client/3.0/FB30Events.pas

(*
 *  Firebird Interface (fbintf). The fbintf components provide a set of
 *  Pascal language bindings for the Firebird API.
 *
 *  The contents of this file are subject to the Initial Developer's
 *  Public License Version 1.0 (the "License"); you may not use this
 *  file except in compliance with the License. You may obtain a copy
 *  of the License here:
 *
 *    http://www.firebirdsql.org/index.php?op=doc&id=idpl
 *
 *  Software distributed under the License is distributed on an "AS
 *  IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 *  implied. See the License for the specific language governing rights
 *  and limitations under the License.
 *
 *  The Initial Developer of the Original Code is Tony Whyman.
 *
 *  The Original Code is (C) 2016 Tony Whyman, MWA Software
 *  (http://www.mwasoftware.co.uk).
 *
 *  All Rights Reserved.
 *
 *  Contributor(s): ______________________________________.
 *
*)
unit FB30Events;
{$IFDEF MSWINDOWS} 
{$DEFINE WINDOWS} 
{$ENDIF}

{$IFDEF FPC}
{$mode delphi}
{$interfaces COM}
{$ENDIF}

interface

uses
  {$IFDEF WINDOWS}Windows, {$ENDIF} Classes, SysUtils, Firebird, IB, FB30ClientAPI, FB30Attachment,
  syncobjs, FBEvents;

type
  TFB30Events = class;

  { TEventhandlerInterface }

  TEventhandlerInterface = class(Firebird.IEventCallbackImpl)
  private
    FOwner: TFB30Events;
    FName: AnsiString;
    FRef: integer;
    {$IFDEF WINDOWS}
    {Make direct use of Windows API as TEventObject don't seem to work under
     Windows!}
    FEventHandler: THandle;
    {$ELSE}
    FEventWaiting: TEventObject;
    {$ENDIF}
  public
    constructor Create(aOwner: TFB30Events; aName: AnsiString);
    destructor Destroy; override;
    procedure addRef();  override;
    function release(): Integer; override;
    procedure eventCallbackFunction(length: Cardinal; events: BytePtr); override;
    procedure WaitForEvent;
    procedure CancelWait;
 end;

  { TFB30Events }

  TFB30Events = class(TFBEvents,IEvents)
  private
    FAttachmentIntf: Firebird.IAttachment;
    FEventHandlerThread: TObject;
    FEventsIntf: Firebird.IEvents;
    FAsyncEventCallback: TEventhandlerInterface;
    FSyncEventCallback: TEventhandlerInterface;
    procedure InternalAsyncWaitForEvent(EventHandler: TEventHandler; EventCallBack: TEventhandlerInterface);
    procedure ReleaseIntf;
  protected
    procedure CancelEvents(Force: boolean = false); override;
    function GetIEvents: IEvents; override;
  public
    constructor Create(DBAttachment: TFB30Attachment; Events: TStrings);
    destructor Destroy; override;

    {IEvents}
    procedure WaitForEvent;
    procedure AsyncWaitForEvent(EventHandler: TEventHandler); override;
  end;

implementation

uses  FBMessages, FBClientAPI;

type
  { TEventHandlerThread }

  TEventHandlerThread = class(TThread)
  private
    FOwner: TFB30Events;
    FEventHandler: TEventhandlerInterface;
  protected
    procedure Execute; override;
  public
    constructor Create(Owner: TFB30Events; EventHandler: TEventhandlerInterface);
    procedure Terminate;
  end;

constructor TEventhandlerInterface.Create(aOwner: TFB30Events; aName: AnsiString);
var
  PSa : PSecurityAttributes;
{$IFDEF WINDOWS}
  Sd : TSecurityDescriptor;
  Sa : TSecurityAttributes;
begin
  InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
  SetSecurityDescriptorDacl(@Sd,true,nil,false);
  Sa.nLength := SizeOf(Sa);
  Sa.lpSecurityDescriptor := @Sd;
  Sa.bInheritHandle := true;
  PSa := @Sa;
{$ELSE}
  GUID : TGUID;
begin
  PSa:= nil;
{$ENDIF}
  inherited Create;
{$IFDEF WINDOWS}
  FEventHandler := CreateEvent(PSa,false,false,nil);
{$ELSE}
  CreateGuid(GUID);
  FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
{$ENDIF}
  FOWner := aOwner;
  FName := aName;
  addRef;
end;

destructor TEventhandlerInterface.Destroy;
begin
{$IFDEF WINDOWS}
  CloseHandle(FEventHandler);
{$ELSE}
  if assigned(FEventWaiting) then FEventWaiting.Free;
{$ENDIF}
  inherited Destroy;
end;

procedure TEventhandlerInterface.addRef;
begin
  Inc(FRef);
//  writeln(FName,': ref count = ',FRef);
end;

function TEventhandlerInterface.release: Integer;
begin
  Dec(FRef);
//  writeln(FName,': ref count = ',FRef);
  if FRef = 0 then Free;
  Result := FRef;
end;

procedure TEventhandlerInterface.eventCallbackFunction(length: Cardinal;
  events: BytePtr);
begin
//  writeln('TEventhandlerInterface: Event Callback');
  FOwner.FCriticalSection.Enter;
  try
    if FOwner.FResultBuffer <> nil then
      Move(events^, FOwner.FResultBuffer^, Length);
  finally
    FOwner.FCriticalSection.Leave
  end;
  //writeln('TEventhandlerInterface: Set Event Called');
  {$IFDEF WINDOWS}
  SetEvent(FEventHandler);
  {$ELSE}
  FEventWaiting.SetEvent;
  {$ENDIF}
end;

procedure TEventhandlerInterface.WaitForEvent;
begin
//  writeln('TEventhandlerInterface: Start Event Wait');
  {$IFDEF WINDOWS}
  WaitForSingleObject(FEventHandler,INFINITE);
  {$ELSE}
  FEventWaiting.WaitFor(INFINITE);
  {$ENDIF}
//  writeln('TEventhandlerInterface: Event Wait Ends');
end;

procedure TEventhandlerInterface.CancelWait;
begin
  {$IFDEF WINDOWS}
    SetEvent(FEventHandler);
  {$ELSE}
    FEventWaiting.SetEvent;
  {$ENDIF}
end;

 { TEventHandlerThread }

procedure TEventHandlerThread.Execute;
begin
  while not Terminated do
  begin
    FEventHandler.WaitForEvent;

    if not Terminated  then
      FOwner.EventSignaled;
  end;
end;

constructor TEventHandlerThread.Create(Owner: TFB30Events;
  EventHandler: TEventhandlerInterface);
begin
  inherited Create(false);
  FOwner := Owner;
  FEventHandler := EventHandler;
  FreeOnTerminate := true;
end;

procedure TEventHandlerThread.Terminate;
begin
  inherited Terminate;
  FEventHandler.CancelWait;
end;

  { TFB30Events }

procedure TFB30Events.CancelEvents(Force: boolean);
begin
  FCriticalSection.Enter;
  try
    if not FInWaitState then Exit;
    if FEventsIntf <> nil then
    with Firebird30ClientAPI do
    begin
      FEventsIntf.Cancel(StatusIntf);
      if not Force then
        Check4DataBaseError;
    end;
    FInWaitState := false;
    ReleaseIntf;
    inherited CancelEvents(Force);
  finally
    FCriticalSection.Leave
  end;
end;

function TFB30Events.GetIEvents: IEvents;
begin
  Result := self;
end;

procedure TFB30Events.InternalAsyncWaitForEvent(EventHandler: TEventHandler;
  EventCallBack: TEventhandlerInterface);
begin
  FCriticalSection.Enter;
  try
    if FInWaitState then
      IBError(ibxeInEventWait,[nil]);

    FEventHandler := EventHandler;
    ReleaseIntf;
    with Firebird30ClientAPI do
    begin
      FEventsIntf := FAttachmentIntf.queEvents(
                                StatusIntf,EventCallBack,
                                FEventBufferLen, BytePtr(FEventBuffer));
      Check4DataBaseError;
    end;
    FInWaitState := true;

  finally
    FCriticalSection.Leave
  end;
end;

procedure TFB30Events.ReleaseIntf;
begin
  if FEventsIntf <> nil then
    FEventsIntf.release;
  FEventsIntf := nil;
end;

constructor TFB30Events.Create(DBAttachment: TFB30Attachment; Events: TStrings);
begin
  inherited Create(DBAttachment,DBAttachment,Events);
  FAttachmentIntf := DBAttachment.AttachmentIntf;
  FSyncEventCallback := TEventhandlerInterface.Create(self,'Sync');
end;

destructor TFB30Events.Destroy;
begin
  CancelEvents(true);
  if assigned(FEventHandlerThread) then
    TEventHandlerThread(FEventHandlerThread).Terminate;
  if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
  if assigned(FSyncEventCallback) then TEventhandlerInterface(FSyncEventCallback).release;
  ReleaseIntf;
  inherited Destroy;
end;

procedure TFB30Events.AsyncWaitForEvent(EventHandler: TEventHandler);
begin
  {Seems like we have to create a new callback object each time to avoid empty events}
  if assigned(FEventHandlerThread) then
    TEventHandlerThread(FEventHandlerThread).Terminate;
  if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
  FAsyncEventCallback := TEventhandlerInterface.Create(self,'Async');
  FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
  InternalAsyncWaitForEvent(EventHandler,FAsyncEventCallback);
end;

procedure TFB30Events.WaitForEvent;
begin
  InternalAsyncWaitForEvent(nil,FSyncEventCallback);
  FSyncEventCallback.WaitForEvent;
end;

end.

Revision:	56
Committed:	Mon Mar 6 10:20:02 2017 UTC (7 years, 1 month ago) by tony
Content type:	text/x-pascal
Original Path:	*ibx/trunk/fbintf/client/3.0/FB30Events.pas*
File size:	8316 byte(s)
Log Message:	Committing updates for Trunk
#	User	Rev	Content
1	tony	45	(*
2			* Firebird Interface (fbintf). The fbintf components provide a set of
3			* Pascal language bindings for the Firebird API.
4			*
5			* The contents of this file are subject to the Initial Developer's
6			* Public License Version 1.0 (the "License"); you may not use this
7			* file except in compliance with the License. You may obtain a copy
8			* of the License here:
9			*
10			* http://www.firebirdsql.org/index.php?op=doc&id=idpl
11			*
12			* Software distributed under the License is distributed on an "AS
13			* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
14			* implied. See the License for the specific language governing rights
15			* and limitations under the License.
16			*
17			* The Initial Developer of the Original Code is Tony Whyman.
18			*
19			* The Original Code is (C) 2016 Tony Whyman, MWA Software
20			* (http://www.mwasoftware.co.uk).
21			*
22			* All Rights Reserved.
23			*
24			* Contributor(s): ______________________________________.
25			*
26			*)
27			unit FB30Events;
28	tony	56	{$IFDEF MSWINDOWS}
29			{$DEFINE WINDOWS}
30			{$ENDIF}
31	tony	45
32			{$IFDEF FPC}
33	tony	56	{$mode delphi}
34	tony	45	{$interfaces COM}
35			{$ENDIF}
36
37			interface
38
39			uses
40			{$IFDEF WINDOWS}Windows, {$ENDIF} Classes, SysUtils, Firebird, IB, FB30ClientAPI, FB30Attachment,
41			syncobjs, FBEvents;
42
43			type
44			TFB30Events = class;
45
46			{ TEventhandlerInterface }
47
48			TEventhandlerInterface = class(Firebird.IEventCallbackImpl)
49			private
50			FOwner: TFB30Events;
51	tony	56	FName: AnsiString;
52	tony	45	FRef: integer;
53			{$IFDEF WINDOWS}
54			{Make direct use of Windows API as TEventObject don't seem to work under
55			Windows!}
56			FEventHandler: THandle;
57			{$ELSE}
58			FEventWaiting: TEventObject;
59			{$ENDIF}
60			public
61	tony	56	constructor Create(aOwner: TFB30Events; aName: AnsiString);
62	tony	45	destructor Destroy; override;
63			procedure addRef(); override;
64			function release(): Integer; override;
65			procedure eventCallbackFunction(length: Cardinal; events: BytePtr); override;
66			procedure WaitForEvent;
67			procedure CancelWait;
68			end;
69
70			{ TFB30Events }
71
72			TFB30Events = class(TFBEvents,IEvents)
73			private
74			FAttachmentIntf: Firebird.IAttachment;
75			FEventHandlerThread: TObject;
76			FEventsIntf: Firebird.IEvents;
77			FAsyncEventCallback: TEventhandlerInterface;
78			FSyncEventCallback: TEventhandlerInterface;
79			procedure InternalAsyncWaitForEvent(EventHandler: TEventHandler; EventCallBack: TEventhandlerInterface);
80			procedure ReleaseIntf;
81			protected
82			procedure CancelEvents(Force: boolean = false); override;
83			function GetIEvents: IEvents; override;
84			public
85			constructor Create(DBAttachment: TFB30Attachment; Events: TStrings);
86			destructor Destroy; override;
87
88			{IEvents}
89			procedure WaitForEvent;
90	tony	47	procedure AsyncWaitForEvent(EventHandler: TEventHandler); override;
91	tony	45	end;
92
93			implementation
94
95			uses FBMessages, FBClientAPI;
96
97			type
98			{ TEventHandlerThread }
99
100			TEventHandlerThread = class(TThread)
101			private
102			FOwner: TFB30Events;
103			FEventHandler: TEventhandlerInterface;
104			protected
105			procedure Execute; override;
106			public
107			constructor Create(Owner: TFB30Events; EventHandler: TEventhandlerInterface);
108			procedure Terminate;
109			end;
110
111	tony	56	constructor TEventhandlerInterface.Create(aOwner: TFB30Events; aName: AnsiString);
112	tony	45	var
113			PSa : PSecurityAttributes;
114			{$IFDEF WINDOWS}
115			Sd : TSecurityDescriptor;
116			Sa : TSecurityAttributes;
117			begin
118			InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
119			SetSecurityDescriptorDacl(@Sd,true,nil,false);
120			Sa.nLength := SizeOf(Sa);
121			Sa.lpSecurityDescriptor := @Sd;
122			Sa.bInheritHandle := true;
123			PSa := @Sa;
124			{$ELSE}
125			GUID : TGUID;
126			begin
127			PSa:= nil;
128			{$ENDIF}
129			inherited Create;
130			{$IFDEF WINDOWS}
131	tony	47	FEventHandler := CreateEvent(PSa,false,false,nil);
132	tony	45	{$ELSE}
133			CreateGuid(GUID);
134			FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
135			{$ENDIF}
136			FOWner := aOwner;
137			FName := aName;
138			addRef;
139			end;
140
141			destructor TEventhandlerInterface.Destroy;
142			begin
143			{$IFDEF WINDOWS}
144			CloseHandle(FEventHandler);
145			{$ELSE}
146			if assigned(FEventWaiting) then FEventWaiting.Free;
147			{$ENDIF}
148			inherited Destroy;
149			end;
150
151			procedure TEventhandlerInterface.addRef;
152			begin
153			Inc(FRef);
154			// writeln(FName,': ref count = ',FRef);
155			end;
156
157			function TEventhandlerInterface.release: Integer;
158			begin
159			Dec(FRef);
160			// writeln(FName,': ref count = ',FRef);
161			if FRef = 0 then Free;
162			Result := FRef;
163			end;
164
165			procedure TEventhandlerInterface.eventCallbackFunction(length: Cardinal;
166			events: BytePtr);
167			begin
168	tony	56	// writeln('TEventhandlerInterface: Event Callback');
169	tony	45	FOwner.FCriticalSection.Enter;
170			try
171			if FOwner.FResultBuffer <> nil then
172	tony	56	Move(events^, FOwner.FResultBuffer^, Length);
173	tony	45	finally
174			FOwner.FCriticalSection.Leave
175			end;
176	tony	56	//writeln('TEventhandlerInterface: Set Event Called');
177	tony	47	{$IFDEF WINDOWS}
178			SetEvent(FEventHandler);
179			{$ELSE}
180			FEventWaiting.SetEvent;
181			{$ENDIF}
182	tony	45	end;
183
184			procedure TEventhandlerInterface.WaitForEvent;
185			begin
186	tony	56	// writeln('TEventhandlerInterface: Start Event Wait');
187	tony	45	{$IFDEF WINDOWS}
188			WaitForSingleObject(FEventHandler,INFINITE);
189			{$ELSE}
190			FEventWaiting.WaitFor(INFINITE);
191			{$ENDIF}
192	tony	56	// writeln('TEventhandlerInterface: Event Wait Ends');
193	tony	45	end;
194
195			procedure TEventhandlerInterface.CancelWait;
196			begin
197			{$IFDEF WINDOWS}
198			SetEvent(FEventHandler);
199			{$ELSE}
200			FEventWaiting.SetEvent;
201			{$ENDIF}
202			end;
203
204			{ TEventHandlerThread }
205
206			procedure TEventHandlerThread.Execute;
207			begin
208			while not Terminated do
209			begin
210			FEventHandler.WaitForEvent;
211
212			if not Terminated then
213			FOwner.EventSignaled;
214			end;
215			end;
216
217			constructor TEventHandlerThread.Create(Owner: TFB30Events;
218			EventHandler: TEventhandlerInterface);
219			begin
220	tony	56	inherited Create(false);
221	tony	45	FOwner := Owner;
222			FEventHandler := EventHandler;
223			FreeOnTerminate := true;
224			end;
225
226			procedure TEventHandlerThread.Terminate;
227			begin
228			inherited Terminate;
229			FEventHandler.CancelWait;
230			end;
231
232			{ TFB30Events }
233
234			procedure TFB30Events.CancelEvents(Force: boolean);
235			begin
236			FCriticalSection.Enter;
237			try
238			if not FInWaitState then Exit;
239			if FEventsIntf <> nil then
240			with Firebird30ClientAPI do
241			begin
242			FEventsIntf.Cancel(StatusIntf);
243			if not Force then
244			Check4DataBaseError;
245			end;
246			FInWaitState := false;
247			ReleaseIntf;
248			inherited CancelEvents(Force);
249			finally
250			FCriticalSection.Leave
251			end;
252			end;
253
254			function TFB30Events.GetIEvents: IEvents;
255			begin
256			Result := self;
257			end;
258
259			procedure TFB30Events.InternalAsyncWaitForEvent(EventHandler: TEventHandler;
260			EventCallBack: TEventhandlerInterface);
261			begin
262			FCriticalSection.Enter;
263			try
264			if FInWaitState then
265			IBError(ibxeInEventWait,[nil]);
266
267			FEventHandler := EventHandler;
268			ReleaseIntf;
269			with Firebird30ClientAPI do
270			begin
271			FEventsIntf := FAttachmentIntf.queEvents(
272			StatusIntf,EventCallBack,
273			FEventBufferLen, BytePtr(FEventBuffer));
274			Check4DataBaseError;
275			end;
276			FInWaitState := true;
277
278			finally
279			FCriticalSection.Leave
280			end;
281			end;
282
283			procedure TFB30Events.ReleaseIntf;
284			begin
285			if FEventsIntf <> nil then
286			FEventsIntf.release;
287			FEventsIntf := nil;
288			end;
289
290			constructor TFB30Events.Create(DBAttachment: TFB30Attachment; Events: TStrings);
291			begin
292			inherited Create(DBAttachment,DBAttachment,Events);
293			FAttachmentIntf := DBAttachment.AttachmentIntf;
294			FSyncEventCallback := TEventhandlerInterface.Create(self,'Sync');
295			end;
296
297			destructor TFB30Events.Destroy;
298			begin
299			CancelEvents(true);
300			if assigned(FEventHandlerThread) then
301			TEventHandlerThread(FEventHandlerThread).Terminate;
302			if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
303			if assigned(FSyncEventCallback) then TEventhandlerInterface(FSyncEventCallback).release;
304			ReleaseIntf;
305			inherited Destroy;
306			end;
307
308			procedure TFB30Events.AsyncWaitForEvent(EventHandler: TEventHandler);
309			begin
310	tony	47	{Seems like we have to create a new callback object each time to avoid empty events}
311			if assigned(FEventHandlerThread) then
312			TEventHandlerThread(FEventHandlerThread).Terminate;
313			if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
314			FAsyncEventCallback := TEventhandlerInterface.Create(self,'Async');
315			FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
316	tony	45	InternalAsyncWaitForEvent(EventHandler,FAsyncEventCallback);
317			end;
318
319			procedure TFB30Events.WaitForEvent;
320			begin
321			InternalAsyncWaitForEvent(nil,FSyncEventCallback);
322			FSyncEventCallback.WaitForEvent;
323			end;
324
325			end.
326