127 lines
4.3 KiB
C++
127 lines
4.3 KiB
C++
/*
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* Copyright (C) 2014 Cloudius Systems, Ltd.
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*/
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#ifndef PACKET_UTIL_HH_
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#define PACKET_UTIL_HH_
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#include "net/packet.hh"
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#include <map>
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#include <iostream>
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namespace net {
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template <typename Offset>
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class packet_merger {
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public:
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std::map<Offset, packet> map;
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void merge(Offset offset, packet p) {
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bool insert;
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auto beg = offset;
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auto end = beg + p.len();
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// Fisrt, try to merge the packet with existing segment
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for (auto it = map.begin(); it != map.end();) {
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auto& seg_pkt = it->second;
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auto seg_beg = it->first;
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auto seg_end = seg_beg + seg_pkt.len();
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// There are 6 cases:
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if (seg_beg <= beg && end <= seg_end) {
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// 1) seg_beg beg end seg_end
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// We already have data in this packet
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return;
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} else if (beg <= seg_beg && seg_end <= end) {
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// 2) beg seg_beg seg_end end
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// The new segment contains more data than this old segment
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// Delete the old one, insert the new one
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it = map.erase(it);
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insert = true;
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break;
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} else if (beg < seg_beg && seg_beg <= end && end <= seg_end) {
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// 3) beg seg_beg end seg_end
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// Merge two segments, trim front of old segment
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auto trim = end - seg_beg;
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seg_pkt.trim_front(trim);
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p.append(std::move(seg_pkt));
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// Delete the old one, insert the new one
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it = map.erase(it);
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insert = true;
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break;
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} else if (seg_beg <= beg && beg <= seg_end && seg_end < end) {
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// 4) seg_beg beg seg_end end
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// Merge two segments, trim front of new segment
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auto trim = seg_end - beg;
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p.trim_front(trim);
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// Append new data to the old segment, keep the old segment
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seg_pkt.append(std::move(p));
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insert = false;
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break;
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} else {
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// 5) beg end < seg_beg seg_end
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// or
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// 6) seg_beg seg_end < beg end
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// Can not merge with this segment, keep looking
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it++;
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insert = true;
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}
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}
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if (insert) {
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p.linearize();
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map.emplace(beg, std::move(p));
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}
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// Second, merge adjacent segments after this packet has been merged,
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// becasue this packet might fill a "whole" and make two adjacent
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// segments mergable
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for (auto it = map.begin(); it != map.end();) {
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// The first segment
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auto& seg_pkt = it->second;
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auto seg_beg = it->first;
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auto seg_end = seg_beg + seg_pkt.len();
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// The second segment
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auto it_next = it;
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it_next++;
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if (it_next == map.end()) {
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break;
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}
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auto& p = it_next->second;
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auto beg = it_next->first;
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auto end = beg + p.len();
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// Merge the the second segment into first segment if possible
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if (seg_beg <= beg && beg <= seg_end && seg_end < end) {
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// Merge two segments, trim front of second segment
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auto trim = seg_end - beg;
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p.trim_front(trim);
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// Append new data to the first segment, keep the first segment
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seg_pkt.append(std::move(p));
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// Delete the second segment
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map.erase(it_next);
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// Keep merging this first segment with its new next packet
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// So we do not update the iterator: it
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continue;
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} else if (end <= seg_end) {
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// The first segment has all the data in the second segment
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// Delete the second segment
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map.erase(it_next);
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continue;
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} else if (seg_end < beg) {
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// Can not merge first segment with second segment
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it = it_next;
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continue;
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} else {
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// If we reach here, we have a bug with merge.
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std::cout << "packet_merger: merge error\n";
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abort();
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break;
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}
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}
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}
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};
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}
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#endif
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