Input listener and replay session

.run/SpaceWar (P1) (save).run.xml

@@ -0,0 +1,20 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="SpaceWar (P1) (save)" type="DotNetProject" factoryName=".NET Project">
+    <option name="EXE_PATH" value="$PROJECT_DIR$/samples/SpaceWar/bin/Debug/net8.0/SpaceWar.exe" />
+    <option name="PROGRAM_PARAMETERS" value="9000 2 --save-to replay.inputs local 127.0.0.1:9001 " />
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/samples/SpaceWar/bin/Debug/net8.0" />
+    <option name="PASS_PARENT_ENVS" value="1" />
+    <option name="USE_EXTERNAL_CONSOLE" value="0" />
+    <option name="USE_MONO" value="0" />
+    <option name="RUNTIME_ARGUMENTS" value="" />
+    <option name="PROJECT_PATH" value="$PROJECT_DIR$/samples/SpaceWar/SpaceWar.csproj" />
+    <option name="PROJECT_EXE_PATH_TRACKING" value="1" />
+    <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
+    <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
+    <option name="PROJECT_KIND" value="DotNetCore" />
+    <option name="PROJECT_TFM" value="net8.0" />
+    <method v="2">
+      <option name="Build" />
+    </method>
+  </configuration>
+</component>

.run/SpaceWar (replay).run.xml

@@ -0,0 +1,20 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="SpaceWar (replay)" type="DotNetProject" factoryName=".NET Project">
+    <option name="EXE_PATH" value="$PROJECT_DIR$/samples/SpaceWar/bin/Debug/net8.0/SpaceWar.exe" />
+    <option name="PROGRAM_PARAMETERS" value="9000 2 replay replay.inputs" />
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/samples/SpaceWar/bin/Debug/net8.0" />
+    <option name="PASS_PARENT_ENVS" value="1" />
+    <option name="USE_EXTERNAL_CONSOLE" value="0" />
+    <option name="USE_MONO" value="0" />
+    <option name="RUNTIME_ARGUMENTS" value="" />
+    <option name="PROJECT_PATH" value="$PROJECT_DIR$/samples/SpaceWar/SpaceWar.csproj" />
+    <option name="PROJECT_EXE_PATH_TRACKING" value="1" />
+    <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
+    <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
+    <option name="PROJECT_KIND" value="DotNetCore" />
+    <option name="PROJECT_TFM" value="net8.0" />
+    <method v="2">
+      <option name="Build" />
+    </method>
+  </configuration>
+</component>

samples/SpaceWar/GameSessionFactory.cs

@@ -1,6 +1,7 @@
 using System.Net;
 using Backdash;
 using Backdash.Sync.Input;
+using Backdash.Sync.Input.Confirmed;
 using SpaceWar.Logic;
 
 namespace SpaceWar;
@@ -11,16 +12,15 @@ public static IRollbackSession<PlayerInputs, GameState> ParseArgs(
         string[] args, RollbackOptions options
     )
     {
-        if (args is not [{ } portArg, { } playerCountArg, .. { } endpoints]
+        if (args is not [{ } portArg, { } playerCountArg, .. { } lastArgs]
             || !int.TryParse(portArg, out var port)
-            || !int.TryParse(playerCountArg, out var playerCount)
-           )
+            || !int.TryParse(playerCountArg, out var playerCount))
             throw new InvalidOperationException("Invalid port argument");
 
         if (playerCount > Config.MaxShips)
             throw new InvalidOperationException("Too many players");
 
-        if (endpoints is ["sync-test"])
+        if (lastArgs is ["sync-test"])
             return RollbackNetcode.CreateSyncTestSession<PlayerInputs, GameState>(
                 options: options,
                 services: new()
@@ -29,12 +29,33 @@ public static IRollbackSession<PlayerInputs, GameState> ParseArgs(
                 }
             );
 
-        if (endpoints is ["spectate", { } hostArg] && IPEndPoint.TryParse(hostArg, out var host))
+        if (lastArgs is ["spectate", { } hostArg] && IPEndPoint.TryParse(hostArg, out var host))
             return RollbackNetcode.CreateSpectatorSession<PlayerInputs, GameState>(
                 port, host, playerCount, options
             );
 
-        var players = endpoints.Select((x, i) => ParsePlayer(playerCount, i + 1, x)).ToArray();
+        if (lastArgs is ["replay", { } replayFile])
+        {
+            if (!File.Exists(replayFile))
+                throw new InvalidOperationException("Invalid replay file");
+
+            var inputs = SaveInputsToFileListener.GetInputs(playerCount, replayFile).ToArray();
+
+            return RollbackNetcode.CreateReplaySession<PlayerInputs, GameState>(
+                playerCount, inputs
+            );
+        }
+
+
+        // save confirmed inputs to file
+        IInputListener<PlayerInputs>? saveInputsListener = null;
+        if (lastArgs is ["--save-to", { } filename, .. var argsAfterSave])
+        {
+            saveInputsListener = new SaveInputsToFileListener(filename);
+            lastArgs = argsAfterSave;
+        }
+
+        var players = lastArgs.Select((x, i) => ParsePlayer(playerCount, i + 1, x)).ToArray();
         var localPlayer = players.FirstOrDefault(x => x.IsLocal());
 
         if (localPlayer is null)
@@ -43,6 +64,7 @@ public static IRollbackSession<PlayerInputs, GameState> ParseArgs(
         var session = RollbackNetcode.CreateSession<PlayerInputs, GameState>(port, options, new()
         {
             // LogWriter = new FileLogWriter($"log_{localPlayer.Number}.log"),
+            InputListener = saveInputsListener,
         });
 
         session.AddPlayers(players);

samples/SpaceWar/SaveInputsToFileListener.cs

@@ -0,0 +1,51 @@
+using Backdash.Data;
+using Backdash.Sync.Input.Confirmed;
+using SpaceWar.Logic;
+
+namespace SpaceWar;
+
+sealed class SaveInputsToFileListener(string filename) : IInputListener<PlayerInputs>
+{
+    const int InputSize = sizeof(PlayerInputs);
+    readonly FileStream fileStream = File.Create(filename);
+    readonly byte[] inputBuffer = new byte[InputSize];
+
+    public void OnConfirmed(in Frame frame, in ConfirmedInputs<PlayerInputs> inputs)
+    {
+        for (var i = 0; i < inputs.Count; i++)
+        {
+            var input = (ushort)inputs.Inputs[i];
+            Array.Clear(inputBuffer);
+            if (!input.TryFormat(inputBuffer, out _))
+                throw new InvalidOperationException("unable to save input");
+
+            fileStream.Write(inputBuffer);
+        }
+
+        fileStream.Write("\n"u8);
+    }
+
+    public void Dispose() => fileStream.Dispose();
+
+    public static IEnumerable<ConfirmedInputs<PlayerInputs>> GetInputs(int players, string file)
+    {
+        using var replayStream = File.OpenRead(file);
+        var buffer = new byte[InputSize * players];
+        var inputsBuffer = new PlayerInputs[players];
+        var lineBreak = new byte[1];
+
+        while (replayStream.Read(buffer) > 0)
+        {
+            for (var i = 0; i < players; i++)
+            {
+                if (ushort.TryParse(buffer.AsSpan().Slice(i * InputSize, InputSize), out var value))
+                    inputsBuffer[i] = (PlayerInputs)value;
+            }
+
+            yield return new ConfirmedInputs<PlayerInputs>(inputsBuffer.AsSpan()[..players]);
+
+            if (replayStream.Read(lineBreak) is 0 || lineBreak[0] != '\n')
+                throw new InvalidOperationException("invalid replay file content");
+        }
+    }
+}

samples/SpaceWar/SpaceWar.csproj

@@ -13,6 +13,9 @@
     <ItemGroup>
         <None Remove="Icon.ico"/>
         <None Remove="Icon.bmp"/>
+        <None Update="replay.inputs">
+          <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+        </None>
     </ItemGroup>
     <ItemGroup>
         <EmbeddedResource Include="Icon.ico"/>

samples/SpaceWar/scripts/linux/start_2players_save.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+dotnet build -c Release "$(dirname "$0")/../.."
+pushd "$(dirname "$0")/../../bin/Release/net8.0" || exit
+rm ./*.log
+dotnet SpaceWar.dll 9000 2 --save-to replay.inputs local 127.0.0.1:9001 &
+dotnet SpaceWar.dll 9001 2 127.0.0.1:9000 local &
+popd || exit

samples/SpaceWar/scripts/linux/start_replay.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+dotnet build -c Release "$(dirname "$0")/../.."
+pushd "$(dirname "$0")/../../bin/Release/net8.0" || exit
+rm ./*.log
+dotnet SpaceWar.dll 9000 2 replay replay.inputs &
+popd || exit

samples/SpaceWar/scripts/windows/start_2players_save.cmd

@@ -0,0 +1,6 @@
+dotnet build -c Release %~dp0\..\..
+pushd %~dp0\..\..\bin\Release\net8.0
+del *.log
+start SpaceWar 9000 2 --save-to replay.inputs local 127.0.0.1:9001
+start SpaceWar 9001 2 127.0.0.1:9000 local
+popd

samples/SpaceWar/scripts/windows/start_replay.cmd

@@ -0,0 +1,5 @@
+dotnet build -c Release %~dp0\..\..
+pushd %~dp0\..\..\bin\Release\net8.0
+del *.log
+start SpaceWar 9000 2 replay replay.inputs
+popd

src/Backdash/Backends/BackendServices.cs

@@ -4,6 +4,7 @@
 using Backdash.Network.Protocol;
 using Backdash.Serialization;
 using Backdash.Sync.Input;
+using Backdash.Sync.Input.Confirmed;
 using Backdash.Sync.State;
 using Backdash.Sync.State.Stores;
 
@@ -23,11 +24,13 @@ sealed class BackendServices<TInput, TGameState>
     public IInputGenerator<TInput>? InputGenerator { get; }
     public IRandomNumberGenerator Random { get; }
     public IDelayStrategy DelayStrategy { get; }
+    public IInputListener<TInput>? InputListener { get; }
 
     public BackendServices(RollbackOptions options, SessionServices<TInput, TGameState>? services)
     {
         ChecksumProvider = services?.ChecksumProvider ?? ChecksumProviderFactory.Create<TGameState>();
         StateStore = services?.StateStore ?? StateStoreFactory.Create(services?.StateSerializer);
+        InputListener = services?.InputListener;
         Random = new DefaultRandomNumberGenerator(services?.Random ?? System.Random.Shared);
         DelayStrategy = DelayStrategyFactory.Create(Random, options.Protocol.DelayStrategy);
         InputGenerator = services?.InputGenerator;

src/Backdash/Backends/Peer2PeerBackend.cs

@@ -8,7 +8,7 @@
 using Backdash.Network.Protocol.Comm;
 using Backdash.Serialization;
 using Backdash.Sync.Input;
-using Backdash.Sync.Input.Spectator;
+using Backdash.Sync.Input.Confirmed;
 using Backdash.Sync.State;
 
 namespace Backdash.Backends;
@@ -19,7 +19,7 @@ sealed class Peer2PeerBackend<TInput, TGameState> : IRollbackSession<TInput, TGa
 {
     readonly RollbackOptions options;
     readonly IBinarySerializer<TInput> inputSerializer;
-    readonly IBinarySerializer<CombinedInputs<TInput>> inputGroupSerializer;
+    readonly IBinarySerializer<ConfirmedInputs<TInput>> inputGroupSerializer;
     readonly Logger logger;
     readonly IStateStore<TGameState> stateStore;
     readonly IProtocolClient udp;
@@ -28,15 +28,18 @@ sealed class Peer2PeerBackend<TInput, TGameState> : IRollbackSession<TInput, TGa
     readonly ConnectionsState localConnections;
     readonly IBackgroundJobManager backgroundJobManager;
     readonly ProtocolInputEventQueue<TInput> peerInputEventQueue;
-    readonly IProtocolInputEventPublisher<CombinedInputs<TInput>> peerCombinedInputsEventPublisher;
+    readonly IProtocolInputEventPublisher<ConfirmedInputs<TInput>> peerCombinedInputsEventPublisher;
     readonly PeerConnectionFactory peerConnectionFactory;
-    readonly List<PeerConnection<CombinedInputs<TInput>>> spectators;
+    readonly List<PeerConnection<ConfirmedInputs<TInput>>> spectators;
     readonly List<PeerConnection<TInput>?> endpoints;
     readonly HashSet<PlayerHandle> addedPlayers = [];
     readonly HashSet<PlayerHandle> addedSpectators = [];
+    readonly IInputListener<TInput>? inputListener;
+
     bool isSynchronizing = true;
     int nextRecommendedInterval;
     Frame nextSpectatorFrame = Frame.Zero;
+    Frame nextListenerFrame = Frame.Zero;
     IRollbackHandler<TGameState> callbacks;
     SynchronizedInput<TInput>[] syncInputBuffer = [];
     Task backgroundJobTask = Task.CompletedTask;
@@ -61,9 +64,11 @@ BackendServices<TInput, TGameState> services
         stateStore = services.StateStore;
         backgroundJobManager = services.JobManager;
         logger = services.Logger;
+        inputListener = services.InputListener;
+
         peerInputEventQueue = new ProtocolInputEventQueue<TInput>();
         peerCombinedInputsEventPublisher = new ProtocolCombinedInputsEventPublisher<TInput>(peerInputEventQueue);
-        inputGroupSerializer = new CombinedInputsSerializer<TInput>(inputSerializer);
+        inputGroupSerializer = new ConfirmedInputsSerializer<TInput>(inputSerializer);
         localConnections = new(Max.NumberOfPlayers);
         spectators = [];
         endpoints = [];
@@ -107,6 +112,7 @@ public void Dispose()
         stateStore.Dispose();
         logger.Dispose();
         backgroundJobManager.Dispose();
+        inputListener?.Dispose();
     }
 
     public void Close()
@@ -431,19 +437,36 @@ void DoSync()
         {
             if (NumberOfSpectators > 0)
             {
-                GameInput<CombinedInputs<TInput>> confirmed = new(nextSpectatorFrame);
+                GameInput<ConfirmedInputs<TInput>> confirmed = new(nextSpectatorFrame);
                 while (nextSpectatorFrame <= minConfirmedFrame)
                 {
-                    logger.Write(LogLevel.Debug, $"pushing frame {nextSpectatorFrame} to spectators");
                     if (!synchronizer.GetConfirmedInputGroup(in nextSpectatorFrame, ref confirmed))
                         break;
+
+                    logger.Write(LogLevel.Debug, $"pushing frame {nextSpectatorFrame} to spectators");
                     for (var s = 0; s < spectators.Count; s++)
                         if (spectators[s].IsRunning)
                             spectators[s].SendInput(in confirmed);
+
                     nextSpectatorFrame++;
                 }
             }
 
+            if (inputListener is not null)
+            {
+                GameInput<ConfirmedInputs<TInput>> confirmed = new(nextListenerFrame);
+                while (nextListenerFrame <= minConfirmedFrame)
+                {
+                    if (!synchronizer.GetConfirmedInputGroup(in nextListenerFrame, ref confirmed))
+                        break;
+
+                    logger.Write(LogLevel.Debug, $"pushing frame {nextListenerFrame} to listener");
+                    inputListener.OnConfirmed(in confirmed.Frame, in confirmed.Data);
+
+                    nextListenerFrame++;
+                }
+            }
+
             logger.Write(LogLevel.Debug, $"setting confirmed frame in sync to {minConfirmedFrame}");
             synchronizer.SetLastConfirmedFrame(minConfirmedFrame);
         }