// Cancel - Creates a new thread with long running query when the letter 'a' is typed.
// Cancels a query when letter 'C' is typed.
// All threads are terminated when the letter 'Q' is entered.
//
// This program requires the multithread library.
#include
#include
#include
#include
#include
#include
#include
#include
void main(void); /* Thread 1: main */
void KbdFunc(void ); /* Keyboard input, thread dispatch */
void LongQuery(void *addl); /* Threads 2: Long running query */
void LongQueryCancel();
void ShutDown(void); /* Program shutdown */
void WriteTitle(); /* Display title bar information */
HANDLE hConsoleOut; /* Handle to the console */
HANDLE hQueryMutex; /* "Query Running" mutex */
HANDLE hScreenMutex; /* "Screen update" mutex */
SAConnection g_Conn;
SACommand g_Cmd(&g_Conn);
// connection and query information
// modify here to provide your real information
const char *LONG_RUNNING_QUERY =
"select * from test_bulk "
" where fvarchar20 like '%hj' or fvarchar20 like '%dfds'"
" or fvarchar20 in (select fvarchar20 from test_bulk)"
" order by fvarchar20 desc, finteger desc";
const char *DATABASE = "test";
const char *USER = "tester";
const char *PASSWORD = "tester";
SAClient_t CLIENT = SA_DB2_Client;
void main() /* Thread One */
{
/* Get display screen information & clear the screen.*/
hConsoleOut = GetStdHandle(STD_OUTPUT_HANDLE);
WriteTitle();
/* Create the mutexes and reset thread count. */
hScreenMutex = CreateMutex(NULL, FALSE, NULL); /* Cleared */
hQueryMutex = CreateMutex(NULL, FALSE, NULL); /* Cleared */
try
{
// connect
g_Conn.Connect(DATABASE, USER, PASSWORD, CLIENT);
/* Start waiting for keyboard input to dispatch threads or exit. */
KbdFunc();
}
catch(SAException &x)
{
std::cout << x.ErrText().GetMultiByteChars() << std::endl;
try
{
g_Conn.Rollback();
}
catch(SAException &)
{
}
}
/* All threads done. Clean up handles. */
CloseHandle(hScreenMutex);
CloseHandle(hQueryMutex);
CloseHandle(hConsoleOut);
}
void ShutDown(void)
{
// try to cancel the query if still running
if(WaitForSingleObject(hQueryMutex, 75L) == WAIT_TIMEOUT)
LongQueryCancel();
else
ReleaseMutex(hQueryMutex);
}
void KbdFunc(void)
{
int KeyInfo;
do
{
KeyInfo = _getch();
if(tolower(KeyInfo) == 'a')
_beginthread(LongQuery, 0, NULL);
if(tolower(KeyInfo) == 'c')
LongQueryCancel();
}
while(tolower(KeyInfo) != 'q');
ShutDown();
}
void LongQuery(void *addl)
{
if(WaitForSingleObject(hQueryMutex, 75L) == WAIT_TIMEOUT)
{
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << "query still running, use 'C' to cancel it." << std::endl;
ReleaseMutex(hScreenMutex);
return;
}
try
{
g_Cmd.setCommandText(LONG_RUNNING_QUERY);
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << "executing " << g_Cmd.CommandText().GetMultiByteChars() << std::endl;
ReleaseMutex(hScreenMutex);
g_Cmd.Execute();
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << "executed" << std::endl;
ReleaseMutex(hScreenMutex);
}
catch(SAException &x)
{
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << x.ErrText().GetMultiByteChars() << std::endl;
ReleaseMutex(hScreenMutex);
}
ReleaseMutex(hQueryMutex);
}
void LongQueryCancel()
{
try
{
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << "CANCELLING..." << std::endl;
ReleaseMutex(hScreenMutex);
g_Cmd.Cancel();
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << "CANCELLED" << std::endl;
ReleaseMutex(hScreenMutex);
}
catch(SAException &x)
{
WaitForSingleObject(hScreenMutex, INFINITE);
std::cout << x.ErrText().GetMultiByteChars() << std::endl;
ReleaseMutex(hScreenMutex);
}
}
void WriteTitle()
{
char NThreadMsg[1024];
sprintf(NThreadMsg, "Press 'A' to start a long running query in a thread, 'C' to cancel it, 'Q' to quit.");
SetConsoleTitle(NThreadMsg);
}