webgpu: implement fence

Author: AndyHovingh

filament/backend/CMakeLists.txt

@@ -269,6 +269,8 @@ if (FILAMENT_SUPPORTS_WEBGPU)
             src/webgpu/WebGPUDescriptorSetLayout.h
             src/webgpu/WebGPUDriver.cpp
             src/webgpu/WebGPUDriver.h
+            src/webgpu/WebGPUFence.cpp
+            src/webgpu/WebGPUFence.h
             src/webgpu/WebGPUIndexBuffer.cpp
             src/webgpu/WebGPUIndexBuffer.h
             src/webgpu/WebGPUPipelineCreation.cpp

filament/backend/src/webgpu/WebGPUDriver.cpp

@@ -18,6 +18,7 @@
 #include "WebGPUBufferObject.h"
 #include "WebGPUDescriptorSet.h"
 #include "WebGPUDescriptorSetLayout.h"
+#include "WebGPUFence.h"
 #include "WebGPUIndexBuffer.h"
 #include "WebGPUPipelineCreation.h"
 #include "WebGPUProgram.h"
@@ -103,6 +104,7 @@ void WebGPUDriver::terminate() {
 
 void WebGPUDriver::tick(int) {
     mDevice.Tick();
+    mAdapter.GetInstance().ProcessEvents();
 }
 
 void WebGPUDriver::beginFrame(int64_t monotonic_clock_ns,
@@ -264,7 +266,9 @@ Handle<HwProgram> WebGPUDriver::createProgramS() noexcept {
 }
 
 Handle<HwFence> WebGPUDriver::createFenceS() noexcept {
-    return Handle<HwFence>((Handle<HwFence>::HandleId) mNextFakeHandle++);
+    // The handle must be constructed here, as a synchronous call to get the status
+    // might happen before createFenceR is executed.
+    return allocAndConstructHandle<WebGPUFence, HwFence>();
 }
 
 Handle<HwTimerQuery> WebGPUDriver::createTimerQueryS() noexcept {
@@ -455,8 +459,11 @@ void WebGPUDriver::createRenderTargetR(Handle<HwRenderTarget> renderTargetHandle
             color, depth, stencil);
 }
 
-void WebGPUDriver::createFenceR(Handle<HwFence> fh, int) {
-    //todo
+void WebGPUDriver::createFenceR(Handle<HwFence> fenceHandle, const int /* dummy */) {
+    // the handle was already constructed in createFenceS
+    const auto fence = handleCast<WebGPUFence>(fenceHandle);
+    assert_invariant(mQueue);
+    fence->addMarkerToQueueState(mQueue);
 }
 
 void WebGPUDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, int) {}
@@ -509,13 +516,18 @@ void WebGPUDriver::updateStreams(CommandStream* driver) {
     //todo
 }
 
-void WebGPUDriver::destroyFence(Handle<HwFence> fh) {
-    //todo
+void WebGPUDriver::destroyFence(Handle<HwFence> fenceHandle) {
+    if (fenceHandle) {
+        destructHandle<WebGPUFence>(fenceHandle);
+    }
 }
 
-FenceStatus WebGPUDriver::getFenceStatus(Handle<HwFence> fh) {
-    //todo
-    return FenceStatus::CONDITION_SATISFIED;
+FenceStatus WebGPUDriver::getFenceStatus(Handle<HwFence> fenceHandle) {
+    const auto fence = handleCast<WebGPUFence>(fenceHandle);
+    if (!fence) {
+        return FenceStatus::ERROR;
+    }
+    return fence->getStatus();
 }
 
 // We create all textures using VK_IMAGE_TILING_OPTIMAL, so our definition of "supported" is that

filament/backend/src/webgpu/WebGPUDriver.h

@@ -121,6 +121,11 @@ class WebGPUDriver final : public DriverBase {
         return mHandleAllocator.construct<D>(handle, std::forward<ARGS>(args)...);
     }
 
+    template<typename D, typename B, typename... ARGS>
+    Handle<B> allocAndConstructHandle(ARGS&&... args) {
+        return mHandleAllocator.allocateAndConstruct<D>(std::forward<ARGS>(args)...);
+    }
+
     template<typename D, typename B>
     D* handleCast(Handle<B> handle) noexcept {
         return mHandleAllocator.handle_cast<D*>(handle);

filament/backend/src/webgpu/WebGPUFence.cpp

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WebGPUFence.h"
+
+#include <backend/DriverEnums.h>
+
+#include <webgpu/webgpu_cpp.h>
+
+#include <atomic>
+
+namespace filament::backend {
+
+FenceStatus WebGPUFence::getStatus() { return mStatus.load(); }
+
+void WebGPUFence::addMarkerToQueueState(wgpu::Queue const& queue) {
+    queue.OnSubmittedWorkDone(
+            wgpu::CallbackMode::AllowSpontaneous,
+            [](const wgpu::QueueWorkDoneStatus status,
+                    std::atomic<FenceStatus>* const fenceStatus) {
+                if (!fenceStatus) {
+                    return;
+                }
+                switch (status) {
+                    case wgpu::QueueWorkDoneStatus::Success:
+                        fenceStatus->store(FenceStatus::CONDITION_SATISFIED);
+                        break;
+                    case wgpu::QueueWorkDoneStatus::CallbackCancelled:
+                    case wgpu::QueueWorkDoneStatus::Error:
+                        fenceStatus->store(FenceStatus::ERROR);
+                        break;
+                }
+            },
+            &mStatus);
+}
+
+} // namespace filament::backend

filament/backend/src/webgpu/WebGPUFence.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TNT_FILAMENT_BACKEND_WEBGPUFENCE_H
+#define TNT_FILAMENT_BACKEND_WEBGPUFENCE_H
+
+#include "DriverBase.h"
+#include <backend/DriverEnums.h>
+
+#include <atomic>
+
+namespace wgpu {
+class Queue;
+} // namespace wgpu
+
+namespace filament::backend {
+
+class WebGPUFence final : public HwFence {
+public:
+    [[nodiscard]] FenceStatus getStatus();
+
+    void addMarkerToQueueState(wgpu::Queue const&);
+
+private:
+    std::atomic<FenceStatus> mStatus{ FenceStatus::TIMEOUT_EXPIRED };
+};
+
+} // namespace filament::backend
+
+#endif // TNT_FILAMENT_BACKEND_WEBGPUFENCE_H