// @flow
// Copyright (c) 2016 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
export default class RateLimiter {
_creditsPerSecond: number;
_balance: number;
_lastTick: number;
constructor(creditsPerSecond: number) {
this._creditsPerSecond = creditsPerSecond;
this._balance = creditsPerSecond;
this._lastTick = new Date().getTime();
}
checkCredit(itemCost: number): boolean {
let currentTime: number = new Date().getTime();
let elapsedTime: number = (currentTime - this._lastTick) / 1000;
this._lastTick = currentTime;
this._balance += elapsedTime * this._creditsPerSecond;
if (this._balance > this._creditsPerSecond) {
this._balance = this._creditsPerSecond;
}
if (this._balance >= itemCost) {
this._balance -= itemCost;
return true;
}
return false;
}
}
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