122 lines
3.3 KiB
JavaScript
122 lines
3.3 KiB
JavaScript
/**
|
|
* Copyright (c) 2013-present, Facebook, Inc.
|
|
*
|
|
* This source code is licensed under the MIT license found in the
|
|
* LICENSE file in the root directory of this source tree.
|
|
*
|
|
* @providesModule PooledClass
|
|
* @flow
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
const invariant = require('fbjs/lib/invariant');
|
|
|
|
/**
|
|
* Static poolers. Several custom versions for each potential number of
|
|
* arguments. A completely generic pooler is easy to implement, but would
|
|
* require accessing the `arguments` object. In each of these, `this` refers to
|
|
* the Class itself, not an instance. If any others are needed, simply add them
|
|
* here, or in their own files.
|
|
*/
|
|
const oneArgumentPooler = function(copyFieldsFrom) {
|
|
const Klass = this;
|
|
if (Klass.instancePool.length) {
|
|
const instance = Klass.instancePool.pop();
|
|
Klass.call(instance, copyFieldsFrom);
|
|
return instance;
|
|
} else {
|
|
return new Klass(copyFieldsFrom);
|
|
}
|
|
};
|
|
|
|
const twoArgumentPooler = function(a1, a2) {
|
|
const Klass = this;
|
|
if (Klass.instancePool.length) {
|
|
const instance = Klass.instancePool.pop();
|
|
Klass.call(instance, a1, a2);
|
|
return instance;
|
|
} else {
|
|
return new Klass(a1, a2);
|
|
}
|
|
};
|
|
|
|
const threeArgumentPooler = function(a1, a2, a3) {
|
|
const Klass = this;
|
|
if (Klass.instancePool.length) {
|
|
const instance = Klass.instancePool.pop();
|
|
Klass.call(instance, a1, a2, a3);
|
|
return instance;
|
|
} else {
|
|
return new Klass(a1, a2, a3);
|
|
}
|
|
};
|
|
|
|
const fourArgumentPooler = function(a1, a2, a3, a4) {
|
|
const Klass = this;
|
|
if (Klass.instancePool.length) {
|
|
const instance = Klass.instancePool.pop();
|
|
Klass.call(instance, a1, a2, a3, a4);
|
|
return instance;
|
|
} else {
|
|
return new Klass(a1, a2, a3, a4);
|
|
}
|
|
};
|
|
|
|
const standardReleaser = function(instance) {
|
|
const Klass = this;
|
|
invariant(
|
|
instance instanceof Klass,
|
|
'Trying to release an instance into a pool of a different type.',
|
|
);
|
|
instance.destructor();
|
|
if (Klass.instancePool.length < Klass.poolSize) {
|
|
Klass.instancePool.push(instance);
|
|
}
|
|
};
|
|
|
|
const DEFAULT_POOL_SIZE = 10;
|
|
const DEFAULT_POOLER = oneArgumentPooler;
|
|
|
|
type Pooler = any;
|
|
|
|
/**
|
|
* Augments `CopyConstructor` to be a poolable class, augmenting only the class
|
|
* itself (statically) not adding any prototypical fields. Any CopyConstructor
|
|
* you give this may have a `poolSize` property, and will look for a
|
|
* prototypical `destructor` on instances.
|
|
*
|
|
* @param {Function} CopyConstructor Constructor that can be used to reset.
|
|
* @param {Function} pooler Customizable pooler.
|
|
*/
|
|
const addPoolingTo = function<T>(
|
|
CopyConstructor: Class<T>,
|
|
pooler: Pooler,
|
|
): Class<T> & {
|
|
getPooled(
|
|
...args: $ReadOnlyArray<mixed>
|
|
): /* arguments of the constructor */ T,
|
|
release(instance: mixed): void,
|
|
} {
|
|
// Casting as any so that flow ignores the actual implementation and trusts
|
|
// it to match the type we declared
|
|
const NewKlass = (CopyConstructor: any);
|
|
NewKlass.instancePool = [];
|
|
NewKlass.getPooled = pooler || DEFAULT_POOLER;
|
|
if (!NewKlass.poolSize) {
|
|
NewKlass.poolSize = DEFAULT_POOL_SIZE;
|
|
}
|
|
NewKlass.release = standardReleaser;
|
|
return NewKlass;
|
|
};
|
|
|
|
const PooledClass = {
|
|
addPoolingTo: addPoolingTo,
|
|
oneArgumentPooler: (oneArgumentPooler: Pooler),
|
|
twoArgumentPooler: (twoArgumentPooler: Pooler),
|
|
threeArgumentPooler: (threeArgumentPooler: Pooler),
|
|
fourArgumentPooler: (fourArgumentPooler: Pooler),
|
|
};
|
|
|
|
module.exports = PooledClass;
|