client/2.5/FB25Events.pas

(*
 *  Firebird Interface (fbintf). The fbintf components provide a set of
 *  Pascal language bindings for the Firebird API. Although predominantly
 *  a new development they include source code taken from IBX and may be
 *  considered a derived product. This software thus also includes the copyright
 *  notice and license conditions from IBX.
 *
 *  Except for those parts dervied from IBX, 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): ______________________________________.
 *
*)
{************************************************************************}
{                                                                        }
{       Borland Delphi Visual Component Library                          }
{       InterBase Express core components                                }
{                                                                        }
{       Copyright (c) 1998-2000 Inprise Corporation                      }
{                                                                        }
{    InterBase Express is based in part on the product                   }
{    Free IB Components, written by Gregory H. Deatz for                 }
{    Hoagland, Longo, Moran, Dunst & Doukas Company.                     }
{    Free IB Components is used under license.                           }
{                                                                        }
{    The contents of this file are subject to the InterBase              }
{    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 at http://www.Inprise.com/IPL.html }
{    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 Original Code was created by InterBase Software Corporation     }
{       and its successors.                                              }
{    Portions created by Inprise Corporation are Copyright (C) Inprise   }
{       Corporation. All Rights Reserved.                                }
{    Contributor(s): Jeff Overcash                                       }
{                                                                        }
{    IBX For Lazarus (Firebird Express)                                  }
{    Contributor: Tony Whyman, MWA Software http://www.mwasoftware.co.uk }
{    Portions created by MWA Software are copyright McCallum Whyman      }
{    Associates Ltd 2011 - 2015                                                }
{                                                                        }
{************************************************************************}
unit FB25Events;
{$IFDEF MSWINDOWS} 
{$DEFINE WINDOWS} 
{$ENDIF}

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

interface

uses
  {$IFDEF WINDOWS}Windows, {$ENDIF}Classes, SysUtils, IB, FB25ClientAPI, FB25Attachment,
  IBExternals, IBHeader, syncobjs, FBEvents;

type
  TFB25Events = class;

  { TEventhandlerInterface }

  TEventhandlerInterface = class
  private
    FOwner: TFB25Events;
    {$IFDEF WINDOWS}
    {Make direct use of Windows API as TEventObject don't seem to work under
     Windows!}
    FEventHandler: THandle;
    {$ELSE}
    FEventWaiting: TEventObject;
    {$ENDIF}
  public
    constructor Create(aOwner: TFB25Events);
    destructor Destroy; override;
    procedure eventCallbackFunction(length: short; updated: PAnsiChar);
    procedure WaitForEvent;
    procedure CancelWait;
 end;

  { TFB25Events }

  TFB25Events = class(TFBEvents,IEvents)
  private
    FEventID: ISC_LONG;
    FDBHandle: TISC_DB_HANDLE;
    FEventHandlerThread: TObject;
    FAsyncEventCallback: TEventhandlerInterface;
  protected
    procedure CancelEvents(Force: boolean = false); override;
    function GetIEvents: IEvents; override;
  public
    constructor Create(DBAttachment: TFB25Attachment; Events: TStrings);
    destructor Destroy; override;

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

implementation

uses  FBMessages;

type

  { TEventHandlerThread }

  TEventHandlerThread = class(TThread)
  private
    FOwner: TFB25Events;
    FEventHandler: TEventhandlerInterface;
  protected
    procedure Execute; override;
  public
    constructor Create(Owner: TFB25Events; EventHandler: TEventhandlerInterface);
    procedure Terminate;
  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: TFB25Events;
   EventHandler: TEventhandlerInterface);
 begin
   inherited Create(false);
   FOwner := Owner;
   FEventHandler := EventHandler;
   FreeOnTerminate := true;
 end;

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

  {This procedure is used for the event call back - note the cdecl }

 procedure IBEventCallback( ptr: pointer; length: short; updated: PAnsiChar); cdecl;
 begin
   if (ptr = nil) or (length = 0) or (updated = nil) then
     Exit;
   { Handle events asynchronously in second thread }
   TEventhandlerInterface(ptr).eventCallbackFunction(length,updated);
 end;

{ TEventhandlerInterface }

constructor TEventhandlerInterface.Create(aOwner: TFB25Events);
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;
end;

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

procedure TEventhandlerInterface.eventCallbackFunction(length: short;
  updated: PAnsiChar);
begin
  FOwner.FCriticalSection.Enter;
  try
    if FOwner.FResultBuffer <> nil then
      Move(updated[0], FOwner.FResultBuffer[0], length);
  finally
    FOwner.FCriticalSection.Leave
  end;
//  writeln('Set Event');
  {$IFDEF WINDOWS}
  SetEvent(FEventHandler);
  {$ELSE}
  FEventWaiting.SetEvent;
  {$ENDIF}
end;

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

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


  { TFB25Events }

procedure TFB25Events.CancelEvents(Force: boolean);
begin
  FCriticalSection.Enter;
  try
    if not FInWaitState then Exit;
    with Firebird25ClientAPI do
      if (Call(isc_Cancel_events( StatusVector, @FDBHandle, @FEventID),false) > 0) and not Force then
        IBDatabaseError;

    FInWaitState := false;
    inherited CancelEvents(Force);
  finally
    FCriticalSection.Leave
  end;
end;

function TFB25Events.GetIEvents: IEvents;
begin
  Result := self;
end;

constructor TFB25Events.Create(DBAttachment: TFB25Attachment; Events: TStrings);
begin
  inherited Create(DBAttachment,DBAttachment,Events);
  FDBHandle := DBAttachment.Handle;
  FAsyncEventCallback := TEventhandlerInterface.Create(self);
  FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
end;

destructor TFB25Events.Destroy;
begin
  CancelEvents(true);
  if assigned(FEventHandlerThread) then
    TEventHandlerThread(FEventHandlerThread).Terminate;
  if assigned(FAsyncEventCallback) then
    TEventhandlerInterface(FAsyncEventCallback).Free;
  inherited Destroy;
end;

procedure TFB25Events.AsyncWaitForEvent(EventHandler: TEventHandler);
var callback: pointer;
begin
  FCriticalSection.Enter;
  try
    if FInWaitState then
      IBError(ibxeInEventWait,[nil]);

    FEventHandler := EventHandler;
    callback := @IBEventCallback;
    with Firebird25ClientAPI do
      Call(isc_que_events( StatusVector, @FDBHandle, @FEventID, FEventBufferLen,
                     FEventBuffer, TISC_CALLBACK(callback), PVoid(FAsyncEventCallback)));
    FInWaitState := true;
  finally
    FCriticalSection.Leave
  end;
end;

procedure TFB25Events.WaitForEvent;
begin
  if FInWaitState then
    IBError(ibxeInEventWait,[nil]);

  FInWaitState := true;
  try
    with Firebird25ClientAPI do
       Call(isc_wait_for_event(StatusVector,@FDBHandle, FEventBufferlen,FEventBuffer,FResultBuffer));
  finally
    FInWaitState := false;
  end;
end;

end.

Revision:	216
Committed:	Thu Mar 15 17:21:13 2018 UTC (6 years, 1 month ago) by tony
Content type:	text/x-pascal
Original Path:	*ibx/trunk/fbintf/client/2.5/FB25Events.pas*
File size:	9874 byte(s)
Log Message:	Fixes Merged
#	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. Although predominantly
4			* a new development they include source code taken from IBX and may be
5			* considered a derived product. This software thus also includes the copyright
6			* notice and license conditions from IBX.
7			*
8			* Except for those parts dervied from IBX, contents of this file are subject
9			* to the Initial Developer's Public License Version 1.0 (the "License"); you
10			* may not use this file except in compliance with the License. You may obtain a
11			* copy of the License here:
12			*
13			* http://www.firebirdsql.org/index.php?op=doc&id=idpl
14			*
15			* Software distributed under the License is distributed on an "AS
16			* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
17			* implied. See the License for the specific language governing rights
18			* and limitations under the License.
19			*
20			* The Initial Developer of the Original Code is Tony Whyman.
21			*
22			* The Original Code is (C) 2016 Tony Whyman, MWA Software
23			* (http://www.mwasoftware.co.uk).
24			*
25			* All Rights Reserved.
26			*
27			* Contributor(s): ______________________________________.
28			*
29			*)
30			{************************************************************************}
31			{ }
32			{ Borland Delphi Visual Component Library }
33			{ InterBase Express core components }
34			{ }
35			{ Copyright (c) 1998-2000 Inprise Corporation }
36			{ }
37			{ InterBase Express is based in part on the product }
38			{ Free IB Components, written by Gregory H. Deatz for }
39			{ Hoagland, Longo, Moran, Dunst & Doukas Company. }
40			{ Free IB Components is used under license. }
41			{ }
42			{ The contents of this file are subject to the InterBase }
43			{ Public License Version 1.0 (the "License"); you may not }
44			{ use this file except in compliance with the License. You }
45			{ may obtain a copy of the License at http://www.Inprise.com/IPL.html }
46			{ Software distributed under the License is distributed on }
47			{ an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either }
48			{ express or implied. See the License for the specific language }
49			{ governing rights and limitations under the License. }
50			{ The Original Code was created by InterBase Software Corporation }
51			{ and its successors. }
52			{ Portions created by Inprise Corporation are Copyright (C) Inprise }
53			{ Corporation. All Rights Reserved. }
54			{ Contributor(s): Jeff Overcash }
55			{ }
56			{ IBX For Lazarus (Firebird Express) }
57			{ Contributor: Tony Whyman, MWA Software http://www.mwasoftware.co.uk }
58			{ Portions created by MWA Software are copyright McCallum Whyman }
59			{ Associates Ltd 2011 - 2015 }
60			{ }
61			{************************************************************************}
62			unit FB25Events;
63	tony	56	{$IFDEF MSWINDOWS}
64			{$DEFINE WINDOWS}
65			{$ENDIF}
66	tony	45
67			{$IFDEF FPC}
68	tony	56	{$mode delphi}
69	tony	45	{$interfaces COM}
70			{$ENDIF}
71
72			interface
73
74			uses
75			{$IFDEF WINDOWS}Windows, {$ENDIF}Classes, SysUtils, IB, FB25ClientAPI, FB25Attachment,
76	tony	216	IBExternals, IBHeader, syncobjs, FBEvents;
77	tony	45
78			type
79			TFB25Events = class;
80
81			{ TEventhandlerInterface }
82
83			TEventhandlerInterface = class
84			private
85			FOwner: TFB25Events;
86			{$IFDEF WINDOWS}
87			{Make direct use of Windows API as TEventObject don't seem to work under
88			Windows!}
89			FEventHandler: THandle;
90			{$ELSE}
91			FEventWaiting: TEventObject;
92			{$ENDIF}
93			public
94			constructor Create(aOwner: TFB25Events);
95			destructor Destroy; override;
96	tony	56	procedure eventCallbackFunction(length: short; updated: PAnsiChar);
97	tony	45	procedure WaitForEvent;
98			procedure CancelWait;
99			end;
100
101			{ TFB25Events }
102
103			TFB25Events = class(TFBEvents,IEvents)
104			private
105			FEventID: ISC_LONG;
106			FDBHandle: TISC_DB_HANDLE;
107			FEventHandlerThread: TObject;
108			FAsyncEventCallback: TEventhandlerInterface;
109			protected
110			procedure CancelEvents(Force: boolean = false); override;
111			function GetIEvents: IEvents; override;
112			public
113			constructor Create(DBAttachment: TFB25Attachment; Events: TStrings);
114			destructor Destroy; override;
115
116			{IEvents}
117			procedure WaitForEvent;
118	tony	47	procedure AsyncWaitForEvent(EventHandler: TEventHandler); override;
119	tony	45	end;
120
121			implementation
122
123			uses FBMessages;
124
125			type
126
127			{ TEventHandlerThread }
128
129			TEventHandlerThread = class(TThread)
130			private
131			FOwner: TFB25Events;
132			FEventHandler: TEventhandlerInterface;
133			protected
134			procedure Execute; override;
135			public
136			constructor Create(Owner: TFB25Events; EventHandler: TEventhandlerInterface);
137			procedure Terminate;
138			end;
139
140			{ TEventHandlerThread }
141
142			procedure TEventHandlerThread.Execute;
143			begin
144			while not Terminated do
145			begin
146			FEventHandler.WaitForEvent;
147
148			if not Terminated then
149			FOwner.EventSignaled;
150			end;
151			end;
152
153			constructor TEventHandlerThread.Create(Owner: TFB25Events;
154			EventHandler: TEventhandlerInterface);
155			begin
156	tony	56	inherited Create(false);
157	tony	45	FOwner := Owner;
158			FEventHandler := EventHandler;
159			FreeOnTerminate := true;
160			end;
161
162			procedure TEventHandlerThread.Terminate;
163			begin
164			inherited Terminate;
165			FEventHandler.CancelWait;
166			end;
167
168			{This procedure is used for the event call back - note the cdecl }
169
170	tony	56	procedure IBEventCallback( ptr: pointer; length: short; updated: PAnsiChar); cdecl;
171	tony	45	begin
172			if (ptr = nil) or (length = 0) or (updated = nil) then
173			Exit;
174			{ Handle events asynchronously in second thread }
175			TEventhandlerInterface(ptr).eventCallbackFunction(length,updated);
176			end;
177
178			{ TEventhandlerInterface }
179
180			constructor TEventhandlerInterface.Create(aOwner: TFB25Events);
181			var
182			PSa : PSecurityAttributes;
183			{$IFDEF WINDOWS}
184			Sd : TSecurityDescriptor;
185			Sa : TSecurityAttributes;
186			begin
187			InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
188			SetSecurityDescriptorDacl(@Sd,true,nil,false);
189			Sa.nLength := SizeOf(Sa);
190			Sa.lpSecurityDescriptor := @Sd;
191			Sa.bInheritHandle := true;
192			PSa := @Sa;
193			{$ELSE}
194			GUID : TGUID;
195			begin
196			PSa:= nil;
197			{$ENDIF}
198			inherited Create;
199			{$IFDEF WINDOWS}
200	tony	47	FEventHandler := CreateEvent(PSa,false,false,nil);
201	tony	45	{$ELSE}
202			CreateGuid(GUID);
203			FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
204			{$ENDIF}
205			FOWner := aOwner;
206			end;
207
208			destructor TEventhandlerInterface.Destroy;
209			begin
210			{$IFDEF WINDOWS}
211			CloseHandle(FEventHandler);
212			{$ELSE}
213			if assigned(FEventWaiting) then FEventWaiting.Free;
214			{$ENDIF}
215			inherited Destroy;
216			end;
217
218			procedure TEventhandlerInterface.eventCallbackFunction(length: short;
219	tony	56	updated: PAnsiChar);
220	tony	45	begin
221			FOwner.FCriticalSection.Enter;
222			try
223			if FOwner.FResultBuffer <> nil then
224			Move(updated[0], FOwner.FResultBuffer[0], length);
225			finally
226			FOwner.FCriticalSection.Leave
227			end;
228	tony	47	// writeln('Set Event');
229			{$IFDEF WINDOWS}
230			SetEvent(FEventHandler);
231			{$ELSE}
232			FEventWaiting.SetEvent;
233			{$ENDIF}
234	tony	45	end;
235
236			procedure TEventhandlerInterface.WaitForEvent;
237			begin
238			{$IFDEF WINDOWS}
239			WaitForSingleObject(FEventHandler,INFINITE);
240			{$ELSE}
241			FEventWaiting.WaitFor(INFINITE);
242			{$ENDIF}
243	tony	47	// writeln('Event Wait Ends');
244	tony	45	end;
245
246			procedure TEventhandlerInterface.CancelWait;
247			begin
248			{$IFDEF WINDOWS}
249			SetEvent(FEventHandler);
250			{$ELSE}
251			FEventWaiting.SetEvent;
252			{$ENDIF}
253			end;
254
255
256			{ TFB25Events }
257
258			procedure TFB25Events.CancelEvents(Force: boolean);
259			begin
260			FCriticalSection.Enter;
261			try
262			if not FInWaitState then Exit;
263			with Firebird25ClientAPI do
264			if (Call(isc_Cancel_events( StatusVector, @FDBHandle, @FEventID),false) > 0) and not Force then
265			IBDatabaseError;
266
267			FInWaitState := false;
268			inherited CancelEvents(Force);
269			finally
270			FCriticalSection.Leave
271			end;
272			end;
273
274			function TFB25Events.GetIEvents: IEvents;
275			begin
276			Result := self;
277			end;
278
279			constructor TFB25Events.Create(DBAttachment: TFB25Attachment; Events: TStrings);
280			begin
281			inherited Create(DBAttachment,DBAttachment,Events);
282			FDBHandle := DBAttachment.Handle;
283			FAsyncEventCallback := TEventhandlerInterface.Create(self);
284			FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
285			end;
286
287			destructor TFB25Events.Destroy;
288			begin
289			CancelEvents(true);
290			if assigned(FEventHandlerThread) then
291			TEventHandlerThread(FEventHandlerThread).Terminate;
292			if assigned(FAsyncEventCallback) then
293			TEventhandlerInterface(FAsyncEventCallback).Free;
294			inherited Destroy;
295			end;
296
297			procedure TFB25Events.AsyncWaitForEvent(EventHandler: TEventHandler);
298			var callback: pointer;
299			begin
300			FCriticalSection.Enter;
301			try
302			if FInWaitState then
303			IBError(ibxeInEventWait,[nil]);
304
305			FEventHandler := EventHandler;
306			callback := @IBEventCallback;
307			with Firebird25ClientAPI do
308			Call(isc_que_events( StatusVector, @FDBHandle, @FEventID, FEventBufferLen,
309			FEventBuffer, TISC_CALLBACK(callback), PVoid(FAsyncEventCallback)));
310			FInWaitState := true;
311			finally
312			FCriticalSection.Leave
313			end;
314			end;
315
316			procedure TFB25Events.WaitForEvent;
317			begin
318			if FInWaitState then
319			IBError(ibxeInEventWait,[nil]);
320
321			FInWaitState := true;
322			try
323			with Firebird25ClientAPI do
324			Call(isc_wait_for_event(StatusVector,@FDBHandle, FEventBufferlen,FEventBuffer,FResultBuffer));
325			finally
326			FInWaitState := false;
327			end;
328			end;
329
330			end.
331