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
  {$IF defined(FPC) and defined(UNIX)} ,cthreads {$IFEND};

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:	215
Committed:	Thu Mar 15 16:25:03 2018 UTC (6 years, 1 month ago) by tony
Content type:	text/x-pascal
File size:	8374 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	{$ENDIF}
36
37	interface
38
39	uses
40	{$IFDEF WINDOWS}Windows, {$ENDIF} Classes, SysUtils, Firebird, IB, FB30ClientAPI, FB30Attachment,
41	syncobjs, FBEvents
42	{$IF defined(FPC) and defined(UNIX)} ,cthreads {$IFEND};
43
44	type
45	TFB30Events = class;
46
47	{ TEventhandlerInterface }
48
49	TEventhandlerInterface = class(Firebird.IEventCallbackImpl)
50	private
51	FOwner: TFB30Events;
52	FName: AnsiString;
53	FRef: integer;
54	{$IFDEF WINDOWS}
55	{Make direct use of Windows API as TEventObject don't seem to work under
56	Windows!}
57	FEventHandler: THandle;
58	{$ELSE}
59	FEventWaiting: TEventObject;
60	{$ENDIF}
61	public
62	constructor Create(aOwner: TFB30Events; aName: AnsiString);
63	destructor Destroy; override;
64	procedure addRef(); override;
65	function release(): Integer; override;
66	procedure eventCallbackFunction(length: Cardinal; events: BytePtr); override;
67	procedure WaitForEvent;
68	procedure CancelWait;
69	end;
70
71	{ TFB30Events }
72
73	TFB30Events = class(TFBEvents,IEvents)
74	private
75	FAttachmentIntf: Firebird.IAttachment;
76	FEventHandlerThread: TObject;
77	FEventsIntf: Firebird.IEvents;
78	FAsyncEventCallback: TEventhandlerInterface;
79	FSyncEventCallback: TEventhandlerInterface;
80	procedure InternalAsyncWaitForEvent(EventHandler: TEventHandler; EventCallBack: TEventhandlerInterface);
81	procedure ReleaseIntf;
82	protected
83	procedure CancelEvents(Force: boolean = false); override;
84	function GetIEvents: IEvents; override;
85	public
86	constructor Create(DBAttachment: TFB30Attachment; Events: TStrings);
87	destructor Destroy; override;
88
89	{IEvents}
90	procedure WaitForEvent;
91	procedure AsyncWaitForEvent(EventHandler: TEventHandler); override;
92	end;
93
94	implementation
95
96	uses FBMessages, FBClientAPI;
97
98	type
99	{ TEventHandlerThread }
100
101	TEventHandlerThread = class(TThread)
102	private
103	FOwner: TFB30Events;
104	FEventHandler: TEventhandlerInterface;
105	protected
106	procedure Execute; override;
107	public
108	constructor Create(Owner: TFB30Events; EventHandler: TEventhandlerInterface);
109	procedure Terminate;
110	end;
111
112	constructor TEventhandlerInterface.Create(aOwner: TFB30Events; aName: AnsiString);
113	var
114	PSa : PSecurityAttributes;
115	{$IFDEF WINDOWS}
116	Sd : TSecurityDescriptor;
117	Sa : TSecurityAttributes;
118	begin
119	InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
120	SetSecurityDescriptorDacl(@Sd,true,nil,false);
121	Sa.nLength := SizeOf(Sa);
122	Sa.lpSecurityDescriptor := @Sd;
123	Sa.bInheritHandle := true;
124	PSa := @Sa;
125	{$ELSE}
126	GUID : TGUID;
127	begin
128	PSa:= nil;
129	{$ENDIF}
130	inherited Create;
131	{$IFDEF WINDOWS}
132	FEventHandler := CreateEvent(PSa,false,false,nil);
133	{$ELSE}
134	CreateGuid(GUID);
135	FEventWaiting := TEventObject.Create(PSa,false,false,GUIDToString(GUID));
136	{$ENDIF}
137	FOWner := aOwner;
138	FName := aName;
139	addRef;
140	end;
141
142	destructor TEventhandlerInterface.Destroy;
143	begin
144	{$IFDEF WINDOWS}
145	CloseHandle(FEventHandler);
146	{$ELSE}
147	if assigned(FEventWaiting) then FEventWaiting.Free;
148	{$ENDIF}
149	inherited Destroy;
150	end;
151
152	procedure TEventhandlerInterface.addRef;
153	begin
154	Inc(FRef);
155	// writeln(FName,': ref count = ',FRef);
156	end;
157
158	function TEventhandlerInterface.release: Integer;
159	begin
160	Dec(FRef);
161	// writeln(FName,': ref count = ',FRef);
162	if FRef = 0 then Free;
163	Result := FRef;
164	end;
165
166	procedure TEventhandlerInterface.eventCallbackFunction(length: Cardinal;
167	events: BytePtr);
168	begin
169	// writeln('TEventhandlerInterface: Event Callback');
170	FOwner.FCriticalSection.Enter;
171	try
172	if FOwner.FResultBuffer <> nil then
173	Move(events^, FOwner.FResultBuffer^, Length);
174	finally
175	FOwner.FCriticalSection.Leave
176	end;
177	//writeln('TEventhandlerInterface: Set Event Called');
178	{$IFDEF WINDOWS}
179	SetEvent(FEventHandler);
180	{$ELSE}
181	FEventWaiting.SetEvent;
182	{$ENDIF}
183	end;
184
185	procedure TEventhandlerInterface.WaitForEvent;
186	begin
187	// writeln('TEventhandlerInterface: Start Event Wait');
188	{$IFDEF WINDOWS}
189	WaitForSingleObject(FEventHandler,INFINITE);
190	{$ELSE}
191	FEventWaiting.WaitFor(INFINITE);
192	{$ENDIF}
193	// writeln('TEventhandlerInterface: Event Wait Ends');
194	end;
195
196	procedure TEventhandlerInterface.CancelWait;
197	begin
198	{$IFDEF WINDOWS}
199	SetEvent(FEventHandler);
200	{$ELSE}
201	FEventWaiting.SetEvent;
202	{$ENDIF}
203	end;
204
205	{ TEventHandlerThread }
206
207	procedure TEventHandlerThread.Execute;
208	begin
209	while not Terminated do
210	begin
211	FEventHandler.WaitForEvent;
212
213	if not Terminated then
214	FOwner.EventSignaled;
215	end;
216	end;
217
218	constructor TEventHandlerThread.Create(Owner: TFB30Events;
219	EventHandler: TEventhandlerInterface);
220	begin
221	inherited Create(false);
222	FOwner := Owner;
223	FEventHandler := EventHandler;
224	FreeOnTerminate := true;
225	end;
226
227	procedure TEventHandlerThread.Terminate;
228	begin
229	inherited Terminate;
230	FEventHandler.CancelWait;
231	end;
232
233	{ TFB30Events }
234
235	procedure TFB30Events.CancelEvents(Force: boolean);
236	begin
237	FCriticalSection.Enter;
238	try
239	if not FInWaitState then Exit;
240	if FEventsIntf <> nil then
241	with Firebird30ClientAPI do
242	begin
243	FEventsIntf.Cancel(StatusIntf);
244	if not Force then
245	Check4DataBaseError;
246	end;
247	FInWaitState := false;
248	ReleaseIntf;
249	inherited CancelEvents(Force);
250	finally
251	FCriticalSection.Leave
252	end;
253	end;
254
255	function TFB30Events.GetIEvents: IEvents;
256	begin
257	Result := self;
258	end;
259
260	procedure TFB30Events.InternalAsyncWaitForEvent(EventHandler: TEventHandler;
261	EventCallBack: TEventhandlerInterface);
262	begin
263	FCriticalSection.Enter;
264	try
265	if FInWaitState then
266	IBError(ibxeInEventWait,[nil]);
267
268	FEventHandler := EventHandler;
269	ReleaseIntf;
270	with Firebird30ClientAPI do
271	begin
272	FEventsIntf := FAttachmentIntf.queEvents(
273	StatusIntf,EventCallBack,
274	FEventBufferLen, BytePtr(FEventBuffer));
275	Check4DataBaseError;
276	end;
277	FInWaitState := true;
278
279	finally
280	FCriticalSection.Leave
281	end;
282	end;
283
284	procedure TFB30Events.ReleaseIntf;
285	begin
286	if FEventsIntf <> nil then
287	FEventsIntf.release;
288	FEventsIntf := nil;
289	end;
290
291	constructor TFB30Events.Create(DBAttachment: TFB30Attachment; Events: TStrings);
292	begin
293	inherited Create(DBAttachment,DBAttachment,Events);
294	FAttachmentIntf := DBAttachment.AttachmentIntf;
295	FSyncEventCallback := TEventhandlerInterface.Create(self,'Sync');
296	end;
297
298	destructor TFB30Events.Destroy;
299	begin
300	CancelEvents(true);
301	if assigned(FEventHandlerThread) then
302	TEventHandlerThread(FEventHandlerThread).Terminate;
303	if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
304	if assigned(FSyncEventCallback) then TEventhandlerInterface(FSyncEventCallback).release;
305	ReleaseIntf;
306	inherited Destroy;
307	end;
308
309	procedure TFB30Events.AsyncWaitForEvent(EventHandler: TEventHandler);
310	begin
311	{Seems like we have to create a new callback object each time to avoid empty events}
312	if assigned(FEventHandlerThread) then
313	TEventHandlerThread(FEventHandlerThread).Terminate;
314	if assigned(FAsyncEventCallback) then TEventhandlerInterface(FAsyncEventCallback).release;
315	FAsyncEventCallback := TEventhandlerInterface.Create(self,'Async');
316	FEventHandlerThread := TEventHandlerThread.Create(self,FAsyncEventCallback);
317	InternalAsyncWaitForEvent(EventHandler,FAsyncEventCallback);
318	end;
319
320	procedure TFB30Events.WaitForEvent;
321	begin
322	InternalAsyncWaitForEvent(nil,FSyncEventCallback);
323	FSyncEventCallback.WaitForEvent;
324	end;
325
326	end.
327