Implement basic network flow control (#2803)

Co-authored-by: Cameron Gutman <aicommander@gmail.com>

src/platform/windows/display.h

@@ -161,9 +161,6 @@ namespace platf::dxgi {
     int
     init(const ::video::config_t &config, const std::string &display_name);
 
-    void
-    high_precision_sleep(std::chrono::nanoseconds duration);
-
     capture_e
     capture(const push_captured_image_cb_t &push_captured_image_cb, const pull_free_image_cb_t &pull_free_image_cb, bool *cursor) override;
 
@@ -184,7 +181,7 @@ namespace platf::dxgi {
     DXGI_FORMAT capture_format;
     D3D_FEATURE_LEVEL feature_level;
 
-    util::safe_ptr_v2<std::remove_pointer_t<HANDLE>, BOOL, CloseHandle> timer;
+    std::unique_ptr<high_precision_timer> timer = create_high_precision_timer();
 
     typedef enum _D3DKMT_SCHEDULINGPRIORITYCLASS {
       D3DKMT_SCHEDULINGPRIORITYCLASS_IDLE,  ///< Idle priority class

src/platform/windows/display_base.cpp

@@ -182,27 +182,6 @@ namespace platf::dxgi {
     release_frame();
   }
 
-  void
-  display_base_t::high_precision_sleep(std::chrono::nanoseconds duration) {
-    if (!timer) {
-      BOOST_LOG(error) << "Attempting high_precision_sleep() with uninitialized timer";
-      return;
-    }
-    if (duration < 0s) {
-      BOOST_LOG(error) << "Attempting high_precision_sleep() with negative duration";
-      return;
-    }
-    if (duration > 5s) {
-      BOOST_LOG(error) << "Attempting high_precision_sleep() with unexpectedly large duration (>5s)";
-      return;
-    }
-
-    LARGE_INTEGER due_time;
-    due_time.QuadPart = duration.count() / -100;
-    SetWaitableTimer(timer.get(), &due_time, 0, nullptr, nullptr, false);
-    WaitForSingleObject(timer.get(), INFINITE);
-  }
-
   capture_e
   display_base_t::capture(const push_captured_image_cb_t &push_captured_image_cb, const pull_free_image_cb_t &pull_free_image_cb, bool *cursor) {
     auto adjust_client_frame_rate = [&]() -> DXGI_RATIONAL {
@@ -268,7 +247,7 @@ namespace platf::dxgi {
           status = capture_e::timeout;
         }
         else {
-          high_precision_sleep(sleep_period);
+          timer->sleep_for(sleep_period);
           std::chrono::nanoseconds overshoot_ns = std::chrono::steady_clock::now() - sleep_target;
           log_sleep_overshoot(overshoot_ns);
 
@@ -799,15 +778,9 @@ namespace platf::dxgi {
         << "Max Full Luminance : "sv << desc1.MaxFullFrameLuminance << " nits"sv;
     }
 
-    // Use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION if supported (Windows 10 1809+)
-    timer.reset(CreateWaitableTimerEx(nullptr, nullptr, CREATE_WAITABLE_TIMER_HIGH_RESOLUTION, TIMER_ALL_ACCESS));
-    if (!timer) {
-      timer.reset(CreateWaitableTimerEx(nullptr, nullptr, 0, TIMER_ALL_ACCESS));
-      if (!timer) {
-        auto winerr = GetLastError();
-        BOOST_LOG(error) << "Failed to create timer: "sv << winerr;
-        return -1;
-      }
+    if (!timer || !*timer) {
+      BOOST_LOG(error) << "Uninitialized high precision timer";
+      return -1;
     }
 
     return 0;

src/platform/windows/misc.cpp

@@ -61,6 +61,38 @@
   #define WLAN_API_MAKE_VERSION(_major, _minor) (((DWORD) (_minor)) << 16 | (_major))
 #endif
 
+#include <winternl.h>
+extern "C" {
+NTSTATUS NTAPI
+NtSetTimerResolution(ULONG DesiredResolution, BOOLEAN SetResolution, PULONG CurrentResolution);
+}
+
+namespace {
+
+  std::atomic<bool> used_nt_set_timer_resolution = false;
+
+  bool
+  nt_set_timer_resolution_max() {
+    ULONG minimum, maximum, current;
+    if (!NT_SUCCESS(NtQueryTimerResolution(&minimum, &maximum, &current)) ||
+        !NT_SUCCESS(NtSetTimerResolution(maximum, TRUE, &current))) {
+      return false;
+    }
+    return true;
+  }
+
+  bool
+  nt_set_timer_resolution_min() {
+    ULONG minimum, maximum, current;
+    if (!NT_SUCCESS(NtQueryTimerResolution(&minimum, &maximum, &current)) ||
+        !NT_SUCCESS(NtSetTimerResolution(minimum, TRUE, &current))) {
+      return false;
+    }
+    return true;
+  }
+
+}  // namespace
+
 namespace bp = boost::process;
 
 using namespace std::literals;
@@ -1115,8 +1147,15 @@ namespace platf {
     // Enable MMCSS scheduling for DWM
     DwmEnableMMCSS(true);
 
-    // Reduce timer period to 1ms
-    timeBeginPeriod(1);
+    // Reduce timer period to 0.5ms
+    if (nt_set_timer_resolution_max()) {
+      used_nt_set_timer_resolution = true;
+    }
+    else {
+      BOOST_LOG(error) << "NtSetTimerResolution() failed, falling back to timeBeginPeriod()";
+      timeBeginPeriod(1);
+      used_nt_set_timer_resolution = false;
+    }
 
     // Promote ourselves to high priority class
     SetPriorityClass(GetCurrentProcess(), HIGH_PRIORITY_CLASS);
@@ -1199,8 +1238,16 @@ namespace platf {
     // Demote ourselves back to normal priority class
     SetPriorityClass(GetCurrentProcess(), NORMAL_PRIORITY_CLASS);
 
-    // End our 1ms timer request
-    timeEndPeriod(1);
+    // End our 0.5ms timer request
+    if (used_nt_set_timer_resolution) {
+      used_nt_set_timer_resolution = false;
+      if (!nt_set_timer_resolution_min()) {
+        BOOST_LOG(error) << "nt_set_timer_resolution_min() failed even though nt_set_timer_resolution_max() succeeded";
+      }
+    }
+    else {
+      timeEndPeriod(1);
+    }
 
     // Disable MMCSS scheduling for DWM
     DwmEnableMMCSS(false);
@@ -1756,4 +1803,55 @@ namespace platf {
 
     return output;
   }
+
+  class win32_high_precision_timer: public high_precision_timer {
+  public:
+    win32_high_precision_timer() {
+      // Use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION if supported (Windows 10 1809+)
+      timer = CreateWaitableTimerEx(nullptr, nullptr, CREATE_WAITABLE_TIMER_HIGH_RESOLUTION, TIMER_ALL_ACCESS);
+      if (!timer) {
+        timer = CreateWaitableTimerEx(nullptr, nullptr, 0, TIMER_ALL_ACCESS);
+        if (!timer) {
+          BOOST_LOG(error) << "Unable to create high_precision_timer, CreateWaitableTimerEx() failed: " << GetLastError();
+        }
+      }
+    }
+
+    ~win32_high_precision_timer() {
+      if (timer) CloseHandle(timer);
+    }
+
+    void
+    sleep_for(const std::chrono::nanoseconds &duration) override {
+      if (!timer) {
+        BOOST_LOG(error) << "Attempting high_precision_timer::sleep_for() with uninitialized timer";
+        return;
+      }
+      if (duration < 0s) {
+        BOOST_LOG(error) << "Attempting high_precision_timer::sleep_for() with negative duration";
+        return;
+      }
+      if (duration > 5s) {
+        BOOST_LOG(error) << "Attempting high_precision_timer::sleep_for() with unexpectedly large duration (>5s)";
+        return;
+      }
+
+      LARGE_INTEGER due_time;
+      due_time.QuadPart = duration.count() / -100;
+      SetWaitableTimer(timer, &due_time, 0, nullptr, nullptr, false);
+      WaitForSingleObject(timer, INFINITE);
+    }
+
+    operator bool() override {
+      return timer != NULL;
+    }
+
+  private:
+    HANDLE timer = NULL;
+  };
+
+  std::unique_ptr<high_precision_timer>
+  create_high_precision_timer() {
+    return std::make_unique<win32_high_precision_timer>();
+  }
 }  // namespace platf