Move the trajectory computation into another thread.

Change-Id: I9dff7a20752e6cdfe05ec71d3435f3006ae45353
diff --git a/frc971/control_loops/drivetrain/splinedrivetrain.cc b/frc971/control_loops/drivetrain/splinedrivetrain.cc
index 9aa1708..d8e2f9a 100644
--- a/frc971/control_loops/drivetrain/splinedrivetrain.cc
+++ b/frc971/control_loops/drivetrain/splinedrivetrain.cc
@@ -1,38 +1,44 @@
 #include "frc971/control_loops/drivetrain/splinedrivetrain.h"
 
-#include <iostream>
-
 #include "Eigen/Dense"
 
 #include "frc971/control_loops/drivetrain/drivetrain.q.h"
 #include "frc971/control_loops/drivetrain/drivetrain_config.h"
 
-const int kMaxSplineConstraints = 6;
-
 namespace frc971 {
 namespace control_loops {
 namespace drivetrain {
 
 SplineDrivetrain::SplineDrivetrain(const DrivetrainConfig<double> &dt_config)
-    : dt_config_(dt_config),
-      current_state_(::Eigen::Matrix<double, 2, 1>::Zero()) {}
+    : dt_config_(dt_config), new_goal_(&mutex_) {
+  worker_thread_ = std::thread(&SplineDrivetrain::ComputeTrajectory, this);
+}
 
 void SplineDrivetrain::ScaleCapU(Eigen::Matrix<double, 2, 1> *U) {
-  bool output_was_capped = ::std::abs((*U)(0, 0)) > 12.0 ||
-                       ::std::abs((*U)(1, 0)) > 12.0;
+  output_was_capped_ =
+      ::std::abs((*U)(0, 0)) > 12.0 || ::std::abs((*U)(1, 0)) > 12.0;
 
-  if (output_was_capped) {
+  if (output_was_capped_) {
     *U *= 12.0 / U->lpNorm<Eigen::Infinity>();
   }
 }
 
-// TODO(alex): put in another thread to avoid malloc in RT.
-void SplineDrivetrain::SetGoal(
-    const ::frc971::control_loops::DrivetrainQueue::Goal &goal) {
-  current_spline_handle_ = goal.spline_handle;
-  const ::frc971::MultiSpline &multispline = goal.spline;
-  if (multispline.spline_idx) {
-    current_spline_idx_ = multispline.spline_idx;
+// TODO(alex): work on setting priority.
+void SplineDrivetrain::ComputeTrajectory() {
+  ::aos::MutexLocker locker(&mutex_);
+  while (run_) {
+    while (goal_.spline.spline_idx == future_spline_idx_) {
+      CHECK(!new_goal_.Wait());
+      if (!run_) {
+        return;
+      }
+    }
+    past_distance_spline_.reset();
+    past_trajectory_.reset();
+
+    plan_state_ = PlanState::kBuildingTrajectory;
+    const ::frc971::MultiSpline &multispline = goal_.spline;
+    future_spline_idx_ = multispline.spline_idx;
     auto x = multispline.spline_x;
     auto y = multispline.spline_y;
     ::std::vector<Spline> splines = ::std::vector<Spline>();
@@ -46,63 +52,100 @@
       splines.emplace_back(Spline(points));
     }
 
-    distance_spline_ = ::std::unique_ptr<DistanceSpline>(
+    future_distance_spline_ = ::std::unique_ptr<DistanceSpline>(
         new DistanceSpline(::std::move(splines)));
 
-    current_trajectory_ = ::std::unique_ptr<Trajectory>(
-        new Trajectory(distance_spline_.get(), dt_config_));
+    future_trajectory_ = ::std::unique_ptr<Trajectory>(
+        new Trajectory(future_distance_spline_.get(), dt_config_));
 
-    for (int i = 0; i < kMaxSplineConstraints; ++i) {
+    for (size_t i = 0; i < multispline.constraints.size(); ++i) {
       const ::frc971::Constraint &constraint = multispline.constraints[i];
       switch (constraint.constraint_type) {
         case 0:
           break;
         case 1:
-          current_trajectory_->set_longitudal_acceleration(constraint.value);
+          future_trajectory_->set_longitudal_acceleration(constraint.value);
           break;
         case 2:
-          current_trajectory_->set_lateral_acceleration(constraint.value);
+          future_trajectory_->set_lateral_acceleration(constraint.value);
           break;
         case 3:
-          current_trajectory_->set_voltage_limit(constraint.value);
+          future_trajectory_->set_voltage_limit(constraint.value);
           break;
         case 4:
-          current_trajectory_->LimitVelocity(constraint.start_distance,
-                                             constraint.end_distance,
-                                             constraint.value);
+          future_trajectory_->LimitVelocity(constraint.start_distance,
+                                            constraint.end_distance,
+                                            constraint.value);
           break;
       }
     }
+    plan_state_ = PlanState::kPlanningTrajectory;
 
-    current_trajectory_->Plan();
-    current_xva_ = current_trajectory_->FFAcceleration(0);
-    current_xva_(1) = 0.0;
-    current_state_ = ::Eigen::Matrix<double, 2, 1>::Zero();
+    future_trajectory_->Plan();
+    plan_state_ = PlanState::kPlannedTrajectory;
+  }
+}
+
+void SplineDrivetrain::SetGoal(
+    const ::frc971::control_loops::DrivetrainQueue::Goal &goal) {
+  current_spline_handle_ = goal.spline_handle;
+  // If told to stop, set the executing spline to an invalid index.
+  if (current_spline_handle_ == 0) {
+    current_spline_idx_ = -1;
+  }
+
+  ::aos::Mutex::State mutex_state = mutex_.TryLock();
+  if (mutex_state == ::aos::Mutex::State::kLocked) {
+    if (goal.spline.spline_idx && future_spline_idx_ != goal.spline.spline_idx) {
+      goal_ = goal;
+      new_goal_.Broadcast();
+    }
+    if (future_trajectory_ &&
+        (!current_trajectory_ ||
+         current_trajectory_->is_at_end(current_xva_.block<2, 1>(0, 0)) ||
+         current_spline_idx_ == -1)) {
+      // Move current data to other variables to be cleared by worker.
+      past_trajectory_ = std::move(current_trajectory_);
+      past_distance_spline_ = std::move(current_distance_spline_);
+
+      // Move the computed data to be executed.
+      current_trajectory_ = std::move(future_trajectory_);
+      current_distance_spline_ = std::move(future_distance_spline_);
+      current_spline_idx_ = future_spline_idx_;
+
+      // Reset internal state to a trajectory start position.
+      current_xva_ = current_trajectory_->FFAcceleration(0);
+      current_xva_(1) = 0.0;
+    }
+    mutex_.Unlock();
   }
 }
 
 // TODO(alex): Hold position when done following the spline.
 // TODO(Austin): Compensate for voltage error.
-void SplineDrivetrain::Update(bool enable,
-                              const ::Eigen::Matrix<double, 5, 1> &state) {
+void SplineDrivetrain::Update(bool enable, const ::Eigen::Matrix<double, 5, 1> &state) {
+  next_U_ = ::Eigen::Matrix<double, 2, 1>::Zero();
   enable_ = enable;
   if (enable && current_trajectory_) {
     ::Eigen::Matrix<double, 2, 1> U_ff = ::Eigen::Matrix<double, 2, 1>::Zero();
-    if (!IsAtEnd()) {
+    if (!IsAtEnd() &&
+        current_spline_handle_ == current_spline_idx_) {
       // TODO(alex): It takes about a cycle for the outputs to propagate to the
       // motors. Consider delaying the output by a cycle.
       U_ff = current_trajectory_->FFVoltage(current_xva_(0));
     }
+
     ::Eigen::Matrix<double, 2, 5> K =
         current_trajectory_->KForState(state, dt_config_.dt, Q, R);
     ::Eigen::Matrix<double, 5, 1> goal_state = CurrentGoalState();
     ::Eigen::Matrix<double, 5, 1> state_error = goal_state - state;
     ::Eigen::Matrix<double, 2, 1> U_fb = K * state_error;
+
+    ::Eigen::Matrix<double, 2, 1> xv_state = current_xva_.block<2,1>(0,0);
+    next_xva_ = current_trajectory_->GetNextXVA(dt_config_.dt, &xv_state);
     next_U_ = U_ff + U_fb;
     uncapped_U_ = next_U_;
     ScaleCapU(&next_U_);
-
-    next_xva_ = current_trajectory_->GetNextXVA(dt_config_.dt, &current_state_);
   }
 }
 
@@ -111,9 +154,6 @@
   if (!output) {
     return;
   }
-  if (!current_trajectory_) {
-    return;
-  }
   if (current_spline_handle_ == current_spline_idx_) {
     if (!IsAtEnd()) {
       output->left_voltage = next_U_(0);
@@ -121,6 +161,8 @@
       current_xva_ = next_xva_;
     }
   }
+  output->left_voltage = next_U_(0);
+  output->right_voltage = next_U_(1);
 }
 
 void SplineDrivetrain::PopulateStatus(
@@ -129,6 +171,22 @@
     status->uncapped_left_voltage = uncapped_U_(0);
     status->uncapped_right_voltage = uncapped_U_(1);
     status->robot_speed = current_xva_(1);
+    status->output_was_capped = output_was_capped_;
+  }
+
+  if (status) {
+    if (current_distance_spline_) {
+      ::Eigen::Matrix<double, 5, 1> goal_state = CurrentGoalState();
+      status->trajectory_logging.x = goal_state(0);
+      status->trajectory_logging.y = goal_state(1);
+      status->trajectory_logging.theta = goal_state(2);
+      status->trajectory_logging.left_velocity = goal_state(3);
+      status->trajectory_logging.right_velocity = goal_state(4);
+    }
+    status->trajectory_logging.planning_state = static_cast<int8_t>(plan_state_.load());
+    status->trajectory_logging.is_executing = !IsAtEnd();
+    status->trajectory_logging.current_spline_handle = current_spline_handle_;
+    status->trajectory_logging.current_spline_idx = current_spline_idx_;
   }
 }