Project import generated by Copybara.

GitOrigin-RevId: 0517756260533d374df93679965ca662d0ec6943

mediapipe/gpu/BUILD

@@ -303,6 +303,7 @@ objc_library(
     visibility = ["//visibility:public"],
     deps = [
         "//mediapipe/objc:mediapipe_framework_ios",
+        "@com_google_absl//absl/time",
         "@google_toolbox_for_mac//:GTM_Defines",
     ],
 )

mediapipe/gpu/MPPMetalUtil.h

@@ -42,6 +42,12 @@ NS_ASSUME_NONNULL_BEGIN
                  blocking:(bool)blocking
             commandBuffer:(id<MTLCommandBuffer>)commandBuffer;
 
+/// Commits the command buffer and waits until execution completes. This is
+/// functionally equivalent to calling commit and waitUntilCompleted on the
+/// command buffer, but may use different synchronization strategies, such as
+/// active wait.
++ (void)commitCommandBufferAndWait:(id<MTLCommandBuffer>)commandBuffer;
+
 @end
 
 NS_ASSUME_NONNULL_END

mediapipe/gpu/MPPMetalUtil.mm

@@ -14,6 +14,9 @@
 
 #import "mediapipe/gpu/MPPMetalUtil.h"
 
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+
 @implementation MPPMetalUtil
 
 + (void)blitMetalBufferTo:(id<MTLBuffer>)destination
@@ -44,8 +47,41 @@
              destinationOffset:destinationOffset
                           size:bytes];
   [blit_command endEncoding];
+  if (blocking) {
+    [MPPMetalUtil commitCommandBufferAndWait:commandBuffer];
+  } else {
+    [commandBuffer commit];
+  }
+}
+
++ (void)commitCommandBufferAndWait:(id<MTLCommandBuffer>)commandBuffer {
+#if !defined(MEDIAPIPE_DISABLE_ACTIVE_WAIT)
+  // The bufferCompleted variable doesn't require atomic access.
+  // std::atomic<> can't be used here because the variable must be captured
+  // with the block. Also std::atomic<> orders changes of the variable but
+  // in this case any kind of out-of-order execution will be serialized.
+  __block volatile bool bufferCompleted = false;
+  [commandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) {
+    bufferCompleted = true;
+  }];
   [commandBuffer commit];
-  if (blocking) [commandBuffer waitUntilCompleted];
+  absl::Time start_time = absl::Now();
+  while (!bufferCompleted) {
+    auto duration = absl::Now() - start_time;
+    // If the spin-lock takes more than 5 ms then go to blocking wait:
+    // - it frees the CPU core for another threads: increase the performance/decrease power
+    // consumption.
+    // - if a driver thread that notifies that the GPU buffer is completed has lower priority then
+    // the CPU core is allocated for the thread.
+    if (duration >= absl::Milliseconds(5)) {
+      [commandBuffer waitUntilCompleted];
+      break;
+    }
+  }
+#else
+  [commandBuffer commit];
+  [commandBuffer waitUntilCompleted];
+#endif
 }
 
 @end

mediapipe/gpu/gl_context_webgl.cc

@@ -23,6 +23,7 @@
 #include "mediapipe/gpu/gl_context_internal.h"
 
 #if defined(__EMSCRIPTEN__)
+#include <emscripten.h>
 
 namespace mediapipe {
 
@@ -62,8 +63,48 @@ GlContext::StatusOrGlContext GlContext::Create(
   // pushing resulting texture through MediaPipe pipeline.
   attrs.preserveDrawingBuffer = 0;
 
-  // We use id of "0" for now to target our webassembly Module.canvas
-  // specifically for all GL contexts.
+  // Since the Emscripten canvas target finding function is visible from here,
+  // we hijack findCanvasEventTarget directly for enforcing old Module.canvas
+  // behavior if the user desires, falling back to the new DOM element CSS
+  // selector behavior next if that is specified, and finally just allowing the
+  // lookup to proceed on a null target.
+  // TODO: Ensure this works with all options (in particular,
+  //   multithreading options, like the special-case combination of USE_PTHREADS
+  //   and OFFSCREEN_FRAMEBUFFER)
+  EM_ASM(let init_once = true; if (init_once) {
+    const __cachedFindCanvasEventTarget = __findCanvasEventTarget;
+
+    if (typeof __cachedFindCanvasEventTarget != = 'function') {
+      if (typeof console != = 'undefined') {
+        console.error(
+            'Expected Emscripten global function ' +
+            '"__findCanvasEventTarget" not found. WebGL context creation ' +
+            'may fail.');
+      }
+      return;
+    }
+
+    __findCanvasEventTarget = function(target) {
+      if (Module && Module.canvas) {
+        return Module.canvas;
+      } else if (Module && Module.canvasCssSelector) {
+        return __cachedFindCanvasEventTarget(Module.canvasCssSelector);
+      } else {
+        if (typeof console != = 'undefined') {
+          console.warn('Module properties canvas and canvasCssSelector not ' +
+                       'found during WebGL context creation.');
+        }
+        // We still go through with the find attempt, although for most use
+        // cases it will not succeed, just in case the user does want to fall-
+        // back.
+        return __cachedFindCanvasEventTarget(target);
+      }
+    };  // NOLINT: Necessary semicolon.
+    init_once = false;
+  });
+
+  // Note: below id parameter is only actually used if both Module.canvas and
+  // Module.canvasCssSelector are undefined.
   EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context_handle =
       emscripten_webgl_create_context(0 /* id */, &attrs);
 
@@ -73,6 +114,9 @@ GlContext::StatusOrGlContext GlContext::Create(
     return ::mediapipe::UnknownErrorBuilder(MEDIAPIPE_LOC)
            << "emscripten_webgl_create_context() returned error "
            << context_handle;
+  } else {
+    emscripten_webgl_get_context_attributes(context_handle, &attrs);
+    webgl_version = attrs.majorVersion;
   }
   context_ = context_handle;
   attrs_ = attrs;