CRITICAL_SECTION , . , , ( . 7.1), :
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, , . , CRITICAL_SECTION, , . 8.2. CRITICAL_SECTION 8.1, , .
CS , , . 8.1, . , , . volatile, , , . , ; , , , . 8.1.
CRITICAL_SECTION cs1;
volatile DWORD N = 0, ;
/* N , . */
InitializeCriticalSection (&cs1);
EnterCriticalSection (&cs1);
if (N < N_MAX) { M = N; M += 1; N = M; }
LeaveCriticalSection (&cs1);
DeleteCriticalSection (&cs1);
. 8.2 , . 8.1, , CS .
8.1 , CS.
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8.1 , CS. , , , (invariant) , ( ), .
. 8.2.
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, (producer) (consumer), .
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, ; . , , , "". , .
[28] , , , , . , , ; CS , . (message block invariant) .
, .
8.1.simplePC: "/"
/* 8. simplePC. */
/* . */
/* */
/* , " ", */
/* . */
#include "EvryThng.h"
#include <time.h>
#define DATA_SIZE 256
typedef struct msg_block_tag { /* . */
volatile DWORD f_ready, f_stop; /* . */
volatile DWORD sequence; /* . */
volatile DWORD nCons, nLost;
time_t timestamp;
CRITICAL_SECTION mguard; /* . */
DWORD checksum; /* . */
DWORD data[DATA_SIZE]; /* . */
} MSG_BLOCK;
/* , . */
MSG_BLOCK mblock = { 0, 0, 0, 0, 0 };
DWORD WINAPI produce(void*);
DWORD WINAPI consume(void*);
void MessageFill(MSG_BLOCK*);
void MessageDisplay(MSG_BLOCK*);
DWORD _tmain(DWORD argc, LPTSTR argv[]) {
DWORD Status, ThId;
HANDLE produce h, consume_h;
/* . */
InitializeCriticalSection (&mblock.mguard);
/* . */
produce_h = (HANDLE)_beginthreadex(NULL, 0, produce, NULL, 0, &ThId);
consume_h = (HANDLE)_beginthreadex (NULL, 0, consume, NULL, 0, &ThId);
/* . */
WaitForSingleObject(consume_h, INFINITE);
WaitForSingleObject(produce_h, INFINITE);
DeleteCriticalSection(&mblock.mguard);
_tprintf(_T(" \n"));
_tprintf(_T(": %d, : %d, : %d\n"), mblock.sequence, mblock.nCons, mblock.nLost);
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return 0;
}
DWORD WINAPI produce(void *arg)
/* */
/* . */
{
srand((DWORD)time(NULL)); /* . */
while (!mblock.f_stop) {
/* . */
Sleep(rand() / 100);
/* . */
EnterCriticalSection(&mblock.mguard);
__try {
if (!mblock.f_stop) {
mblock.f_ready = 0;
MessageFill(&mblock);
mblock.f_ready = 1;
mblock.sequence++;
}
} __finally { LeaveCriticalSection (&mblock.mguard); }
}
return 0;
}
DWORD WINAPI consume (void *arg) {
DWORD ShutDown = 0;
CHAR command, extra;
/* . */
while (!ShutDown) { /* , /. */
_tprintf(_T("\n** '' ; 's' : "));
_tscanf("%c%c", &command, &extra);
if (command == 's') {
EnterCriticalSection(&mblock.mguard);
ShutDown = mblock.f_stop = 1;
LeaveCriticalSection(&mblock.mguard);
} else if (command == 'c') { /* . */
EnterCriticalSection(&mblock.mguard);
__try {
if (mblock.f_ready == 0) _tprintf(_T(" . .\n"));
else {
MessageDisplay(&mblock);
mblock.nCons++;
mblock.nLost = mblock.sequence mblock.nCons;
mblock.f_ready = 0; /* . */
}
} __finally { LeaveCriticalSection (&mblock.mguard); }
} else {
tprintf(_T(" . .\n"));
}
}
return 0;
}
void MessageFill(MSG_BLOCK *mblock) {
/* , . */
DWORD i;
mblock->checksum = 0;
for (i = 0; i < DATA_SIZE; i++) {
mblock->data[i] = rand();
mblock->checksum ^= mblock->data[i];
}
mblock->timestamp = time(NULL);
return;
}
void MessageDisplay(MSG_BLOCK *mblock) {
/* , . */
DWORD i, tcheck = 0;
for (i = 0; i < DATA_SIZE; i++) tcheck ^= mblock->data[i];
_tprintf(_T("\n %d: %s"), mblock->sequence, _tctime(&(mblock->timestamp)));
_tprintf(_T(" : % %\n"), mblock->data[0], mblock->data[DATA_SIZE 1]);
if (tcheck == mblock->checksum) _tprintf(_T(" > .\n"));
else tprintf(_T(" > . .\n"));
return;
}
"/"
, , .
CRITICAL_SECTION ( ), .
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, , volatile.
, CS . , , LeaveCriticalSection . , , C++.
MessageFill MessageDisplay , . , , .
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0 <= nLost + nCons <= sequence
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, . , TerminateThread , . , , . , , , ; 10.
CRITICAL_SECTION , , , . , , (time-out). Windows , .
