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/**
* @file llpacketring.h
* @brief LLPacketRing: a simple ring buffer for LLPacketBuffers.
*
* LLPacketRing stores incoming UDP packets that have already been received
* from the network socket. It has no socket or proxy awareness; callers
* push packets in with pushPacket() and retrieve them in FIFO order with
* popPacket().
*
* The ring starts at DEFAULT_BUFFER_RING_SIZE slots and grows in increments
* of BUFFER_RING_EXPANSION up to MAX_BUFFER_RING_SIZE. Once at the ceiling,
* pushPacket() silently overwrites the oldest queued packet to make room for
* the incoming one.
*
* $LicenseInfo:firstyear=2001&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#pragma once
#include <vector>
#include "llpacketbuffer.h"
class LLPacketRing
{
public:
LLPacketRing();
~LLPacketRing();
// Copy 'packet' onto the tail of the ring, growing the ring or
// overwriting the oldest entry when the ring is at capacity.
void pushPacket(const LLPacketBuffer& packet);
// Copy the head (oldest) packet into 'packet'.
// Returns true if a packet was available, false if the ring was empty.
bool popPacket(LLPacketBuffer& packet);
S32 getNumBufferedPackets() const { return (S32)(mNumBufferedPackets); }
S32 getNumBufferedBytes() const { return mNumBufferedBytes; }
// Ratio of buffered packets to DEFAULT_BUFFER_RING_SIZE (0 = empty, 1 = nominal full).
F32 getBufferLoadRate() const;
private:
// Returns true if the ring was expanded, false if already at the ceiling.
bool expandRing();
std::vector<LLPacketBuffer*> mRing;
S16 mHeadIndex { 0 };
S16 mNumBufferedPackets { 0 };
S32 mNumBufferedBytes { 0 };
};
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