public void CreateUser(UserCreationSpec userToCreate)
{
if (userToCreate == null)
{
throw new ArgumentNullException(nameof(userToCreate));
}
userToCreate.Validate();
/*
* Typical usage of SessionScope for a read-write business transaction.
* It's as simple as it looks.
*/
using (var sessionScope = _sessionScopeFactory.Create())
{
//-- Build domain model
var user = new User()
{
Id = userToCreate.Id,
Name = userToCreate.Name,
Email = userToCreate.Email,
WelcomeEmailSent = false,
CreatedOn = DateTime.UtcNow
};
//-- Persist
_userRepository.Add(user);
sessionScope.SaveChanges();
}
}
public void UpdateCreditScoreForAllUsers()
{
/*
* Demo of SessionScope + parallel programming.
*/
using (var sessionScope = _sessionScopeFactory.Create())
{
//-- Get all users
var session = sessionScope.Session;
var userIds = session.CreateCriteria <User>().List <User>().Select(u => u.Id).ToList();
Console.WriteLine("Found {0} users in the database. Will calculate and store their credit scores in parallel.", userIds.Count);
//-- Calculate and store the credit score of each user
// We're going to imagine that calculating a credit score of a user takes some time.
// So we'll do it in parallel.
// You MUST call SuppressAmbientScope() when kicking off a parallel execution flow
// within a SessionScope. Otherwise, this SessionScope will remain the ambient scope
// in the parallel flows of execution, potentially leading to multiple threads
// accessing the same ISession instance.
using (_sessionScopeFactory.SuppressAmbientScope())
{
Parallel.ForEach(userIds, UpdateCreditScore);
}
// Note: SaveChanges() isn't going to do anything in this instance since all the changes
// were actually made and saved in separate DbScopes created in separate threads.
sessionScope.SaveChanges();
}
}
public void Intercept(IInvocation invocation)
{
var sessionScopeAttribute = invocation.MethodInvocationTarget
.GetCustomAttributes(typeof(SessionScopeAttribute), true)
.FirstOrDefault() as SessionScopeAttribute;
if (sessionScopeAttribute != null)
{
var returnType = invocation.MethodInvocationTarget.ReturnType;
if (returnType == typeof(Task) ||
returnType.IsGenericType && returnType.GetGenericTypeDefinition() == typeof(Task <>))
{
var ctArgument = invocation.Arguments.FirstOrDefault(a => a is CancellationToken);
var cancellationToken = (CancellationToken?)ctArgument ?? CancellationToken.None;
var scope = _scopeFactory
.Create(sessionScopeAttribute.ReadOnly, sessionScopeAttribute.Option,
sessionScopeAttribute.IsolationLevel);
invocation.Proceed();
invocation.ReturnValue = InterceptAsync((dynamic)invocation.ReturnValue, scope, cancellationToken);
}
else
{
using (var scope = _scopeFactory
.Create(sessionScopeAttribute.ReadOnly, sessionScopeAttribute.Option,
sessionScopeAttribute.IsolationLevel))
{
invocation.Proceed();
scope.SaveChanges();
}
}
}
else
{
invocation.Proceed();
}
}
