcurrency),
onState: (factory, onStateCallback) => factory.setOnState(onStateCallback),
restartable: (factory, value) =>
value && factory.setBufferPolicy(RestartableSchedulerPolicy),
};
/**
* Callback type defining a task modifier
*
* @callback TaskFactory~TaskModifier
* @param {TaskFactory} factory
* @param {*} taskModifierOption
*/
/**
* Registers a new modifier with the modifier registry
*
* @param {string} name Name of the modifier
* @param {TaskFactory~TaskModifier} callback
*/
export function registerModifier(name, callback) {
if (MODIFIER_REGISTRY[name]) {
throw new Error(
`A modifier with the name '${name}' has already been defined.`
);
}
MODIFIER_REGISTRY[name] = callback;
}
/**
* Returns a specified modifier, if it exists in the registry
*
* @param {string} name Name of the modifier
* @returns {TaskFactory~TaskModifier?}
*/
export function getModifier(name) {
return MODIFIER_REGISTRY[name];
}
/**
* Returns whether a specified modifier exists in the registry
*
* @param {string} name Name of the modifier
* @returns {boolean}
*/
export function hasModifier(name) {
return name in MODIFIER_REGISTRY;
}
/**
* Factory used for instantiating Tasks and Task Groups. Mostly for internal
* use, but some public APIs exposed via the Task Modifier APIs.
*
* <style>
* .ignore-this--this-is-here-to-hide-constructor,
* #TaskFactory { display: none }
* </style>
*
* @class TaskFactory
*/
export class TaskFactory {
_debug = null;
_enabledModifiers = [];
_hasSetConcurrencyConstraint = false;
_hasSetBufferPolicy = false;
_hasEnabledEvents = false;
_maxConcurrency = null;
_onStateCallback = (state, taskable) => taskable.setState(state);
_schedulerPolicyClass = UnboundedSchedulerPolicy;
_taskGroupPath = null;
constructor(name = '<unknown>', taskDefinition = null, options = {}) {
this.name = name;
this.taskDefinition = taskDefinition;
this.options = options;
this._processModifierOptions(options);
}
/**
* Returns a new Task bound to the given context
*
* @protected
* @param {*} context
* @returns {Task}
*/
createTask(context) {
let options = this.getTaskOptions(context);
return new Task(
Object.assign(
{
generatorFactory: (args) => this.taskDefinition.apply(context, args),
},
options
)
);
}
/**
* Returns a new TaskGroup bound to the given context
*
* @protected
* @param {*} context
* @returns {Task}
*/
createTaskGroup(context) {
let options = this.getTaskOptions(context);
return new TaskGroup(options);
}
/**
* Returns a modifier callback with the given name bound to this TaskFactory,
* if registered.
*
* @protected
* @param {string} name
* @returns {TaskFactory~TaskModifier?}
*/
getModifier(name) {
if (hasModifier(name)) {
return MODIFIER_REGISTRY[name].bind(null, this);
}
}
/**
* Returns the options provided to TaskFactory
*
* @public
* @returns {object}
*/
getOptions() {
return this.options;
}
/**
* Returns a new Scheduler instance
*
* @protected
* @param {*} schedulerPolicy
* @param {boolean} stateTrackingEnabled
* @returns {Scheduler}
*/
getScheduler(schedulerPolicy, stateTrackingEnabled) {
return new Scheduler(schedulerPolicy, stateTrackingEnabled);
}
/**
* Returns the options to pass to a Task or TaskGroup constructor
*
* @protected
* @param {*} context
* @returns {object}
*/
getTaskOptions(context) {
let group, scheduler;
let onStateCallback = this._onStateCallback;
if (this._taskGroupPath) {
group = context[this._taskGroupPath];
if (!(group instanceof TaskGroup)) {
throw new Error(
`Expected group '${this._taskGroupPath}' to be defined but was not found.`
);
}
scheduler = group.scheduler;
} else {
let schedulerPolicy = new this._schedulerPolicyClass(
this._maxConcurrency
);
scheduler = this.getScheduler(
schedulerPolicy,
onStateCallback && typeof onStateCallback === 'function'
);
}
return {
context,
debug: this._debug,
name: this.name,
group,
scheduler,
hasEnabledEvents: this._hasEnabledEvents,
onStateCallback,
enabledModifiers: this._enabledModifiers,
modifierOptions: this.getOptions(),
};
}
/**
* Sets the Scheduler buffer policy class to the specified value.
*
* Will raise an assertion if a buffer policy has already been specified
*
* @param {*} policy
* @returns {TaskFactory}
*/
setBufferPolicy(policy) {
assertUnsetBufferPolicy(this);
this._hasSetBufferPolicy = true;
this._hasSetConcurrencyConstraint = true;
this._schedulerPolicyClass = policy;
assertModifiersNotMixedWithGroup(this);
return this;
}
/**
* Sets debug mode
*
* @param {boolean} enabled
* @returns {TaskFactory}
*/
setDebug(enabled) {
this._debug = enabled;
return this;
}
/**
* Sets whether Task will dispatch Task events or not
*
* @param {boolean} enabled
* @returns {TaskFactory}
*/
setEvented(enabled) {
this._hasEnabledEvents = enabled;
return this;
}
/**
* Sets Scheduling policy's `maxConcurrency`
*
* @param {number} maxConcurrency
* @returns {TaskFactory}
*/
setMaxConcurrency(maxConcurrency) {
this._hasSetConcurrencyConstraint = true;
this._maxConcurrency = maxConcurrency;
return this;
}
/**
* Assigns Task created from this factory to the specified group name
*
* @param {string} group
* @returns {TaskFactory}
*/
setGroup(group) {
this._taskGroupPath = group;
return this;
}
/**
* Sets the name of tasks created from this factory
*
* @param {string} name
* @returns {TaskFactory}
*/
setName(name) {
this.name = name;
return this;
}
/**
* Sets the callback used on state updates. Can be set to null to disable
* state tracking on tasks.
*
* @param {function} onStateCallback
* @returns {TaskFactory}
*/
setOnState(onStateCallback) {
this._onStateCallback = onStateCallback;
return this;
}
/**
* Sets the definition for tasks created from this factory
*
* @param {*} taskDefinition
* @returns {TaskFactory}
*/
setTaskDefinition(taskDefinition) {
this.taskDefinition = taskDefinition;
return this;
}
_processModifierOptions(options) {
for (let key of Object.keys(options)) {
let value = options[key];
let modifier = this.getModifier(key);
if (typeof modifier === 'function' && modifier(value)) {
this._enabledModifiers.push(key);
}
}
}
}