552 lines
13 KiB
C++
552 lines
13 KiB
C++
/*++
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Copyright (c) 1994 Microsoft Corporation
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All rights reserved
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Module Name:
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ThreadM.c
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Abstract:
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Generic thread manager for spooler.
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Author:
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Albert Ting (AlbertT) 13-Feb-1994
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Environment:
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User Mode -Win32
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Revision History:
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Albert Ting (AlbertT) 28-May-1994 C++ized
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--*/
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#include "spllibp.hxx"
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#pragma hdrstop
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/********************************************************************
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Public interfaces.
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********************************************************************/
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TThreadM::
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TThreadM(
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UINT uMaxThreads,
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UINT uIdleLife,
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MCritSec* pCritSec OPTIONAL
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) :
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_uMaxThreads(uMaxThreads), _uIdleLife(uIdleLife), _uActiveThreads(0),
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_uRunNowThreads(0), _iIdleThreads(0)
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/*++
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Routine Description:
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Construct a Thread Manager object.
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Arguments:
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uMaxThreads - Upper limit of threads that will be created.
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uIdleLife - Maximum life once a thread goes idle (in ms).
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pCritSec - Use this crit sec for synchronization (if not specified,
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a private one will be created).
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Return Value:
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Notes:
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_hTrigger is our validity variable. When this value is NULL,
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instantiation failed. If it's non-NULL, the entire object is valid.
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--*/
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{
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_hTrigger = CreateEvent( NULL,
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FALSE,
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FALSE,
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NULL );
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if( !_hTrigger ){
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return;
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}
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//
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// If no critical section, create our own.
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//
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if (!pCritSec) {
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_pCritSec = new MCritSec();
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if( !VALID_PTR( _pCritSec )){
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//
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// _hTrigger is our valid variable. If we fail to create
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// the critical section, prepare to return failure.
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//
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CloseHandle( _hTrigger );
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_hTrigger = NULL;
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return;
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}
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_State |= kPrivateCritSec;
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} else {
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_pCritSec = pCritSec;
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}
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}
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VOID
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TThreadM::
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vDelete(
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VOID
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)
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/*++
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Routine Description:
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Indicates that the object is pending deletion. Any object that
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inherits from vDelete should _not_ call the destructor directly,
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since there may be pending jobs. Instead, they should call
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TThreadM::vDelete().
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Arguments:
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Return Value:
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--*/
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{
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BOOL bDestroy = FALSE;
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{
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TCritSecLock CSL( *_pCritSec );
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//
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// Mark as wanting to be destroyed.
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//
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_State |= kDestroyReq;
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if( !_iIdleThreads && !_uActiveThreads ){
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bDestroy = TRUE;
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}
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}
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if( bDestroy ){
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//
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// Delete the object. Note that absolutely no object fields
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// can be accessed after this, since the object is returned
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// to free store.
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//
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delete this;
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}
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}
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BOOL
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TThreadM::
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bJobAdded(
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BOOL bRunNow
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)
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/*++
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Routine Description:
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Notify the thread manager that a new job has been added. This job
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will be processed fifo.
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Arguments:
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bRunNow - Ignore the thread limits and run the job now.
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Return Value:
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TRUE - Job successfully added.
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FALSE - Job could not be added.
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--*/
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{
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DWORD dwThreadId;
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HANDLE hThread;
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BOOL rc = TRUE;
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TCritSecLock CSL( *_pCritSec );
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if( _State.bBit( kDestroyReq )){
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DBGMSG( DBG_THREADM | DBG_ERROR,
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( "ThreadM.bJobAdded: add failed since DESTROY requested.\n" ));
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SetLastError( ERROR_INVALID_PARAMETER );
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rc = FALSE;
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} else {
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//
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// We either: give it to an idle thread, create a new thread,
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// or leave it in the queue.
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//
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if( _iIdleThreads > 0 ){
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//
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// There are some idle threads--trigger the event and it
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// will be picked up.
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//
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--_iIdleThreads;
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DBGMSG( DBG_THREADM,
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( "ThreadM.bJobAdded: Trigger: --iIdle %d, uActive %d\n",
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_iIdleThreads, _uActiveThreads ));
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//
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// If we set the event, then the worker thread that receives
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// this event should _not_ decrement _iIdleThreads, since
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// we already did this.
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//
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SetEvent( _hTrigger );
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} else if( _uActiveThreads < _uMaxThreads || bRunNow ){
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//
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// No idle threads, but we can create a new one since we
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// haven't reached the limit, or the bRunNow flag is set.
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//
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hThread = CreateThread( NULL,
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0,
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xdwThreadProc,
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this,
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0,
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&dwThreadId );
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if( hThread ){
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CloseHandle( hThread );
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//
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// We have successfully created a thread; up the
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// count.
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//
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++_uActiveThreads;
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//
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// We have less active threads than the max; create a new one.
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//
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DBGMSG( DBG_THREADM,
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( "ThreadM.bJobAdded: ct: iIdle %d, ++uActive %d\n",
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_iIdleThreads,
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_uActiveThreads ));
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} else {
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rc = FALSE;
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DBGMSG( DBG_THREADM | DBG_WARN,
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( "ThreadM.bJobAdded: unable to ct %d\n",
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GetLastError( )));
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}
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} else {
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//
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// No idle threads, and we are already at the max so we
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// can't create new threads. Dec iIdleThreads anyway
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// (may go negative, but that's ok).
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//
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// iIdleThreads represents the number of threads that
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// are currently not processing jobs. If the number is
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// negative, this indicates that even if a thread suddenly
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// completes a job and would go idle, there is a queued
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// job that would immediately grab it, so the thread really
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// didn't go into an idle state.
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//
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// The negative number indicates the number of outstanding
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// jobs that are queued (e.g., -5 indicate 5 jobs queued).
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//
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// There is always an increment of iIdleThreads when a
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// job is compeleted.
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//
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--_iIdleThreads;
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//
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// No threads idle, and at max threads.
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//
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DBGMSG( DBG_THREADM,
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( "ThreadM.bJobAdded: wait: --iIdle %d, uActive %d\n",
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_iIdleThreads,
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_uActiveThreads ));
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}
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//
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// If we succeeded and bRunNow is set, this indicates that
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// we were able to start a special thread, so we need to adjust
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// the maximum number of threads. When a this special thread
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// job completes, we will decrement it.
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//
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if( bRunNow && rc ){
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++_uMaxThreads;
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++_uRunNowThreads;
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}
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}
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return rc;
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}
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/********************************************************************
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Private routines.
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********************************************************************/
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TThreadM::
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~TThreadM(
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VOID
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)
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/*++
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Routine Description:
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Destroy the thread manager object. This is private; to request
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that the thread manager quit, call vDelete().
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Arguments:
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Return Value:
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--*/
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{
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SPLASSERT( _State.bBit( kDestroyReq ));
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if( _State.bBit( kPrivateCritSec )){
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SPLASSERT( _pCritSec->bOutside( ));
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delete _pCritSec;
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}
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if( _hTrigger )
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CloseHandle( _hTrigger );
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vThreadMDeleteComplete();
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}
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VOID
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TThreadM::
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vThreadMDeleteComplete(
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VOID
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)
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/*++
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Routine Description:
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Stub routine for objects that don't need deletion
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complete notification.
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Arguments:
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Return Value:
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--*/
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{
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}
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DWORD
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TThreadM::
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xdwThreadProc(
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LPVOID pVoid
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)
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/*++
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Routine Description:
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Worker thread routine that calls the client to process the jobs.
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Arguments:
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pVoid - pTMStateVar
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Return Value:
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Ignored.
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--*/
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{
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TThreadM* pThreadM = (TThreadM*)pVoid;
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return pThreadM->dwThreadProc();
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}
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DWORD
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TThreadM::
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dwThreadProc(
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VOID
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)
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{
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BOOL bDestroy = FALSE;
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{
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TCritSecLock CSL( *_pCritSec );
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: ct: iIdle %d, uActive %d\n",
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_iIdleThreads,
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_uActiveThreads));
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PJOB pJob = pThreadMJobNext();
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while( TRUE ){
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for( ; pJob; pJob=pThreadMJobNext( )){
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//
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// If bRunNow count is non-zero, this indicates that we just
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// picked up a RunNow job. As soon as it completes, we
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// can decrement the count.
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//
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BOOL bRunNowCompleted = _uRunNowThreads > 0;
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{
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TCritSecUnlock CSU( *_pCritSec );
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//
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// Call back to client to process the job.
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//
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: %x processing\n",
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(DWORD)pJob ));
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//
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// Call through virtual function to process the
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// user's job.
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//
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vThreadMJobProcess( pJob );
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: %x processing done\n",
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(DWORD)pJob ));
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}
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//
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// If a RunNow job has been completed, then decrement both
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// counts. uMaxThreads was increased by one when the job was
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// accepted, so now it must be lowered.
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//
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if( bRunNowCompleted ){
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--_uMaxThreads;
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--_uRunNowThreads;
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}
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++_iIdleThreads;
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: ++iIdle %d, uActive %d\n",
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_iIdleThreads,
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_uActiveThreads ));
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}
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: Sleep: iIdle %d, uActive %d\n",
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_iIdleThreads,
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_uActiveThreads ));
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{
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TCritSecUnlock CSU( *_pCritSec );
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//
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// Done, now relax and go idle for a bit. We don't
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// care whether we timeout or get triggered; in either
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// case we check for another job.
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//
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WaitForSingleObject( _hTrigger, _uIdleLife );
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}
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//
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// We must check here instead of relying on the return value
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// of WaitForSingleObject since someone may see iIdleThreads!=0
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// and set the trigger, but we timeout before it gets set.
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//
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pJob = pThreadMJobNext();
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if( pJob ){
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: Woke and found job: iIdle %d, uActive %d\n",
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_iIdleThreads,
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_uActiveThreads ));
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} else {
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//
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// No jobs found; break. Be sure to reset the hTrigger, since
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// there are no waiting jobs, and the main thread might
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// have set it in the following case:
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//
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// MainThread: WorkerThread:
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// Sleeping
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// Awoke, not yet in CS.
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// GotJob
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// SetEvent
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// --iIdleThreads
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// Enter CS, found job, process it.
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//
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// In this case, the event is set, but there is no thread
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// to pick it up.
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//
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ResetEvent( _hTrigger );
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break;
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}
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}
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//
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// Decrement ActiveThreads. This was incremented when the thread
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// was successfully created, and should be decremented when the thread
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// is about to exit.
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//
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--_uActiveThreads;
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//
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// The thread enters an idle state right before it goes to sleep.
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//
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// When a job is added, the idle count is decremented by the main
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// thread, so the worker thread doesn't decrement it (avoids sync
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// problems). If the worker thread timed out and there were no jobs,
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// then we need to decrement the matching initial increment here.
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//
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--_iIdleThreads;
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if( _State.bBit( kDestroyReq ) &&
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!_uActiveThreads &&
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!_iIdleThreads ){
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//
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// Destroy requested.
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//
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bDestroy = TRUE;
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}
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DBGMSG( DBG_THREADM,
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( "ThreadM.dwThreadProc: dt: --iIdle %d, --uActive %d\n",
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_iIdleThreads,
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_uActiveThreads));
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}
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if( bDestroy ){
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delete this;
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}
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return 0;
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}
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