From 4a97c6be7953ece290fb2eba70a8630bb43d86b0 Mon Sep 17 00:00:00 2001
From: Chris Sibbitt <csibbitt@gmail.com>
Date: Fri, 13 Oct 2023 23:55:12 -0400
Subject: [PATCH] Sequenced vectors with efficient replication

* Adds sp::SeqVector for tracking elements that have a sequence number
* Tracks last sequence # to replicate
* Provides significant performance improvements for EE ships_log
---
 src/multiplayer.h          | 70 ++++++++++++++++++++++++++++++++++++++
 src/multiplayer_server.cpp |  6 +++-
 src/multiplayer_server.h   |  1 +
 src/seqvector.h            | 16 +++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 src/seqvector.h

diff --git a/src/multiplayer.h b/src/multiplayer.h
index 42111bed..bffaec79 100644
--- a/src/multiplayer.h
+++ b/src/multiplayer.h
@@ -5,6 +5,7 @@
 #include <stdint.h>
 #include "Updatable.h"
 #include "stringImproved.h"
+#include "seqvector.h"
 
 class MultiplayerObject;
 
@@ -107,6 +108,55 @@ template <typename T> struct multiplayerReplicationFunctions
         std::vector<T>* prev_data = *(std::vector<T>**)prev_data_ptr;
         delete prev_data;
     }
+
+    static bool isChangedSeqVector(void* data, void* prev_data_ptr)
+    {
+        sp::SeqVector<T>* ptr = (sp::SeqVector<T>*)data;
+        bool changed = false;
+        if (ptr->back().seq != ptr->last_seq)
+            changed = true;
+
+        return changed;
+    }
+
+    static void sendDataSeqVector(void* data, sp::io::DataBuffer& packet)
+    {
+        sp::SeqVector<T>* ptr = (sp::SeqVector<T>*)data;
+        uint16_t count = ptr->size();
+        unsigned int to_send = std::min(ptr->back().seq - ptr->last_seq, static_cast<unsigned int>(count));
+
+        ptr->last_seq = ptr->back().seq;
+
+        packet << count << to_send;
+        for(; to_send > 0; to_send--)
+            packet << (*ptr)[count - to_send];
+    }
+
+    static void sendWholeDataSeqVector(void* data, sp::io::DataBuffer& packet)
+    {
+        sp::SeqVector<T>* ptr = (sp::SeqVector<T>*)data;
+        auto last_seq = ptr->last_seq;
+        ptr->last_seq = ptr->front().seq - 1;
+        sendDataSeqVector(data, packet);
+        ptr->last_seq = last_seq;
+    }
+
+    static void receiveDataSeqVector(void* data, sp::io::DataBuffer& packet)
+    {
+        sp::SeqVector<T>* ptr = (sp::SeqVector<T>*)data;
+        uint16_t count;
+        unsigned int to_recv;
+        packet >> count >> to_recv;
+
+        // Remove oldest entries if local vector would grow larger than server's
+        while (ptr->size() + to_recv > count)
+            ptr->erase(ptr->begin());
+
+        ptr->resize(count);
+
+        for(unsigned int n=count - to_recv; n<count; n++)
+            packet >> (*ptr)[n];
+    }
 };
 
 template <typename T>
@@ -146,6 +196,7 @@ class MultiplayerObject : public virtual PObject
 
         bool(*isChangedFunction)(void* data, void* prev_data_ptr);
         void(*sendFunction)(void* data, sp::io::DataBuffer& packet);
+        void(*sendWholeFunction)(void* data, sp::io::DataBuffer& packet) = nullptr;
         void(*receiveFunction)(void* data, sp::io::DataBuffer& packet);
         void(*cleanupFunction)(void* prev_data_ptr);
     };
@@ -217,6 +268,25 @@ class MultiplayerObject : public virtual PObject
         memberReplicationInfo.push_back(info);
     }
 
+    template <typename T> void registerMemberReplication_(F_PARAM sp::SeqVector<T>* member, float update_delay = 0.0f)
+    {
+        SDL_assert(!replicated);
+        SDL_assert(memberReplicationInfo.size() < 0xFFFF);
+        MemberReplicationInfo info;
+#ifdef DEBUG
+        info.name = name;
+#endif
+        info.ptr = member;
+        info.update_delay = update_delay;
+        info.update_timeout = 0.0f;
+        info.isChangedFunction = &multiplayerReplicationFunctions<T>::isChangedSeqVector;
+        info.sendFunction = &multiplayerReplicationFunctions<T>::sendDataSeqVector;
+        info.sendWholeFunction = &multiplayerReplicationFunctions<T>::sendWholeDataSeqVector;
+        info.receiveFunction = &multiplayerReplicationFunctions<T>::receiveDataSeqVector;
+        info.cleanupFunction = nullptr;
+        memberReplicationInfo.push_back(info);
+    }
+
     void registerMemberReplication_(F_PARAM glm::vec3* member, float update_delay = 0.0f)
     {
         registerMemberReplication(&member->x, update_delay);
diff --git a/src/multiplayer_server.cpp b/src/multiplayer_server.cpp
index 3c9245ee..ae033a3a 100644
--- a/src/multiplayer_server.cpp
+++ b/src/multiplayer_server.cpp
@@ -562,7 +562,11 @@ void GameServer::generateCreatePacketFor(P<MultiplayerObject> obj, sp::io::DataB
     for(unsigned int n=0; n<obj->memberReplicationInfo.size(); n++)
     {
         packet << int16_t(n);
-        (obj->memberReplicationInfo[n].sendFunction)(obj->memberReplicationInfo[n].ptr, packet);
+        if (obj->memberReplicationInfo[n].sendWholeFunction)
+            (obj->memberReplicationInfo[n].sendWholeFunction)(obj->memberReplicationInfo[n].ptr, packet);
+        else
+            (obj->memberReplicationInfo[n].sendFunction)(obj->memberReplicationInfo[n].ptr, packet);
+
     }
 }
 
diff --git a/src/multiplayer_server.h b/src/multiplayer_server.h
index 988db30b..a058328d 100644
--- a/src/multiplayer_server.h
+++ b/src/multiplayer_server.h
@@ -12,6 +12,7 @@
 #include "stringImproved.h"
 #include "networkAudioStream.h"
 #include "timer.h"
+#include "seqvector.h"
 
 #include <stdint.h>
 #include <unordered_map>
diff --git a/src/seqvector.h b/src/seqvector.h
new file mode 100644
index 00000000..0c7589e9
--- /dev/null
+++ b/src/seqvector.h
@@ -0,0 +1,16 @@
+#ifndef SEQVECTOR_H
+#define SEQVECTOR_H
+
+#include <vector>
+
+namespace sp {
+
+// A vector that tracks sequenced elements
+template<typename T> class SeqVector : public std::vector<T>{
+public:
+    unsigned int last_seq = 0;
+};
+
+}//namespace sp
+
+#endif//SEQVECTOR_H