From 5e8a110f45f7d91e1fa6fdf88e2980695064ddb5 Mon Sep 17 00:00:00 2001
From: Christoph Urlacher <christoph.urlacher@protonmail.com>
Date: Tue, 24 Feb 2026 02:05:44 +0100
Subject: [PATCH] wip: don't lock command mutex for each mass/spring in
 FillGraph()

---
 include/config.hpp  |  2 +-
 include/physics.hpp |  4 ++++
 src/main.cpp        |  4 ++--
 src/physics.cpp     | 16 ++++++++++++++++
 src/state.cpp       | 18 +++++++++++++-----
 5 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/include/config.hpp b/include/config.hpp
index 7440163..88029bf 100644
--- a/include/config.hpp
+++ b/include/config.hpp
@@ -30,7 +30,7 @@ constexpr float ROT_SPEED = 1.0;
 constexpr float CAMERA_SMOOTH_SPEED = 15.0;
 
 // Physics Engine
-constexpr float SIM_SPEED = 4.0;          // How large each update should be
+constexpr float SIM_SPEED = 0.2;          // How large each update should be
 constexpr float TIMESTEP = 1.0 / 90;      // Do 90 physics updates per second
 constexpr float MASS = 1.0;               // Mass spring system
 constexpr float SPRING_CONSTANT = 5.0;    // Mass spring system
diff --git a/include/physics.hpp b/include/physics.hpp
index 92f96be..6e8349e 100644
--- a/include/physics.hpp
+++ b/include/physics.hpp
@@ -188,6 +188,10 @@ public:
   auto AddSpringCmd(const State &a, const State &b) -> void;
 
   auto ClearCmd() -> void;
+
+  auto NonLockingAddMassCmd(const State &_state) -> void;
+
+  auto NonLockingAddSpringCmd(const State &a, const State &b) -> void;
 };
 
 // https://en.cppreference.com/w/cpp/utility/variant/visit
diff --git a/src/main.cpp b/src/main.cpp
index 405238e..fc8c98b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -39,7 +39,7 @@ auto main(int argc, char *argv[]) -> int {
   OrbitCamera3D camera;
   Renderer renderer(camera);
   ThreadedPhysics physics;
-  StateManager state(physics);
+  StateManager state(physics); // TODO: What is this warning?
   InputHandler input(state, renderer);
 
   std::vector<Mass> masses;                    // Read from physics
@@ -74,7 +74,7 @@ auto main(int argc, char *argv[]) -> int {
     */
 
     // Read positions from physics thread
-    // TODO: We're reading a HUGE amount of SHIT, because the state
+    // TODO: We're copying a HUGE amount of SHIT, because the state
     //       representations (std::string, ~100 Bytes) are copied ~3 times per
     //       spring: state_masses<State, int> and state_springs<<State, State>,
     //       int>
diff --git a/src/physics.cpp b/src/physics.cpp
index 850cc7f..9f0e486 100644
--- a/src/physics.cpp
+++ b/src/physics.cpp
@@ -366,11 +366,18 @@ auto ThreadedPhysics::PhysicsThread(ThreadedPhysics::PhysicsState &state)
     }
 
     // Physics update
+    // TODO: I need this thread to run at a constant rate
     mass_springs.ClearForces();
     mass_springs.CalculateSpringForces();
     mass_springs.CalculateRepulsionForces();
     mass_springs.VerletUpdate(TIMESTEP * SIM_SPEED);
 
+    // TODO: Notify the main thread of update
+    // TODO: Just wait here until the main thread has fetched the data?
+    //       Then only the copying would be sequential, while the main thread
+    //       renders this thread can already calculate the physics...
+    // TODO: Would std::swap help in any way?
+
     // Publish the positions for the renderer (copy)
     {
       std::lock_guard<LockableBase(std::mutex)> lock(state.pos_mtx);
@@ -402,3 +409,12 @@ auto ThreadedPhysics::ClearCmd() -> void {
     state.pending_commands.push(ClearGraph{});
   }
 }
+
+auto ThreadedPhysics::NonLockingAddMassCmd(const State &_state) -> void {
+  state.pending_commands.push(AddMass{_state});
+}
+
+auto ThreadedPhysics::NonLockingAddSpringCmd(const State &a, const State &b)
+    -> void {
+  state.pending_commands.push(AddSpring{a, b});
+}
diff --git a/src/state.cpp b/src/state.cpp
index a49b663..2a8933c 100644
--- a/src/state.cpp
+++ b/src/state.cpp
@@ -37,12 +37,20 @@ auto StateManager::FillGraph() -> void {
 
   std::pair<std::unordered_set<State>, std::vector<std::pair<State, State>>>
       closure = current_state.Closure();
-  for (const auto &state : closure.first) {
-    physics.AddMassCmd(state);
-  }
-  for (const auto &[from, to] : closure.second) {
-    physics.AddSpringCmd(from, to);
+
+  {
+    std::lock_guard<LockableBase(std::mutex)> lock(physics.state.command_mtx);
+    for (const auto &state : closure.first) {
+      physics.NonLockingAddMassCmd(state);
+    }
+    for (const auto &[from, to] : closure.second) {
+      physics.NonLockingAddSpringCmd(from, to);
+    }
   }
+
+  // TODO: We have only dispatched the commands, the states won't be downloaded
+  //       when calling this... Make FindWinningStates() another command?
+  //       Or recalculate whenever masses.size() changes?
   FindWinningStates();
 }