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fredericDelaportefredericDelaporte
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NH-4031 - adding AsyncLocalSessionContext.
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‎doc/reference/modules/architecture.xml

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@@ -239,12 +239,21 @@
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</para>
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<itemizedlist>
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<listitem>
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<para>
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<literal>NHibernate.Context.AsyncLocalSessionContext</literal> - current sessions are tracked
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by current asynchronous flow. You are responsible to bind and unbind an
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<literal>ISession</literal> instance with static methods of class
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<literal>CurrentSessionContext</literal>. Binding operations from inner flows will not be
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propagated to outer or siblings flows.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>NHibernate.Context.CallSessionContext</literal> - current sessions are tracked
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by <literal>CallContext</literal>. You are responsible to bind and unbind an <literal>
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ISession</literal> instance with static methods of class <literal>CurrentSessionContext
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</literal>.
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by <literal>CallContext</literal>. You are responsible to bind and unbind an
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<literal>ISession</literal> instance with static methods of class
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<literal>CurrentSessionContext</literal>.
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</para>
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</listitem>
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<listitem>
@@ -257,26 +266,26 @@
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</listitem>
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<listitem>
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<para>
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<literal>NHibernate.Context.WebSessionContext</literal> -
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stores the current session in <literal>HttpContext</literal>.
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You are responsible to bind and unbind an <literal>ISession</literal>
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instance with static methods of class <literal>CurrentSessionContext</literal>.
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<literal>NHibernate.Context.WebSessionContext</literal> -
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stores the current session in <literal>HttpContext</literal>.
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You are responsible to bind and unbind an <literal>ISession</literal>
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instance with static methods of class <literal>CurrentSessionContext</literal>.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>NHibernate.Context.WcfOperationSessionContext</literal> - current sessions are tracked
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by WCF <literal>OperationContext</literal>. You need to register the <literal>WcfStateExtension</literal>
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extension in WCF. You are responsible to bind and unbind an <literal>ISession
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</literal> instance with static methods of class <literal>CurrentSessionContext</literal>.
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extension in WCF. You are responsible to bind and unbind an <literal>ISession</literal>
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instance with static methods of class <literal>CurrentSessionContext</literal>.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>NHibernate.Context.ManagedWebSessionContext</literal> - current
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sessions are tracked by <literal>HttpContext</literal>. Removed in NHibernate 4.0
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- <literal>NHibernate.Context.WebSessionContext</literal> should be used instead.
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You are responsible to bind and unbind an <literal>ISession</literal> instance with static methods
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sessions are tracked by <literal>HttpContext</literal>. Removed in NHibernate 4.0
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- <literal>NHibernate.Context.WebSessionContext</literal> should be used instead.
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You are responsible to bind and unbind an <literal>ISession</literal> instance with static methods
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on this class, it never opens, flushes, or closes an <literal>ISession</literal> itself.
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</para>
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</listitem>
@@ -287,7 +296,8 @@
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defines which <literal>NHibernate.Context.ICurrentSessionContext</literal> implementation
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should be used. Typically, the value of this parameter would just name the implementation
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class to use (including the assembly name); for the out-of-the-box implementations, however,
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there are corresponding short names: "call", "thread_static", "web" and "wcf_operation",
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there are corresponding short names: <literal>async_local</literal>, <literal>call</literal>,
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<literal>thread_static</literal>, <literal>web</literal> and <literal>wcf_operation</literal>,
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respectively.
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</para>
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</sect1>

‎src/NHibernate.Test/ConnectionTest/AsyncLocalSessionContextFixture.cs

Lines changed: 66 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,66 @@
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using System.Threading.Tasks;
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using NHibernate.Cfg;
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using NHibernate.Context;
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using NUnit.Framework;
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namespace NHibernate.Test.ConnectionTest
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{
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[TestFixture]
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public class AsyncLocalSessionContextFixture : ConnectionManagementTestCase
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{
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protected override ISession GetSessionUnderTest()
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{
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var session = OpenSession();
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session.BeginTransaction();
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return session;
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}
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protected override void Configure(Configuration configuration)
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{
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base.Configure(cfg);
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cfg.SetProperty(Environment.CurrentSessionContextClass, "async_local");
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}
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[Test]
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public async Task AsyncLocalIsolation()
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{
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using (var session = OpenSession())
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{
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CurrentSessionContext.Bind(session);
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AssertCurrentSession(session, "Unexpected session after outer bind.");
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await SubBind(session);
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AssertCurrentSession(session, "Unexpected session after end of SubBind call.");
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}
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}
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private async Task SubBind(ISession firstSession)
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{
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AssertCurrentSession(firstSession, "Unexpected session at start of SubBind.");
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using (var session = OpenSession())
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{
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CurrentSessionContext.Bind(session);
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AssertCurrentSession(session, "Unexpected session after inner bind.");
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await Dummy();
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AssertCurrentSession(session, "Unexpected session after dummy await.");
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}
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}
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private Task Dummy()
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{
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return Task.FromResult(0);
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}
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private void AssertCurrentSession(ISession session, string message)
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{
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Assert.That(
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Sfi.GetCurrentSession(),
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Is.EqualTo(session),
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"{0} {1} instead of {2}.", message,
62+
Sfi.GetCurrentSession().GetSessionImplementation().SessionId,
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session.GetSessionImplementation().SessionId);
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}
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}
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}

‎src/NHibernate.Test/NHibernate.Test.csproj

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Original file line numberDiff line numberDiff line change
@@ -208,6 +208,7 @@
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<Compile Include="ConnectionTest\BatcherFixture.cs" />
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<Compile Include="ConnectionTest\AggressiveReleaseTest.cs" />
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<Compile Include="ConnectionTest\ConnectionManagementTestCase.cs" />
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<Compile Include="ConnectionTest\AsyncLocalSessionContextFixture.cs" />
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<Compile Include="ConnectionTest\YetAnother.cs" />
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<Compile Include="ConnectionTest\Other.cs" />
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<Compile Include="ConnectionTest\Silly.cs" />

‎src/NHibernate/Context/AsyncLocalSessionContext.cs

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using System;
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using System.Threading;
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using NHibernate.Engine;
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namespace NHibernate.Context
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{
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// Session contextes are serializable while not actually serializing any data. Others contextes just retrieve it back
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// from their context, if it does still live when/where they are de-serialized. For having that with AsyncLocal,
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// we would need to store it as static, and then we need to use a MapBasedSessionContext.
10+
// But this would cause bindings operations done in inner flows to be potentially propagated to outer flows, depending
11+
// on which flow has initialized the map. This is undesirable.
12+
// So current implementation just loses its context in case of serialization, since AsyncLocal is not serializable.
13+
// Another option would be to change MapBasedSessionContext for recreating a new dictionary from the
14+
// previous one at each change, essentially using those dictionaries as immutable objects.
15+
/// <summary>
16+
/// Provides a <see cref="ISessionFactory.GetCurrentSession()">current session</see>
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/// for current asynchronous flow.
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/// </summary>
19+
[Serializable]
20+
public class AsyncLocalSessionContext : CurrentSessionContext
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{
22+
private readonly AsyncLocal<ISession> _session = new AsyncLocal<ISession>();
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24+
// Constructor signature required for dynamic invocation code.
25+
public AsyncLocalSessionContext(ISessionFactoryImplementor factory) { }
26+
27+
protected override ISession Session
28+
{
29+
get => _session.Value;
30+
set => _session.Value = value;
31+
}
32+
}
33+
}

‎src/NHibernate/Impl/SessionFactoryImpl.cs

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Original file line numberDiff line numberDiff line change
@@ -1223,6 +1223,8 @@ private ICurrentSessionContext BuildCurrentSessionContext()
12231223
{
12241224
case null:
12251225
return null;
1226+
case "async_local":
1227+
return new AsyncLocalSessionContext(this);
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case "call":
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return new CallSessionContext(this);
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case "thread_static":

‎src/NHibernate/NHibernate.csproj

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@@ -144,6 +144,7 @@
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<Compile Include="Connection\DriverConnectionProvider.cs" />
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<Compile Include="Connection\IConnectionProvider.cs" />
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<Compile Include="Connection\UserSuppliedConnectionProvider.cs" />
147+
<Compile Include="Context\AsyncLocalSessionContext.cs" />
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<Compile Include="Dialect\PostgreSQL83Dialect.cs" />
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<Compile Include="Impl\ISharedSessionCreationOptions.cs" />
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<Compile Include="ISharedSessionBuilder.cs" />

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