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a35560ba S |
1 | import { isKillBehavior, KillBehaviors } from '../worker/worker-options' |
2 | import type { IWorker } from './abstract-pool' | |
3 | import type { IPoolInternal } from './pool-internal' | |
4 | ||
5 | /** | |
6 | * Enumeration of worker choice strategies. | |
7 | */ | |
8 | export const WorkerChoiceStrategies = Object.freeze({ | |
9 | /** | |
10 | * Round robin worker selection strategy. | |
11 | */ | |
12 | ROUND_ROBIN: 'ROUND_ROBIN', | |
13 | /** | |
14 | * Less recently used worker selection strategy. | |
15 | */ | |
16 | LESS_RECENTLY_USED: 'LESS_RECENTLY_USED' | |
17 | } as const) | |
18 | ||
19 | /** | |
20 | * Worker choice strategy. | |
21 | */ | |
22 | export type WorkerChoiceStrategy = keyof typeof WorkerChoiceStrategies | |
23 | ||
24 | /** | |
25 | * Worker choice strategy interface. | |
26 | * | |
27 | * @template Worker Type of worker which manages the strategy. | |
28 | */ | |
29 | interface IWorkerChoiceStrategy<Worker extends IWorker> { | |
30 | /** | |
31 | * Choose a worker in the pool. | |
32 | */ | |
33 | choose(): Worker | |
34 | } | |
35 | ||
36 | /** | |
37 | * Selects the next worker in a round robin fashion. | |
38 | * | |
39 | * @template Worker Type of worker which manages the strategy. | |
40 | * @template Data Type of data sent to the worker. This can only be serializable data. | |
41 | * @template Response Type of response of execution. This can only be serializable data. | |
42 | */ | |
43 | class RoundRobinWorkerChoiceStrategy<Worker extends IWorker, Data, Response> | |
44 | implements IWorkerChoiceStrategy<Worker> { | |
45 | /** | |
46 | * Index for the next worker. | |
47 | */ | |
48 | private nextWorkerIndex: number = 0 | |
49 | ||
50 | /** | |
51 | * Constructs a worker choice strategy that selects in a round robin fashion. | |
52 | * | |
53 | * @param pool The pool instance. | |
54 | */ | |
55 | public constructor ( | |
56 | private readonly pool: IPoolInternal<Worker, Data, Response> | |
57 | ) {} | |
58 | ||
59 | /** @inheritdoc */ | |
60 | public choose (): Worker { | |
61 | const chosenWorker = this.pool.workers[this.nextWorkerIndex] | |
62 | this.nextWorkerIndex = | |
63 | this.pool.workers.length - 1 === this.nextWorkerIndex | |
64 | ? 0 | |
65 | : this.nextWorkerIndex + 1 | |
66 | return chosenWorker | |
67 | } | |
68 | } | |
69 | ||
70 | /** | |
71 | * Selects the less recently used worker. | |
72 | * | |
73 | * @template Worker Type of worker which manages the strategy. | |
74 | * @template Data Type of data sent to the worker. This can only be serializable data. | |
75 | * @template Response Type of response of execution. This can only be serializable data. | |
76 | */ | |
77 | class LessRecentlyUsedWorkerChoiceStrategy< | |
78 | Worker extends IWorker, | |
79 | Data, | |
80 | Response | |
81 | > implements IWorkerChoiceStrategy<Worker> { | |
82 | /** | |
83 | * Constructs a worker choice strategy that selects based on less recently used. | |
84 | * | |
85 | * @param pool The pool instance. | |
86 | */ | |
87 | public constructor ( | |
88 | private readonly pool: IPoolInternal<Worker, Data, Response> | |
89 | ) {} | |
90 | ||
91 | /** @inheritdoc */ | |
92 | public choose (): Worker { | |
ff5e76e1 | 93 | const isPoolDynamic = this.pool.dynamic |
a35560ba S |
94 | let minNumberOfTasks = Infinity |
95 | // A worker is always found because it picks the one with fewer tasks | |
96 | let lessRecentlyUsedWorker!: Worker | |
97 | for (const [worker, numberOfTasks] of this.pool.tasks) { | |
ff5e76e1 | 98 | if (!isPoolDynamic && numberOfTasks === 0) { |
a35560ba S |
99 | return worker |
100 | } else if (numberOfTasks < minNumberOfTasks) { | |
101 | minNumberOfTasks = numberOfTasks | |
102 | lessRecentlyUsedWorker = worker | |
103 | } | |
104 | } | |
105 | return lessRecentlyUsedWorker | |
106 | } | |
107 | } | |
108 | ||
a35560ba S |
109 | /** |
110 | * Dynamically choose a worker. | |
111 | * | |
112 | * @template Worker Type of worker which manages the strategy. | |
113 | * @template Data Type of data sent to the worker. This can only be serializable data. | |
114 | * @template Response Type of response of execution. This can only be serializable data. | |
115 | */ | |
116 | class DynamicPoolWorkerChoiceStrategy<Worker extends IWorker, Data, Response> | |
117 | implements IWorkerChoiceStrategy<Worker> { | |
118 | private workerChoiceStrategy: IWorkerChoiceStrategy<Worker> | |
119 | ||
120 | /** | |
121 | * Constructs a worker choice strategy for dynamical pools. | |
122 | * | |
123 | * @param pool The pool instance. | |
124 | * @param workerChoiceStrategy The worker choice strategy when the pull is full. | |
125 | */ | |
126 | public constructor ( | |
127 | private readonly pool: IPoolInternal<Worker, Data, Response>, | |
128 | workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN | |
129 | ) { | |
ff5e76e1 | 130 | this.workerChoiceStrategy = SelectionStrategiesUtils.getWorkerChoiceStrategy( |
a35560ba S |
131 | this.pool, |
132 | workerChoiceStrategy | |
133 | ) | |
134 | } | |
135 | ||
a35560ba S |
136 | /** @inheritdoc */ |
137 | public choose (): Worker { | |
ff5e76e1 JB |
138 | const freeWorker = SelectionStrategiesUtils.findFreeWorkerBasedOnTasks( |
139 | this.pool | |
140 | ) | |
a35560ba S |
141 | if (freeWorker) { |
142 | return freeWorker | |
143 | } | |
144 | ||
145 | if (this.pool.workers.length === this.pool.max) { | |
146 | this.pool.emitter.emit('FullPool') | |
147 | return this.workerChoiceStrategy.choose() | |
148 | } | |
149 | ||
150 | // All workers are busy, create a new worker | |
151 | const workerCreated = this.pool.createAndSetupWorker() | |
152 | this.pool.registerWorkerMessageListener(workerCreated, message => { | |
153 | const tasksInProgress = this.pool.tasks.get(workerCreated) | |
154 | if ( | |
155 | isKillBehavior(KillBehaviors.HARD, message.kill) || | |
156 | tasksInProgress === 0 | |
157 | ) { | |
158 | // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime) | |
159 | void this.pool.destroyWorker(workerCreated) | |
160 | } | |
161 | }) | |
162 | return workerCreated | |
163 | } | |
164 | } | |
165 | ||
166 | /** | |
167 | * The worker choice strategy context. | |
168 | * | |
169 | * @template Worker Type of worker. | |
170 | * @template Data Type of data sent to the worker. This can only be serializable data. | |
171 | * @template Response Type of response of execution. This can only be serializable data. | |
172 | */ | |
173 | export class WorkerChoiceStrategyContext< | |
174 | Worker extends IWorker, | |
175 | Data, | |
176 | Response | |
177 | > { | |
178 | // Will be set by setter in constructor | |
179 | private workerChoiceStrategy!: IWorkerChoiceStrategy<Worker> | |
180 | ||
181 | /** | |
182 | * Worker choice strategy context constructor. | |
183 | * | |
184 | * @param pool The pool instance. | |
185 | * @param workerChoiceStrategy The worker choice strategy. | |
186 | */ | |
187 | public constructor ( | |
188 | private readonly pool: IPoolInternal<Worker, Data, Response>, | |
189 | workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN | |
190 | ) { | |
191 | this.setWorkerChoiceStrategy(workerChoiceStrategy) | |
192 | } | |
193 | ||
194 | /** | |
195 | * Get the worker choice strategy instance specific to the pool type. | |
196 | * | |
197 | * @param workerChoiceStrategy The worker choice strategy. | |
198 | * @returns The worker choice strategy instance for the pool type. | |
199 | */ | |
200 | private getPoolWorkerChoiceStrategy ( | |
201 | workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN | |
202 | ): IWorkerChoiceStrategy<Worker> { | |
ff5e76e1 | 203 | if (this.pool.dynamic) { |
a35560ba S |
204 | return new DynamicPoolWorkerChoiceStrategy( |
205 | this.pool, | |
206 | workerChoiceStrategy | |
207 | ) | |
208 | } | |
ff5e76e1 JB |
209 | return SelectionStrategiesUtils.getWorkerChoiceStrategy( |
210 | this.pool, | |
211 | workerChoiceStrategy | |
212 | ) | |
a35560ba S |
213 | } |
214 | ||
215 | /** | |
216 | * Set the worker choice strategy to use in the context. | |
217 | * | |
218 | * @param workerChoiceStrategy The worker choice strategy to set. | |
219 | */ | |
220 | public setWorkerChoiceStrategy ( | |
221 | workerChoiceStrategy: WorkerChoiceStrategy | |
222 | ): void { | |
223 | this.workerChoiceStrategy = this.getPoolWorkerChoiceStrategy( | |
224 | workerChoiceStrategy | |
225 | ) | |
226 | } | |
227 | ||
228 | /** | |
229 | * Choose a worker with the underlying selection strategy. | |
230 | * | |
231 | * @returns The chosen one. | |
232 | */ | |
233 | public execute (): Worker { | |
234 | return this.workerChoiceStrategy.choose() | |
235 | } | |
236 | } | |
ff5e76e1 JB |
237 | |
238 | /** | |
239 | * Worker selection strategies helpers. | |
240 | */ | |
241 | class SelectionStrategiesUtils { | |
242 | /** | |
243 | * Find a free worker based on number of tasks the worker has applied. | |
244 | * | |
245 | * If a worker was found that has `0` tasks, it is detected as free and will be returned. | |
246 | * | |
247 | * If no free worker was found, `null` will be returned. | |
248 | * | |
249 | * @param pool The pool instance. | |
250 | * @returns A free worker if there was one, otherwise `null`. | |
251 | */ | |
252 | public static findFreeWorkerBasedOnTasks< | |
253 | Worker extends IWorker, | |
254 | Data, | |
255 | Response | |
256 | > (pool: IPoolInternal<Worker, Data, Response>): Worker | null { | |
257 | for (const [worker, numberOfTasks] of pool.tasks) { | |
258 | if (numberOfTasks === 0) { | |
259 | // A worker is free, use it | |
260 | return worker | |
261 | } | |
262 | } | |
263 | return null | |
264 | } | |
265 | ||
266 | /** | |
267 | * Get the worker choice strategy instance. | |
268 | * | |
269 | * @param pool The pool instance. | |
270 | * @param workerChoiceStrategy The worker choice strategy. | |
271 | * @returns The worker choice strategy instance. | |
272 | */ | |
273 | public static getWorkerChoiceStrategy< | |
274 | Worker extends IWorker, | |
275 | Data, | |
276 | Response | |
277 | > ( | |
278 | pool: IPoolInternal<Worker, Data, Response>, | |
279 | workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN | |
280 | ): IWorkerChoiceStrategy<Worker> { | |
281 | switch (workerChoiceStrategy) { | |
282 | case WorkerChoiceStrategies.ROUND_ROBIN: | |
283 | return new RoundRobinWorkerChoiceStrategy(pool) | |
284 | case WorkerChoiceStrategies.LESS_RECENTLY_USED: | |
285 | return new LessRecentlyUsedWorkerChoiceStrategy(pool) | |
286 | default: | |
287 | throw new Error( | |
288 | `Worker choice strategy '${workerChoiceStrategy}' not found` | |
289 | ) | |
290 | } | |
291 | } | |
292 | } |