Refactor trajectory generation to separate process

This pulls all the trajectory planning into a TrajectoryGenerator class,
which produces a Trajectory spline that the drivetrain code can consume
and use to track the spline.

Broadly speaking, this change:
- Separates the Trajectory class into a generation class and a
  FinishedTrajectory class, where the generator produces a flatbuffer
  and the FinishedTrajectory reads all the required information from
  the flatbuffer.
- Add an option for serialization/deserialization of a DistanceSpline.
- Removes some dead code from Trajectory class (mostly having to do with
  the old feedback algorithm).
- Uses floats in more places, to keep the size of the Trajectory
  flatbuffer under control
- Update the tests & autonomous code to use the new spline code.

Further work that may make sense:
- Experiment with alternatives to current structure of the Trajectory
  flatbuffer to see whether (a) the size is a problem; and (b) if so,
  what we should do about it.
- Add shims to allow replaying logfiles with old-style spline goals.

Change-Id: Ic80ce4e384ec4d1bd22940580e3652ecd305b352
diff --git a/y2019/BUILD b/y2019/BUILD
index 3f361a7..0954157 100644
--- a/y2019/BUILD
+++ b/y2019/BUILD
@@ -14,6 +14,7 @@
         ":joystick_reader",
         ":wpilib_interface",
         "//y2019/control_loops/drivetrain:drivetrain",
+        "//y2019/control_loops/drivetrain:trajectory_generator",
         "//y2019/control_loops/superstructure:superstructure",
         "//y2019/actors:binaries",
         "//y2019/vision/server",
diff --git a/y2019/actors/auto_splines.cc b/y2019/actors/auto_splines.cc
index 397229c..67f9e85 100644
--- a/y2019/actors/auto_splines.cc
+++ b/y2019/actors/auto_splines.cc
@@ -6,10 +6,10 @@
 namespace actors {
 
 void MaybeFlipSpline(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     flatbuffers::Offset<flatbuffers::Vector<float>> spline_y_offset,
     bool is_left) {
-
   flatbuffers::Vector<float> *spline_y =
       GetMutableTemporaryPointer(*builder->fbb(), spline_y_offset);
 
@@ -22,7 +22,8 @@
 
 // Path off of level 2 to the far side of the rocket with a panel
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HABToFarRocket(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
@@ -97,7 +98,8 @@
 
 // Path from the far side of the rocket to the loading station to pickup
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::FarRocketToHP(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
@@ -170,7 +172,8 @@
 
 // Path from the human player station to the far side of the rocket with a panel
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HPToFarRocket(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
@@ -245,7 +248,8 @@
 
 // Path from the far side of the rocket to close to the loading station
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::FarRocketToNearHP(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   // TODO(theo): Add some real constraints.
   flatbuffers::Offset<flatbuffers::Vector<float>> spline_x_offset =
@@ -269,8 +273,10 @@
 }
 
 // Path from level 2 to 2nd cargo ship bay with a hatch panel
-flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HABToSecondCargoShipBay(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+flatbuffers::Offset<frc971::MultiSpline>
+AutonomousSplines::HABToSecondCargoShipBay(
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
@@ -335,8 +341,10 @@
 }
 
 // Path from 2nd cargo ship bay to loading station
-flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::SecondCargoShipBayToHP(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+flatbuffers::Offset<frc971::MultiSpline>
+AutonomousSplines::SecondCargoShipBayToHP(
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> velocity_constraint_offset;
@@ -390,8 +398,10 @@
 }
 
 // Path from loading station to 3rd cargo ship bay with a hatch panel
-flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HPToThirdCargoShipBay(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+flatbuffers::Offset<frc971::MultiSpline>
+AutonomousSplines::HPToThirdCargoShipBay(
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> velocity_constraint_offset;
@@ -456,8 +466,10 @@
 }
 
 // Path from 3rd cargo ship bay to near the loading station
-flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::ThirdCargoShipBayToNearHP(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+flatbuffers::Offset<frc971::MultiSpline>
+AutonomousSplines::ThirdCargoShipBayToNearHP(
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> velocity_constraint_offset;
 
@@ -500,7 +512,8 @@
 }
 
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HabToFarRocketTest(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder,
     bool is_left) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
@@ -574,7 +587,8 @@
 }
 
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::FarRocketToHPTest(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder) {
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
@@ -642,7 +656,8 @@
 }
 
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::HPToNearRocketTest(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder) {
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
@@ -710,7 +725,8 @@
 }
 
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::BasicSSpline(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder) {
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder) {
   flatbuffers::Offset<frc971::Constraint> longitudinal_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> lateral_constraint_offset;
   flatbuffers::Offset<frc971::Constraint> voltage_constraint_offset;
@@ -772,7 +788,8 @@
 }
 
 flatbuffers::Offset<frc971::MultiSpline> AutonomousSplines::StraightLine(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder) {
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder) {
   flatbuffers::Offset<flatbuffers::Vector<float>> spline_x_offset =
       builder->fbb()->CreateVector<float>(
           {-12.3, -11.9, -11.5, -11.1, -10.6, -10.0});
diff --git a/y2019/actors/auto_splines.h b/y2019/actors/auto_splines.h
index 5d79ba9..7b56c11 100644
--- a/y2019/actors/auto_splines.h
+++ b/y2019/actors/auto_splines.h
@@ -20,59 +20,72 @@
 
   // Path off of level 2 to the far side of the rocket with a panel
   static flatbuffers::Offset<frc971::MultiSpline> HABToFarRocket(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from the far side of the rocket to the loading station to pickup
   static flatbuffers::Offset<frc971::MultiSpline> FarRocketToHP(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from the far side of the rocket to the loading station to pickup
   static flatbuffers::Offset<frc971::MultiSpline> HPToFarRocket(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from the far side of the rocket to close to the loading station
   static flatbuffers::Offset<frc971::MultiSpline> FarRocketToNearHP(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Splines for 2 Panels on the far reaches of the cargo ship
 
   // Path from level 2 to 2nd cargo ship bay with a hatch panel
   static flatbuffers::Offset<frc971::MultiSpline> HABToSecondCargoShipBay(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from 2nd cargo ship bay to loading station
   static flatbuffers::Offset<frc971::MultiSpline> SecondCargoShipBayToHP(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from loading station to 3rd cargo ship bay with a hatch panel
   static flatbuffers::Offset<frc971::MultiSpline> HPToThirdCargoShipBay(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Path from 3rd cargo ship bay to near the loading station
   static flatbuffers::Offset<frc971::MultiSpline> ThirdCargoShipBayToNearHP(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
 
   // Testing Splines
   static flatbuffers::Offset<frc971::MultiSpline> HPToNearRocketTest(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder);
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder);
   static flatbuffers::Offset<frc971::MultiSpline> HabToFarRocketTest(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder,
       bool is_left);
   static flatbuffers::Offset<frc971::MultiSpline> FarRocketToHPTest(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder);
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder);
 
   static flatbuffers::Offset<frc971::MultiSpline> BasicSSpline(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder);
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder);
   static flatbuffers::Offset<frc971::MultiSpline> StraightLine(
-      aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder);
+      aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+          *builder);
 };
 
 }  // namespace actors
diff --git a/y2019/actors/autonomous_actor.cc b/y2019/actors/autonomous_actor.cc
index aa2c808..078ad64 100644
--- a/y2019/actors/autonomous_actor.cc
+++ b/y2019/actors/autonomous_actor.cc
@@ -144,11 +144,12 @@
 
 template <typename Functor>
 std::function<flatbuffers::Offset<frc971::MultiSpline>(
-    aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder)>
+    aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+        *builder)>
 BindIsLeft(Functor f, bool is_left) {
-  return
-      [is_left, f](aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder
-                       *builder) { return f(builder, is_left); };
+  return [is_left,
+          f](aos::Sender<frc971::control_loops::drivetrain::SplineGoal>::Builder
+                 *builder) { return f(builder, is_left); };
 }
 
 bool AutonomousActor::RunAction(
diff --git a/y2019/control_loops/drivetrain/BUILD b/y2019/control_loops/drivetrain/BUILD
index c21433b..9a0e879 100644
--- a/y2019/control_loops/drivetrain/BUILD
+++ b/y2019/control_loops/drivetrain/BUILD
@@ -74,6 +74,21 @@
 )
 
 cc_binary(
+    name = "trajectory_generator",
+    srcs = [
+        "trajectory_generator_main.cc",
+    ],
+    target_compatible_with = ["@platforms//os:linux"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":drivetrain_base",
+        "//aos:init",
+        "//aos/events:shm_event_loop",
+        "//frc971/control_loops/drivetrain:trajectory_generator",
+    ],
+)
+
+cc_binary(
     name = "drivetrain",
     srcs = [
         "drivetrain_main.cc",
diff --git a/y2019/control_loops/drivetrain/localizer_test.cc b/y2019/control_loops/drivetrain/localizer_test.cc
index b811688..87dbaee 100644
--- a/y2019/control_loops/drivetrain/localizer_test.cc
+++ b/y2019/control_loops/drivetrain/localizer_test.cc
@@ -142,10 +142,8 @@
   }
 
   void SetUp() {
-    flatbuffers::DetachedBuffer goal_buffer;
     {
       flatbuffers::FlatBufferBuilder fbb;
-
       flatbuffers::Offset<flatbuffers::Vector<float>> spline_x_offset =
           fbb.CreateVector<float>(GetParam().control_pts_x.begin(),
                                   GetParam().control_pts_x.size());
@@ -169,12 +167,31 @@
       spline_builder.add_spline_idx(1);
       spline_builder.add_spline(multispline_offset);
 
-      flatbuffers::Offset<frc971::control_loops::drivetrain::SplineGoal>
-          spline_offset = spline_builder.Finish();
+      fbb.Finish(spline_builder.Finish());
+      aos::FlatbufferDetachedBuffer<
+          frc971::control_loops::drivetrain::SplineGoal>
+          spline_goal_buffer(fbb.Release());
+
+      frc971::control_loops::drivetrain::Trajectory trajectory(
+          spline_goal_buffer.message(), dt_config_);
+      trajectory.Plan();
+
+      flatbuffers::FlatBufferBuilder traj_fbb;
+
+      traj_fbb.Finish(trajectory.Serialize(&traj_fbb));
+
+      trajectory_ = std::make_unique<aos::FlatbufferDetachedBuffer<
+          frc971::control_loops::drivetrain::fb::Trajectory>>(
+          traj_fbb.Release());
+      spline_drivetrain_.AddTrajectory(&trajectory_->message());
+    }
+
+    flatbuffers::DetachedBuffer goal_buffer;
+    {
+      flatbuffers::FlatBufferBuilder fbb;
 
       frc971::control_loops::drivetrain::Goal::Builder goal_builder(fbb);
 
-      goal_builder.add_spline(spline_offset);
       goal_builder.add_controller_type(
           frc971::control_loops::drivetrain::ControllerType::SPLINE_FOLLOWER);
       goal_builder.add_spline_handle(1);
@@ -186,33 +203,6 @@
     aos::FlatbufferDetachedBuffer<frc971::control_loops::drivetrain::Goal> goal(
         std::move(goal_buffer));
 
-    // Let the spline drivetrain compute the spline.
-    while (true) {
-      // We need to keep sending the goal.  There are conditions when the
-      // trajectory lock isn't grabbed the first time, and we want to keep
-      // banging on it to keep trying.  Otherwise we deadlock.
-      spline_drivetrain_.SetGoal(&goal.message());
-
-      ::std::this_thread::sleep_for(::std::chrono::milliseconds(5));
-
-      flatbuffers::FlatBufferBuilder fbb;
-
-      flatbuffers::Offset<frc971::control_loops::drivetrain::TrajectoryLogging>
-          trajectory_logging_offset =
-              spline_drivetrain_.MakeTrajectoryLogging(&fbb);
-
-      ::frc971::control_loops::drivetrain::Status::Builder status_builder(fbb);
-      status_builder.add_trajectory_logging(trajectory_logging_offset);
-      spline_drivetrain_.PopulateStatus(&status_builder);
-      fbb.Finish(status_builder.Finish());
-      aos::FlatbufferDetachedBuffer<::frc971::control_loops::drivetrain::Status>
-          status(fbb.Release());
-
-      if (status.message().trajectory_logging()->planning_state() ==
-          ::frc971::control_loops::drivetrain::PlanningState::PLANNED) {
-        break;
-      }
-    }
     spline_drivetrain_.SetGoal(&goal.message());
   }
 
@@ -357,6 +347,9 @@
 
   TestLocalizer localizer_;
 
+  std::unique_ptr<aos::FlatbufferDetachedBuffer<
+      frc971::control_loops::drivetrain::fb::Trajectory>>
+      trajectory_;
   ::frc971::control_loops::drivetrain::SplineDrivetrain spline_drivetrain_;
 
   // All the data we want to end up plotting.
diff --git a/y2019/control_loops/drivetrain/trajectory_generator_main.cc b/y2019/control_loops/drivetrain/trajectory_generator_main.cc
new file mode 100644
index 0000000..cc3d2bf
--- /dev/null
+++ b/y2019/control_loops/drivetrain/trajectory_generator_main.cc
@@ -0,0 +1,39 @@
+#include <sys/resource.h>
+#include <sys/time.h>
+
+#include "aos/events/shm_event_loop.h"
+#include "aos/init.h"
+#include "frc971/control_loops/drivetrain/trajectory_generator.h"
+#include "y2019/control_loops/drivetrain/drivetrain_base.h"
+
+using ::frc971::control_loops::drivetrain::TrajectoryGenerator;
+
+DEFINE_bool(skip_renicing, false,
+            "If true, skip renicing the trajectory generator.");
+
+int main(int argc, char *argv[]) {
+  ::aos::InitGoogle(&argc, &argv);
+
+  aos::FlatbufferDetachedBuffer<aos::Configuration> config =
+      aos::configuration::ReadConfig("config.json");
+
+  ::aos::ShmEventLoop event_loop(&config.message());
+  TrajectoryGenerator generator(
+      &event_loop, ::y2019::control_loops::drivetrain::GetDrivetrainConfig());
+
+  event_loop.OnRun([]() {
+    if (FLAGS_skip_renicing) {
+      LOG(WARNING) << "Ignoring request to renice to -20 due to "
+                      "--skip_renicing.";
+    } else {
+      errno = 0;
+      setpriority(PRIO_PROCESS, 0, -20);
+      PCHECK(errno == 0)
+          << ": Renicing to -20 failed, use --skip_renicing to skip renicing.";
+    }
+  });
+
+  event_loop.Run();
+
+  return 0;
+}