/// <summary>
/// This method asynchronously loads an instance of <see cref="AsyncResourceFactory{TResource}"/> using this <see cref="ResourceFactoryDynamicCreationConfiguration"/> along with required callbacks.
/// </summary>
/// <typeparam name="TResource">The type of resource that returned <see cref="AsyncResourceFactory{TResource}"/> provides.</typeparam>
/// <param name="configuration">This <see cref="ResourceFactoryDynamicCreationConfiguration"/>.</param>
/// <param name="assemblyLoader">The callback to asynchronously load assembly. The parameters are, in this order: package ID, package version, and path within the package.</param>
/// <param name="creationParametersProvider">The callback to create creation parameters to bind the returned <see cref="AsyncResourceFactory{TResource}"/> to.</param>
/// <param name="token">The <see cref="CancellationToken"/> for this asynchronous operation.</param>
/// <returns>Asynchronously returns instance of <see cref="AsyncResourceFactory{TResource}"/>, or throws an exception.</returns>
/// <exception cref="NullReferenceException">If this <see cref="ResourceFactoryDynamicCreationConfiguration"/> is <c>null.</c></exception>
/// <exception cref="InvalidOperationException">If for some reason the <see cref="AsyncResourceFactory{TResource}"/> could not be loaded.</exception>
/// <seealso cref="AcquireResourcePoolProvider"/>
public static async Task <AsyncResourceFactory <TResource> > CreateAsyncResourceFactory <TResource>(
this ResourceFactoryDynamicCreationConfiguration configuration,
Func <String, String, String, CancellationToken, Task <Assembly> > assemblyLoader,
Func <AsyncResourceFactoryProvider, Object> creationParametersProvider,
CancellationToken token
)
{
var factory = await ArgumentValidator.ValidateNotNullReference(configuration).AcquireResourcePoolProvider(assemblyLoader, token);
var value = factory.GetFirstOrDefault();
return((value ?? throw new InvalidOperationException(factory.GetSecondOrDefault() ?? "Unspecified error."))
.BindCreationParameters <TResource>(creationParametersProvider(value)));
}
/// <summary>
/// This method asynchornously loads an instance of <see cref="AsyncResourceFactoryProvider"/> using this <see cref="ResourceFactoryDynamicCreationConfiguration"/> along with assembly loader callback.
/// </summary>
/// <param name="configuration">This <see cref="ResourceFactoryDynamicCreationConfiguration"/>.</param>
/// <param name="assemblyLoader">The callback to asynchronously load assembly. The parameters are, in this order: package ID, package version, and path within the package.</param>
/// <param name="token">The <see cref="CancellationToken"/> for this asynchronous operation.</param>
/// <returns>Asynchronously returns a value which either has <see cref="AsyncResourceFactoryProvider"/> or an error message.</returns>
/// <exception cref="NullReferenceException">If this <see cref="ResourceFactoryDynamicCreationConfiguration"/> is <c>null</c>.</exception>
public static async Task <EitherOr <AsyncResourceFactoryProvider, String> > AcquireResourcePoolProvider(
this ResourceFactoryDynamicCreationConfiguration configuration,
Func <String, String, String, CancellationToken, Task <Assembly> > assemblyLoader,
CancellationToken token
)
{
AsyncResourceFactoryProvider retVal = null;
String errorMessage = null;
if (configuration != null)
{
if (assemblyLoader != null)
{
var packageID = configuration.PoolProviderPackageID;
if (!String.IsNullOrEmpty(packageID))
{
try
{
var assembly = await assemblyLoader(
packageID, // package ID
configuration.PoolProviderVersion, // optional package version
configuration.PoolProviderAssemblyPath, // optional assembly path within package
token
);
if (assembly != null)
{
// Now search for the type
var typeName = configuration.PoolProviderTypeName;
var parentType = typeof(AsyncResourceFactoryProvider).GetTypeInfo();
var checkParentType = !String.IsNullOrEmpty(typeName);
Type providerType;
if (checkParentType)
{
// Instantiate directly
providerType = assembly.GetType(typeName); //, false, false );
}
else
{
// Search for first available
providerType = assembly.
#if NET40
GetTypes()
#else
DefinedTypes
#endif
.FirstOrDefault(t => !t.IsInterface && !t.IsAbstract && t.IsPublic && parentType.IsAssignableFromIgnoreAssemblyVersion(t))
#if !NET40
?.AsType()
#endif
;
}
if (providerType != null)
{
if (!checkParentType || parentType.IsAssignableFromIgnoreAssemblyVersion(providerType.GetTypeInfo()))
{
// All checks passed, instantiate the pool provider
retVal = (AsyncResourceFactoryProvider)Activator.CreateInstance(providerType);
}
else
{
errorMessage = $"The type \"{providerType.FullName}\" in \"{assembly}\" does not have required parent type \"{parentType.FullName}\".";
}
}
else
{
errorMessage = $"Failed to find type within assembly in \"{assembly}\", try specify \"{nameof( configuration.PoolProviderTypeName )}\" configuration parameter.";
}
}
else
{
errorMessage = $"Failed to load resource pool provider package \"{packageID}\".";
}
}
catch (Exception exc)
{
errorMessage = $"An exception occurred when acquiring resource pool provider: {exc.Message}";
}
}
else
{
errorMessage = $"No NuGet package ID were provided as \"{nameof( configuration.PoolProviderPackageID )}\" configuration parameter. The package ID should be of the package holding implementation for \"{nameof( AsyncResourceFactoryProvider )}\" type.";
}
}
else
{
errorMessage = "Task must be provided callback to load NuGet packages (just make constructor taking it as argument and use UtilPack.NuGet.MSBuild task factory).";
}
}
else
{
errorMessage = "Configuration was not provided.";
}
return(retVal == null ?
new EitherOr <AsyncResourceFactoryProvider, String>(errorMessage) :
new EitherOr <AsyncResourceFactoryProvider, String>(retVal));
}
