Add drivetrain replay application

This adds a basic example application for replaying the 2019 drivetrain.

I also make it so that the LogReader will stop event processing once it
is done.

Change-Id: Icd0187f240191b8d23e31608eb6e5a5a49fd068c
diff --git a/aos/events/logging/logger.cc b/aos/events/logging/logger.cc
index 486cda9..d71c2d2 100644
--- a/aos/events/logging/logger.cc
+++ b/aos/events/logging/logger.cc
@@ -307,6 +307,10 @@
   }
 
   timer_handler_ = event_loop_->AddTimer([this]() {
+    if (sorted_message_reader_.active_channel_count() == 0u) {
+      event_loop_factory_->Exit();
+      return;
+    }
     monotonic_clock::time_point channel_timestamp;
     int channel_index;
     FlatbufferVector<MessageHeader> channel_data =
@@ -358,6 +362,11 @@
 
     if (sorted_message_reader_.active_channel_count() > 0u) {
       timer_handler_->Setup(sorted_message_reader_.oldest_message().first);
+    } else {
+      // Set a timer up immediately after now to die. If we don't do this, then
+      // the senders waiting on the message we just read will never get called.
+      timer_handler_->Setup(monotonic_now + event_loop_factory_->send_delay() +
+                            std::chrono::nanoseconds(1));
     }
   });
 
diff --git a/aos/events/simulated_event_loop.cc b/aos/events/simulated_event_loop.cc
index 1dfb3af..bfe0de7 100644
--- a/aos/events/simulated_event_loop.cc
+++ b/aos/events/simulated_event_loop.cc
@@ -467,6 +467,10 @@
   }
 }
 
+std::chrono::nanoseconds SimulatedEventLoopFactory::send_delay() const {
+  return send_delay_;
+}
+
 void SimulatedEventLoop::MakeRawWatcher(
     const Channel *channel,
     std::function<void(const Context &channel, const void *message)> watcher) {
diff --git a/aos/events/simulated_event_loop.h b/aos/events/simulated_event_loop.h
index db0b840..99450a3 100644
--- a/aos/events/simulated_event_loop.h
+++ b/aos/events/simulated_event_loop.h
@@ -71,6 +71,7 @@
 
   // Sets the simulated send delay for the factory.
   void set_send_delay(std::chrono::nanoseconds send_delay);
+  std::chrono::nanoseconds send_delay() const;
 
   // Returns the node that this factory is running as, or nullptr if this is a
   // single node setup.
diff --git a/y2019/control_loops/drivetrain/BUILD b/y2019/control_loops/drivetrain/BUILD
index 1575584..bc76d7a 100644
--- a/y2019/control_loops/drivetrain/BUILD
+++ b/y2019/control_loops/drivetrain/BUILD
@@ -214,3 +214,21 @@
         "//frc971/control_loops/drivetrain:drivetrain_test_lib",
     ],
 )
+
+cc_binary(
+    name = "drivetrain_replay",
+    srcs = ["drivetrain_replay.cc"],
+    data = ["//y2019:config.json"],
+    deps = [
+        ":drivetrain_base",
+        ":event_loop_localizer",
+        "//aos:configuration",
+        "//aos:init",
+        "//aos/events:shm_event_loop",
+        "//aos/events:simulated_event_loop",
+        "//aos/events/logging:logger",
+        "//frc971/control_loops/drivetrain:drivetrain_lib",
+        "@com_github_gflags_gflags//:gflags",
+        "@com_github_google_glog//:glog",
+    ],
+)
diff --git a/y2019/control_loops/drivetrain/drivetrain_replay.cc b/y2019/control_loops/drivetrain/drivetrain_replay.cc
new file mode 100644
index 0000000..cb07b68
--- /dev/null
+++ b/y2019/control_loops/drivetrain/drivetrain_replay.cc
@@ -0,0 +1,62 @@
+#include <iostream>
+
+#include "aos/configuration.h"
+#include "aos/events/logging/logger.h"
+#include "aos/events/simulated_event_loop.h"
+#include "aos/init.h"
+#include "aos/json_to_flatbuffer.h"
+#include "aos/network/team_number.h"
+#include "frc971/control_loops/drivetrain/drivetrain.h"
+#include "gflags/gflags.h"
+#include "y2019/control_loops/drivetrain/drivetrain_base.h"
+#include "y2019/control_loops/drivetrain/event_loop_localizer.h"
+
+DEFINE_string(logfile, "/tmp/logfile.bfbs",
+              "Name of the logfile to read from.");
+DEFINE_string(config, "y2019/config.json",
+              "Name of the config file to replay using.");
+DEFINE_string(output_file, "/tmp/replayed.bfbs",
+              "Name of the logfile to write replayed data to.");
+DEFINE_int32(team, 971, "Team number to use for logfile replay.");
+int main(int argc, char **argv) {
+  aos::InitGoogle(&argc, &argv);
+
+  aos::network::OverrideTeamNumber(FLAGS_team);
+
+  aos::InitCreate();
+
+  const aos::FlatbufferDetachedBuffer<aos::Configuration> config =
+      aos::configuration::ReadConfig(FLAGS_config);
+
+  aos::logger::LogReader reader(FLAGS_logfile, &config.message());
+  // TODO(james): Actually enforce not sending on the same buses as the logfile
+  // spews out.
+  reader.RemapLoggedChannel("/drivetrain",
+                            "frc971.control_loops.drivetrain.Status");
+  reader.RemapLoggedChannel("/drivetrain",
+                            "frc971.control_loops.drivetrain.Output");
+  reader.Register();
+
+  aos::logger::DetachedBufferWriter file_writer(FLAGS_output_file);
+  std::unique_ptr<aos::EventLoop> log_writer_event_loop =
+      reader.event_loop_factory()->MakeEventLoop("log_writer");
+  log_writer_event_loop->SkipTimingReport();
+  CHECK(nullptr == log_writer_event_loop->node());
+  aos::logger::Logger writer(&file_writer, log_writer_event_loop.get());
+
+  std::unique_ptr<aos::EventLoop> drivetrain_event_loop =
+      reader.event_loop_factory()->MakeEventLoop("drivetrain");
+  drivetrain_event_loop->SkipTimingReport();
+
+  y2019::control_loops::drivetrain::EventLoopLocalizer localizer(
+      drivetrain_event_loop.get(),
+      y2019::control_loops::drivetrain::GetDrivetrainConfig());
+  frc971::control_loops::drivetrain::DrivetrainLoop drivetrain(
+      y2019::control_loops::drivetrain::GetDrivetrainConfig(),
+      drivetrain_event_loop.get(), &localizer);
+
+  reader.event_loop_factory()->Run();
+
+  aos::Cleanup();
+  return 0;
+}