refactoring tasks

Src/Myc.Core.Tasks.pas

@@ -32,7 +32,9 @@ type
         // 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(StartCount: Integer; Job: TProc): IMycSubscriber;
+        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)
@@ -67,7 +69,6 @@ type
         procedure WorkerThread;
 
     protected
-        procedure EnqueueJob(const Job: TProc);
         procedure ExecuteJob;
         function GetThreadCount: Integer;
         property WaitSemaphores: TMycAtomicStack<TSemaphore> read FWaitSemaphores;
@@ -78,7 +79,8 @@ type
         class function CreateAnonymousThread(const DbgName: String; const Proc: TProc): TThread;
         function CreateThread(const Proc: TProc): IMycState;
         procedure HandleException;
-        function Run(StartCount: Integer; Job: TProc): IMycSubscriber;
+        procedure EnqueueJob(const Job: TProc);
+        function Run(Job: TProc): IMycSubscriber;
         procedure WaitFor(State: IMycState);
         procedure Teardown;
         function InMainThread: Boolean;
@@ -91,7 +93,6 @@ type
     TMycPendingJob = class(TInterfacedObject, IMycSubscriber)
     private
         [volatile]
-        FCount: Integer; // Countdown counter
         FJob: TProc; // The job to execute when count reaches zero
         FOwner: TMycTaskFactory; // The task factory to enqueue the job on
 
@@ -99,7 +100,7 @@ type
         function Notify: Boolean;
 
     public
-        constructor Create(StartCountValue: Integer; OwnerTaskFactory: TMycTaskFactory; const JobProc: TProc);
+        constructor Create(OwnerTaskFactory: TMycTaskFactory; const JobProc: TProc);
         property Owner: TMycTaskFactory read FOwner;
     end;
 
@@ -200,6 +201,9 @@ end;
 
 procedure TMycTaskFactory.EnqueueJob(const Job: TProc);
 begin
+    if FTerminated <> 0 then
+        raise ETaskException.Create('Task factory terminated');
+
     if Assigned(Job) then
     begin
         FWorkStack.Push(Job); // Push job onto the lock-free stack
@@ -257,7 +261,7 @@ begin
     exit(false); // Not found in worker thread list
 end;
 
-function TMycTaskFactory.Run(StartCount: Integer; Job: TProc): IMycSubscriber;
+function TMycTaskFactory.Run(Job: TProc): IMycSubscriber;
 begin
     if FTerminated <> 0 then
         raise ETaskException.Create('Task factory terminated');
@@ -265,14 +269,8 @@ begin
     if not Assigned(Job) then
         exit(TMycLatch.Null); // Already correct, uses direct static property on TMycLatch
 
-    if StartCount <= 0 then
-    begin
-        EnqueueJob(Job); // Enqueue immediately if no countdown needed
-        Result := TMycLatch.Null; // Already correct
-    end
-    else
-        // Create a pending job that waits for StartCount notifications
-        Result := TMycPendingJob.Create(StartCount, Self, Job);
+    // Create a pending job
+    Result := TMycPendingJob.Create(Self, Job);
 end;
 
 procedure TMycTaskFactory.Teardown;
@@ -353,11 +351,10 @@ end;
 
 { TMycPendingJob }
 
-constructor TMycPendingJob.Create(StartCountValue: Integer; OwnerTaskFactory: TMycTaskFactory; const JobProc: TProc);
+constructor TMycPendingJob.Create(OwnerTaskFactory: TMycTaskFactory; const
+    JobProc: TProc);
 begin
     inherited Create;
-    Assert(StartCountValue > 0);
-    FCount := StartCountValue;
     FOwner := OwnerTaskFactory;
     FJob := JobProc;
 end;
@@ -365,20 +362,16 @@ end;
 function TMycPendingJob.Notify: Boolean;
 var
     newCount: Integer;
+    P: TProc;
 begin
-    newCount := TInterlocked.Decrement(FCount);
-    if newCount < -MaxInt div 2 then
-        TInterlocked.Increment(FCount);
-
-    if newCount = 0 then
+    PPointer(@P)^ := TInterlocked.Exchange( PPointer(@FJob)^, nil );
+    Result := Assigned(P);
+    if Result then
     begin
-        if Assigned(FOwner) and Assigned(FJob) then
-        begin
-            FOwner.EnqueueJob(FJob);
-            FJob := nil;
-        end;
+        if Assigned(FOwner) then
+            FOwner.EnqueueJob(P);
+         P := nil;
     end;
-    Result := newCount > 0;
 end;
 
 { TMycTaskWait }