调用本机代码的通信 (messaging) 和 错误处理 (error handling) 。 什么是 waPC? WASM 外部函数 接口 FFI Input type Return type Platform 底层 I32 I32 Unknown waPC &[u8] Result,error > Linux x86_64, macOS x86_64 可执行任务 • Guest 也可返回请求 host Invoke(ctx,operation,payload) WAPC 流程 • Uses Length of response and error to return result res,err:= Invoke… WAPC 流程 #[no_mangle] pub fn wapc_init() { wapc::register_function("ping" HttpPath){ } req.HttpProxyUrl = String::from(“localhost:8000"); req.HttpScheme = String::from("http"); let request = serde_json::to_string(&req)?; Ok(request.as_bytes().to_vec()) } fn do_nothing(msg:

sender … transforms the result value of the operation with a function. upon_[error|done](sender, fn) → sender … transforms the error and done signals with a function. let_[value|…](sender, fn) → sender … passes er) → sender … commutes the done signal into a nullopt. done_as_error(sender, error) → sender … commutes the done signal into an error.19 SENDER/RECEIVER CONTROL FLOW20 BASIC LIFETIME OF AN ASYNC then. then(sender, fn) -> sender22 SHAPE OF A RECEIVER RECEIVER set_value(values... ) set_error(error ) set_done() Operation state notifies receiver by calling one of these exactly once.23

help with compiler error messages  Easier to read template error messages: e.g.: void Foo(Incrementable auto t) { ... } class Bar {}; int main() { Bar b; Foo(b); } Error: cannot call Foo() pointer  Use global non-member atomic operations, e.g. std::atomic_load(), atomic_store(), …  Error-prone, easy to accidently not use global non-member atomic operations  C++20: atomic> ints span b {data}; // dynamic-size: 42 ints span c {data}; // compilation error span d { ptr, len }; // dynamic-size: len ints  Read-only span:  span, not const

std::expected contains either  A value of type T, the expected value type  A value of type E, an error type  Guaranteed to never be empty  std::unexpected() is used to create an unexpected value90 std::expected a { 21 }; std::expected b { std::unexpected("Some error"s) };  Member functions:  has_value(): true if the expected contains a value, false otherwise reference to the contained value, or throws bad_expected_access if no value  error(): returns reference to the error91 Agenda  C++23 Core Language  Explicit Object Parameters  if consteval 

all compile-time constants: intmax_t n { 1 }; intmax_t d { 60 }; using r1 = ratio; // Error7 Compile-Time Rational Numbers  Arithmetic with ratio_add, ratio_subtract, ratio_multiply, and d8.count()); // 30sec = 0.5min duration> d8 { d7 }; // minutes // Error! // Force conversion (0 instead of 0.5) auto d8 { duration_cast>>(d7) }; Literals  Warning: predefined durations use integral types, so: seconds s { 90 }; minutes m { s }; // Error duration> m { s }; // 1.519 Agenda  Compile-Time Rational Numbers  Durations

表示是仅仅给项目作者看的警 告信息 AUTHOR_WARNING 的不同之处：可以通过 -Wno-dev 关闭 message(FATAL_ERROR “...”) 表示是错误信息，会终止 CMake 的 运行 message(SEND_ERROR “...”) 表示是错误信息，但之后的语句仍继续 执行 message 可以用于打印变量 如果 set 没加引号会怎样？会变成分号分割的列表

ICE, Infra tools, code refactor, algorithms improvements Some PR stories • Rust cares about error messages • We are building a sufficiently empathetic compiler • It’s a trade-off Diagnostic

u32 from_size, __be32 * to, u32 to_size); pass skb->len to bpf_csum_diff() the verifier reports error Future work • Open source • The modification to IPVS is already open source • https://github.

function to IOS/Android? - Hard to maintain - Hard to define the return value - Hard to process the error? Panic? App Crash ？ Treat the rust module as an independent service - Command <> Response - Using

whose specification has to be givenProgram verification • Program verification does not mean error-proof programs • There is no magic here either, mathematical proofs can be faulty • Even perfect