/*
 * Copyright (C) 1996-2021 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

#ifndef BANDWIDTHBUCKET_H
#define BANDWIDTHBUCKET_H

#if USE_DELAY_POOLS

#include "comm/IoCallback.h"

class fde;

/// Base class for Squid-to-client bandwidth limiting
class BandwidthBucket
{
public:
    BandwidthBucket(const int speed, const int initialLevelPercent, const double sizeLimit);
    virtual ~BandwidthBucket() {}

    static BandwidthBucket *SelectBucket(fde *f);

    /// \returns the number of bytes this bucket allows to write,
    /// also considering aggregates, if any. Negative quota means
    /// no limitations by this bucket.
    virtual int quota() = 0;
    /// Adjusts nleft to not exceed the current bucket quota value,
    /// if needed.
    virtual bool applyQuota(int &nleft, Comm::IoCallback *state);
    /// Will plan another write call.
    virtual void scheduleWrite(Comm::IoCallback *state) = 0;
    /// Performs cleanup when the related file descriptor becomes closed.
    virtual void onFdClosed() { selectWaiting = false; }
    /// Decreases the bucket level.
    virtual void reduceBucket(const int len);
    /// Whether this bucket will not do bandwidth limiting.
    bool noLimit() const { return writeSpeedLimit < 0; }

protected:
    /// Increases the bucket level with the writeSpeedLimit speed.
    void refillBucket();

public:
    double bucketLevel; ///< how much can be written now
    bool selectWaiting; ///< is between commSetSelect and commHandleWrite

protected:
    double prevTime; ///< previous time when we checked
    double writeSpeedLimit; ///< Write speed limit in bytes per second.
    double bucketSizeLimit; ///< maximum bucket size
};

#endif /* USE_DELAY_POOLS */

#endif

