1 files changed, 267 insertions, 0 deletions
diff --git a/dom/canvas/WebGLCommandQueue.h b/dom/canvas/WebGLCommandQueue.h
new file mode 100644
index 0000000000..bbbb1034c1
--- /dev/null
+++ b/dom/canvas/WebGLCommandQueue.h
@@ -0,0 +1,267 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WEBGLCOMMANDQUEUE_H_
+#define WEBGLCOMMANDQUEUE_H_
+
+#include <type_traits>
+#include "mozilla/FunctionTypeTraits.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/ipc/IPDLParamTraits.h"
+#include "QueueParamTraits.h"
+#include "WebGLTypes.h"
+
+namespace mozilla {
+
+namespace webgl {
+
+class RangeConsumerView final : public webgl::ConsumerView<RangeConsumerView> {
+  RangedPtr<const uint8_t> mSrcItr;
+  const RangedPtr<const uint8_t> mSrcEnd;
+
+ public:
+  auto Remaining() const { return *MaybeAs<size_t>(mSrcEnd - mSrcItr); }
+
+  explicit RangeConsumerView(const Range<const uint8_t> range)
+      : ConsumerView(this), mSrcItr(range.begin()), mSrcEnd(range.end()) {
+    (void)Remaining();  // assert size non-negative
+  }
+
+  void AlignTo(const size_t alignment) {
+    const auto padToAlign = AlignmentOffset(alignment, mSrcItr.get());
+    if (MOZ_UNLIKELY(padToAlign > Remaining())) {
+      mSrcItr = mSrcEnd;
+      return;
+    }
+    mSrcItr += padToAlign;
+  }
+
+  template <typename T>
+  Maybe<Range<const T>> ReadRange(const size_t elemCount) {
+    constexpr auto alignment = alignof(T);
+    AlignTo(alignment);
+
+    constexpr auto elemSize = sizeof(T);
+    const auto byteSizeChecked = CheckedInt<size_t>(elemCount) * elemSize;
+    MOZ_RELEASE_ASSERT(byteSizeChecked.isValid());
+    const auto& byteSize = byteSizeChecked.value();
+
+    const auto remaining = Remaining();
+    if (MOZ_UNLIKELY(byteSize > remaining)) return {};
+
+    const auto begin = reinterpret_cast<const T*>(mSrcItr.get());
+    mSrcItr += byteSize;
+    return Some(Range<const T>{begin, elemCount});
+  }
+};
+
+// -
+
+namespace details {
+
+class SizeOnlyProducerView final
+    : public webgl::ProducerView<SizeOnlyProducerView> {
+  struct Info {
+    size_t requiredByteCount = 0;
+    size_t alignmentOverhead = 0;
+  };
+  Info mInfo;
+
+ public:
+  SizeOnlyProducerView() : ProducerView(this) {}
+
+  template <typename T>
+  bool WriteFromRange(const Range<const T>& src) {
+    constexpr auto alignment = alignof(T);
+    const size_t byteSize = ByteSize(src);
+    // printf_stderr("SizeOnlyProducerView: @%zu +%zu\n", alignment, byteSize);
+
+    const auto padToAlign = AlignmentOffset(alignment, mInfo.requiredByteCount);
+    mInfo.alignmentOverhead += padToAlign;
+
+    mInfo.requiredByteCount += padToAlign;
+    mInfo.requiredByteCount += byteSize;
+    return true;
+  }
+
+  const auto& Info() const { return mInfo; }
+};
+
+// -
+
+class RangeProducerView final : public webgl::ProducerView<RangeProducerView> {
+  const RangedPtr<uint8_t> mDestBegin;
+  const RangedPtr<uint8_t> mDestEnd;
+  RangedPtr<uint8_t> mDestItr;
+
+ public:
+  auto Remaining() const { return *MaybeAs<size_t>(mDestEnd - mDestItr); }
+
+  explicit RangeProducerView(const Range<uint8_t> range)
+      : ProducerView(this),
+        mDestBegin(range.begin()),
+        mDestEnd(range.end()),
+        mDestItr(mDestBegin) {
+    (void)Remaining();  // assert size non-negative
+  }
+
+  template <typename T>
+  bool WriteFromRange(const Range<const T>& src) {
+    // uint32_t/float data may masquerade as a Range<uint8_t>.
+    constexpr auto alignment = alignof(T);
+    const size_t byteSize = ByteSize(src);
+    // printf_stderr("RangeProducerView: @%zu +%zu\n", alignment, byteSize);
+
+    const auto padToAlign = AlignmentOffset(alignment, mDestItr.get());
+    mDestItr += padToAlign;
+
+    MOZ_ASSERT(byteSize <= Remaining());
+    if (MOZ_LIKELY(byteSize)) {
+      memcpy(mDestItr.get(), src.begin().get(), byteSize);
+    }
+    mDestItr += byteSize;
+    return true;
+  }
+};
+
+// -
+
+template <typename ProducerViewT>
+inline void Serialize(ProducerViewT&) {}
+
+template <typename ProducerViewT, typename Arg, typename... Args>
+inline void Serialize(ProducerViewT& view, const Arg& arg,
+                      const Args&... args) {
+  MOZ_ALWAYS_TRUE(view.WriteParam(arg));
+  Serialize(view, args...);
+}
+
+}  // namespace details
+
+// -
+
+template <typename... Args>
+auto SerializationInfo(const Args&... args) {
+  webgl::details::SizeOnlyProducerView sizeView;
+  webgl::details::Serialize(sizeView, args...);
+  return sizeView.Info();
+}
+
+template <typename... Args>
+void Serialize(Range<uint8_t> dest, const Args&... args) {
+  webgl::details::RangeProducerView view(dest);
+  webgl::details::Serialize(view, args...);
+}
+
+// -
+
+inline Maybe<uint16_t> Deserialize(RangeConsumerView&, size_t) { return {}; }
+
+template <typename Arg, typename... Args>
+inline Maybe<uint16_t> Deserialize(RangeConsumerView& view,
+                                   const uint16_t argId, Arg& arg,
+                                   Args&... args) {
+  if (!webgl::QueueParamTraits<Arg>::Read(view, &arg)) {
+    return Some(argId);
+  }
+  return Deserialize(view, argId + 1, args...);
+}
+
+}  // namespace webgl
+
+// The MethodDispatcher setup uses a CommandSink to read parameters, call the
+// given method using the given synchronization protocol, and provide
+// compile-time lookup of the ID by class method.
+// To use this system, first define a dispatcher subclass of
+// EmptyMethodDispatcher.  This class must be parameterized by command ID.
+//
+// Example:
+// template <size_t id=0> class MyDispatcher
+//    : public EmptyMethodDispatcher<MyDispatcher> {};
+//
+// Then, for each command handled, specialize this to subclass MethodDispatcher.
+// The subclass must define the Method.  It may optionally define isSync for
+// synchronous methods.
+//
+// Example:
+// template <>
+// class MyDispatcher<0>
+//    : public MethodDispatcher<MyDispatcher, 0,
+//        decltype(&MyClass::MyMethod), MyClass::MyMethod> {};
+//
+// The method may then be called from the source and run on the sink.
+//
+// Example:
+// int result = Run<MyClass::MyMethod>(param1, std::move(param2));
+
+template <template <size_t> typename Derived>
+class EmptyMethodDispatcher {
+ public:
+  template <typename ObjectT>
+  static MOZ_ALWAYS_INLINE bool DispatchCommand(ObjectT&, const size_t id,
+                                                webgl::RangeConsumerView&) {
+    const nsPrintfCString cstr(
+        "MethodDispatcher<%i> not found. Please file a bug!", int(id));
+    const auto str = ToString(cstr);
+    gfxCriticalError() << str;
+    return false;
+  }
+};
+
+// -
+
+template <typename ReturnT, typename ObjectT, typename... Args>
+std::tuple<std::remove_cv_t<std::remove_reference_t<Args>>...> ArgsTuple(
+    ReturnT (ObjectT::*)(Args... args)) {
+  return std::tuple<std::remove_cv_t<std::remove_reference_t<Args>>...>{};
+}
+
+template <typename ReturnT, typename ObjectT, typename... Args>
+std::tuple<std::remove_cv_t<std::remove_reference_t<Args>>...> ArgsTuple(
+    ReturnT (ObjectT::*)(Args... args) const) {
+  return std::tuple<std::remove_cv_t<std::remove_reference_t<Args>>...>{};
+}
+
+// Derived type must be parameterized by the ID.
+template <template <size_t> typename Derived, size_t ID, typename MethodType,
+          MethodType method>
+class MethodDispatcher {
+  static constexpr size_t kId = ID;
+  using DerivedType = Derived<ID>;
+  using NextDispatcher = Derived<ID + 1>;
+
+ public:
+  template <typename ObjectT>
+  static MOZ_ALWAYS_INLINE bool DispatchCommand(
+      ObjectT& obj, const size_t id, webgl::RangeConsumerView& view) {
+    if (id == kId) {
+      auto argsTuple = ArgsTuple(method);
+
+      const auto viewWas = view;
+      (void)viewWas;  // For debugging.
+      return std::apply(
+          [&](auto&... args) {
+            const auto badArgId = webgl::Deserialize(view, 1, args...);
+            if (badArgId) {
+              const auto& name = DerivedType::Name();
+              gfxCriticalError() << "webgl::Deserialize failed for " << name
+                                 << " arg " << *badArgId;
+              return false;
+            }
+            (obj.*method)(args...);
+            return true;
+          },
+          argsTuple);
+    }
+    return Derived<kId + 1>::DispatchCommand(obj, id, view);
+  }
+
+  static constexpr size_t Id() { return kId; }
+  static constexpr MethodType Method() { return method; }
+};
+
+}  // namespace mozilla
+
+#endif  // WEBGLCOMMANDQUEUE_H_