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;

{$IFDEF FPC}
{$mode objfpc}{$H+}
{$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: PChar);
    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);
  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(true);
   FOwner := Owner;
   FEventHandler := EventHandler;
   FreeOnTerminate := true;
   Start;
 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: PChar); 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,true,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: PChar);
begin
  FOwner.FCriticalSection.Enter;
  try
    if FOwner.FResultBuffer <> nil then
      Move(updated[0], FOwner.FResultBuffer[0], length);
    {$IFDEF WINDOWS}
    SetEvent(FEventHandler);
    {$ELSE}
    FEventWaiting.SetEvent;
    {$ENDIF}
  finally
    FOwner.FCriticalSection.Leave
  end;
end;

procedure TEventhandlerInterface.WaitForEvent;
begin
  {$IFDEF WINDOWS}
  WaitForSingleObject(FEventHandler,INFINITE);
  {$ELSE}
  FEventWaiting.WaitFor(INFINITE);
  {$ENDIF}
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]);

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

end.

Revision:	45
Committed:	Tue Dec 6 10:33:46 2016 UTC (7 years, 4 months ago) by tony
Content type:	text/x-pascal
Original Path:	*ibx/trunk/fbintf/client/2.5/FB25Events.pas*
File size:	9813 byte(s)
Log Message:	Committing updates for Release R2-0-0
#	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
64			{$IFDEF FPC}
65			{$mode objfpc}{$H+}
66			{$interfaces COM}
67			{$ENDIF}
68
69			interface
70
71			uses
72			{$IFDEF WINDOWS}Windows, {$ENDIF}Classes, SysUtils, IB, FB25ClientAPI, FB25Attachment,
73			IBExternals, IBHeader, syncobjs, FBEvents;
74
75			type
76			TFB25Events = class;
77
78			{ TEventhandlerInterface }
79
80			TEventhandlerInterface = class
81			private
82			FOwner: TFB25Events;
83			{$IFDEF WINDOWS}
84			{Make direct use of Windows API as TEventObject don't seem to work under
85			Windows!}
86			FEventHandler: THandle;
87			{$ELSE}
88			FEventWaiting: TEventObject;
89			{$ENDIF}
90			public
91			constructor Create(aOwner: TFB25Events);
92			destructor Destroy; override;
93			procedure eventCallbackFunction(length: short; updated: PChar);
94			procedure WaitForEvent;
95			procedure CancelWait;
96			end;
97
98			{ TFB25Events }
99
100			TFB25Events = class(TFBEvents,IEvents)
101			private
102			FEventID: ISC_LONG;
103			FDBHandle: TISC_DB_HANDLE;
104			FEventHandlerThread: TObject;
105			FAsyncEventCallback: TEventhandlerInterface;
106			protected
107			procedure CancelEvents(Force: boolean = false); override;
108			function GetIEvents: IEvents; override;
109			public
110			constructor Create(DBAttachment: TFB25Attachment; Events: TStrings);
111			destructor Destroy; override;
112
113			{IEvents}
114			procedure WaitForEvent;
115			procedure AsyncWaitForEvent(EventHandler: TEventHandler);
116			end;
117
118			implementation
119
120			uses FBMessages;
121
122			type
123
124			{ TEventHandlerThread }
125
126			TEventHandlerThread = class(TThread)
127			private
128			FOwner: TFB25Events;
129			FEventHandler: TEventhandlerInterface;
130			protected
131			procedure Execute; override;
132			public
133			constructor Create(Owner: TFB25Events; EventHandler: TEventhandlerInterface);
134			procedure Terminate;
135			end;
136
137			{ TEventHandlerThread }
138
139			procedure TEventHandlerThread.Execute;
140			begin
141			while not Terminated do
142			begin
143			FEventHandler.WaitForEvent;
144
145			if not Terminated then
146			FOwner.EventSignaled;
147			end;
148			end;
149
150			constructor TEventHandlerThread.Create(Owner: TFB25Events;
151			EventHandler: TEventhandlerInterface);
152			begin
153			inherited Create(true);
154			FOwner := Owner;
155			FEventHandler := EventHandler;
156			FreeOnTerminate := true;
157			Start;
158			end;
159
160			procedure TEventHandlerThread.Terminate;
161			begin
162			inherited Terminate;
163			FEventHandler.CancelWait;
164			end;
165
166			{This procedure is used for the event call back - note the cdecl }
167
168			procedure IBEventCallback( ptr: pointer; length: short; updated: PChar); cdecl;
169			begin
170			if (ptr = nil) or (length = 0) or (updated = nil) then
171			Exit;
172			{ Handle events asynchronously in second thread }
173			TEventhandlerInterface(ptr).eventCallbackFunction(length,updated);
174			end;
175
176			{ TEventhandlerInterface }
177
178			constructor TEventhandlerInterface.Create(aOwner: TFB25Events);
179			var
180			PSa : PSecurityAttributes;
181			{$IFDEF WINDOWS}
182			Sd : TSecurityDescriptor;
183			Sa : TSecurityAttributes;
184			begin
185			InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
186			SetSecurityDescriptorDacl(@Sd,true,nil,false);
187			Sa.nLength := SizeOf(Sa);
188			Sa.lpSecurityDescriptor := @Sd;
189			Sa.bInheritHandle := true;
190			PSa := @Sa;
191			{$ELSE}
192			GUID : TGUID;
193			begin
194			PSa:= nil;
195			{$ENDIF}
196			inherited Create;
197			{$IFDEF WINDOWS}
198			FEventHandler := CreateEvent(PSa,false,true,nil);
199			{$ELSE}
200			CreateGuid(GUID);
201			FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
202			{$ENDIF}
203			FOWner := aOwner;
204			end;
205
206			destructor TEventhandlerInterface.Destroy;
207			begin
208			{$IFDEF WINDOWS}
209			CloseHandle(FEventHandler);
210			{$ELSE}
211			if assigned(FEventWaiting) then FEventWaiting.Free;
212			{$ENDIF}
213			inherited Destroy;
214			end;
215
216			procedure TEventhandlerInterface.eventCallbackFunction(length: short;
217			updated: PChar);
218			begin
219			FOwner.FCriticalSection.Enter;
220			try
221			if FOwner.FResultBuffer <> nil then
222			Move(updated[0], FOwner.FResultBuffer[0], length);
223			{$IFDEF WINDOWS}
224			SetEvent(FEventHandler);
225			{$ELSE}
226			FEventWaiting.SetEvent;
227			{$ENDIF}
228			finally
229			FOwner.FCriticalSection.Leave
230			end;
231			end;
232
233			procedure TEventhandlerInterface.WaitForEvent;
234			begin
235			{$IFDEF WINDOWS}
236			WaitForSingleObject(FEventHandler,INFINITE);
237			{$ELSE}
238			FEventWaiting.WaitFor(INFINITE);
239			{$ENDIF}
240			end;
241
242			procedure TEventhandlerInterface.CancelWait;
243			begin
244			{$IFDEF WINDOWS}
245			SetEvent(FEventHandler);
246			{$ELSE}
247			FEventWaiting.SetEvent;
248			{$ENDIF}
249			end;
250
251
252			{ TFB25Events }
253
254			procedure TFB25Events.CancelEvents(Force: boolean);
255			begin
256			FCriticalSection.Enter;
257			try
258			if not FInWaitState then Exit;
259			with Firebird25ClientAPI do
260			if (Call(isc_Cancel_events( StatusVector, @FDBHandle, @FEventID),false) > 0) and not Force then
261			IBDatabaseError;
262
263			FInWaitState := false;
264			inherited CancelEvents(Force);
265			finally
266			FCriticalSection.Leave
267			end;
268			end;
269
270			function TFB25Events.GetIEvents: IEvents;
271			begin
272			Result := self;
273			end;
274
275			constructor TFB25Events.Create(DBAttachment: TFB25Attachment; Events: TStrings);
276			begin
277			inherited Create(DBAttachment,DBAttachment,Events);
278			FDBHandle := DBAttachment.Handle;
279			FAsyncEventCallback := TEventhandlerInterface.Create(self);
280			FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
281			end;
282
283			destructor TFB25Events.Destroy;
284			begin
285			CancelEvents(true);
286			if assigned(FEventHandlerThread) then
287			TEventHandlerThread(FEventHandlerThread).Terminate;
288			if assigned(FAsyncEventCallback) then
289			TEventhandlerInterface(FAsyncEventCallback).Free;
290			inherited Destroy;
291			end;
292
293			procedure TFB25Events.AsyncWaitForEvent(EventHandler: TEventHandler);
294			var callback: pointer;
295			begin
296			FCriticalSection.Enter;
297			try
298			if FInWaitState then
299			IBError(ibxeInEventWait,[nil]);
300
301			CreateEventBlock;
302			FEventHandler := EventHandler;
303			callback := @IBEventCallback;
304			with Firebird25ClientAPI do
305			Call(isc_que_events( StatusVector, @FDBHandle, @FEventID, FEventBufferLen,
306			FEventBuffer, TISC_CALLBACK(callback), PVoid(FAsyncEventCallback)));
307			FInWaitState := true;
308			finally
309			FCriticalSection.Leave
310			end;
311			end;
312
313			procedure TFB25Events.WaitForEvent;
314			begin
315			if FInWaitState then
316			IBError(ibxeInEventWait,[nil]);
317
318			FInWaitState := true;
319			try
320			CreateEventBlock;
321			with Firebird25ClientAPI do
322			Call(isc_wait_for_event(StatusVector,@FDBHandle, FEventBufferlen,FEventBuffer,FResultBuffer));
323			finally
324			FInWaitState := false;
325			end;
326			end;
327
328			end.
329