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}

{ $DEFINE EVENTDEBUG}

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;
  {$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Create'); {$ENDIF}
end;

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

procedure TEventhandlerInterface.addRef;
begin
  Inc(FRef);
{$IFDEF EVENTDEBUG}  writeln(FName,': ref count = ',FRef);{$ENDIF}
end;

function TEventhandlerInterface.release: Integer;
begin
  Dec(FRef);
{$IFDEF EVENTDEBUG}  writeln(FName,': ref count = ',FRef);{$ENDIF}
  if FRef = 0 then Free;
  Result := FRef;
end;

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

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

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

 { TEventHandlerThread }

procedure TEventHandlerThread.Execute;
begin
  {$IFDEF EVENTDEBUG}  writeln('Event Handler Thread Starts'); {$ENDIF}
  while not Terminated do
  begin
    FEventHandler.WaitForEvent;
    {$IFDEF EVENTDEBUG}  writeln('Event Handler Ends Wait ',Terminated); {$ENDIF}

    if not Terminated  then
      FOwner.EventSignaled;
  end;
  {$IFDEF EVENTDEBUG}  writeln('Event Handler Thread Ends'); {$ENDIF}
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;
  {$IFDEF EVENTDEBUG}  writeln('Event Handler Thread Cancelled'); {$ENDIF}
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:	217
Committed:	Fri Mar 16 10:27:26 2018 UTC (6 years, 1 month ago) by tony
Content type:	text/x-pascal
Original Path:	*ibx/trunk/fbintf/client/3.0/FB30Events.pas*
File size:	8980 byte(s)
Log Message:	Fixes Merged
#	Content
1	(*
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	{$IFDEF MSWINDOWS}
29	{$DEFINE WINDOWS}
30	{$ENDIF}
31
32	{$IFDEF FPC}
33	{$mode delphi}
34	{$interfaces COM}
35	{$ENDIF}
36
37	{ $DEFINE EVENTDEBUG}
38
39	interface
40
41	uses
42	{$IFDEF WINDOWS}Windows, {$ENDIF} Classes, SysUtils, Firebird, IB, FB30ClientAPI, FB30Attachment,
43	syncobjs, FBEvents;
44
45	type
46	TFB30Events = class;
47
48	{ TEventhandlerInterface }
49
50	TEventhandlerInterface = class(Firebird.IEventCallbackImpl)
51	private
52	FOwner: TFB30Events;
53	FName: AnsiString;
54	FRef: integer;
55	{$IFDEF WINDOWS}
56	{Make direct use of Windows API as TEventObject don't seem to work under
57	Windows!}
58	FEventHandler: THandle;
59	{$ELSE}
60	FEventWaiting: TEventObject;
61	{$ENDIF}
62	public
63	constructor Create(aOwner: TFB30Events; aName: AnsiString);
64	destructor Destroy; override;
65	procedure addRef(); override;
66	function release(): Integer; override;
67	procedure eventCallbackFunction(length: Cardinal; events: BytePtr); override;
68	procedure WaitForEvent;
69	procedure CancelWait;
70	end;
71
72	{ TFB30Events }
73
74	TFB30Events = class(TFBEvents,IEvents)
75	private
76	FAttachmentIntf: Firebird.IAttachment;
77	FEventHandlerThread: TObject;
78	FEventsIntf: Firebird.IEvents;
79	FAsyncEventCallback: TEventhandlerInterface;
80	FSyncEventCallback: TEventhandlerInterface;
81	procedure InternalAsyncWaitForEvent(EventHandler: TEventHandler; EventCallBack: TEventhandlerInterface);
82	procedure ReleaseIntf;
83	protected
84	procedure CancelEvents(Force: boolean = false); override;
85	function GetIEvents: IEvents; override;
86	public
87	constructor Create(DBAttachment: TFB30Attachment; Events: TStrings);
88	destructor Destroy; override;
89
90	{IEvents}
91	procedure WaitForEvent;
92	procedure AsyncWaitForEvent(EventHandler: TEventHandler); override;
93	end;
94
95	implementation
96
97	uses FBMessages, FBClientAPI;
98
99	type
100	{ TEventHandlerThread }
101
102	TEventHandlerThread = class(TThread)
103	private
104	FOwner: TFB30Events;
105	FEventHandler: TEventhandlerInterface;
106	protected
107	procedure Execute; override;
108	public
109	constructor Create(Owner: TFB30Events; EventHandler: TEventhandlerInterface);
110	procedure Terminate;
111	end;
112
113	constructor TEventhandlerInterface.Create(aOwner: TFB30Events; aName: AnsiString);
114	var
115	PSa : PSecurityAttributes;
116	{$IFDEF WINDOWS}
117	Sd : TSecurityDescriptor;
118	Sa : TSecurityAttributes;
119	begin
120	InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
121	SetSecurityDescriptorDacl(@Sd,true,nil,false);
122	Sa.nLength := SizeOf(Sa);
123	Sa.lpSecurityDescriptor := @Sd;
124	Sa.bInheritHandle := true;
125	PSa := @Sa;
126	{$ELSE}
127	GUID : TGUID;
128	begin
129	PSa:= nil;
130	{$ENDIF}
131	inherited Create;
132	{$IFDEF WINDOWS}
133	FEventHandler := CreateEvent(PSa,false,false,nil);
134	{$ELSE}
135	CreateGuid(GUID);
136	FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
137	{$ENDIF}
138	FOWner := aOwner;
139	FName := aName;
140	addRef;
141	{$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Create'); {$ENDIF}
142	end;
143
144	destructor TEventhandlerInterface.Destroy;
145	begin
146	{$IFDEF WINDOWS}
147	CloseHandle(FEventHandler);
148	{$ELSE}
149	if assigned(FEventWaiting) then FEventWaiting.Free;
150	{$ENDIF}
151	{$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Destroy'); {$ENDIF}
152	inherited Destroy;
153	end;
154
155	procedure TEventhandlerInterface.addRef;
156	begin
157	Inc(FRef);
158	{$IFDEF EVENTDEBUG} writeln(FName,': ref count = ',FRef);{$ENDIF}
159	end;
160
161	function TEventhandlerInterface.release: Integer;
162	begin
163	Dec(FRef);
164	{$IFDEF EVENTDEBUG} writeln(FName,': ref count = ',FRef);{$ENDIF}
165	if FRef = 0 then Free;
166	Result := FRef;
167	end;
168
169	procedure TEventhandlerInterface.eventCallbackFunction(length: Cardinal;
170	events: BytePtr);
171	begin
172	{$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Event Callback'); {$ENDIF}
173	FOwner.FCriticalSection.Enter;
174	try
175	if FOwner.FResultBuffer <> nil then
176	Move(events^, FOwner.FResultBuffer^, Length);
177	finally
178	FOwner.FCriticalSection.Leave
179	end;
180	{$IFDEF EVENTDEBUG}writeln(FName,' TEventhandlerInterface: Set Event Called'); {$ENDIF}
181	{$IFDEF WINDOWS}
182	SetEvent(FEventHandler);
183	{$ELSE}
184	FEventWaiting.SetEvent;
185	{$ENDIF}
186	end;
187
188	procedure TEventhandlerInterface.WaitForEvent;
189	begin
190	{$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Start Event Wait'); {$ENDIF}
191	{$IFDEF WINDOWS}
192	WaitForSingleObject(FEventHandler,INFINITE);
193	{$ELSE}
194	FEventWaiting.WaitFor(INFINITE);
195	{$ENDIF}
196	{$IFDEF EVENTDEBUG} writeln(FName,' TEventhandlerInterface: Event Wait Ends');{$ENDIF}
197	end;
198
199	procedure TEventhandlerInterface.CancelWait;
200	begin
201	{$IFDEF WINDOWS}
202	SetEvent(FEventHandler);
203	{$ELSE}
204	FEventWaiting.SetEvent;
205	{$ENDIF}
206	end;
207
208	{ TEventHandlerThread }
209
210	procedure TEventHandlerThread.Execute;
211	begin
212	{$IFDEF EVENTDEBUG} writeln('Event Handler Thread Starts'); {$ENDIF}
213	while not Terminated do
214	begin
215	FEventHandler.WaitForEvent;
216	{$IFDEF EVENTDEBUG} writeln('Event Handler Ends Wait ',Terminated); {$ENDIF}
217
218	if not Terminated then
219	FOwner.EventSignaled;
220	end;
221	{$IFDEF EVENTDEBUG} writeln('Event Handler Thread Ends'); {$ENDIF}
222	end;
223
224	constructor TEventHandlerThread.Create(Owner: TFB30Events;
225	EventHandler: TEventhandlerInterface);
226	begin
227	inherited Create(false);
228	FOwner := Owner;
229	FEventHandler := EventHandler;
230	FreeOnTerminate := true;
231	end;
232
233	procedure TEventHandlerThread.Terminate;
234	begin
235	inherited Terminate;
236	FEventHandler.CancelWait;
237	{$IFDEF EVENTDEBUG} writeln('Event Handler Thread Cancelled'); {$ENDIF}
238	end;
239
240	{ TFB30Events }
241
242	procedure TFB30Events.CancelEvents(Force: boolean);
243	begin
244	FCriticalSection.Enter;
245	try
246	if not FInWaitState then Exit;
247	if FEventsIntf <> nil then
248	with Firebird30ClientAPI do
249	begin
250	FEventsIntf.Cancel(StatusIntf);
251	if not Force then
252	Check4DataBaseError;
253	end;
254	FInWaitState := false;
255	ReleaseIntf;
256	inherited CancelEvents(Force);
257	finally
258	FCriticalSection.Leave
259	end;
260	end;
261
262	function TFB30Events.GetIEvents: IEvents;
263	begin
264	Result := self;
265	end;
266
267	procedure TFB30Events.InternalAsyncWaitForEvent(EventHandler: TEventHandler;
268	EventCallBack: TEventhandlerInterface);
269	begin
270	FCriticalSection.Enter;
271	try
272	if FInWaitState then
273	IBError(ibxeInEventWait,[nil]);
274
275	FEventHandler := EventHandler;
276	ReleaseIntf;
277	with Firebird30ClientAPI do
278	begin
279	FEventsIntf := FAttachmentIntf.queEvents(
280	StatusIntf,EventCallBack,
281	FEventBufferLen, BytePtr(FEventBuffer));
282	Check4DataBaseError;
283	end;
284	FInWaitState := true;
285
286	finally
287	FCriticalSection.Leave
288	end;
289	end;
290
291	procedure TFB30Events.ReleaseIntf;
292	begin
293	if FEventsIntf <> nil then
294	FEventsIntf.release;
295	FEventsIntf := nil;
296	end;
297
298	constructor TFB30Events.Create(DBAttachment: TFB30Attachment; Events: TStrings);
299	begin
300	inherited Create(DBAttachment,DBAttachment,Events);
301	FAttachmentIntf := DBAttachment.AttachmentIntf;
302	FSyncEventCallback := TEventhandlerInterface.Create(self,'Sync');
303	end;
304
305	destructor TFB30Events.Destroy;
306	begin
307	CancelEvents(true);
308	if assigned(FEventHandlerThread) then
309	TEventHandlerThread(FEventHandlerThread).Terminate;
310	if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
311	if assigned(FSyncEventCallback) then TEventhandlerInterface(FSyncEventCallback).release;
312	ReleaseIntf;
313	inherited Destroy;
314	end;
315
316	procedure TFB30Events.AsyncWaitForEvent(EventHandler: TEventHandler);
317	begin
318	{Seems like we have to create a new callback object each time to avoid empty events}
319	if assigned(FEventHandlerThread) then
320	TEventHandlerThread(FEventHandlerThread).Terminate;
321	if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
322	FAsyncEventCallback := TEventhandlerInterface.Create(self,'Async');
323	FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
324	InternalAsyncWaitForEvent(EventHandler,FAsyncEventCallback);
325	end;
326
327	procedure TFB30Events.WaitForEvent;
328	begin
329	InternalAsyncWaitForEvent(nil,FSyncEventCallback);
330	FSyncEventCallback.WaitForEvent;
331	end;
332
333	end.
334