Merge branch 'goplus:main' into main

x/io/README.md

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+# Async I/O Design
+
+## Async functions in different languages
+
+### JavaScript
+
+- [Async/Await](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function)
+
+Prototype:
+
+```javascript
+async function name(param0) {
+  statements;
+}
+async function name(param0, param1) {
+  statements;
+}
+async function name(param0, param1, /* …, */ paramN) {
+  statements;
+}
+```
+
+Example:
+
+```typescript
+async function resolveAfter1Second(): Promise<string> {
+  return new Promise((resolve) => {
+    setTimeout(() => {
+      resolve("Resolved after 1 second");
+    }, 1000);
+  });
+}
+
+async function asyncCall(): Promise<string> {
+  const result = await resolveAfter1Second();
+  return `AsyncCall: ${result}`;
+}
+
+async function asyncCall2(): Promise<string> {
+  const result = await resolveAfter1Second();
+  return `AsyncCall2: ${result}`;
+}
+
+function asyncCall3(): void {
+  resolveAfter1Second().then((result) => {
+    console.log(`AsyncCall3: ${result}`);
+  });
+}
+
+async function main() {
+  console.log("Starting AsyncCall");
+  const result1 = await asyncCall();
+  console.log(result1);
+
+  console.log("Starting AsyncCall2");
+  const result2 = await asyncCall2();
+  console.log(result2);
+
+  console.log("Starting AsyncCall3");
+  asyncCall3();
+
+  // Wait for AsyncCall3 to complete
+  await new Promise((resolve) => setTimeout(resolve, 1000));
+
+  console.log("Main function completed");
+}
+
+main().catch(console.error);
+```
+
+### Python
+
+- [async def](https://docs.python.org/3/library/asyncio-task.html#coroutines)
+
+Prototype:
+
+```python
+async def name(param0):
+  statements
+```
+
+Example:
+
+```python
+import asyncio
+
+async def resolve_after_1_second() -> str:
+    await asyncio.sleep(1)
+    return "Resolved after 1 second"
+
+async def async_call() -> str:
+    result = await resolve_after_1_second()
+    return f"AsyncCall: {result}"
+
+async def async_call2() -> str:
+    result = await resolve_after_1_second()
+    return f"AsyncCall2: {result}"
+
+def async_call3() -> None:
+    asyncio.create_task(print_after_1_second())
+
+async def print_after_1_second() -> None:
+    result = await resolve_after_1_second()
+    print(f"AsyncCall3: {result}")
+
+async def main():
+    print("Starting AsyncCall")
+    result1 = await async_call()
+    print(result1)
+
+    print("Starting AsyncCall2")
+    result2 = await async_call2()
+    print(result2)
+
+    print("Starting AsyncCall3")
+    async_call3()
+
+    # Wait for AsyncCall3 to complete
+    await asyncio.sleep(1)
+
+    print("Main function completed")
+
+# Run the main coroutine
+asyncio.run(main())
+```
+
+### Rust
+
+- [async fn](https://doc.rust-lang.org/std/keyword.async.html)
+
+Prototype:
+
+```rust
+async fn name(param0: Type) -> ReturnType {
+  statements
+}
+```
+
+Example:
+
+```rust
+use tokio::time::{sleep, Duration};
+
+async fn resolve_after_1_second() -> String {
+    sleep(Duration::from_secs(1)).await;
+    "Resolved after 1 second".to_string()
+}
+
+async fn async_call() -> String {
+    let result = resolve_after_1_second().await;
+    format!("AsyncCall: {}", result)
+}
+
+async fn async_call2() -> String {
+    let result = resolve_after_1_second().await;
+    format!("AsyncCall2: {}", result)
+}
+
+fn async_call3() {
+    tokio::spawn(async {
+        let result = resolve_after_1_second().await;
+        println!("AsyncCall3: {}", result);
+    });
+}
+
+#[tokio::main]
+async fn main() {
+    println!("Starting AsyncCall");
+    let result1 = async_call().await;
+    println!("{}", result1);
+
+    println!("Starting AsyncCall2");
+    let result2 = async_call2().await;
+    println!("{}", result2);
+
+    println!("Starting AsyncCall3");
+    async_call3();
+
+    // Wait for AsyncCall3 to complete
+    sleep(Duration::from_secs(1)).await;
+
+    println!("Main function completed");
+}
+```
+
+### C#
+
+- [async](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/)
+
+Prototype:
+
+```csharp
+async Task<ReturnType> NameAsync(Type param0)
+{
+  statements;
+}
+```
+
+Example:
+
+```csharp
+using System;
+using System.Threading.Tasks;
+
+class Program
+{
+    static async Task<string> ResolveAfter1Second()
+    {
+        await Task.Delay(1000);
+        return "Resolved after 1 second";
+    }
+
+    static async Task<string> AsyncCall()
+    {
+        string result = await ResolveAfter1Second();
+        return $"AsyncCall: {result}";
+    }
+
+    static async Task<string> AsyncCall2()
+    {
+        string result = await ResolveAfter1Second();
+        return $"AsyncCall2: {result}";
+    }
+
+    static void AsyncCall3()
+    {
+        _ = Task.Run(async () =>
+        {
+            string result = await ResolveAfter1Second();
+            Console.WriteLine($"AsyncCall3: {result}");
+        });
+    }
+
+    static async Task Main()
+    {
+        Console.WriteLine("Starting AsyncCall");
+        string result1 = await AsyncCall();
+        Console.WriteLine(result1);
+
+        Console.WriteLine("Starting AsyncCall2");
+        string result2 = await AsyncCall2();
+        Console.WriteLine(result2);
+
+        Console.WriteLine("Starting AsyncCall3");
+        AsyncCall3();
+
+        // Wait for AsyncCall3 to complete
+        await Task.Delay(1000);
+
+        Console.WriteLine("Main method completed");
+    }
+}
+```
+
+### C++ 20 Coroutines
+
+- [co_await](https://en.cppreference.com/w/cpp/language/coroutines)
+
+Prototype:
+
+```cpp
+TaskReturnType NameAsync(Type param0)
+{
+  co_return co_await expression;
+}
+```
+
+Example:
+
+```cpp
+#include <cppcoro/task.hpp>
+#include <cppcoro/sync_wait.hpp>
+#include <cppcoro/when_all.hpp>
+#include <chrono>
+#include <iostream>
+#include <thread>
+
+cppcoro::task<std::string> resolveAfter1Second() {
+    co_await std::chrono::seconds(1);
+    co_return "Resolved after 1 second";
+}
+
+cppcoro::task<std::string> asyncCall() {
+    auto result = co_await resolveAfter1Second();
+    co_return "AsyncCall: " + result;
+}
+
+cppcoro::task<std::string> asyncCall2() {
+    auto result = co_await resolveAfter1Second();
+    co_return "AsyncCall2: " + result;
+}
+
+cppcoro::task<void> asyncCall3() {
+    auto result = co_await resolveAfter1Second();
+    std::cout << "AsyncCall3: " << result << std::endl;
+}
+
+cppcoro::task<void> main() {
+    std::cout << "Starting AsyncCall" << std::endl;
+    auto result1 = co_await asyncCall();
+    std::cout << result1 << std::endl;
+
+    std::cout << "Starting AsyncCall2" << std::endl;
+    auto result2 = co_await asyncCall2();
+    std::cout << result2 << std::endl;
+
+    std::cout << "Starting AsyncCall3" << std::endl;
+    auto asyncCall3Task = asyncCall3();
+
+    // Wait for AsyncCall3 to complete
+    co_await asyncCall3Task;
+
+    std::cout << "Main function completed" << std::endl;
+}
+
+int main() {
+    try {
+        cppcoro::sync_wait(::main());
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << std::endl;
+        return 1;
+    }
+    return 0;
+}
+```