Split Ganesh-specific parts of SkiaVkRenderEngine into subclass

Similarly to Ia65306cc825b71fe0b89c7f8545ce1c71a81d86b, this will allow
for a Graphite-specific variant of SkiaVkRenderEngine.

waitFence and flushAndSubmit are kept on the *RenderEngine classes (as
opposed to the recently added SkiaGpuContext abstraction) because they
are specific to the intersection of both <Skia backend> x <GPU API>,
with 3 variants. Their logic is also RE-specific, and not suitable for
a Skia abstraction.

Misc. cleanup:
- Remove SkiaVkRenderEngine's flush() and mBackendContext declarations
  as they were undefined and unnecessary.
- Mark some local variables as const.
- Pass named constant to GrDirectContext::wait in
  GaneshVkRenderEngine::waitFence

Test: manual validation & existing tests (refactor)
Bug: b/293371537
Change-Id: I695a0554b20ca14cf475aeff1b92c4445c1af55b
diff --git a/libs/renderengine/skia/GaneshVkRenderEngine.cpp b/libs/renderengine/skia/GaneshVkRenderEngine.cpp
new file mode 100644
index 0000000..e76a4c3
--- /dev/null
+++ b/libs/renderengine/skia/GaneshVkRenderEngine.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2024 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 "GaneshVkRenderEngine.h"
+
+#undef LOG_TAG
+#define LOG_TAG "RenderEngine"
+
+#include <include/gpu/ganesh/vk/GrVkBackendSemaphore.h>
+
+#include <log/log_main.h>
+#include <sync/sync.h>
+
+namespace android::renderengine::skia {
+
+// Ganesh-specific function signature for fFinishedProc callback.
+static void unref_semaphore(void* semaphore) {
+    SkiaVkRenderEngine::DestroySemaphoreInfo* info =
+            reinterpret_cast<SkiaVkRenderEngine::DestroySemaphoreInfo*>(semaphore);
+    info->unref();
+}
+
+void GaneshVkRenderEngine::waitFence(SkiaGpuContext* context, base::borrowed_fd fenceFd) {
+    if (fenceFd.get() < 0) return;
+
+    const int dupedFd = dup(fenceFd.get());
+    if (dupedFd < 0) {
+        ALOGE("failed to create duplicate fence fd: %d", dupedFd);
+        sync_wait(fenceFd.get(), -1);
+        return;
+    }
+
+    base::unique_fd fenceDup(dupedFd);
+    VkSemaphore waitSemaphore =
+            getVulkanInterface(isProtected()).importSemaphoreFromSyncFd(fenceDup.release());
+    GrBackendSemaphore beSemaphore = GrBackendSemaphores::MakeVk(waitSemaphore);
+    constexpr bool kDeleteAfterWait = true;
+    context->grDirectContext()->wait(1, &beSemaphore, kDeleteAfterWait);
+}
+
+base::unique_fd GaneshVkRenderEngine::flushAndSubmit(SkiaGpuContext* context) {
+    sk_sp<GrDirectContext> grContext = context->grDirectContext();
+    VulkanInterface& vi = getVulkanInterface(isProtected());
+    VkSemaphore semaphore = vi.createExportableSemaphore();
+
+    GrBackendSemaphore backendSemaphore = GrBackendSemaphores::MakeVk(semaphore);
+
+    GrFlushInfo flushInfo;
+    DestroySemaphoreInfo* destroySemaphoreInfo = nullptr;
+    if (semaphore != VK_NULL_HANDLE) {
+        destroySemaphoreInfo = new DestroySemaphoreInfo(vi, semaphore);
+        flushInfo.fNumSemaphores = 1;
+        flushInfo.fSignalSemaphores = &backendSemaphore;
+        flushInfo.fFinishedProc = unref_semaphore;
+        flushInfo.fFinishedContext = destroySemaphoreInfo;
+    }
+    GrSemaphoresSubmitted submitted = grContext->flush(flushInfo);
+    grContext->submit(GrSyncCpu::kNo);
+    int drawFenceFd = -1;
+    if (semaphore != VK_NULL_HANDLE) {
+        if (GrSemaphoresSubmitted::kYes == submitted) {
+            drawFenceFd = vi.exportSemaphoreSyncFd(semaphore);
+        }
+        // Now that drawFenceFd has been created, we can delete our reference to this semaphore
+        flushInfo.fFinishedProc(destroySemaphoreInfo);
+    }
+    base::unique_fd res(drawFenceFd);
+    return res;
+}
+
+} // namespace android::renderengine::skia