Fix framebuffer image memory retention

frameos/src/apps/render/image/app.nim

@@ -17,6 +17,10 @@ type
   App* = ref object of AppRoot
     appConfig*: AppConfig
 
+proc clearTransientInputs(self: App) =
+  self.appConfig.inputImage = none(Image)
+  self.appConfig.image = nil
+
 proc render*(self: App, context: ExecutionContext, image: Image) =
   try:
     let sourceImage = self.appConfig.image
@@ -53,13 +57,19 @@ proc render*(self: App, context: ExecutionContext, image: Image) =
     scaleAndDrawImage(image, errorImage, self.appConfig.placement)
 
 proc run*(self: App, context: ExecutionContext) =
-  render(self, context, context.image)
+  try:
+    render(self, context, context.image)
+  finally:
+    self.clearTransientInputs()
 
 proc get*(self: App, context: ExecutionContext): Image =
-  result = if self.appConfig.inputImage.isSome:
-    self.appConfig.inputImage.get()
-  elif context.hasImage:
-    newImage(context.image.width, context.image.height)
-  else:
-    newImage(self.frameConfig.renderWidth(), self.frameConfig.renderHeight())
-  render(self, context, result)
+  try:
+    result = if self.appConfig.inputImage.isSome:
+      self.appConfig.inputImage.get()
+    elif context.hasImage:
+      newImage(context.image.width, context.image.height)
+    else:
+      newImage(self.frameConfig.renderWidth(), self.frameConfig.renderHeight())
+    render(self, context, result)
+  finally:
+    self.clearTransientInputs()

frameos/src/apps/render/image/tests/test_app.nim

@@ -45,6 +45,7 @@ suite "render/image app":
   test "run renders onto context image in place":
     let source = newImage(1, 1)
     source.data[0] = rgbx(200, 100, 50, 255)
+    let input = newImage(3, 2)
     let config = makeConfig(3, 2)
     let app = App(
       frameConfig: config,
@@ -58,14 +59,41 @@ suite "render/image app":
         blendMode: "normal"
       )
     )
-    let context = ExecutionContext(image: newImage(3, 2), hasImage: true)
+    let context = ExecutionContext(image: input, hasImage: true)
 
     app.run(context)
 
     let sample = pixel(context.image, 2, 1)
     check sample.r > 0
     check sample.g > 0
     check sample.b > 0
+    check app.appConfig.image.isNil
+    check app.appConfig.inputImage.isNone
+
+  test "get clears transient source images after returning output":
+    let source = newImage(1, 1)
+    source.data[0] = rgbx(50, 200, 100, 255)
+    let input = newImage(3, 2)
+    let config = makeConfig(3, 2)
+    let app = App(
+      frameConfig: config,
+      scene: makeScene(config),
+      appConfig: AppConfig(
+        inputImage: some(input),
+        image: source,
+        placement: "stretch",
+        offsetX: 0,
+        offsetY: 0,
+        blendMode: "normal"
+      )
+    )
+
+    let output = app.get(ExecutionContext(hasImage: false))
+
+    check output == input
+    check pixel(output, 2, 1).g > 0
+    check app.appConfig.image.isNil
+    check app.appConfig.inputImage.isNone
 
   test "missing source image is handled by error path without raising":
     let config = makeConfig(4, 3)

frameos/src/frameos/runner.nim

@@ -16,6 +16,7 @@ import frameos/utils/time
 import frameos/scenes
 import frameos/boot_guard
 import frameos/runtime_diagnostics
+import frameos/utils/memory
 import frameos/watchdog
 
 import drivers/drivers as drivers
@@ -225,7 +226,9 @@ proc startRenderLoop*(self: RunnerThread, maxCycles = -1): Future[void] {.async.
       self.triggerRenderNext = false # used to debounce render events received while rendering
 
       let interval = currentScene.refreshInterval
-      let (lastRotatedImage, nextSleep) = self.renderSceneImage(exportedScene.get(), currentScene)
+      var renderResult = self.renderSceneImage(exportedScene.get(), currentScene)
+      var lastRotatedImage = renderResult[0]
+      let nextSleep = renderResult[1]
       reclaimRetiredExportedScenes(currentExportedScenesGeneration(), self.logger)
       clearBootCrashCount()
       successfulSceneRenders += 1
@@ -261,6 +264,10 @@ proc startRenderLoop*(self: RunnerThread, maxCycles = -1): Future[void] {.async.
       except Exception as e:
         self.logger.log(%*{"event": "render:driver:error", "error": $e.msg, "stacktrace": e.getStackTrace()})
       finally:
+        lastRotatedImage = nil
+        renderResult[0] = nil
+        if self.frameConfig.device == "framebuffer":
+          reclaimRenderMemory()
         clearNextRenderSeconds()
       markRuntimeDone()
 

frameos/src/frameos/utils/memory.nim

@@ -0,0 +1,9 @@
+proc reclaimRenderMemory*() =
+  ## Large image decodes can leave sizeable temporary allocations behind.
+  ## Collect unreachable Nim objects first, then ask glibc malloc to return
+  ## free heap pages to the OS on Linux frame targets.
+  GC_fullCollect()
+
+  when defined(linux):
+    proc malloc_trim(pad: csize_t): cint {.importc: "malloc_trim", header: "<malloc.h>".}
+    discard malloc_trim(0.csize_t)