Cancel

Service is cancelled when it is disposed, or when any of the attached cancel tokens signals close.

.AddCancellationToken(CancellationToken) adds a cancel token to service.

try
{
    // Create token source
    CancellationTokenSource cancellationTokenSource = new();
    // Service collection
    IServiceCollection serviceCollection = new ServiceCollection()
        .AddHandlers<ServiceHandlers>()
        .AddCancellationToken(cancellationTokenSource.Token);
    // Create avalanche service
    using var service = serviceCollection.BuildAvalancheServiceProvider();
    // Cancel service
    cancellationTokenSource.Cancel();
    //
    IRequestFor<Type> typeRequest = new TypeRequest("System.String");
    // 
    Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
} catch (OperationCanceledException oce)
{
    Console.WriteLine(oce.Message);
}

.AddCancellationTokenSource(CancellationTokenSource) adds the token of a specific cancel token source to service.

IServiceCollection serviceCollection = new ServiceCollection()
    .AddHandlers<ServiceHandlers>()
    .AddCancellationTokenSource(cancellationTokenSource);

CancellationTokenSource can be added as ServiceDescriptor to be constructed with service.

IServiceCollection serviceCollection = new ServiceCollection()
    .AddSingleton<CancellationTokenSource>();

This source can be acquired from IServiceProvider.

// Get cancellation token source
CancellationTokenSource cancellationTokenSource = service.GetRequiredService<CancellationTokenSource>();
// Cancel service
cancellationTokenSource.Cancel();

And cancel will result queries to fail, though cached results will be returned.

try
{
    // Service collection
    IServiceCollection serviceCollection = new ServiceCollection()
        .AddHandlers<ServiceHandlers>()
        .AddSingleton<CancellationTokenSource>();
    // Create avalanche DI service
    using var service = serviceCollection.BuildAvalancheServiceProvider();
    // Get cancellation token source
    CancellationTokenSource cancellationTokenSource = service.GetRequiredService<CancellationTokenSource>();
    // Cancel service
    cancellationTokenSource.Cancel();
    //
    IRequestFor<Type> typeRequest = new TypeRequest("System.String");
    // 
    Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
} catch (OperationCanceledException oce)
{
    Console.WriteLine(oce.Message);
}

Full Example

Full example

using System;
using System.Collections.Generic;
using System.Threading;
using Avalanche.Accessor;
using Avalanche.Accessor.List;
using Avalanche.Emit;
using Avalanche.Service;
using Avalanche.Utilities;
using Microsoft.Extensions.DependencyInjection;
using static System.Console;

class di_cancel
{
    public static void Run()
    {
        {
            // <01>
            try
            {
                // Create token source
                CancellationTokenSource cancellationTokenSource = new();
                // Service collection
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddHandlers<ServiceHandlers>()
                    .AddCancellationToken(cancellationTokenSource.Token);
                // Create avalanche service
                using var service = serviceCollection.BuildAvalancheServiceProvider();
                // Cancel service
                cancellationTokenSource.Cancel();
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
            // </01>
        }
        {
            try
            {
                // Create token source
                CancellationTokenSource cancellationTokenSource = new();
                // Service collection
                // <02>
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddHandlers<ServiceHandlers>()
                    .AddCancellationTokenSource(cancellationTokenSource);
                // </02>
                // Create avalanche service
                using var service = serviceCollection.BuildAvalancheServiceProvider();
                // Cancel service
                cancellationTokenSource.Cancel();
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
        }

        {
            // <03>
            try
            {
                // Service collection
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddAvalancheService()
                    .AddHandlers<ServiceHandlers>()
                    .AddSingleton<CancellationTokenSource>();
                // Create microsoft DI service
                using var msService = serviceCollection.BuildServiceProvider();
                // Create avalanche service
                var avService = msService.GetRequiredService<IService>();
                // Get cancellation token source
                CancellationTokenSource cancellationTokenSource = msService.GetRequiredService<CancellationTokenSource>();
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type2 = avService.GetRequired<IRequestFor<Type>, Type>(typeRequest);
                // Cancel service
                cancellationTokenSource.Cancel();
                // 
                Type type = avService.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
            // </03>
        }
        {
            try
            {
                // Service collection
                // <04>
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddSingleton<CancellationTokenSource>();
                // </04>
                serviceCollection.AddHandlers<ServiceHandlers>();
                // Create avalanche DI service
                using var service = serviceCollection.BuildAvalancheServiceProvider();
                // Get cancellation token source
                CancellationTokenSource cancellationTokenSource = service.GetRequiredService<CancellationTokenSource>();
                // Cancel service
                cancellationTokenSource.Cancel();
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
        }

        {
            try
            {
                // Service collection
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddHandlers<ServiceHandlers>()
                    .AddSingleton<CancellationTokenSource>();
                // Create avalanche DI service
                using var service = serviceCollection.BuildAvalancheServiceProvider();
                // <05>
                // Get cancellation token source
                CancellationTokenSource cancellationTokenSource = service.GetRequiredService<CancellationTokenSource>();
                // Cancel service
                cancellationTokenSource.Cancel();
                // </05>
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
        }
        {
            // <06>
            try
            {
                // Service collection
                IServiceCollection serviceCollection = new ServiceCollection()
                    .AddHandlers<ServiceHandlers>()
                    .AddSingleton<CancellationTokenSource>();
                // Create avalanche DI service
                using var service = serviceCollection.BuildAvalancheServiceProvider();
                // Get cancellation token source
                CancellationTokenSource cancellationTokenSource = service.GetRequiredService<CancellationTokenSource>();
                // Cancel service
                cancellationTokenSource.Cancel();
                //
                IRequestFor<Type> typeRequest = new TypeRequest("System.String");
                // 
                Type type = service.GetRequired<IRequestFor<Type>, Type>(typeRequest);
            } catch (OperationCanceledException oce)
            {
                Console.WriteLine(oce.Message);
            }
            // </06>
        }
    }
}