Virtqueue 基类（C++23 Deducing this 编译期多态） More...

#include <virtqueue_base.hpp>

Inheritance diagram for virtio::VirtqueueBase:

Collaboration diagram for virtio::VirtqueueBase:

Public Member Functions
auto	SubmitChainWithBarrier (this auto &&self, const IoVec readable, size_t readable_count, const IoVec writable, size_t writable_count) -> Expected< uint16_t >
	提交 Scatter-Gather 链并通知设备

template<typename Callback >
auto	ProcessUsedWithCallback (this auto &&self, Callback &&callback) -> uint32_t
	处理已完成的缓冲区并释放描述符链

Protected Member Functions
构造/析构函数（仅允许派生类使用）
	VirtqueueBase ()=default

	~VirtqueueBase ()=default

	VirtqueueBase (VirtqueueBase &&) noexcept=default

auto	operator= (VirtqueueBase &&) noexcept -> VirtqueueBase &=default

	VirtqueueBase (const VirtqueueBase &)=delete

auto	operator= (const VirtqueueBase &) -> VirtqueueBase &=delete

Detailed Description

Virtqueue 基类（C++23 Deducing this 编译期多态）

提供 Split/Packed Virtqueue 共享的通用逻辑接口。利用 C++23 Deducing this（显式对象参数）在编译期静态分发到派生类的具体实现，零虚表开销，无需传统 CRTP 的 static_cast。

派生类应提供以下方法（隐式接口）：

IsValid() const -> bool
Size() const -> uint16_t
NumFree() const -> uint16_t
AllocDesc() -> Expected<uint16_t>
FreeDesc(uint16_t) -> Expected<void>
Submit(uint16_t head) -> void
HasUsed() const -> bool
PopUsed() -> Expected<UsedElem>
SubmitChain(const IoVec*, size_t, const IoVec*, size_t) -> Expected<uint16_t>
FreeChain(uint16_t head) -> Expected<void>
DescPhys() const -> uint64_t
AvailPhys() const -> uint64_t
UsedPhys() const -> uint64_t

See also: cpu_io::Wmb/Rmb for barrier semantics; virtio-v1.2#2.7 / #2.8

Definition at line 42 of file virtqueue_base.hpp.

Constructor & Destructor Documentation

◆ VirtqueueBase() [1/3]

virtio::VirtqueueBase::VirtqueueBase ( )

protecteddefault

◆ ~VirtqueueBase()

virtio::VirtqueueBase::~VirtqueueBase ( )

protecteddefault

◆ VirtqueueBase() [2/3]

virtio::VirtqueueBase::VirtqueueBase ( VirtqueueBase && )

protecteddefaultnoexcept

◆ VirtqueueBase() [3/3]

virtio::VirtqueueBase::VirtqueueBase ( const VirtqueueBase & )

protecteddelete

Member Function Documentation

◆ operator=() [1/2]

auto virtio::VirtqueueBase::operator= ( const VirtqueueBase & ) -> VirtqueueBase &=delete

protecteddelete

◆ operator=() [2/2]

auto virtio::VirtqueueBase::operator= ( VirtqueueBase && ) -> VirtqueueBase &=default

protecteddefaultnoexcept

◆ ProcessUsedWithCallback()

template<typename Callback >

auto virtio::VirtqueueBase::ProcessUsedWithCallback	(	this auto &&	self,
		Callback &&	callback
	)		-> uint32_t

inline

处理已完成的缓冲区并释放描述符链

通用逻辑：从 Used Ring 弹出已完成的元素，对每个元素调用回调函数，然后释放描述符链。通过 Deducing this 在编译期分发到派生类的 HasUsed/PopUsed/FreeChain。

Template Parameters

Callback 回调函数类型，签名：void(uint16_t head, uint32_t len)

Parameters

callback 对每个已完成请求的回调

Returns: 处理的已完成请求数量

See also: virtio-v1.2#2.7.14 Receiving Used Buffers From The Device

Definition at line 85 of file virtqueue_base.hpp.

                  {
    // 读屏障：确保读取到设备最新的 Used Ring 写入
    cpu_io::Rmb();
 
    uint32_t processed = 0;
    while (self.HasUsed()) {
      auto result = self.PopUsed();
      if (!result.has_value()) {
        break;
      }
 
      auto elem = *result;
      auto head = static_cast<uint16_t>(elem.id);
      callback(head, elem.len);
      (void)self.FreeChain(head);
      ++processed;
    }
    return processed;
  }

Here is the call graph for this function:

◆ SubmitChainWithBarrier()

auto virtio::VirtqueueBase::SubmitChainWithBarrier	(	this auto &&	self,
		const IoVec *	readable,
		size_t	readable_count,
		const IoVec *	writable,
		size_t	writable_count
	)		-> Expected<uint16_t>