/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server.wifi.util;
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import com.android.server.wifi.Clock;
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/**
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* Manages a quota that is reset at the beginning of each new time period.
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*/
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public class TimedQuotaManager {
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private final Clock mClock;
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private final long mQuota;
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private final long mPeriodMillis;
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private final long mStartTimeMillis;
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/**
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* The number of elapsed periods between {@link #mStartTimeMillis} and the time of the last call
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* to {@link #requestQuota()}.
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*/
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private long mLastPeriod;
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/** How much quota has been consumed in the current period. */
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private long mConsumedQuota;
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/**
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* Constructor.
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* @param clock Clock instance.
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* @param quota the maximum quota for a given period.
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* @param periodMillis the quota will be reset at the beginning of each new period.
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*/
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public TimedQuotaManager(Clock clock, long quota, long periodMillis) {
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mClock = clock;
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mQuota = quota;
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mPeriodMillis = periodMillis;
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mStartTimeMillis = clock.getElapsedSinceBootMillis();
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mLastPeriod = 0;
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mConsumedQuota = 0;
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}
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/**
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* Requests one quota. If there is sufficient remaining quota for the current period,
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* returns true and consumes one quota. Otherwise, returns false.
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*/
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public boolean requestQuota() {
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long currentPeriod = getCurrentPeriod();
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if (mLastPeriod < currentPeriod) {
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mLastPeriod = currentPeriod;
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mConsumedQuota = 0;
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}
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if (mConsumedQuota < mQuota) {
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mConsumedQuota++;
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return true;
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}
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return false;
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}
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private long getCurrentPeriod() {
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return (mClock.getElapsedSinceBootMillis() - mStartTimeMillis) / mPeriodMillis;
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}
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@Override
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public String toString() {
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return "TimedQuotaManager{"
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+ "mQuota=" + mQuota
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+ ", mPeriodMillis=" + mPeriodMillis
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+ ", mStartTimeMillis=" + mStartTimeMillis
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+ ", mLastPeriod=" + mLastPeriod
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+ ", mConsumedQuota=" + mConsumedQuota
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+ '}';
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}
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}
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