Refactoring

Src/Myc.Core.Futures.pas

@@ -0,0 +1,80 @@
+unit Myc.Core.Futures;
+
+interface
+
+uses
+    System.SysUtils,
+    Myc.Signals, Myc.TaskManager, Myc.Futures;
+
+type
+    // Abstract base class for IMycFuture<T> implementations.
+    TMycFuture<T> = class abstract( TInterfacedObject, IMycFuture<T> )
+    protected
+        function GetResult: T; virtual; abstract;
+        function GetDone: IMycState; virtual; abstract;
+    end;
+
+    // Concrete future implementation triggered by an initial state, executing a TFunc<T>.
+    TMycInitStateFuncFuture<T> = class( TMycFuture<T> )
+    private
+        FInit: TMycSubscription;
+        FDone: IMycLatch;
+        FResult: T;
+    protected
+        function GetResult: T; override;
+        function GetDone: IMycState; override;
+    public
+        // Creates a future that executes AProc after AGate is set, using ATaskFactory.
+        constructor Create( const ATaskManager: IMycTaskManager; const AGate: IMycState; AProc: TFunc<T> );
+        destructor Destroy; override;
+    end;
+
+implementation
+
+{ TMycInitStateFuncFuture<T> }
+
+constructor TMycInitStateFuncFuture<T>.Create( const ATaskManager: IMycTaskManager; const AGate: IMycState; AProc: TFunc<T> );
+begin
+    inherited Create;
+
+    FDone := TMycLatch.CreateLatch( 1 );
+
+    // Subscribe the job execution to AGate.
+    // The job will run when AGate notifies the subscriber returned by Run.
+    FInit := ATaskManager.CreateTask(
+        AGate,
+        procedure
+        begin
+            try
+                try
+                    Self.FResult := AProc( );
+                except
+                    Self.FResult := Default ( T ); // Set result to Default(T) on error
+                    raise; // Re-raise for TaskFactory to handle
+                end;
+            finally
+                Self.FDone.Notify; // Signal that this future is done (successfully or with error)
+            end;
+        end );
+end;
+
+destructor TMycInitStateFuncFuture<T>.Destroy;
+begin
+    Assert( FDone.State.IsSet );
+
+    FInit.Unsubscribe;
+    inherited Destroy;
+end;
+
+function TMycInitStateFuncFuture<T>.GetDone: IMycState;
+begin
+    Result := FDone.State;
+end;
+
+function TMycInitStateFuncFuture<T>.GetResult: T;
+begin
+    Assert( FDone.State.IsSet, 'Result is not yet available.' );
+    Result := FResult;
+end;
+
+end.

Src/Myc.Core.Tasks.pas

@@ -4,55 +4,55 @@ interface
 
 uses
     System.SysUtils, System.Classes, System.SyncObjs,
-    Myc.Core.Atomic, Myc.Signals; // Myc.Signals now requires direct use of TMycLatch static members
+    Myc.Core.Atomic, Myc.TaskManager, Myc.Signals; // Myc.Signals now requires direct use of TMycLatch static members
 
 type
-    IMycTaskFactory = interface
-        {$region 'property access'}
-        // Retrieves the number of worker threads.
-        function GetThreadCount: Integer;
-        {$endregion}
-
-        // Creates and starts a new, independent thread executing Proc.
-        // Returns IMycState to await thread completion.
-        // Exceptions within Proc are caught; the first one is stored
-        // and can be re-raised in the main thread via WaitFor or Teardown.
-        function CreateThread(const Proc: TProc): IMycState;
-
-        // Returns True if called from the main application thread.
-        function InMainThread: Boolean;
-
-        // Returns True if called from one of the factory's worker threads.
-        function InWorkerThread: Boolean;
-
-        // Schedules Job for execution by a worker thread.
-        // If StartCount > 0, Job is deferred until Notify is called StartCount times on the returned IMycSubscriber.
-        // If StartCount <= 0, Job is enqueued immediately.
-        // Returns IMycSubscriber for deferred jobs, or TMycLatch.Null for immediate jobs or if Job is nil.
-        // Exceptions during Job execution are caught; the first one is stored
-        // and can be re-raised in the main thread via WaitFor or Teardown.
-        // Raises ETaskException if the factory is already terminated.
-        function Run(Job: TProc): IMycSubscriber;
-
-        procedure EnqueueJob(const Job: TProc);
-
-        // Shuts down the task factory: terminates worker threads and cleans up resources.
-        // Before shutdown, any first stored exception from a worker thread (from Run or CreateThread tasks managed by this factory)
-        // will be re-raised in the calling (main) thread.
-        procedure Teardown;
-
-        // Waits for the operation associated with State to complete.
-        // Must not be called from a worker thread of this factory.
-        // After waiting, or if the state is already set, any first stored exception
-        // from any worker thread of this factory will be re-raised in the calling (main) thread.
-        // Raises ETaskException if called from within a worker thread.
-        procedure WaitFor(State: IMycState);
-
-        // Gets the number of worker threads.
-        property ThreadCount: Integer read GetThreadCount;
-    end;
+    IMycTaskFactory = interface( IMycTaskManager )
+        {$region 'property access'}
+        // Retrieves the number of worker threads.
+        function GetThreadCount: Integer;
+        {$endregion}
 
-    TMycTaskFactory = class(TInterfacedObject, IMycTaskFactory)
+        // Creates and starts a new, independent thread executing Proc.
+        // Returns IMycState to await thread completion.
+        // Exceptions within Proc are caught; the first one is stored
+        // and can be re-raised in the main thread via WaitFor or Teardown.
+        function CreateThread(const Proc: TProc): IMycState;
+
+        // Returns True if called from the main application thread.
+        function InMainThread: Boolean;
+
+        // Returns True if called from one of the factory's worker threads.
+        function InWorkerThread: Boolean;
+
+        // Schedules Job for execution by a worker thread.
+        // If StartCount > 0, Job is deferred until Notify is called StartCount times on the returned IMycSubscriber.
+        // If StartCount <= 0, Job is enqueued immediately.
+        // Returns IMycSubscriber for deferred jobs, or TMycLatch.Null for immediate jobs or if Job is nil.
+        // Exceptions during Job execution are caught; the first one is stored
+        // and can be re-raised in the main thread via WaitFor or Teardown.
+        // Raises ETaskException if the factory is already terminated.
+        function Run(Job: TProc): IMycSubscriber;
+
+        procedure EnqueueJob(const Job: TProc);
+
+        // Shuts down the task factory: terminates worker threads and cleans up resources.
+        // Before shutdown, any first stored exception from a worker thread (from Run or CreateThread tasks managed by this factory)
+        // will be re-raised in the calling (main) thread.
+        procedure Teardown;
+
+        // Waits for the operation associated with State to complete.
+        // Must not be called from a worker thread of this factory.
+        // After waiting, or if the state is already set, any first stored exception
+        // from any worker thread of this factory will be re-raised in the calling (main) thread.
+        // Raises ETaskException if called from within a worker thread.
+        procedure WaitFor(State: IMycState);
+
+        // Gets the number of worker threads.
+        property ThreadCount: Integer read GetThreadCount;
+    end;
+
+    TMycTaskFactory = class(TInterfacedObject, IMycTaskManager, IMycTaskFactory)
     type
         ETaskException = class(Exception) end;
     private
@@ -67,6 +67,8 @@ type
         FWorkStack: TMycAtomicStack<TProc>; // Stack of pending jobs
         FWorkThreads: TArray<TThread>; // Array of worker threads
         procedure WorkerThread;
+    class var
+        FTaskManagerLock: Integer;
 
     protected
         procedure ExecuteJob;
@@ -81,10 +83,14 @@ type
         procedure HandleException;
         procedure EnqueueJob(const Job: TProc);
         function Run(Job: TProc): IMycSubscriber;
+        function CreateTask(const Gate: IMycState; const Proc: TProc): TMycSubscription;
         procedure WaitFor(State: IMycState);
         procedure Teardown;
         function InMainThread: Boolean;
         function InWorkerThread: Boolean;
+
+        class procedure AquireTaskManager;
+        class procedure ReleaseTaskManager;
     end;
 
 implementation
@@ -175,6 +181,20 @@ begin
         Result.NameThreadForDebugging(DbgName); // Set thread name for debugging
 end;
 
+function TMycTaskFactory.CreateTask(const Gate: IMycState; const Proc: TProc):
+    TMycSubscription;
+begin
+    if not Assigned(Gate) or Gate.IsSet then
+    begin
+        EnqueueJob( Proc );
+    end
+    else
+    begin
+        // The job will run when Gate notifies the subscriber returned by Run.
+        Result := Gate.Subscribe( Run( Proc ) );
+    end;
+end;
+
 function TMycTaskFactory.CreateThread(const Proc: TProc): IMycState;
 var
     res: IMycLatch;
@@ -261,6 +281,20 @@ begin
     exit(false); // Not found in worker thread list
 end;
 
+class procedure TMycTaskFactory.AquireTaskManager;
+begin
+    if not Assigned(TaskManager) then
+        TaskManager := TMycTaskFactory.Create;
+    inc( FTaskManagerLock );
+end;
+
+class procedure TMycTaskFactory.ReleaseTaskManager;
+begin
+    dec( FTaskManagerLock );
+    if FTaskManagerLock = 0 then
+        TaskManager := nil;
+end;
+
 function TMycTaskFactory.Run(Job: TProc): IMycSubscriber;
 begin
     if FTerminated <> 0 then
@@ -361,7 +395,6 @@ end;
 
 function TMycPendingJob.Notify: Boolean;
 var
-    newCount: Integer;
     P: TProc;
 begin
     PPointer(@P)^ := TInterlocked.Exchange( PPointer(@FJob)^, nil );

Src/Myc.Futures.pas

@@ -4,7 +4,7 @@ interface
 
 uses
     System.SysUtils,
-    Myc.Signals, Myc.Core.Tasks;
+    Myc.Signals, Myc.TaskManager;
 
 type
     // Represents the eventual result of an asynchronous operation.
@@ -19,91 +19,58 @@ type
         property Done: IMycState read GetDone;
     end;
 
-    // Abstract base class for IMycFuture<T> implementations.
-    TMycFuture<T> = class abstract(TInterfacedObject, IMycFuture<T>)
-      protected
-        function GetResult: T; virtual; abstract;
-        function GetDone: IMycState; virtual; abstract;
-    end;
+    Future<T> = record
+    strict private
+        FFuture: IMycFuture<T>;
+        class constructor CreateClass;
+        class destructor DestroyClass;
+        constructor Create(const AFuture: IMycFuture<T>);
+    public
+        class function Construct(const Proc: TFunc<T>): Future<T>; overload; static;
+        class function Construct(const Gate: IMycState; const Proc: TFunc<T>): Future<T>; overload; static;
 
-    // Concrete future implementation triggered by an initial state, executing a TFunc<T>.
-    TMycInitStateFuncFuture<T> = class(TMycFuture<T>)
-      private
-        FInit: TMycSubscription;
-        FDone: IMycLatch;
-        FResult: T;
-      protected
-        function GetResult: T; override;
-        function GetDone: IMycState; override;
-      public
-        // Creates a future that executes AProc after AInitState is set, using ATaskFactory.
-        constructor Create(const ATaskFactory: IMycTaskFactory; const AInitState:
-            IMycState; AProc: TFunc<T>);
-        // Cleans up resources, primarily by unsubscribing from the initial state.
-        destructor Destroy; override;
+        function Chain<S>(const Proc: TFunc<T, S>): Future<S>;
     end;
 
 implementation
 
-{ TMycInitStateFuncFuture<T> }
+uses
+    Myc.Core.Futures, Myc.Core.Tasks;
 
-constructor TMycInitStateFuncFuture<T>.Create(const ATaskFactory:
-    IMycTaskFactory; const AInitState: IMycState; AProc: TFunc<T>);
+constructor Future<T>.Create(const AFuture: IMycFuture<T>);
 begin
-    inherited Create;
-    Assert(Assigned(AInitState), 'AInitState must be assigned.');
-
-    FDone := TMycLatch.CreateLatch(1);
-
-    // Subscribe the job execution to AInitState.
-    // The job will run when AInitState notifies the subscriber returned by Run.
-    // AStartCount for Run is 1, meaning it waits for one Notify from AInitState's subscription.
-    FInit := AInitState.Subscribe(
-        ATaskFactory.Run(
-
-            procedure
-            begin
-                try
-                    try
-                        Self.FResult := AProc();
-                    except
-                        Self.FResult := Default(T); // Set result to Default(T) on error
-                        raise; // Re-raise for TaskFactory to handle
-                    end;
-                finally
-                    Self.FDone.Notify; // Signal that this future is done (successfully or with error)
-                end;
-            end
-        )
-    );
+    FFuture := AFuture;
 end;
 
-destructor TMycInitStateFuncFuture<T>.Destroy;
+class constructor Future<T>.CreateClass;
 begin
-    Assert( FInit.State.IsSet );
-
-    // Explicitly unsubscribe from the initial state to ensure cleanup.
-    FInit.Unsubscribe;
-    inherited Destroy;
+    TMycTaskFactory.AquireTaskManager;
 end;
 
-
-function TMycInitStateFuncFuture<T>.GetDone: IMycState;
+class destructor Future<T>.DestroyClass;
 begin
-    Result := FDone.State;
+    TMycTaskFactory.ReleaseTaskManager;
 end;
 
-function TMycInitStateFuncFuture<T>.GetResult: T;
+function Future<T>.Chain<S>(const Proc: TFunc<T, S>): Future<S>;
 begin
-    if not FDone.State.IsSet then
-    begin
-        // Design decision: Caller must ensure future is done.
-        raise Exception.Create('Result is not yet available for the future.');
-    end;
+    var Cap := FFuture;
 
-    // Returns FResult. If AProc failed, FResult is Default(T) and the exception
-    // was raised to be handled by the TaskFactory.
-    Result := FResult;
+    Result := Future<S>.Construct( FFuture.Done,
+        function: S
+        begin
+            Result := Proc( Cap.Result );
+        end );
+end;
+
+class function Future<T>.Construct(const Proc: TFunc<T>): Future<T>;
+begin
+    Result.Create( TMycInitStateFuncFuture<T>.Create( TaskManager, nil, Proc ) );
+end;
+
+class function Future<T>.Construct(const Gate: IMycState; const Proc: TFunc<T>): Future<T>;
+begin
+    Result.Create( TMycInitStateFuncFuture<T>.Create( TaskManager, Gate, Proc ) );
 end;
 
 end.

Src/Myc.Signals.pas

@@ -21,10 +21,11 @@ type
         FState: IMycState;
         FTag: TMycNotifyList<IMycSubscriber>.TTag; // Tag identifying this subscription within the notifier list.
         function GetState: IMycState;
-        constructor Create(const AState: IMycState; ATag: TMycNotifyList<IMycSubscriber>.TTag);
     public
+        constructor Create(const AState: IMycState; ATag: TMycNotifyList<IMycSubscriber>.TTag);
         // Unsubscribes from the associated signal.
         procedure Unsubscribe;
+        class operator Initialize(out Dest: TMycSubscription);
         property State: IMycState read GetState;
     end;
 
@@ -154,44 +155,44 @@ uses
     System.SyncObjs; // For TInterlocked
 
 type
-    // TMycNullState implements a "null object" pattern for IMycState.
-    // This state is always considered "set".
-    TMycNullState = class(TInterfacedObject, IMycState)
-    protected
-        // IMycState
-        function GetIsSet: Boolean;
-        function Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
-        procedure Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
-    public
-        constructor Create;
-    end;
-
-{ TMycNullState }
-
-constructor TMycNullState.Create;
-begin
-    inherited Create;
-end;
-
-function TMycNullState.GetIsSet: Boolean;
-begin
-    Result := true; // Null state is always set.
-end;
-
-function TMycNullState.Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
-begin
-    // Since the state is always set, notify the subscriber immediately.
-    if Assigned(Subscriber) then
-    begin
-        Subscriber.Notify;
-    end;
-    // No ongoing subscription is necessary or meaningful for a null state.
-    Result.Create(Self, nil); // Return an empty subscription.
-end;
-
-procedure TMycNullState.Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
-begin
-    // Unsubscribing from a null state has no effect.
+    // TMycNullState implements a "null object" pattern for IMycState.
+    // This state is always considered "set".
+    TMycNullState = class(TInterfacedObject, IMycState)
+    protected
+        // IMycState
+        function GetIsSet: Boolean;
+        function Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
+        procedure Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
+    public
+        constructor Create;
+    end;
+
+{ TMycNullState }
+
+constructor TMycNullState.Create;
+begin
+    inherited Create;
+end;
+
+function TMycNullState.GetIsSet: Boolean;
+begin
+    Result := true; // Null state is always set.
+end;
+
+function TMycNullState.Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
+begin
+    // Since the state is always set, notify the subscriber immediately.
+    if Assigned(Subscriber) then
+    begin
+        Subscriber.Notify;
+    end;
+    // No ongoing subscription is necessary or meaningful for a null state.
+    Result.Create(Self, nil); // Return an empty subscription.
+end;
+
+procedure TMycNullState.Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
+begin
+    // Unsubscribing from a null state has no effect.
 end;
 
 { TMycSubscription }
@@ -206,17 +207,20 @@ end;
 
 procedure TMycSubscription.Unsubscribe;
 begin
-    if Assigned(FState) then
-    begin
-        FState.Unsubscribe(FTag);
-        FTag := nil;
-        FState := nil;
-    end;
+    FState.Unsubscribe(FTag);
+    FState := TMycState.Null;
+    FTag := nil;
 end;
 
 function TMycSubscription.GetState: IMycState;
 begin
-    Result := FState;
+    Result := FState
+end;
+
+class operator TMycSubscription.Initialize(out Dest: TMycSubscription);
+begin
+    Dest.FState := TMycState.Null;
+    Dest.FTag := nil;
 end;
 
 { TMycLatch }
@@ -301,7 +305,6 @@ function TMycLatch.Subscribe(const Subscriber: IMycSubscriber): TMycSubscription
 var
     alreadySet: Boolean;
 begin
-    Result.Create(TMycState.Null, nil); // Default to an empty subscription.
     if not Assigned(Subscriber) then
         exit;
 
@@ -409,7 +412,6 @@ end;
 
 function TMycDirty.Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
 begin
-    Result.Create(TMycState.Null, nil); // Default to an empty subscription
     if not Assigned(Subscriber) then
         exit;
 

Src/Myc.TaskManager.pas

@@ -0,0 +1,19 @@
+unit Myc.TaskManager;
+
+interface
+
+uses
+    System.SysUtils,
+    Myc.Signals;
+
+type
+    IMycTaskManager = interface
+        function CreateTask( const Gate: IMycState; const Proc: TProc ): TMycSubscription;
+    end;
+
+var
+    TaskManager: IMycTaskManager;
+
+implementation
+
+end.

Test/MycTests.dpr

@@ -24,7 +24,9 @@ uses
   TestTasks in 'TestTasks.pas',
   TestSignals_Dirty in 'TestSignals_Dirty.pas',
   Myc.Futures in '..\Src\Myc.Futures.pas',
-  TestFutures in 'TestFutures.pas';
+  TestFutures in 'TestFutures.pas',
+  Myc.TaskManager in '..\Src\Myc.TaskManager.pas',
+  Myc.Core.Futures in '..\Src\Myc.Core.Futures.pas';
 
 { keep comment here to protect the following conditional from being removed by the IDE when adding a unit }
 {$IFNDEF TESTINSIGHT}

Test/MycTests.dproj

@@ -124,6 +124,8 @@ $(PostBuildEvent)]]></PostBuildEvent>
         <DCCReference Include="TestSignals_Dirty.pas"/>
         <DCCReference Include="..\Src\Myc.Futures.pas"/>
         <DCCReference Include="TestFutures.pas"/>
+        <DCCReference Include="..\Src\Myc.TaskManager.pas"/>
+        <DCCReference Include="..\Src\Myc.Core.Futures.pas"/>
         <BuildConfiguration Include="Base">
             <Key>Base</Key>
         </BuildConfiguration>
@@ -1129,6 +1131,15 @@ $(PostBuildEvent)]]></PostBuildEvent>
                 <Platform value="Win32">True</Platform>
                 <Platform value="Win64">True</Platform>
             </Platforms>
+            <MMX>
+                <UsesClauseFormatter AutoFormat="0" UseDefault="0">
+                    <GroupNames>Winapi;System.Win;System;Data;REST;Xml;Vcl;FMX</GroupNames>
+                </UsesClauseFormatter>
+                <Parser>
+                    <Defines/>
+                    <IfExpressions/>
+                </Parser>
+            </MMX>
         </BorlandProject>
         <ProjectFileVersion>12</ProjectFileVersion>
     </ProjectExtensions>

Test/TestFutures.pas

@@ -8,7 +8,7 @@ uses
   System.SyncObjs,
   Myc.Signals,    // For IMycLatch, TMycLatch, IMycState, IMycSubscriber [cite: 62, 68, 53, 45]
   Myc.Core.Tasks, // For IMycTaskFactory, TMycTaskFactory [cite: 97, 113]
-  Myc.Futures;    // For IMycFuture, TMycInitStateFuncFuture
+  Myc.Futures, Myc.Core.Futures;    // For IMycFuture, TMycInitStateFuncFuture
 
 type
   // Helper class to notify a latch when its Notify method is called.
@@ -207,12 +207,8 @@ procedure TTestMycInitStateFuncFuture.Test_GetResult_BeforeDone_RaisesException;
 var
   LFuture: IMycFuture<Integer>;
   LInitLatch: IMycLatch;
-  LExpectedExceptionRaised: Boolean;
-const
-  CExpectedExceptionMessage = 'Result is not yet available for the future.';
 begin
-  LExpectedExceptionRaised := False;
-  LInitLatch := TMycLatch.CreateLatch(1); // Create a latch that is not yet set [cite: 77, 212, 330]
+  LInitLatch := TMycLatch.CreateLatch(1);
 
   LFuture := TMycInitStateFuncFuture<Integer>.Create(FTaskFactory, LInitLatch.State,
     function: Integer
@@ -223,19 +219,21 @@ begin
 
   Assert.IsFalse(LFuture.Done.IsSet, 'Future should not be marked as done initially.');
 
-  try
-    LFuture.GetResult;
-  except
-    on E: Exception do
+  Assert.WillRaise(
+    procedure
     begin
-      Assert.AreEqual(CExpectedExceptionMessage, E.Message, 'Exception message mismatch.');
-      LExpectedExceptionRaised := True;
-    end;
-  end;
-  Assert.IsTrue(LExpectedExceptionRaised, 'Calling GetResult before done should raise an exception.');
+        LFuture.GetResult;
+    end );
 
-  LInitLatch.Notify; // [cite: 80, 215, 333]
-  FTaskFactory.WaitFor(LFuture.Done); //
+  LInitLatch.Notify;
+
+  FTaskFactory.WaitFor(LFuture.Done);
+
+  Assert.WillNotRaise(
+    procedure
+    begin
+        LFuture.GetResult;
+    end );
 end;
 
 procedure TTestMycInitStateFuncFuture.Test_FanIn_OneFutureWaitsForMultipleOthers;