[译]. NET 6 新增API

Posted 2022-01-17 初久的私房菜

介绍

接下来我将给大家重点介绍一下.Net 6 之后的一些新的变更，文章都是来自于外国大佬的文章，我这边进行一个翻译，并加上一些自己的理解和解释。

源作者链接：https://blog.okyrylchuk.dev/20-new-apis-in-net-6#heading-a-new-periodictimer

正文

Metrics API

.NET6实现了OpenTelemetry Metrics API规范。“Meter”类创建仪器对象。仪器类别有：

• Counter
• Histogram
• ObservableCounter
• ObservableGauge

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

// Create Meter
var meter = new Meter("MetricsApp", "v1.0");
// Create counter
Counter<int> counter = meter.CreateCounter<int>("Requests");

app.Use((context, next) =>

    // Record the value of measurement
    counter.Add(1);
    return next(context);
);

app.MapGet("/", () => "Hello World");
StartMeterListener();
app.Run();

// Create and start Meter Listener
void StartMeterListener()

    var listener = new MeterListener();
    listener.InstrumentPublished = (instrument, meterListener) =>
    
        if (instrument.Name == "Requests" && instrument.Meter.Name == "MetricsApp")
        
            // Start listening to a specific measurement recording
            meterListener.EnableMeasurementEvents(instrument, null);
        
    ;

    listener.SetMeasurementEventCallback<int>((instrument, measurement, tags, state) =>
    
        Console.WriteLine($"Instrument instrument.Name has recorded the measurement: measurement");
    );

    listener.Start();

Reflection API for Nullability Information（可空性信息的反射 API）

它提供来自反射成员的可空性信息和上下文：

• ParameterInfo
• FieldInfo
• PropertyInfo
• EventInfo

var example = new Example();
var nullabilityInfoContext = new NullabilityInfoContext();
foreach (var propertyInfo in example.GetType().GetProperties())

    var nullabilityInfo = nullabilityInfoContext.Create(propertyInfo);
    Console.WriteLine($"propertyInfo.Name property is nullabilityInfo.WriteState");


// Output:
// Name property is Nullable
// Value property is NotNull

class Example

    public string? Name  get; set; 
    public string Value  get; set; 

嵌套可空性信息的反射 API

它允许您获取嵌套的可空性信息。您可以指定数组属性必须为非空，但元素可以为空，反之亦然。您可以获得数组元素的可空性信息。

Type exampleType = typeof(Example);
PropertyInfo notNullableArrayPI = exampleType.GetProperty(nameof(Example.NotNullableArray));
PropertyInfo nullableArrayPI = exampleType.GetProperty(nameof(Example.NullableArray));

NullabilityInfoContext nullabilityInfoContext = new();

NullabilityInfo notNullableArrayNI = nullabilityInfoContext.Create(notNullableArrayPI);
Console.WriteLine(notNullableArrayNI.ReadState);              // NotNull
Console.WriteLine(notNullableArrayNI.ElementType.ReadState);  // Nullable

NullabilityInfo nullableArrayNI = nullabilityInfoContext.Create(nullableArrayPI);
Console.WriteLine(nullableArrayNI.ReadState);                // Nullable
Console.WriteLine(nullableArrayNI.ElementType.ReadState);    // Nullable

class Example

    public string?[] NotNullableArray  get; set; 
    public string?[]? NullableArray  get; set; 

进程路径和 ID

您可以访问流程路径和 ID，而无需分配新的流程实例。

int processId = Environment.ProcessId
string path = Environment.ProcessPath;

Console.WriteLine(processId);
Console.WriteLine(path);

一个新的配置助手

.NET 6 中添加了一个新的配置帮助程序“GetRequiredSection”。如果缺少必需的配置部分，它将引发异常。

WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
WebApplication app = builder.Build();

MySettings mySettings = new();

// Throws InvalidOperationException if a required section of configuration is missing
app.Configuration.GetRequiredSection("MySettings").Bind(mySettings);
app.Run();

class MySettings

    public string? SettingValue  get; set; 

CSPNG

您可以从加密安全伪随机数生成器 (CSPNG) 轻松生成随机值序列。

它对加密应用程序很有用：

• 密钥生成
• 随机数
• 某些签名方案中的盐

// Fills an array of 300 bytes with a cryptographically strong random sequence of values.
// GetBytes(byte[] data);
// GetBytes(byte[] data, int offset, int count)
// GetBytes(int count)
// GetBytes(Span<byte> data)
byte[] bytes = RandomNumberGenerator.GetBytes(300);

本机内存 API

.NET 6 引入了一个新的 API 来分配本机内存。一种新的 NativeMemory 类型具有分配和释放内存的方法。

unsafe

    byte* buffer = (byte*)NativeMemory.Alloc(100);

    NativeMemory.Free(buffer);

    /* This class contains methods that are mainly used to manage native memory.
    public static class NativeMemory
    
        public unsafe static void* AlignedAlloc(nuint byteCount, nuint alignment);
        public unsafe static void AlignedFree(void* ptr);
        public unsafe static void* AlignedRealloc(void* ptr, nuint byteCount, nuint alignment);
        public unsafe static void* Alloc(nuint byteCount);
        public unsafe static void* Alloc(nuint elementCount, nuint elementSize);
        public unsafe static void* AllocZeroed(nuint byteCount);
        public unsafe static void* AllocZeroed(nuint elementCount, nuint elementSize);
        public unsafe static void Free(void* ptr);
        public unsafe static void* Realloc(void* ptr, nuint byteCount);
    */

结语

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