Log Filament command buffer statistics (#9709)

Author: bejado

filament/backend/include/backend/Platform.h

@@ -561,16 +561,18 @@ class UTILS_PUBLIC Platform {
 
     /**
      * Sets the callback function that the backend can use to update backend-specific statistics
-     * to aid with debugging. This callback is guaranteed to be called on the Filament driver
-     * thread.
+     * to aid with debugging. This callback can be called on either the Filament main thread or
+     * the Filament driver thread.
      *
      * The callback signature is (key, intValue, stringValue). Note that for any given call,
      * only one of the value parameters (intValue or stringValue) will be meaningful, depending on
      * the specific key.
      *
-     * IMPORTANT_NOTE: because the callback is called on the driver thread, only quick, non-blocking
-     * work should be done inside it. Furthermore, no graphics API calls (such as GL calls) should
-     * be made, which could interfere with Filament's driver state.
+     * IMPORTANT_NOTE: because the callback can be called on the driver thread, only quick,
+     * non-blocking work should be done inside it. Furthermore, no graphics API calls (such as GL
+     * calls) should be made, which could interfere with Filament's driver state. Lastly, the
+     * callback implementation must be synchronized (thread-safe) since it can be called from
+     * either thread.
      *
      * @param debugUpdateStat   an Invocable that updates debug statistics
      */
@@ -587,8 +589,7 @@ class UTILS_PUBLIC Platform {
      * with a given key. It is possible for this function to be called multiple times with the
      * same key, in which case newer values should overwrite older values.
      *
-     * This function is guaranteed to be called only on a single thread, the Filament driver
-     * thread.
+     * This function can be called on either the Filament main thread or the Filament driver thread.
      *
      * @param key           a null-terminated C-string with the key of the debug statistic
      * @param intValue      the updated integer value of key (the string value passed to the
@@ -602,8 +603,7 @@ class UTILS_PUBLIC Platform {
      * with a given key. It is possible for this function to be called multiple times with the
      * same key, in which case newer values should overwrite older values.
      *
-     * This function is guaranteed to be called only on a single thread, the Filament driver
-     * thread.
+     * This function can be called on either the Filament main thread or the Filament driver thread.
      *
      * @param key           a null-terminated C-string with the key of the debug statistic
      * @param stringValue   the updated string value of key (the integer value passed to the

filament/src/RenderPass.cpp

@@ -901,6 +901,12 @@ void RenderPass::Executor::execute(FEngine const& engine, DriverApi& driver,
     size_t const capacity = engine.getMinCommandBufferSize();
     CircularBuffer const& circularBuffer = driver.getCircularBuffer();
 
+    // b/479079631: Log the number of commands in this render pass.
+    size_t const commandCount = last - first;
+    if (Platform* platform = engine.getPlatform(); platform->hasDebugUpdateStatFunc()) {
+        platform->debugUpdateStat("filament.renderer.render_pass.command_count", commandCount);
+    }
+
     if (first != last) {
         FILAMENT_TRACING_VALUE(FILAMENT_TRACING_CATEGORY_FILAMENT, "commandCount", last - first);
 

filament/src/RendererUtils.cpp

@@ -258,7 +258,21 @@ RendererUtils::ColorPassOutput RendererUtils::colorPass(
                 }
 
                 driver.beginRenderPass(out.target, out.params);
+                Platform* platform = engine.getPlatform();
+                CircularBuffer const& circularBuffer = driver.getCircularBuffer();
+                // b/479079631: Log the current command buffer size before and after executing the
+                // render pass.
+                if (platform->hasDebugUpdateStatFunc()) {
+                    platform->debugUpdateStat(
+                            "filament.renderer.color_pass.command_buffer_used_start",
+                            circularBuffer.getUsed());
+                }
                 passExecutor.execute(engine, driver);
+                if (platform->hasDebugUpdateStatFunc()) {
+                    platform->debugUpdateStat(
+                            "filament.renderer.color_pass.command_buffer_used_end",
+                            circularBuffer.getUsed());
+                }
                 driver.endRenderPass();
 
                 // unbind all descriptor sets to avoid false dependencies with the next pass