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authorAllan Sandfeld Jensen <allan.jensen@qt.io>2020-10-12 14:27:29 +0200
committerAllan Sandfeld Jensen <allan.jensen@qt.io>2020-10-13 09:35:20 +0000
commitc30a6232df03e1efbd9f3b226777b07e087a1122 (patch)
treee992f45784689f373bcc38d1b79a239ebe17ee23 /chromium/v8/samples/cppgc
parent7b5b123ac58f58ffde0f4f6e488bcd09aa4decd3 (diff)
downloadqtwebengine-chromium-c30a6232df03e1efbd9f3b226777b07e087a1122.tar.gz
BASELINE: Update Chromium to 85.0.4183.14085-based
Change-Id: Iaa42f4680837c57725b1344f108c0196741f6057 Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Diffstat (limited to 'chromium/v8/samples/cppgc')
-rw-r--r--chromium/v8/samples/cppgc/cppgc-for-v8-embedders.cc106
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diff --git a/chromium/v8/samples/cppgc/cppgc-for-v8-embedders.cc b/chromium/v8/samples/cppgc/cppgc-for-v8-embedders.cc
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+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <include/cppgc/allocation.h>
+#include <include/cppgc/garbage-collected.h>
+#include <include/cppgc/heap.h>
+#include <include/cppgc/member.h>
+#include <include/cppgc/platform.h>
+#include <include/cppgc/visitor.h>
+#include <include/libplatform/libplatform.h>
+#include <include/v8.h>
+
+#include <iostream>
+#include <memory>
+#include <string>
+
+/**
+ * This sample program shows how to set up a stand-alone cppgc heap as an
+ * embedder of V8. Most importantly, this example shows how to reuse V8's
+ * platform for cppgc.
+ */
+
+/**
+ * Platform used by cppgc. Can just redirect to v8::Platform for most calls.
+ * Exception: GetForegroundTaskRunner(), see below.
+ *
+ * This example uses V8's default platform implementation to drive the cppgc
+ * platform.
+ */
+class Platform final : public cppgc::Platform {
+ public:
+ Platform() : v8_platform_(v8::platform::NewDefaultPlatform()) {}
+
+ cppgc::PageAllocator* GetPageAllocator() final {
+ return v8_platform_->GetPageAllocator();
+ }
+
+ double MonotonicallyIncreasingTime() final {
+ return v8_platform_->MonotonicallyIncreasingTime();
+ }
+
+ std::shared_ptr<cppgc::TaskRunner> GetForegroundTaskRunner() final {
+ // V8's default platform creates a new task runner when passed the
+ // v8::Isolate pointer the first time. For non-default platforms this will
+ // require getting the appropriate task runner.
+ return v8_platform_->GetForegroundTaskRunner(nullptr);
+ }
+
+ std::unique_ptr<cppgc::JobHandle> PostJob(
+ cppgc::TaskPriority priority,
+ std::unique_ptr<cppgc::JobTask> job_task) final {
+ return v8_platform_->PostJob(priority, std::move(job_task));
+ }
+
+ private:
+ std::unique_ptr<v8::Platform> v8_platform_;
+};
+
+/**
+ * Simple string rope to illustrate allocation and garbage collection below. The
+ * rope keeps the next parts alive via regular managed reference.
+ */
+class Rope final : public cppgc::GarbageCollected<Rope> {
+ public:
+ explicit Rope(std::string part, Rope* next = nullptr)
+ : part_(part), next_(next) {}
+
+ void Trace(cppgc::Visitor* visitor) const { visitor->Trace(next_); }
+
+ private:
+ std::string part_;
+ cppgc::Member<Rope> next_;
+
+ friend std::ostream& operator<<(std::ostream& os, const Rope& rope);
+};
+
+std::ostream& operator<<(std::ostream& os, const Rope& rope) {
+ os << rope.part_;
+ if (rope.next_) {
+ os << *rope.next_;
+ }
+ return os;
+}
+
+int main(int argc, char* argv[]) {
+ // Create a platform that is used by cppgc::Heap for execution and backend
+ // allocation.
+ auto cppgc_platform = std::make_shared<Platform>();
+ // Initialize the process. This must happen before any cppgc::Heap::Create()
+ // calls.
+ cppgc::InitializeProcess(cppgc_platform->GetPageAllocator());
+ // Create a managed heap.
+ std::unique_ptr<cppgc::Heap> heap = cppgc::Heap::Create(cppgc_platform);
+ // Allocate a string rope on the managed heap.
+ auto* greeting = cppgc::MakeGarbageCollected<Rope>(
+ heap->GetAllocationHandle(), "Hello ",
+ cppgc::MakeGarbageCollected<Rope>(heap->GetAllocationHandle(), "World!"));
+ // Manually trigger garbage collection. The object greeting is held alive
+ // through conservative stack scanning.
+ heap->ForceGarbageCollectionSlow("V8 embedders example", "Testing");
+ std::cout << *greeting << std::endl;
+ // Gracefully shutdown the process.
+ cppgc::ShutdownProcess();
+ return 0;
+}