mpool
This library provides a simple object pool implementation.
Usage
import { Pool } from "mpool";
const pool = new Pool(() => ({ value: 0 }));
const obj = pool.get();
use(obj);
pool.put(obj);
The pool is unbounded, meaning that the pool never discards objects. To mitigate unbounded memory growth scenarios, the pool contains a .fit()
method which shrinks the pool to pool.preferredSize
objects, if there are more than pool.preferredSize
objects in the pool. You may call this at the end of your game loop.
import { Pool } from "mpool";
class Thing {}
const pool = new Pool(() => new Thing, /* preferred pool size */ 5);
console.log(pool.length); // 5
pool.put(new Thing);
console.log(pool.length); // 6
pool.fit();
console.log(pool.length); // 5 <- pool has shrunk to our preferred pool size
The recommended way to handle initialization + deinitialization of your objects is to implement init
and free
, for example:
import { Pool } from "mpool";
class Thing {
public value!: number;
init(value: number): this {
this.value = value;
return this;
}
free() {
// be careful: since `init` is *not* called automatically, `this.value` may be undefined.
// in your own code, you should provide default values and employ null checks to mitigate this.
console.log(`freed object: Thing { value: ${this.value} }`);
return this;
}
}
const pool = new Pool(
// callback used for creating new objects when there aren't any in the pool
() => new Thing,
// callback used for freeing objects when they are discarded after
// a call to `.fit()`
o => o.free(),
// preferred size of the pool, calling `.fit()` will only leave at most
// this many objects in the pool
0
);
// When acquiring an object, explicitly initialize it:
const obj = pool.get().init(100);
use(obj);
// at this point you may `.free()` your object, or return it to the pool
pool.put(obj);
// if at some point you `.fit()` the pool, the `free` callback will be called with
// every object beyond capacity, and those objects will be discarded
pool.fit(); // logs 'freed object: Thing { value: 100 }'