commit 0fade37afd60c3f0e387172e03759e055f831d30
author Roman Stratiienko <r.stratiienko@gmail.com> Sat Feb 20 13:59:55 2021 +0200
committer Roman Stratiienko <r.stratiienko@gmail.com> Sat Jul 24 17:59:09 2021 +0300
tree 247fb23bfac5a18ce8dc8d90efffa3166845b36d
parent 5128715b42e6713b98244bd05f218b8800a39b74

drm_hwcomposer: Rework autofd

Motivation:

Current implementation of UniqueFd can be used in a different ways,
making analytical tracking of FD lifecycle much harder than it may be.
Keep this part clean is very important, since any wrong code may open
a hard-to-detect runtime bugs and fd leaks, which may accidentally slip
into the production.

Implementation:

1. Combine UniqueFd anf OutputFd into single class.
2. Reduce the API to be minimal and sufficient.
3. Document the API and use cases.
4. Move to utils/UniqueFd.h.
5. dup(fd) was replaced with fcntl(fd, F_DUPFD_CLOEXEC)) to
   address clang-tidy findings. Find more information at [1]

[1]: https://clang.llvm.org/extra/clang-tidy/checks/android-cloexec-dup.html

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>

compositor/DrmDisplayComposition.h

diff --git a/compositor/DrmDisplayComposition.h b/compositor/DrmDisplayComposition.h
index 27b34f2..1738630 100644
--- a/compositor/DrmDisplayComposition.h
+++ b/compositor/DrmDisplayComposition.h
@@ -127,16 +127,10 @@
     return planner_;
   }
 
-  int take_out_fence() {
-    return out_fence_.Release();
-  }
-
-  void set_out_fence(int out_fence) {
-    out_fence_.Set(out_fence);
-  }
-
   void Dump(std::ostringstream *out) const;
 
+  UniqueFd out_fence_;
+
  private:
   bool validate_composition_type(DrmCompositionType desired);
 
@@ -147,8 +141,6 @@
   uint32_t dpms_mode_ = DRM_MODE_DPMS_ON;
   DrmMode display_mode_;
 
-  UniqueFd out_fence_ = -1;
-
   bool geometry_changed_ = true;
   std::vector<DrmHwcLayer> layers_;
   std::vector<DrmCompositionPlane> composition_planes_;

compositor/DrmDisplayCompositor.cpp

diff --git a/compositor/DrmDisplayCompositor.cpp b/compositor/DrmDisplayCompositor.cpp
index 4e7fe0d..a1fe50f 100644
--- a/compositor/DrmDisplayCompositor.cpp
+++ b/compositor/DrmDisplayCompositor.cpp
@@ -291,7 +291,7 @@
         break;
       }
       fb_id = layer.FbIdHandle->GetFbId();
-      fence_fd = layer.acquire_fence.get();
+      fence_fd = layer.acquire_fence.Get();
       display_frame = layer.display_frame;
       source_crop = layer.source_crop;
       alpha = layer.alpha;
@@ -540,7 +540,7 @@
   }
 
   if (crtc->out_fence_ptr_property().id()) {
-    display_comp->set_out_fence((int)out_fences[crtc->pipe()]);
+    display_comp->out_fence_ = UniqueFd((int)out_fences[crtc->pipe()]);
   }
 
   return ret;

compositor/DrmDisplayCompositor.h

diff --git a/compositor/DrmDisplayCompositor.h b/compositor/DrmDisplayCompositor.h
index aebb6ff..c0eed0c 100644
--- a/compositor/DrmDisplayCompositor.h
+++ b/compositor/DrmDisplayCompositor.h
@@ -72,10 +72,11 @@
   void Dump(std::ostringstream *out) const;
   void Vsync(int display, int64_t timestamp);
   void ClearDisplay();
-  int TakeOutFence() {
-    if (!active_composition_)
-      return -1;
-    return active_composition_->take_out_fence();
+  UniqueFd TakeOutFence() {
+    if (!active_composition_) {
+      return UniqueFd();
+    }
+    return std::move(active_composition_->out_fence_);
   }
 
   FlatteningState GetFlatteningState() const;