[Cpp API Compatibility] Align event api

[youge325]

PR Category

Execute Infrastructure

PR Types

Improvements

Description

拆分自 #78484

Align Event related APIs，将 c10::Event 实现为完整的跨平台兼容类。

变更详情

问题背景

历史上 c10::Event 存在以下问题：

1. 被 #ifdef PADDLE_WITH_CUDA 包裹，非 CUDA 构建时不可用
2. 缺少 EventFlag 枚举和对应构造函数
3. 缺少移动语义和属性读取接口
4. CPU 路径异常行为不一致

变更内容 (c10/core/Event.h)

重构 c10::Event 为完整的跨平台兼容类：

// EventFlag 枚举
enum class EventFlag { PYTORCH_DEFAULT, BACKEND_DEFAULT, INVALID };

// 完整构造函数
Event(const DeviceType device_type,
      const EventFlag flag = EventFlag::PYTORCH_DEFAULT);

// 禁止拷贝、允许移动
Event(const Event&) = delete;
Event& operator=(const Event&) = delete;
Event(Event&&) = default;
Event& operator=(Event&&) = default;

// 属性读取
Device device() const noexcept;
DeviceType device_type() const noexcept;
DeviceIndex device_index() const noexcept;
EventFlag flag() const noexcept;
bool was_marked_for_recording() const noexcept;

// 记录方法
void record(const Stream& stream);
void recordOnce(const Stream& stream);

// 同步/查询
void block(const Stream& stream) const;
bool query() const;
void synchronize() const;
double elapsedTime(const Event& event) const;
void* eventId() const;

跨平台支持

• 将 c10::Event 移出 #ifdef PADDLE_WITH_CUDA 条件编译
• CUDA 构建时包含完整的 CUDA event 功能
• 非 CUDA 构建时提供占位实现，抛出 Backend doesn't support events 异常

对齐效果

测试项	当前 Paddle	PyTorch	结论
EventCompatTest.EventDefault / EventWithFlag / EventRecordThrows / EventRecordOnceThrows / EventMove / EventDevice	已进入常规回归	一致	✅ 已纳入回归

相关文档

• PaddleCppAPITest cAlign 分支 Event 差异

是否引起精度变化

否

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[Copilot]

Pull request overview

This PR updates the C++ compat layer to better match PyTorch’s stream/event APIs, including stream-pool signature parity and a more feature-complete c10::Event surface.

Changes:

• Update c10::cuda::getStreamFromPool to support the (int priority, DeviceIndex) overload and map negative priorities to the high-priority pool.
• Expand c10::Event to track device metadata, add PyTorch-like methods (e.g., recordOnce, query, eventId, synchronize), and tighten stream/device-type checks.
• Remove deprecated/raw stream record_stream overloads and legacy raw_stream() exposure.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
paddle/phi/api/include/compat/c10/cuda/CUDAStream.h	Adds PyTorch-shaped getStreamFromPool(int priority, ...) and updates priority selection logic.
paddle/phi/api/include/compat/c10/core/Stream.h	Exposes c10::Stream into namespace at for API compatibility.
paddle/phi/api/include/compat/c10/core/Event.h	Refactors/extends c10::Event interface and behavior to resemble PyTorch.
paddle/phi/api/include/compat/ATen/ops/record_stream.h	Removes deprecated record_stream overloads (CUDAStream / cudaStream_t) in favor of at::Stream.
paddle/phi/api/include/compat/ATen/core/TensorBody.h	Removes the corresponding record_stream overload declarations.

---

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[Copilot]

This header uses std::mutex/std::unique_lock in EventPool, but doesn't include <mutex> directly (it currently relies on transitive includes from other headers). Adding an explicit #include <mutex> under the PADDLE_WITH_CUDA guard would make this file self-contained and less fragile to include-order changes.

Suggested change

	#include <c10/cuda/CUDAStream.h>
	#include <c10/cuda/CUDAStream.h>
	#include <mutex>

[Copilot]

Now that the record_stream(at::cuda::CUDAStream) overload was removed, the forward-declaration block for at::cuda::CUDAStream near the top of this file (and its comment) appears unused and misleading (the file no longer declares any overload needing it). Consider removing that forward declaration/comment to avoid stale documentation and unnecessary namespace pollution.

[youge325]

/re-run all-failed

[codecov-commenter]

Codecov Report

❌ Patch coverage is 89.28571% with 9 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@638c7c3). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
paddle/phi/api/include/compat/c10/core/Event.h	89.28%	9 Missing ⚠️

❌ Your patch status has failed because the patch coverage (89.28%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop   #78553   +/-   ##
==========================================
  Coverage           ?   89.28%           
==========================================
  Files              ?        1           
  Lines              ?       84           
  Branches           ?        0           
==========================================
  Hits               ?       75           
  Misses             ?        9           
  Partials           ?        0           

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[SigureMo]

/skip-reason: 未覆盖分支均为正常逻辑不可达分支，为确保与 PyTorch 逻辑对齐而添加的完善逻辑

[SigureMo]

LGTMeow