1 |
const
|
2 |
MonitorHookNames: array[0..5] of String = (
|
3 |
'FB.SQL.MONITOR.Mutex1_0',
|
4 |
'FB.SQL.MONITOR.SharedMem1_0',
|
5 |
'FB.SQL.MONITOR.WriteEvent1_0',
|
6 |
'FB.SQL.MONITOR.WriteFinishedEvent1_0',
|
7 |
'FB.SQL.MONITOR.ReadEvent1_0',
|
8 |
'FB.SQL.MONITOR.ReadFinishedEvent1_0'
|
9 |
);
|
10 |
cDefaultTimeout = 1000; { 1 seconds }
|
11 |
|
12 |
type
|
13 |
TGlobalInterface = class;
|
14 |
|
15 |
{Interprocess Communication Objects. All platform dependent IPC is abstracted
|
16 |
into this set of objects }
|
17 |
|
18 |
{ TIpcCommon }
|
19 |
|
20 |
TIpcCommon = class
|
21 |
private
|
22 |
function GetSa: PSecurityAttributes;
|
23 |
protected
|
24 |
class var FInitialiser: boolean;
|
25 |
FSa : TSecurityAttributes;
|
26 |
private
|
27 |
Sd : TSecurityDescriptor;
|
28 |
public
|
29 |
constructor Create;
|
30 |
property Sa : PSecurityAttributes read GetSa;
|
31 |
end;
|
32 |
|
33 |
{ TSharedMemory }
|
34 |
|
35 |
{
|
36 |
The shared memory segment is used for interprocess communication and
|
37 |
holds both a message buffer and a number of shared variables. Shared
|
38 |
memory is allocated to each shared variable using the Allocate function.
|
39 |
An underlying assumption is that each process using the shared memory
|
40 |
calls "Allocate" in the same order and for the same memory sizes.
|
41 |
|
42 |
Windows:
|
43 |
|
44 |
The Windows implementation uses Windows shared memory. This is identified
|
45 |
by a global name known to every process. There is no security with
|
46 |
the windows implementation and the shared memory can be read by
|
47 |
any active process.
|
48 |
|
49 |
}
|
50 |
|
51 |
TSharedMemory = class(TIpcCommon)
|
52 |
private
|
53 |
FBuffer: PChar;
|
54 |
FLastAllocationSize: integer;
|
55 |
FUnused: integer;
|
56 |
FBufptr: PChar;
|
57 |
FSharedBuffer: THandle;
|
58 |
procedure GetSharedMemory(MemSize: integer);
|
59 |
public
|
60 |
constructor Create(MemSize: integer);
|
61 |
destructor Destroy; override;
|
62 |
function Allocate(Size: integer): PChar;
|
63 |
property LastAllocationSize: integer read FLastAllocationSize;
|
64 |
end;
|
65 |
|
66 |
{TMutex}
|
67 |
|
68 |
TMutex = class(TIpcCommon)
|
69 |
private
|
70 |
FMutex: THandle;
|
71 |
public
|
72 |
constructor Create(MutexName: string);
|
73 |
destructor Destroy; override;
|
74 |
procedure Lock;
|
75 |
procedure Unlock;
|
76 |
end;
|
77 |
|
78 |
{ TSingleLockGate }
|
79 |
|
80 |
{
|
81 |
A single lock gate is either open or closed. When open, any thread can pass
|
82 |
through it while, when closed, all threads are blocked as they try to pass
|
83 |
through the gate. When the gate is opened, all blocked threads are resumed.
|
84 |
|
85 |
There is an implementation assumption that only one writer thread at
|
86 |
a time (i.e. the thread which locks or unlocks the gate) can have access to
|
87 |
it at any one time. I.e. an external Mutex prevents race conditions.
|
88 |
|
89 |
Windows:
|
90 |
|
91 |
In the Windows implementation, a Windows Event is used to implement
|
92 |
the "gate". No additional functionality is required as the behaviour
|
93 |
of a Windows event meets the requirement.
|
94 |
|
95 |
|
96 |
Always initialised to the Unlocked state
|
97 |
}
|
98 |
|
99 |
TSingleLockGate = class(TIpcCommon)
|
100 |
private
|
101 |
FOwner: TGlobalInterface;
|
102 |
FEvent: THandle;
|
103 |
public
|
104 |
constructor Create(EventName: string; AOwner: TGlobalInterface);
|
105 |
destructor Destroy; override;
|
106 |
procedure PassthroughGate;
|
107 |
procedure Unlock;
|
108 |
procedure Lock;
|
109 |
end;
|
110 |
|
111 |
{ TMultilockGate }
|
112 |
|
113 |
{ This type of Gate is used where several reader threads must pass
|
114 |
through the gate before it can be opened for a writer thread.
|
115 |
|
116 |
The reader threads register their interest by each locking the gate.
|
117 |
The writer thread then waits on the locked gate until all the reader
|
118 |
threads have separately unlocked the gate.
|
119 |
|
120 |
There is an underlying assumption of a single writer. A Mutex must
|
121 |
be used to control access to the gate from the writer side if this
|
122 |
assumption is invalid.
|
123 |
|
124 |
Windows:
|
125 |
|
126 |
The Windows implementation uses an IPC Event and shared memory to hold
|
127 |
an integer - the reader count.
|
128 |
|
129 |
The readers lock the gate by resetting the event and incrementing the
|
130 |
reader count. They unlock the gate by decrementing the reader count
|
131 |
and calling set event when the reader count reaches zero.
|
132 |
|
133 |
The writer waits on the event for the gate to open. This is a timed wait
|
134 |
to avoid the writer being left in an indefinite wait state should a reader
|
135 |
terminate abnormally.
|
136 |
|
137 |
Always initialised to the Unlocked state
|
138 |
}
|
139 |
|
140 |
TMultilockGate = class(TIpcCommon)
|
141 |
private
|
142 |
FOnGateTimeout: TNotifyEvent;
|
143 |
FOwner: TGlobalInterface;
|
144 |
FEvent: THandle;
|
145 |
FLockCount: PInteger;
|
146 |
FMutex: TMutex;
|
147 |
function GetLockCount: integer;
|
148 |
public
|
149 |
constructor Create(EventName: string; AOwner: TGlobalInterface);
|
150 |
destructor Destroy; override;
|
151 |
procedure Lock;
|
152 |
procedure Unlock;
|
153 |
procedure PassthroughGate;
|
154 |
property LockCount: integer read GetLockCount;
|
155 |
property OnGateTimeout: TNotifyEvent read FOnGateTimeout write FOnGateTimeout;
|
156 |
end;
|
157 |
|
158 |
{ TGlobalInterface }
|
159 |
|
160 |
TGlobalInterface = class(TIpcCommon)
|
161 |
private
|
162 |
FMaxBufferSize: integer;
|
163 |
FSharedMemory: TSharedMemory;
|
164 |
FWriteLock: TMutex;
|
165 |
FBuffer: PChar;
|
166 |
FTraceDataType,
|
167 |
FBufferSize: PInteger;
|
168 |
FTimeStamp: PDateTime;
|
169 |
FReadReadyEvent: TMultiLockGate;
|
170 |
FReadFinishedEvent: TMultiLockGate;
|
171 |
FDataAvailableEvent: TSingleLockGate;
|
172 |
FWriterBusyEvent: TSingleLockGate;
|
173 |
FMonitorCount: PInteger;
|
174 |
procedure HandleGateTimeout(Sender: TObject);
|
175 |
function GetMonitorCount: integer;
|
176 |
public
|
177 |
constructor Create;
|
178 |
destructor Destroy; override;
|
179 |
procedure IncMonitorCount;
|
180 |
procedure DecMonitorCount;
|
181 |
procedure SendTrace(TraceObject: TTraceObject);
|
182 |
procedure ReceiveTrace(TraceObject: TTraceObject);
|
183 |
property DataAvailableEvent: TSingleLockGate read FDataAvailableEvent;
|
184 |
property WriterBusyEvent: TSingleLockGate read FWriterBusyEvent;
|
185 |
property ReadReadyEvent: TMultiLockGate read FReadReadyEvent;
|
186 |
property ReadFinishedEvent: TMultiLockGate read FReadFinishedEvent;
|
187 |
property WriteLock: TMutex read FWriteLock;
|
188 |
property MonitorCount: integer read GetMonitorCount;
|
189 |
property SharedMemory: TSharedMemory read FSharedMemory;
|
190 |
property MaxBufferSize: integer read FMaxBufferSize;
|
191 |
end;
|
192 |
|
193 |
{ TSharedMemory }
|
194 |
|
195 |
procedure TSharedMemory.GetSharedMemory(MemSize: integer);
|
196 |
begin
|
197 |
FSharedBuffer := CreateFileMapping(INVALID_HANDLE_VALUE, sa, PAGE_READWRITE,
|
198 |
0, MemSize, PChar(MonitorHookNames[1]));
|
199 |
|
200 |
if GetLastError = ERROR_ALREADY_EXISTS then
|
201 |
FSharedBuffer := OpenFileMapping(FILE_MAP_ALL_ACCESS, false, PChar(MonitorHookNames[1]))
|
202 |
else
|
203 |
FInitialiser := true;
|
204 |
if (FSharedBuffer = 0) then
|
205 |
IBError(ibxeCannotCreateSharedResource, [GetLastError]);
|
206 |
end;
|
207 |
|
208 |
constructor TSharedMemory.Create(MemSize: integer);
|
209 |
begin
|
210 |
inherited Create;
|
211 |
FInitialiser := false;
|
212 |
GetSharedMemory(MemSize);
|
213 |
FBuffer := MapViewOfFile(FSharedBuffer, FILE_MAP_ALL_ACCESS, 0, 0, 0);
|
214 |
|
215 |
if FBuffer = nil then
|
216 |
IBError(ibxeCannotCreateSharedResource, [GetLastError]);
|
217 |
FBufPtr := FBuffer;
|
218 |
FUnused := MemSize
|
219 |
end;
|
220 |
|
221 |
destructor TSharedMemory.Destroy;
|
222 |
begin
|
223 |
UnmapViewOfFile(FBuffer);
|
224 |
CloseHandle(FSharedBuffer);
|
225 |
inherited Destroy;
|
226 |
end;
|
227 |
|
228 |
function TSharedMemory.Allocate(Size: integer): PChar;
|
229 |
begin
|
230 |
if Size > FUnused then
|
231 |
IBError(ibxeCannotCreateSharedResource, ['Not enough shared memory']);
|
232 |
Result := FBufPtr;
|
233 |
|
234 |
if Size = 0 then
|
235 |
begin
|
236 |
FLastAllocationSize := FUnused;
|
237 |
FUnused := 0
|
238 |
end
|
239 |
else
|
240 |
begin
|
241 |
FLastAllocationSize := Size;
|
242 |
Dec(FUnused,Size);
|
243 |
end;
|
244 |
Inc(FBufPtr,Size)
|
245 |
end;
|
246 |
|
247 |
{ TIpcCommon }
|
248 |
|
249 |
function TIpcCommon.GetSa: PSecurityAttributes;
|
250 |
begin
|
251 |
Result := @FSa
|
252 |
end;
|
253 |
|
254 |
constructor TIpcCommon.Create;
|
255 |
begin
|
256 |
{ Setup Security so anyone can connect to the MMF/Mutex/Event. This is
|
257 |
needed when IBX is used in a Service. }
|
258 |
|
259 |
InitializeSecurityDescriptor(@Sd,SECURITY_DESCRIPTOR_REVISION);
|
260 |
SetSecurityDescriptorDacl(@Sd,true,nil,false);
|
261 |
FSa.nLength := SizeOf(FSa);
|
262 |
FSa.lpSecurityDescriptor := @Sd;
|
263 |
FSa.bInheritHandle := true;
|
264 |
end;
|
265 |
|
266 |
|
267 |
{ TMutex }
|
268 |
|
269 |
constructor TMutex.Create(MutexName: string);
|
270 |
begin
|
271 |
inherited Create;
|
272 |
if FInitialiser then
|
273 |
FMutex := CreateMutex(sa, False, PChar(MutexName))
|
274 |
else
|
275 |
FMutex := OpenMutex(MUTEX_ALL_ACCESS, False, PChar(MutexName));
|
276 |
|
277 |
if FMutex = 0 then
|
278 |
IBError(ibxeCannotCreateSharedResource, [GetLastError])
|
279 |
end;
|
280 |
|
281 |
destructor TMutex.Destroy;
|
282 |
begin
|
283 |
CloseHandle(FMutex);
|
284 |
inherited Destroy;
|
285 |
end;
|
286 |
|
287 |
{ Obtain ownership of the Mutex and prevent other threads from accessing protected resource }
|
288 |
|
289 |
procedure TMutex.Lock;
|
290 |
begin
|
291 |
WaitForSingleObject(FMutex, INFINITE);
|
292 |
end;
|
293 |
|
294 |
{Give up ownership of the Mutex and allow other threads access }
|
295 |
|
296 |
procedure TMutex.Unlock;
|
297 |
begin
|
298 |
ReleaseMutex(FMutex);
|
299 |
end;
|
300 |
|
301 |
{ TSingleLockGate }
|
302 |
constructor TSingleLockGate.Create(EventName: string; AOwner: TGlobalInterface);
|
303 |
begin
|
304 |
inherited Create;
|
305 |
FOwner := AOwner;
|
306 |
if FInitialiser then
|
307 |
FEvent := CreateEvent(sa, true, true, PChar(EventName))
|
308 |
else
|
309 |
FEvent := OpenEvent(EVENT_ALL_ACCESS, true, PChar(EventName));
|
310 |
|
311 |
if FEvent = 0 then
|
312 |
IBError(ibxeCannotCreateSharedResource, [GetLastError])
|
313 |
end;
|
314 |
|
315 |
destructor TSingleLockGate.Destroy;
|
316 |
begin
|
317 |
CloseHandle(FEvent);
|
318 |
inherited Destroy;
|
319 |
end;
|
320 |
|
321 |
|
322 |
procedure TSingleLockGate.PassthroughGate;
|
323 |
begin
|
324 |
WaitForSingleObject(FEvent,INFINITE)
|
325 |
end;
|
326 |
|
327 |
procedure TSingleLockGate.Unlock;
|
328 |
begin
|
329 |
SetEvent(FEvent) //Event State set to "signaled"
|
330 |
end;
|
331 |
|
332 |
procedure TSingleLockGate.Lock;
|
333 |
begin
|
334 |
ResetEvent(FEvent) //Event State set to "unsignaled"
|
335 |
end;
|
336 |
|
337 |
{ TMultilockGate }
|
338 |
|
339 |
constructor TMultilockGate.Create(EventName: string; AOwner: TGlobalInterface);
|
340 |
begin
|
341 |
inherited Create;
|
342 |
FOwner := AOwner;
|
343 |
FLockCount := PInteger(FOwner.SharedMemory.Allocate(sizeof(FLockCount)));
|
344 |
FMutex := TMutex.Create(EventName + '.Mutex');
|
345 |
if FInitialiser then
|
346 |
begin
|
347 |
FEvent := CreateEvent(sa, true, true, PChar(EventName));
|
348 |
FLockCount^ := 0;
|
349 |
end
|
350 |
else
|
351 |
FEvent := OpenEvent(EVENT_ALL_ACCESS, true, PChar(EventName));
|
352 |
|
353 |
if FEvent = 0 then
|
354 |
IBError(ibxeCannotCreateSharedResource, [GetLastError])
|
355 |
end;
|
356 |
|
357 |
destructor TMultilockGate.Destroy;
|
358 |
begin
|
359 |
if assigned(FMutex) then FMutex.Free;
|
360 |
CloseHandle(FEvent);
|
361 |
inherited Destroy;
|
362 |
end;
|
363 |
|
364 |
function TMultilockGate.GetLockCount: integer;
|
365 |
begin
|
366 |
Result := FLockCount^
|
367 |
end;
|
368 |
|
369 |
procedure TMultilockGate.Lock;
|
370 |
begin
|
371 |
FMutex.Lock;
|
372 |
try
|
373 |
Inc(FLockCount^);
|
374 |
ResetEvent(FEvent);
|
375 |
finally
|
376 |
FMutex.Unlock;
|
377 |
end;
|
378 |
//writeln('Lock '+IntToStr(FLockCount^));
|
379 |
end;
|
380 |
|
381 |
procedure TMultilockGate.Unlock;
|
382 |
begin
|
383 |
//writeln('Start UnLock '+IntToStr(FLockCount^));
|
384 |
FMutex.Lock;
|
385 |
try
|
386 |
Dec(FLockCount^);
|
387 |
if FLockCount^ <= 0 then
|
388 |
begin
|
389 |
SetEvent(FEvent);
|
390 |
FLockCount^ := 0
|
391 |
end;
|
392 |
finally
|
393 |
FMutex.Unlock;
|
394 |
end;
|
395 |
//writeln('UnLock '+IntToStr(FLockCount^));
|
396 |
end;
|
397 |
|
398 |
procedure TMultilockGate.PassthroughGate;
|
399 |
begin
|
400 |
if FLockCount^ = 0 then
|
401 |
Exit;
|
402 |
while WaitForSingleObject(FEvent,cDefaultTimeout)= WAIT_TIMEOUT do
|
403 |
{ If we have timed out then we have lost a reader }
|
404 |
begin
|
405 |
if FLockCount^ > 0 then
|
406 |
begin
|
407 |
UnLock;
|
408 |
if assigned(FOnGateTimeout) then
|
409 |
OnGateTimeout(self)
|
410 |
end
|
411 |
end;
|
412 |
end;
|
413 |
|
414 |
|
415 |
{ TGlobalInterface }
|
416 |
|
417 |
function TGlobalInterface.GetMonitorCount: integer;
|
418 |
begin
|
419 |
Result := FMonitorCount^
|
420 |
end;
|
421 |
|
422 |
procedure TGlobalInterface.HandleGateTimeout(Sender: TObject);
|
423 |
begin
|
424 |
//writeln(ClassName+': Gate TimeOut');
|
425 |
DecMonitorCount
|
426 |
end;
|
427 |
|
428 |
constructor TGlobalInterface.Create;
|
429 |
begin
|
430 |
inherited Create;
|
431 |
FSharedMemory := TSharedMemory.Create(cMonitorHookSize);
|
432 |
|
433 |
FWriteLock := TMutex.Create(PChar(MonitorHookNames[0]));
|
434 |
FDataAvailableEvent := TSingleLockGate.Create(MonitorHookNames[2],self);
|
435 |
FWriterBusyEvent := TSingleLockGate.Create(MonitorHookNames[3],self);
|
436 |
FReadReadyEvent := TMultiLockGate.Create(MonitorHookNames[4],self);
|
437 |
FReadReadyEvent.OnGateTimeout := HandleGateTimeout;
|
438 |
FReadFinishedEvent := TMultiLockGate.Create(MonitorHookNames[5],self);
|
439 |
FReadFinishedEvent.OnGateTimeout := HandleGateTimeout;
|
440 |
|
441 |
FMonitorCount := PInteger(FSharedMemory.Allocate(sizeof(FMonitorCount)));
|
442 |
|
443 |
if FInitialiser then
|
444 |
FMonitorCount^ := 0;
|
445 |
FTraceDataType := PInteger(FSharedMemory.Allocate(sizeof(Integer)));
|
446 |
FTimeStamp := PDateTime(FSharedMemory.Allocate(sizeof(TDateTime)));
|
447 |
FBufferSize := PInteger(FSharedMemory.Allocate(sizeof(Integer)));
|
448 |
FBuffer := FSharedMemory.Allocate(0); //All remaining
|
449 |
FMaxBufferSize := FSharedMemory.LastAllocationSize;
|
450 |
|
451 |
if FInitialiser then
|
452 |
begin
|
453 |
FBufferSize^ := 0;
|
454 |
FDataAvailableEvent.Lock
|
455 |
end;
|
456 |
end;
|
457 |
|
458 |
destructor TGlobalInterface.Destroy;
|
459 |
begin
|
460 |
if assigned(FWriteLock) then FWriteLock.Free;
|
461 |
if assigned(FDataAvailableEvent) then FDataAvailableEvent.Free;
|
462 |
if assigned(FWriterBusyEvent) then FWriterBusyEvent.Free;
|
463 |
if assigned(FReadReadyEvent) then FReadReadyEvent.Free;
|
464 |
if assigned(FReadFinishedEvent) then FReadFinishedEvent.Free;
|
465 |
if assigned(FSharedMemory) then FSharedMemory.Free;
|
466 |
inherited Destroy;
|
467 |
end;
|
468 |
|
469 |
procedure TGlobalInterface.IncMonitorCount;
|
470 |
begin
|
471 |
InterlockedIncrement(FMonitorCount^)
|
472 |
end;
|
473 |
|
474 |
procedure TGlobalInterface.DecMonitorCount;
|
475 |
begin
|
476 |
InterlockedDecrement(FMonitorCount^)
|
477 |
end;
|
478 |
|
479 |
procedure TGlobalInterface.SendTrace(TraceObject: TTraceObject);
|
480 |
begin
|
481 |
FTraceDataType^ := Integer(TraceObject.FDataType);
|
482 |
FTimeStamp^ := TraceObject.FTimeStamp;
|
483 |
FBufferSize^ := Min(Length(TraceObject.FMsg), MaxBufferSize);
|
484 |
Move(TraceObject.FMsg[1], FBuffer^, FBufferSize^);
|
485 |
end;
|
486 |
|
487 |
procedure TGlobalInterface.ReceiveTrace(TraceObject: TTraceObject);
|
488 |
begin
|
489 |
SetString(TraceObject.FMsg, FBuffer, FBufferSize^);
|
490 |
TraceObject.FDataType := TTraceFlag(FTraceDataType^);
|
491 |
TraceObject.FTimeStamp := TDateTime(FTimeStamp^);
|
492 |
end;
|
493 |
|
494 |
|
495 |
|