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
#	Content
1	(*
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