DependencyGraph

This package is used to execute processes that are dependent on the execution of at least one other process. The engine builds a directed graph of provided executions, checks for cycles, performs a reverse topological sort, and executes the results in order.

Install

Install the NuGet package into your project.

PM> Install-Package LanceC.DependencyGraph

$ dotnet add package LanceC.DependencyGraph

Usage

• The dependency graph classes must first be registered for DI.
• Processes to be executed need to implement IDependencyExecution<T>.
  • The identifier type has to implement IEquatable<T>.
  • It is recommended to register each execution in the DI container and retrieve them as an IEnumerable<IDependencyExecution<T>>.

Registration

services.AddDependencyGraph();

Execution

The sample below uses string as the identifier type for the executions.

public class Foo
{
    private readonly IDependencyExecutionEngine<string> _dependencyExecutionEngine;
    private readonly IEnumerable<IDependencyExecution<string>> _executions;

    public Foo(
        IDependencyExecutionEngine<string> dependencyExecutionEngine,
        IEnumerable<IDependencyExecution<string>> executions)
    {
        _dependencyExecutionEngine = dependencyExecutionEngine;
        _executions = executions;
    }

    public async Task Execute(CancellationToken cancellationToken)
    {
        await _dependencyExecutionEngine.ExecuteAll(executions, cancellationToken);
    }
}

Errors

• In the case where a circular dependency chain is found (e.g. A has a dependency on B and B has a dependency on A), a CircularDependenciesException is thrown upon engine execution.
  • The exception contains the text representations of the strongly-connected cycles (e.g. 'A' -> 'B').
• In the case where multiple executions contain the same key, a DuplicateKeyException is thrown upon engine execution.