commit dc52475b12c2fb450ca871768d1dfff1022e02ba
author Ravago Jones <ravagojones@gmail.com> Tue Dec 27 01:15:13 2022 -0800
committer Austin Schuh <austin.linux@gmail.com> Mon Jan 02 20:47:03 2023 -0800
tree d929dea99d4d613577ad7f02b93f0f9fdcaf4174
parent dfc87496c469cb3abb50ef0bbdc5a909be2fb8d1

Make v4l2_reader use epoll

It no longer needs to be polled in a loop
and sends images directly to the channel

Signed-off-by: Ravago Jones <ravagojones@gmail.com>
Change-Id: I8fc3efc3fd2cd67836294d9dc47d5342cd7d5de4

frc971/vision/BUILD

diff --git a/frc971/vision/BUILD b/frc971/vision/BUILD
index 159c779..4a8d50b 100644
--- a/frc971/vision/BUILD
+++ b/frc971/vision/BUILD
@@ -28,6 +28,7 @@
     visibility = ["//visibility:public"],
     deps = [
         ":vision_fbs",
+        "//aos/events:epoll",
         "//aos/events:event_loop",
         "//aos/scoped:scoped_fd",
         "@com_github_google_glog//:glog",

frc971/vision/v4l2_reader.cc

diff --git a/frc971/vision/v4l2_reader.cc b/frc971/vision/v4l2_reader.cc
index f3640db..e549ae5 100644
--- a/frc971/vision/v4l2_reader.cc
+++ b/frc971/vision/v4l2_reader.cc
@@ -302,9 +302,19 @@
 }
 
 RockchipV4L2Reader::RockchipV4L2Reader(aos::EventLoop *event_loop,
+                                       aos::internal::EPoll *epoll,
                                        const std::string &device_name)
-    : V4L2ReaderBase(event_loop, device_name) {
+    : V4L2ReaderBase(event_loop, device_name), epoll_(epoll) {
   StreamOn();
+  epoll_->OnReadable(fd().get(), [this]() { OnImageReady(); });
+}
+
+void RockchipV4L2Reader::OnImageReady() {
+  if (!ReadLatestImage()) {
+    return;
+  }
+
+  SendLatestImage();
 }
 
 }  // namespace vision

frc971/vision/v4l2_reader.h

diff --git a/frc971/vision/v4l2_reader.h b/frc971/vision/v4l2_reader.h
index a2b4c25..334ad81 100644
--- a/frc971/vision/v4l2_reader.h
+++ b/frc971/vision/v4l2_reader.h
@@ -5,6 +5,7 @@
 #include <string>
 
 #include "absl/types/span.h"
+#include "aos/events/epoll.h"
 #include "aos/events/event_loop.h"
 #include "aos/ftrace.h"
 #include "aos/scoped/scoped_fd.h"
@@ -62,6 +63,8 @@
   // H.264 frames.
   size_t ImageSize() const { return rows_ * cols_ * 2 /* bytes per pixel */; }
 
+  const aos::ScopedFD &fd() { return fd_; };
+
  private:
   static constexpr int kNumberBuffers = 4;
 
@@ -139,7 +142,13 @@
 // properly configured before this class is constructed.
 class RockchipV4L2Reader : public V4L2ReaderBase {
  public:
-  RockchipV4L2Reader(aos::EventLoop *event_loop, const std::string &device_name);
+  RockchipV4L2Reader(aos::EventLoop *event_loop, aos::internal::EPoll *epoll,
+                     const std::string &device_name);
+
+ private:
+  void OnImageReady();
+
+  aos::internal::EPoll *epoll_;
 };
 
 }  // namespace vision