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TaskFactory added

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This commit is contained in:
Michael Schimmel
2025-05-26 00:27:09 +02:00
parent 10ef4cbcf2
commit 95fddb0181
13 changed files with 1292 additions and 251 deletions
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Src/Myc.Core.Atomic.pas
+22 -15
View File
@@ -56,6 +56,8 @@ type
// Pushes an item onto the stack.
procedure Push(const Data: T); inline;
procedure Clear;
// Allocates an aligned memory block for a stack item.
function Alloc: PItem; inline;
// Pushes a pre-allocated item pointer onto the SList.
@@ -183,22 +185,8 @@ begin
end;
class operator TMycAtomicStack<T>.Finalize(var Dest: TMycAtomicStack<T>);
var
item: PItem;
begin
// Use Dest to access fields and call instance methods
// on the record instance being finalized
item := Dest.PopPtr; // Call instance method PopPtr via Dest
while item <> nil do
begin
item.Data := Default(T);
FreeMemAligned(item); // Global procedure
item := Dest.PopPtr; // Call instance method PopPtr via Dest
end;
if Dest.FSList <> nil then // Check if FSList was initialized
begin
Dest.FSList.Free; // Call instance method Free on FSList via Dest
end;
Dest.Clear;
end;
function TMycAtomicStack<T>.Alloc: PItem;
@@ -209,6 +197,25 @@ begin
Result.Data := Default(T);
end;
procedure TMycAtomicStack<T>.Clear;
var
item: PItem;
begin
// Use Dest to access fields and call instance methods
// on the record instance being finalized
item := PopPtr; // Call instance method PopPtr via Dest
while item <> nil do
begin
item.Data := Default(T);
FreeMemAligned(item); // Global procedure
item := PopPtr; // Call instance method PopPtr via Dest
end;
if FSList <> nil then // Check if FSList was initialized
begin
FSList.Free; // Call instance method Free on FSList via Dest
end;
end;
function TMycAtomicStack<T>.Pop: T;
begin
// Instance method
Src/Myc.Core.Notifier.pas
+46 -69
View File
@@ -1,49 +1,47 @@
unit Myc.Core.Notifier;
interface
uses
System.SysUtils, System.SyncObjs;
type
// Low-level implementation for thread-safe multicast events.
// Implemented as a list referencing IInterface instances, with a locking mechanism for thread safety.
// Utilizes minimal memory.
// `Advise` adds an interface and returns a tag for constant-time removal by `Unadvise`.
// `UnadviseAll` removes all registered interfaces.
// After `Finalize` is called, the list is cleared, and no new interfaces can be added (closed state).
TMycNotifyList<T: IInterface> = record
type
TTag = Pointer; // Opaque tag used to identify a registered receiver for unsubscription.
PItem = ^TItem; // Pointer to an internal list item.
TItem = record // Internal structure for storing a receiver and list linkage.
Next, Prev: PItem; // Pointers to the next and previous items in the doubly linked list.
Receiver: T; // The registered interface instance (the event sink).
end;
strict private
FFirst: NativeUInt; // Stores the first receiver if no list is allocated, or acts as a combined lock and state field.
// Bit 0: Lock state (0 = locked, 1 = unlocked).
// Bit 1: Finalized state (0 = not finalized, 1 = finalized).
// Other bits (if not 0 and bit 0 is 1) can be a direct interface pointer if FList is nil.
FList: PItem; // Head of the linked list for additional receivers beyond the first one.
class function AllocItem: PItem; static; inline; // Allocates and initializes memory for a new TItem.
class procedure FreeItem( Item: PItem ); static; inline; // Frees memory previously allocated for a TItem.
public
procedure Create; // Initializes the notification list, preparing it for use.
procedure Destroy; // Cleans up all resources, including unadvising all receivers. Assumes no concurrent access.
function Advise(const Receiver: T): TTag; // Registers a receiver interface and returns an opaque tag for later unsubscription.
procedure Unadvise(Tag: TTag); // Unregisters a specific receiver using the tag obtained from Advise.
procedure UnadviseAll; // Unregisters all currently advised receivers.
procedure Finalize; // Clears all receivers and permanently prevents new interfaces from being added.
procedure Lock; inline; // Acquires an exclusive lock for thread-safe operations on the list.
procedure Release; inline;// Releases the previously acquired exclusive lock.
function IsLocked: Boolean; inline; // Checks if the list is currently locked by any thread.
function IsFinalized: Boolean; inline; // Checks if the list has been finalized and no longer accepts new receivers.
procedure Notify(Func: TPredicate<T>); // Iterates through registered receivers and invokes the predicate; removes receiver if predicate returns false.
interface
uses
System.SysUtils, System.SyncObjs;
type
// Low-level implementation for thread-safe multicast events.
// Implemented as a list referencing IInterface instances, with a locking mechanism for thread safety.
// Utilizes minimal memory.
// `Advise` adds an interface and returns a tag for constant-time removal by `Unadvise`.
// `UnadviseAll` removes all registered interfaces.
// After `Finalize` is called, the list is cleared, and no new interfaces can be added (closed state).
TMycNotifyList<T: IInterface> = record
type
TTag = Pointer; // Opaque tag used to identify a registered receiver for unsubscription.
PItem = ^TItem; // Pointer to an internal list item.
TItem = record // Internal structure for storing a receiver and list linkage.
Next, Prev: PItem; // Pointers to the next and previous items in the doubly linked list.
Receiver: T; // The registered interface instance (the event sink).
end;
strict private
FFirst: NativeUInt; // Stores the first receiver if no list is allocated, or acts as a combined lock and state field.
// Bit 0: Lock state (0 = locked, 1 = unlocked).
// Bit 1: Finalized state (0 = not finalized, 1 = finalized).
// Other bits (if not 0 and bit 0 is 1) can be a direct interface pointer if FList is nil.
FList: PItem; // Head of the linked list for additional receivers beyond the first one.
class function AllocItem: PItem; static; inline; // Allocates and initializes memory for a new TItem.
class procedure FreeItem( Item: PItem ); static; inline; // Frees memory previously allocated for a TItem.
public
procedure Create; // Initializes the notification list, preparing it for use.
procedure Destroy; // Cleans up all resources, including unadvising all receivers. Assumes no concurrent access.
function Advise(const Receiver: T): TTag; // Registers a receiver interface and returns an opaque tag for later unsubscription.
procedure Unadvise(Tag: TTag); // Unregisters a specific receiver using the tag obtained from Advise.
procedure UnadviseAll; // Unregisters all currently advised receivers.
procedure Lock; inline; // Acquires an exclusive lock for thread-safe operations on the list.
procedure Release; inline;// Releases the previously acquired exclusive lock.
function IsLocked: Boolean; inline; // Checks if the list is currently locked by any thread.
procedure Notify(Func: TPredicate<T>); // Iterates through registered receivers and invokes the predicate; removes receiver if predicate returns false.
end;
implementation
@@ -69,9 +67,6 @@ var
begin
Assert( IsLocked );
if IsFinalized then
exit( 0 );
if FFirst=0 then
begin
IInterface( FFirst ) := Receiver;
@@ -108,13 +103,6 @@ begin
Result := AllocMem( sizeof( TItem ) );
end;
procedure TMycNotifyList<T>.Finalize;
begin
Assert( IsLocked );
UnadviseAll;
FFirst := FFirst or 2;
end;
class procedure TMycNotifyList<T>.FreeItem(Item: PItem);
begin
FreeMem( Item, sizeof( TItem ) );
@@ -125,20 +113,12 @@ begin
Result := FFirst and 1 = 0;
end;
function TMycNotifyList<T>.IsFinalized: Boolean;
begin
Result := FFirst and 2 <> 0;
end;
procedure TMycNotifyList<T>.Notify(Func: TPredicate<T>);
var
Item, P: PItem;
begin
Assert( IsLocked );
if IsFinalized then
exit;
if FFirst<>0 then
if not Func( IInterface( FFirst ) ) then
IInterface( FFirst ) := nil;
@@ -165,15 +145,15 @@ var
begin
Assert( IsLocked );
if IsFinalized then
exit;
if NativeUInt(Tag) = FFirst then
begin
IInterface( FFirst ) := nil;
exit;
end;
if FList = nil then
exit;
Item := PItem( Tag );
if Item = FList then
@@ -193,9 +173,6 @@ procedure TMycNotifyList<T>.UnadviseAll;
begin
Assert( IsLocked );
if IsFinalized then
exit;
IInterface( FFirst ) := nil;
while FList<>nil do
Unadvise( TTag( FList ) );
Src/Myc.Core.Tasks.pas
+382
View File
@@ -0,0 +1,382 @@
unit Myc.Core.Tasks;
interface
uses
System.SysUtils, System.Classes, System.SyncObjs,
Myc.Core.Atomic, Myc.Signals;
type
IMycTaskFactory = interface
{$region 'property access'}
function GetThreadCount: Integer;
{$endregion}
function CreateThread(const Proc: TProc): IMycState;
function InMainThread: Boolean;
function InWorkerThread: Boolean;
function Run(StartCount: Integer; Job: TProc): IMycSubscriber;
procedure Teardown;
procedure WaitFor(State: IMycState);
property ThreadCount: Integer read GetThreadCount;
end;
TMycTaskFactory = class(TInterfacedObject, IMycTaskFactory)
type
ETaskException = class(Exception) end;
private
[volatile]
FException: TObject; // Holds the first exception object from a worker thread
[volatile]
FTerminated: Integer; // Flag to signal worker threads to terminate
[volatile]
FThreadsRunning: Integer; // Counter for active worker threads
FWaitSemaphores: TMycAtomicStack<TSemaphore>; // Pool of semaphores for WaitFor
FWorkGate: TSemaphore; // Semaphore to signal available work to worker threads
FWorkStack: TMycAtomicStack<TProc>; // Stack of pending jobs
FWorkThreads: TArray<TThread>; // Array of worker threads
procedure WorkerThread;
protected
procedure EnqueueJob(const Job: TProc);
procedure ExecuteJob;
function GetThreadCount: Integer;
property WaitSemaphores: TMycAtomicStack<TSemaphore> read FWaitSemaphores;
public
constructor Create;
destructor Destroy; override;
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 WaitFor(State: IMycState);
procedure Teardown;
function InMainThread: Boolean;
function InWorkerThread: Boolean;
end;
implementation
type
TMyc2PendingJob = 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
protected
function Notify: Boolean;
public
constructor Create(StartCountValue: Integer; OwnerTaskFactory: TMycTaskFactory; const JobProc: TProc);
property Owner: TMycTaskFactory read FOwner;
end;
TMyc2TaskWait = class sealed(TInterfacedObject, IMycSubscriber)
private
[volatile]
FSemaphore: TSemaphore; // Semaphore to be released on notification
protected
function Notify: Boolean;
public
constructor Create(SemaphoreToSignal: TSemaphore);
end;
{ TMycTaskFactory }
constructor TMycTaskFactory.Create;
var
i: Integer;
begin
inherited Create;
Assert(InMainThread); // Ensure factory is created in the main thread
FWorkGate := TSemaphore.Create(nil, 0, MaxInt, ''); // Initial count is 0, workers will wait
SetLength(FWorkThreads, TThread.ProcessorCount); // Create one thread per processor core
for i := 0 to High(FWorkThreads) do
begin
FWorkThreads[i] := CreateAnonymousThread('Thread pool [' + IntToStr(i) + ']', WorkerThread);
TInterlocked.Increment(FThreadsRunning); // Increment active thread counter
FWorkThreads[i].Start;
end;
end;
destructor TMycTaskFactory.Destroy;
begin
Teardown; // Perform cleanup and stop threads
FWorkGate.Free;
// FException is an acquired exception object, should not be freed manually.
// If FException <> nil here, it means an unhandled exception was not processed by HandleException.
// FException := nil; // Optionally nil it out if necessary for state clarity
inherited Destroy;
end;
class function TMycTaskFactory.CreateAnonymousThread(const DbgName: String; const Proc: TProc): TThread;
{$IFDEF MSWINDOWS}
{$WARN SYMBOL_PLATFORM OFF}
var
prio: TThreadPriority;
{$ENDIF MSWINDOWS}
begin
Result := TThread.CreateAnonymousThread(Proc);
{$IFDEF MSWINDOWS}
// Set priority lower than MainThread priority if created from main thread
if TThread.CurrentThread.ThreadID = MainThreadID then
begin
prio := TThread.CurrentThread.Priority;
if prio > Low(TThreadPriority) then
prio := TThreadPriority(Ord(prio) - 1); // Decrease priority by one step
Result.Priority := prio;
end;
{$ENDIF MSWINDOWS}
if DbgName <> '' then
Result.NameThreadForDebugging(DbgName); // Set thread name for debugging
end;
function TMycTaskFactory.CreateThread(const Proc: TProc): IMycState;
var
res: IMycSemaphore;
capturedProc: TProc;
begin
res := Signals.CreateSemaphore(1); // Create a semaphore that will be signaled when the proc finishes
capturedProc := Proc; // Capture Proc for the anonymous method
CreateAnonymousThread('Thread',
procedure
begin
try
capturedProc(); // Execute the provided procedure
finally
capturedProc := nil; // Clear the captured proc
res.Notify; // Signal completion
end;
end).Start;
exit(res.State); // Return the state interface of the semaphore
end;
procedure TMycTaskFactory.EnqueueJob(const Job: TProc);
begin
if Assigned(Job) then
begin
FWorkStack.Push(Job); // Push job onto the lock-free stack
FWorkGate.Release; // Signal a worker thread that a job is available
end;
end;
procedure TMycTaskFactory.WorkerThread;
begin
try
repeat
FWorkGate.Acquire; // Wait for a job to be available or for termination
if FTerminated = 0 then // Check if termination has been requested
ExecuteJob; // Execute a job from the stack
until FTerminated <> 0; // Loop until termination is signaled
finally
TInterlocked.Decrement(FThreadsRunning); // Decrement active thread counter
end;
end;
function TMycTaskFactory.GetThreadCount: Integer;
begin
Result := Length(FWorkThreads);
end;
procedure TMycTaskFactory.HandleException;
var
ex: TObject;
begin
if InMainThread then
begin
ex := AtomicExchange(Pointer(FException), nil); // Atomically retrieve and clear the stored exception
if ex <> nil then
raise ex; // Re-raise the exception in the main thread
end;
end;
function TMycTaskFactory.InMainThread: Boolean;
begin
Result := TThread.Current.ThreadID = MainThreadID;
end;
function TMycTaskFactory.InWorkerThread: Boolean;
var
currentThreadId: TThreadID;
i: Integer;
begin
currentThreadId := TThread.Current.ThreadID;
if currentThreadId = MainThreadID then
exit(false); // Not a worker thread if it's the main thread
for i := 0 to High(FWorkThreads) do
if FWorkThreads[i].ThreadID = currentThreadId then
exit(true); // Current thread is one of the worker threads
exit(false); // Not found in worker thread list
end;
function TMycTaskFactory.Run(StartCount: Integer; Job: TProc): IMycSubscriber;
begin
if FTerminated <> 0 then
raise ETaskException.Create('Task factory terminated');
if not Assigned(Job) then
exit(Signals.Null); // Return a null subscriber if no job is provided
if StartCount <= 0 then
begin
EnqueueJob(Job); // Enqueue immediately if no countdown needed
Result := Signals.Null;
end
else
// Create a pending job that waits for StartCount notifications
Result := TMyc2PendingJob.Create(StartCount, Self, Job);
end;
procedure TMycTaskFactory.Teardown;
var
i: Integer;
s: TSemaphore;
job: TProc; // Variable to receive popped job to ensure it's processed/discarded
begin
HandleException; // Process any pending exception before shutdown
if TInterlocked.Exchange(FTerminated, 1) <> 0 then
exit; // Ensure teardown runs only once
// Release the work gate for each thread so they can wake up and terminate
for i := 0 to High(FWorkThreads) do
FWorkGate.Release;
// Wait for all worker threads to finish
TSpinWait.SpinUntil(
function: Boolean
begin
Result := FThreadsRunning = 0;
end);
Assert(FThreadsRunning = 0); // Verify all threads have terminated
// Clear any remaining jobs from the work stack (these will not be executed)
repeat
job := FWorkStack.Pop();
until not Assigned(job);
// Clear and free semaphores from the wait semaphore pool
s := FWaitSemaphores.Pop;
while s <> nil do
begin
s.Free;
s := FWaitSemaphores.Pop;
end;
end;
procedure TMycTaskFactory.WaitFor(State: IMycState);
var
lock: TSemaphore;
begin
// If the state is already set, we are NOT allowed to wait.
if State.IsSet then
exit;
if InWorkerThread then
raise ETaskException.Create('Waiting not allowed within tasks'); // Prevent deadlocks
lock := FWaitSemaphores.Pop(); // Try to get a semaphore from the pool
if lock = nil then
lock := TSemaphore.Create(nil, 0, 1, ''); // Create new one if pool is empty (initial count 0)
try
// Subscribe a temporary waiter that will release the lock when the state is signaled
var subscription := State.Subscribe(TMyc2TaskWait.Create(lock));
lock.Acquire; // Wait until the lock is released
finally
// The lock is now signaled (count 0 after Acquire). Push it back to the pool for reuse.
FWaitSemaphores.Push(lock);
end;
HandleException; // Check for exceptions that might have occurred in worker threads during the wait
end;
procedure TMycTaskFactory.ExecuteJob;
var
job: TProc;
begin
job := FWorkStack.Pop(); // Pop a job from the stack
if Assigned(job) then
begin
try
job(); // Execute the job
except
// If no exception has been captured yet, capture this one
if FException = nil then
FException := AcquireExceptionObject; // Store the exception object to be raised in the main thread
// Else: an exception is already pending, this one is ignored to keep the first one.
end;
end;
end;
{ TMyc2PendingJob }
constructor TMyc2PendingJob.Create(StartCountValue: Integer; OwnerTaskFactory: TMycTaskFactory; const JobProc: TProc);
begin
inherited Create;
Assert(StartCountValue > 0); // StartCount must be positive
FCount := StartCountValue;
FOwner := OwnerTaskFactory;
FJob := JobProc;
end;
function TMyc2PendingJob.Notify: Boolean;
var
newCount: Integer;
begin
newCount := TInterlocked.Decrement(FCount); // Atomically decrement the counter
// Defend against extreme underflow, though ideally FCount should not go far below zero.
if newCount < -MaxInt div 2 then
TInterlocked.Increment(FCount);
if newCount = 0 then // If counter reaches exactly zero
begin
// FOwner and FJob are captured by the class instance
if Assigned(FOwner) and Assigned(FJob) then // Ensure owner and job are still valid
begin
FOwner.EnqueueJob(FJob); // Enqueue the job
FJob := nil; // Clear the job reference to prevent re-enqueuing and allow ARC
end;
end;
Result := newCount > 0; // Returns true if further notifications are expected (count is still positive)
end;
{ TMyc2TaskWait }
constructor TMyc2TaskWait.Create(SemaphoreToSignal: TSemaphore);
begin
inherited Create;
FSemaphore := SemaphoreToSignal;
end;
function TMyc2TaskWait.Notify: Boolean;
var
s: TSemaphore;
begin
// Atomically exchange FSemaphore with nil to ensure Release is called only once
s := TInterlocked.Exchange<TSemaphore>(FSemaphore, nil);
if s <> nil then
s.Release; // Release the semaphore, unblocking the waiting thread
Result := false; // No further notifications expected from this subscriber
end;
initialization
IsMultiThread := true; // Mark the application as multi-threaded
end.
Src/Myc.Signals.pas
+84 -73
View File
@@ -20,11 +20,12 @@ type
FSignal: TMycSignal;
FTag: TMycNotifyList<IMycSubscriber>.TTag;
public
procedure Setup(ASignal: TMycSignal; ATag: TMycNotifyList<IMycSubscriber>.TTag); inline;
class operator Assign(var Dest: TMycSubscription; const [ref] Src:
TMycSubscription);
class operator Initialize(out Dest: TMycSubscription);
class operator Finalize(var Dest: TMycSubscription);
class operator Assign(var Dest: TMycSubscription; const [ref] Src: TMycSubscription);
procedure Setup(ASignal: TMycSignal; ATag: TMycNotifyList<IMycSubscriber>.TTag); inline;
procedure Unsubscribe;
end;
IMycSignal = interface
@@ -32,18 +33,9 @@ type
end;
TMycSignal = class abstract( TInterfacedObject, IMycSignal )
strict private
FSubscribers: TMycNotifyList<IMycSubscriber>;
private
procedure Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
protected
procedure Lock;
procedure Unlock;
procedure Finalize;
procedure Notify;
public
function Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
property Subscribers: TMycNotifyList<IMycSubscriber> read FSubscribers;
function Subscribe(const Subscriber: IMycSubscriber): TMycSubscription; virtual; abstract;
procedure Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag); virtual; abstract;
end;
IMycState = interface( IMycSignal )
@@ -61,18 +53,28 @@ type
end;
TMycSemaphore = class(TMycSignal, IMycSemaphore, IMycState)
strict private
FSubscribers: TMycNotifyList<IMycSubscriber>;
private
[volatile] FCount: Integer;
function GetState: IMycState;
function GetIsSet: Boolean;
protected
function Notify: Boolean;
public
constructor Create(ACount: Integer);
destructor Destroy; override;
function Subscribe(const Subscriber: IMycSubscriber): TMycSubscription; override;
procedure Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag); override;
function Notify: Boolean;
end;
Signals = record
strict private
class var
FNull: IMycSemaphore;
class constructor Create;
public
class function CreateSemaphore(Count: Integer): IMycSemaphore; static;
class property Null: IMycSemaphore read FNull;
end;
implementation
@@ -80,63 +82,23 @@ implementation
uses
System.SyncObjs;
procedure TMycSignal.Finalize;
begin
FSubscribers.Finalize;
end;
procedure TMycSignal.Lock;
begin
FSubscribers.Lock;
end;
procedure TMycSignal.Notify;
begin
FSubscribers.Notify(
function( Subscriber: IMycSubscriber ): Boolean
begin
Result := Subscriber.Notify;
end );
end;
function TMycSignal.Subscribe(const Subscriber: IMycSubscriber): TMycSubscription;
begin
if not Assigned(Subscriber) then
exit;
FSubscribers.Lock;
try
Result.Setup( Self, FSubscribers.Advise( Subscriber ) );
finally
FSubscribers.Release;
end;
end;
procedure TMycSignal.Unlock;
begin
end;
procedure TMycSignal.Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
begin
if Tag=nil then
exit;
FSubscribers.Lock;
try
FSubscribers.Unadvise( Tag );
finally
FSubscribers.Release;
end;
end;
procedure TMycSubscription.Setup(ASignal: TMycSignal; ATag:
TMycNotifyList<IMycSubscriber>.TTag);
begin
Unsubscribe;
FSignal := ASignal;
FTag := ATag;
end;
procedure TMycSubscription.Unsubscribe;
begin
if FTag<>nil then
begin
FSignal.Unsubscribe( FTag );
FTag := nil;
end;
end;
class operator TMycSubscription.Assign(var Dest: TMycSubscription; const [ref]
Src: TMycSubscription);
begin
@@ -150,33 +112,42 @@ end;
class operator TMycSubscription.Finalize(var Dest: TMycSubscription);
begin
if Dest.FTag=nil then
exit;
Dest.FSignal.Unsubscribe( Dest.FTag );
Dest.Unsubscribe;
end;
constructor TMycSemaphore.Create(ACount: Integer);
begin
inherited Create;
FCount := ACount;
FSubscribers.Create;
end;
destructor TMycSemaphore.Destroy;
begin
FSubscribers.Destroy;
inherited;
end;
function TMycSemaphore.Notify: Boolean;
begin
Lock;
FSubscribers.Lock;
try
var n := TInterlocked.Decrement( FCount );
if n < -MaxInt div 2 then
TInterlocked.Increment( FCount );
if n = 0 then
Notify;
FSubscribers.Notify(
function( Subscriber: IMycSubscriber ): Boolean
begin
Result := Subscriber.Notify;
end );
Result := n > 0;
if not Result then
Finalize;
FSubscribers.UnadviseAll;
finally
Release;
FSubscribers.Release;
end;
end;
@@ -190,6 +161,46 @@ begin
exit( Self );
end;
function TMycSemaphore.Subscribe(const Subscriber: IMycSubscriber):
TMycSubscription;
begin
if not Assigned(Subscriber) then
exit;
Subscriber._AddRef;
try
FSubscribers.Lock;
try
if FCount <= 0 then
Subscriber.Notify
else
Result.Setup( Self, FSubscribers.Advise( Subscriber ) );
finally
FSubscribers.Release;
end;
finally
Subscriber._Release;
end;
end;
procedure TMycSemaphore.Unsubscribe(Tag: TMycNotifyList<IMycSubscriber>.TTag);
begin
if Tag=nil then
exit;
FSubscribers.Lock;
try
FSubscribers.Unadvise( Tag );
finally
FSubscribers.Release;
end;
end;
class constructor Signals.Create;
begin
FNull := TMycSemaphore.Create( 0 );
end;
{ Signals }
class function Signals.CreateSemaphore(Count: Integer): IMycSemaphore;