TThread.cxx

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// @(#)root/thread:$Id$
// Author: Fons Rademakers   02/07/97
 
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
/** \class TThread
 
\legacy{TThread}
 
This class implements threads. A thread is an execution environment
much lighter than a process. A single process can have multiple
threads. The actual work is done via the TThreadImp class (either
TPosixThread or TWin32Thread).
 
**/
 
#include "RConfigure.h"
 
#include "TThread.h"
#include "TThreadImp.h"
#include "TThreadFactory.h"
#include "TROOT.h"
#include "TCondition.h"
#include "TApplication.h"
#include "TVirtualPad.h"
#include "TMethodCall.h"
#include "TMutex.h"
#include "TTimeStamp.h"
#include "TInterpreter.h"
#include "TError.h"
#include "TSystem.h"
#include "Varargs.h"
#include "ThreadLocalStorage.h"
#include "TThreadSlots.h"
#include "TRWMutexImp.h"
#include "snprintf.h"
 
TThreadImp     *TThread::fgThreadImp = nullptr;
Long_t          TThread::fgMainId = 0;
TThread        *TThread::fgMain = nullptr;
TMutex         *TThread::fgMainMutex;
std::atomic<char *> volatile TThread::fgXAct{nullptr};
TMutex         *TThread::fgXActMutex = nullptr;
TCondition *TThread::fgXActCondi = nullptr;
void **volatile TThread::fgXArr = nullptr;
volatile Int_t  TThread::fgXAnb = 0;
volatile Int_t  TThread::fgXArt = 0;
 
static void CINT_alloc_lock()   { gGlobalMutex->Lock(); }
static void CINT_alloc_unlock() { gGlobalMutex->UnLock(); }
 
static TMutex  *gMainInternalMutex = nullptr;
 
static void ThreadInternalLock() { if (gMainInternalMutex) gMainInternalMutex->Lock(); }
static void ThreadInternalUnLock() { if (gMainInternalMutex) gMainInternalMutex->UnLock(); }
 
static Bool_t fgIsTearDown(kFALSE);
 
extern "C" void ROOT_TThread_Initialize()
{
   TThread::Initialize();
};
 
//------------------------------------------------------------------------------
 
// Set gGlobalMutex to 0 when Thread library gets unloaded
class TThreadTearDownGuard {
public:
   TThreadTearDownGuard() { fgIsTearDown = kFALSE; }
   ~TThreadTearDownGuard() {
      // Note: we could insert here a wait for all thread to be finished.
      // this is questionable though as we need to balance between fixing a
      // user error (the thread was let lose and the caller did not explicit wait)
      // and the risk that we can not terminate a failing process.
 
      fgIsTearDown = kTRUE;
      TVirtualMutex *m = gGlobalMutex;
      gGlobalMutex = nullptr;
      delete m;
      TThreadImp *imp = TThread::fgThreadImp;
      TThread::fgThreadImp = nullptr;
      delete imp;
   }
};
static TThreadTearDownGuard gTearDownGuard;
 
//------------------------------------------------------------------------------
 
class TJoinHelper {
private:
   TThread    *fT;
   TThread    *fH;
   void      **fRet;
   Long_t      fRc;
   TMutex     *fM;
   TCondition *fC;
   Bool_t      fJoined;
 
   static void* JoinFunc(void *p);
 
public:
   TJoinHelper(TThread *th, void **ret);
   ~TJoinHelper();
 
   Int_t Join();
};
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor of Thread helper class.
 
TJoinHelper::TJoinHelper(TThread *th, void **ret)
   : fT(th), fRet(ret), fRc(0), fM(new TMutex), fC(new TCondition(fM)), fJoined(kFALSE)
{
   fH = new TThread("JoinHelper", JoinFunc, this);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TJoinHelper::~TJoinHelper()
{
   delete fC;
   delete fM;
   delete fH;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which runs in a separate thread to handle thread
/// joins without blocking the main thread.
/// Return a value (zero) so that it makes a joinable thread.
 
void* TJoinHelper::JoinFunc(void *p)
{
   TJoinHelper *jp = (TJoinHelper*)p;
 
   jp->fRc = jp->fT->Join(jp->fRet);
 
   jp->fM->Lock();
   jp->fJoined = kTRUE;
   jp->fC->Signal();
   jp->fM->UnLock();
 
   TThread::Exit(nullptr);
 
   return nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Thread join function.
 
Int_t TJoinHelper::Join()
{
   fM->Lock();
   fH->Run();
 
   while (kTRUE) {
      // TimedWaitRelative will release the mutex (i.e. equivalent to fM->Unlock),
      // then block on the condition variable.  Upon return it will lock the mutex.
      int r = fC->TimedWaitRelative(100);  // 100 ms
 
      // From the man page from pthread_ond_timedwait:
 
      // When using condition variables there is always a Boolean predicate
      // involving shared variables associated with each condition wait that
      // is true if the thread should proceed. Spurious wakeups from the
      // pthread_cond_timedwait() or pthread_cond_wait() functions may occur.
      // Since the return from pthread_cond_timedwait() or pthread_cond_wait()
      // does not imply anything about the value of this predicate, the
      // predicate should be re-evaluated upon such return.
 
      if (r == 0 || r == 1) {
         // If we received the signal or timed out, let's check the value
         if (fJoined) break;
      } else {
         // If any other error occurred, there is no point in trying again
         break;
      }
 
      gSystem->ProcessEvents();
   }
 
   fM->UnLock();
 
   // And wait for the help to finish to avoid the risk that it is still
   // running when the main tread is finished (and the thread library unloaded!)
   TThread::fgThreadImp->Join(fH, nullptr);
 
   return fRc;
}
 
 
//------------------------------------------------------------------------------
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Create a thread. Specify the function or static class method
/// to be executed by the thread and a pointer to the argument structure.
/// The user function should return a void*. To start the thread call Run().
 
TThread::TThread(VoidRtnFunc_t fn, void *arg, EPriority pri)
   : TNamed("<anon>", "")
{
   fDetached  = kFALSE;
   fFcnVoid = nullptr;
   fFcnRetn   = fn;
   fPriority  = pri;
   fThreadArg = arg;
   Constructor();
   fNamed     = kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a detached thread. Specify the function or static class method
/// to be executed by the thread and a pointer to the argument structure.
/// To start the thread call Run().
 
TThread::TThread(VoidFunc_t fn, void *arg, EPriority pri)
   : TNamed("<anon>", "")
{
   fDetached  = kTRUE;
   fFcnRetn = nullptr;
   fFcnVoid   = fn;
   fPriority  = pri;
   fThreadArg = arg;
   Constructor();
   fNamed     = kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create thread with a name. Specify the function or static class method
/// to be executed by the thread and a pointer to the argument structure.
/// The user function should return a void*. To start the thread call Run().
 
TThread::TThread(const char *thname, VoidRtnFunc_t fn, void *arg,
                 EPriority pri) : TNamed(thname, "")
{
   fDetached  = kFALSE;
   fFcnVoid = nullptr;
   fFcnRetn   = fn;
   fPriority  = pri;
   fThreadArg = arg;
   Constructor();
   fNamed     = kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a detached thread with a name. Specify the function or static
/// class method to be executed by the thread and a pointer to the argument
/// structure. To start the thread call Run().
 
TThread::TThread(const char *thname, VoidFunc_t fn, void *arg,
                 EPriority pri) : TNamed(thname, "")
{
   fDetached  = kTRUE;
   fFcnRetn = nullptr;
   fFcnVoid   = fn;
   fPriority  = pri;
   fThreadArg = arg;
   Constructor();
   fNamed     = kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a TThread for a already running thread.
 
TThread::TThread(Long_t id)
{
   fDetached  = kTRUE;
   fFcnRetn = nullptr;
   fFcnVoid = nullptr;
   fPriority  = kNormalPriority;
   fThreadArg = nullptr;
   Constructor();
 
   // Changing the id must be protected as it will be look at by multiple
   // threads (see TThread::GetThread)
   ThreadInternalLock();
   fNamed     = kFALSE;
   fId = (id ? id : SelfId());
   fState = kRunningState;
   ThreadInternalUnLock();
 
   if (gDebug)
      Info("TThread::TThread", "TThread attached to running thread");
}
 
////////////////////////////////////////////////////////////////////////////////
/// Initialize the Thread package. This initializes the TThread and ROOT
/// global mutexes to make parts of ROOT thread safe/aware. This call is
/// implicit in case a TThread is created.
 
void TThread::Initialize()
{
   Init();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return true, if the TThread objects have been initialize. If false,
/// the process is (from ROOT's point of view) single threaded.
 
Bool_t TThread::IsInitialized()
{
   if (fgThreadImp)
      return kTRUE;
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Initialize global state and variables once.
 
void TThread::Init()
{
   if (fgThreadImp || fgIsTearDown) return;
 
   // 'Insure' gROOT is created before initializing the Thread safe behavior
   // (to make sure we do not have two attempting to create it).
   ROOT::GetROOT();
 
   fgThreadImp = gThreadFactory->CreateThreadImp();
   gMainInternalMutex = new TMutex(kTRUE);
 
   fgMainId    = fgThreadImp->SelfId();
   fgMainMutex = new TMutex(kTRUE);
   gThreadTsd  = TThread::Tsd;
   gThreadXAR  = TThread::XARequest;
 
 
   // Create the single global mutex
   gGlobalMutex = new TMutex(kTRUE);
   // We need to make sure that gCling is initialized.
   TInterpreter::Instance()->SetAlloclockfunc(CINT_alloc_lock);
   gCling->SetAllocunlockfunc(CINT_alloc_unlock);
 
   // To avoid deadlocks, gInterpreterMutex and gROOTMutex need
   // to point at the same instance.
   // Both are now deprecated in favor of ROOT::gCoreMutex
   {
     R__LOCKGUARD(gGlobalMutex);
     if (!ROOT::gCoreMutex) {
        // To avoid dead locks, caused by shared library opening and/or static initialization
        // taking the same lock as 'tls_get_addr_tail', we can not use UniqueLockRecurseCount.
#ifdef ROOT_CORE_THREAD_TBB
        ROOT::gCoreMutex = new ROOT::TRWMutexImp<std::mutex, ROOT::Internal::RecurseCountsTBBUnique>();
#else
        ROOT::gCoreMutex = new ROOT::TRWMutexImp<std::mutex, ROOT::Internal::RecurseCounts>();
#endif
     }
     gInterpreterMutex = ROOT::gCoreMutex;
     gROOTMutex = gInterpreterMutex;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Common thread constructor.
 
void TThread::Constructor()
{
   fHolder = nullptr;
   fClean = nullptr;
   fState  = kNewState;
 
   fId = -1;
   fHandle= 0;
   if (!fgThreadImp) Init();
 
   SetComment("Constructor: MainInternalMutex Locking");
   ThreadInternalLock();
   SetComment("Constructor: MainInternalMutex Locked");
 
   if (fgMain) fgMain->fPrev = this;
   fNext = fgMain;
   fPrev = nullptr;
   fgMain = this;
 
   ThreadInternalUnLock();
   SetComment();
 
   // thread is set up in initialisation routine or Run().
}
 
////////////////////////////////////////////////////////////////////////////////
/// Cleanup the thread.
 
TThread::~TThread()
{
   if (gDebug)
      Info("TThread::~TThread", "thread deleted");
 
   // Disconnect thread instance
 
   SetComment("Destructor: MainInternalMutex Locking");
   ThreadInternalLock();
   SetComment("Destructor: MainInternalMutex Locked");
 
   if (fPrev) fPrev->fNext = fNext;
   if (fNext) fNext->fPrev = fPrev;
   if (fgMain == this) fgMain = fNext;
 
   ThreadInternalUnLock();
   SetComment();
   if (fHolder)
      *fHolder = nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to delete the specified thread.
/// Returns -1 in case the thread was running and has been killed. Returns
/// 0 in case the thread has been Delete and Cleaned up. The th pointer is
/// not valid anymore in that case.
 
Int_t TThread::Delete(TThread *&th)
{
   if (!th) return 0;
   th->fHolder = &th;
 
   if (th->fState == kRunningState) {     // Cancel if running
      th->fState = kDeletingState;
 
      if (gDebug)
         th->Info("TThread::Delete", "deleting thread");
 
      th->Kill();
      return -1;
   }
 
   CleanUp();
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to check if threads exist.
/// Returns the number of running threads.
 
Int_t TThread::Exists()
{
   ThreadInternalLock();
 
   Int_t num = 0;
   for (TThread *l = fgMain; l; l = l->fNext)
      num++; //count threads
 
   ThreadInternalUnLock();
 
   return num;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set thread priority.
 
void TThread::SetPriority(EPriority pri)
{
   fPriority = pri;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to find a thread by id.
 
TThread *TThread::GetThread(Long_t id)
{
   TThread *myTh;
 
   ThreadInternalLock();
 
   for (myTh = fgMain; myTh && (myTh->fId != id); myTh = myTh->fNext) { }
 
   ThreadInternalUnLock();
 
   return myTh;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to find a thread by name.
 
TThread *TThread::GetThread(const char *name)
{
   TThread *myTh;
 
   ThreadInternalLock();
 
   for (myTh = fgMain; myTh && (strcmp(name, myTh->GetName())); myTh = myTh->fNext) { }
 
   ThreadInternalUnLock();
 
   return myTh;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method returning pointer to current thread.
 
TThread *TThread::Self()
{
   TTHREAD_TLS(TThread *) self = nullptr;
 
   if (!self || fgIsTearDown) {
      if (fgIsTearDown)
         self = nullptr;
      self = GetThread(SelfId());
   }
   return self;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Join this thread.
 
Long_t TThread::Join(void **ret)
{
   if (fId == -1) {
      Error("Join", "thread not running");
      return -1;
   }
 
   if (fDetached) {
      Error("Join", "cannot join detached thread");
      return -1;
   }
 
   if (SelfId() != fgMainId)
      return fgThreadImp->Join(this, ret);
 
   // do not block the main thread, use helper thread
   TJoinHelper helper(this, ret);
 
   return helper.Join();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to join a thread by id.
 
Long_t TThread::Join(Long_t jid, void **ret)
{
   TThread *myTh = GetThread(jid);
 
   if (!myTh) {
      ::Error("TThread::Join", "cannot find thread 0x%lx", jid);
      return -1L;
   }
 
   return myTh->Join(ret);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method returning the id for the current thread.
 
Long_t TThread::SelfId()
{
   if (fgIsTearDown) return -1;
   if (!fgThreadImp) Init();
 
   return fgThreadImp->SelfId();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Start the thread. This starts the static method TThread::Function()
/// which calls the user function specified in the TThread ctor with
/// the arg argument.
/// If affinity is specified (>=0), a CPU affinity will be associated
/// with the current thread.
/// Returns 0 on success, otherwise an error number will
/// be returned.
 
Int_t TThread::Run(void *arg, const int affinity)
{
   if (arg) fThreadArg = arg;
 
   SetComment("Run: MainInternalMutex locking");
   ThreadInternalLock();
   SetComment("Run: MainMutex locked");
 
   int iret = fgThreadImp->Run(this, affinity);
 
   fState = iret ? kInvalidState : kRunningState;
 
   if (gDebug)
      Info("TThread::Run", "thread run requested");
 
   ThreadInternalUnLock();
   SetComment();
   return iret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Kill this thread. Returns 0 on success, otherwise an error number will
/// be returned.
 
Int_t TThread::Kill()
{
   if (fState != kRunningState && fState != kDeletingState) {
      if (gDebug)
         Warning("TThread::Kill", "thread is not running");
      return 13;
   } else {
      if (fState == kRunningState ) fState = kCancelingState;
      return fgThreadImp->Kill(this);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to kill the thread by id. Returns 0 on success, otherwise
/// an error number will be returned.
 
Int_t TThread::Kill(Long_t id)
{
   TThread *th = GetThread(id);
   if (th) {
      return fgThreadImp->Kill(th);
   } else  {
      if (gDebug)
         ::Warning("TThread::Kill(Long_t)", "thread 0x%lx not found", id);
      return 13;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to kill thread by name. Returns 0 on success, otherwise
/// an error number will be returned.
 
Int_t TThread::Kill(const char *name)
{
   TThread *th = GetThread(name);
   if (th) {
      return fgThreadImp->Kill(th);
   } else  {
      if (gDebug)
         ::Warning("TThread::Kill(const char*)", "thread %s not found", name);
      return 13;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to turn off thread cancellation. Returns 0 on success,
/// otherwise an error number will be returned.
 
Int_t TThread::SetCancelOff()
{
   return fgThreadImp ? fgThreadImp->SetCancelOff() : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to turn on thread cancellation. Returns 0 on success,
/// otherwise an error number will be returned.
 
Int_t TThread::SetCancelOn()
{
   return fgThreadImp ? fgThreadImp->SetCancelOn() : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to set the cancellation response type of the calling thread
/// to asynchronous, i.e. cancel as soon as the cancellation request
/// is received.
 
Int_t TThread::SetCancelAsynchronous()
{
   return fgThreadImp ? fgThreadImp->SetCancelAsynchronous() : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to set the cancellation response type of the calling thread
/// to deferred, i.e. cancel only at next cancellation point.
/// Returns 0 on success, otherwise an error number will be returned.
 
Int_t TThread::SetCancelDeferred()
{
   return fgThreadImp ? fgThreadImp->SetCancelDeferred() : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to set a cancellation point. Returns 0 on success, otherwise
/// an error number will be returned.
 
Int_t TThread::CancelPoint()
{
   return fgThreadImp ? fgThreadImp->CancelPoint() : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which pushes thread cleanup method on stack.
/// Returns 0 in case of success and -1 in case of error.
 
Int_t TThread::CleanUpPush(void *free, void *arg)
{
   TThread *th = Self();
   if (th)
      return fgThreadImp->CleanUpPush(&(th->fClean), free, arg);
   return -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which pops thread cleanup method off stack.
/// Returns 0 in case of success and -1 in case of error.
 
Int_t TThread::CleanUpPop(Int_t exe)
{
   TThread *th = Self();
   if (th)
      return fgThreadImp->CleanUpPop(&(th->fClean), exe);
   return -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to cleanup the calling thread.
 
Int_t TThread::CleanUp()
{
   TThread *th = Self();
   if (!th) return 13;
 
   fgThreadImp->CleanUp(&(th->fClean));
   fgMainMutex->CleanUp();
   if (fgXActMutex)
      fgXActMutex->CleanUp();
 
   gMainInternalMutex->CleanUp();
 
   if (th->fHolder)
      delete th;
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which is called after the thread has been canceled.
 
void TThread::AfterCancel(TThread *th)
{
   if (th) {
      th->fState = kCanceledState;
      if (gDebug)
         th->Info("TThread::AfterCancel", "thread is canceled");
   } else
      ::Error("TThread::AfterCancel", "zero thread pointer passed");
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which terminates the execution of the calling thread.
 
Int_t TThread::Exit(void *ret)
{
   return fgThreadImp ? fgThreadImp->Exit(ret) : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to sleep the calling thread.
 
Int_t TThread::Sleep(ULong_t secs, ULong_t nanos)
{
   UInt_t ms = UInt_t(secs * 1000) + UInt_t(nanos / 1000000);
   if (gSystem) gSystem->Sleep(ms);
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to get the current time. Returns
/// the number of seconds.
 
Int_t TThread::GetTime(ULong_t *absSec, ULong_t *absNanoSec)
{
   TTimeStamp t;
   if (absSec)     *absSec     = t.GetSec();
   if (absNanoSec) *absNanoSec = t.GetNanoSec();
   return t.GetSec();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to lock the main thread mutex.
 
Int_t TThread::Lock()
{
   return (fgMainMutex ? fgMainMutex->Lock() : 0);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to try to lock the main thread mutex.
 
Int_t TThread::TryLock()
{
   return (fgMainMutex ? fgMainMutex->TryLock() : 0);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method to unlock the main thread mutex.
 
Int_t TThread::UnLock()
{
   return (fgMainMutex ? fgMainMutex->UnLock() : 0);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method which is called by the system thread function and
/// which in turn calls the actual user function.
 
void *TThread::Function(void *ptr)
{
   TThread *th;
   void *ret, *arg;
 
   TThreadCleaner dummy;
 
   th = (TThread *)ptr;
 
   // Default cancel state is OFF
   // Default cancel type  is DEFERRED
   // User can change it by call SetCancelOn() and SetCancelAsynchronous()
   SetCancelOff();
   SetCancelDeferred();
   CleanUpPush((void *)&AfterCancel, th);  // Enable standard cancelling function
 
   if (gDebug)
      th->Info("TThread::Function", "thread is running");
 
   arg = th->fThreadArg;
   th->fState = kRunningState;
 
   if (th->fDetached) {
      //Detached, non joinable thread
      (th->fFcnVoid)(arg);
      ret = nullptr;
      th->fState = kFinishedState;
   } else {
      //UnDetached, joinable thread
      ret = (th->fFcnRetn)(arg);
      th->fState = kTerminatedState;
   }
 
   CleanUpPop(1);     // Disable standard canceling function
 
   if (gDebug)
      th->Info("TThread::Function", "thread has finished");
 
   TThread::Exit(ret);
 
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method listing the existing threads.
 
void TThread::Ps()
{
   TThread *l;
   int i;
 
   if (!fgMain) {
      ::Info("TThread::Ps", "no threads have been created");
      return;
   }
 
   ThreadInternalLock();
 
   int num = 0;
   for (l = fgMain; l; l = l->fNext)
      num++;
 
   char cbuf[256];
   printf("     Thread                   State\n");
   for (l = fgMain; l; l = l->fNext) { // loop over threads
      memset(cbuf, ' ', sizeof(cbuf));
      snprintf(cbuf, sizeof(cbuf), "%3d  %s:0x%lx", num--, l->GetName(), l->fId);
      i = (int)strlen(cbuf);
      if (i < 30)
         cbuf[i] = ' ';
      cbuf[30] = 0;
      printf("%30s", cbuf);
 
      switch (l->fState) {   // print states
         case kNewState:        printf("Idle       "); break;
         case kRunningState:    printf("Running    "); break;
         case kTerminatedState: printf("Terminated "); break;
         case kFinishedState:   printf("Finished   "); break;
         case kCancelingState:  printf("Canceling  "); break;
         case kCanceledState:   printf("Canceled   "); break;
         case kDeletingState:   printf("Deleting   "); break;
         default:               printf("Invalid    ");
      }
      if (l->fComment[0]) printf("  // %s", l->fComment);
      printf("\n");
   }  // end of loop
 
   ThreadInternalUnLock();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method returning a pointer to thread specific data container
/// of the calling thread.
/// k should be between 0 and kMaxUserThreadSlot for user application.
/// (and between kMaxUserThreadSlot and kMaxThreadSlot for ROOT libraries).
/// See ROOT::EThreadSlotReservation
 
void **TThread::Tsd(void *dflt, Int_t k)
{
   if (TThread::SelfId() == fgMainId) {   //Main thread
      return (void**)dflt;
   } else {
      return GetTls(k);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method that initializes the TLS array of a thread and returns the
/// reference to a given position in that array.
 
void **TThread::GetTls(Int_t k) {
   TTHREAD_TLS_ARRAY(void*, ROOT::kMaxThreadSlot, tls);
 
   return &(tls[k]);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method providing a thread safe printf. Appends a newline.
 
void TThread::Printf(const char *va_(fmt), ...)
{
   va_list ap;
   va_start(ap,va_(fmt));
 
   Int_t buf_size = 2048;
   char *buf;
 
again:
   buf = new char[buf_size];
 
   int n = vsnprintf(buf, buf_size, va_(fmt), ap);
   // old vsnprintf's return -1 if string is truncated new ones return
   // total number of characters that would have been written
   if (n == -1 || n >= buf_size) {
      buf_size *= 2;
      delete [] buf;
      goto again;
   }
 
   va_end(ap);
 
   void *arr[2];
   arr[1] = (void*) buf;
   if (XARequest("PRTF", 2, arr, nullptr)) {
      delete [] buf;
      return;
   }
 
   printf("%s\n", buf);
   fflush(stdout);
 
   delete [] buf;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Thread specific error handler function.
/// It calls the user set error handler in the main thread.
 
void TThread::ErrorHandler(int level, const char *location, const char *fmt,
                           va_list ap) const
{
   Int_t buf_size = 2048;
   char *buf, *bp;
 
again:
   buf = new char[buf_size];
 
   int n = vsnprintf(buf, buf_size, fmt, ap);
   // old vsnprintf's return -1 if string is truncated new ones return
   // total number of characters that would have been written
   if (n == -1 || n >= buf_size) {
      buf_size *= 2;
      delete [] buf;
      goto again;
   }
   if (level >= kSysError && level < kFatal) {
      const std::size_t bufferSize = buf_size + strlen(gSystem->GetError()) + 5;
      char *buf1 = new char[bufferSize];
      snprintf(buf1, bufferSize, "%s (%s)", buf, gSystem->GetError());
      bp = buf1;
      delete [] buf;
   } else
      bp = buf;
 
   void *arr[4];
   arr[1] = (void*) Longptr_t(level);
   arr[2] = (void*) location;
   arr[3] = (void*) bp;
   if (XARequest("ERRO", 4, arr, nullptr))
      return;
 
   if (level != kFatal)
      ::GetErrorHandler()(level, level >= gErrorAbortLevel, location, bp);
   else
      ::GetErrorHandler()(level, kTRUE, location, bp);
 
   delete [] bp;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to ErrorHandler. User has to specify the class name as
/// part of the location, just like for the global Info(), Warning() and
/// Error() functions.
 
void TThread::DoError(int level, const char *location, const char *fmt,
                      va_list va) const
{
   char *loc = nullptr;
 
   if (location) {
      const std::size_t bufferSize = strlen(location) + strlen(GetName()) + 32;
      loc = new char[bufferSize];
      snprintf(loc, bufferSize, "%s %s:0x%lx", location, GetName(), fId);
   } else {
      const std::size_t bufferSize = strlen(GetName()) + 32;
      loc = new char[bufferSize];
      snprintf(loc, bufferSize, "%s:0x%lx", GetName(), fId);
   }
 
   ErrorHandler(level, loc, fmt, va);
 
   delete [] loc;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method used to allow commands to be executed by the main thread.
 
Int_t TThread::XARequest(const char *xact, Int_t nb, void **ar, Int_t *iret)
{
   if (!gApplication || !gApplication->IsRunning()) return 0;
 
   // The first time, create the related static vars
   if (!fgXActMutex && gGlobalMutex) {
      gGlobalMutex->Lock();
      if (!fgXActMutex) {
         fgXActMutex = new TMutex(kTRUE);
         fgXActCondi = new TCondition;
         new TThreadTimer;
      }
      gGlobalMutex->UnLock();
   }
 
   TThread *th = Self();
   if (th && th->fId != fgMainId) {   // we are in the thread
      th->SetComment("XARequest: XActMutex Locking");
      fgXActMutex->Lock();
      th->SetComment("XARequest: XActMutex Locked");
 
      TConditionImp *condimp = fgXActCondi->fConditionImp;
      TMutexImp *condmutex = fgXActCondi->GetMutex()->fMutexImp;
 
      // Lock now, so the XAction signal will wait
      // and never come before the wait
      condmutex->Lock();
 
      fgXAnb = nb;
      fgXArr = ar;
      fgXArt = 0;
      fgXAct = (char*) xact;
      th->SetComment(fgXAct);
 
      if (condimp) condimp->Wait();
      condmutex->UnLock();
 
      if (iret) *iret = fgXArt;
      fgXActMutex->UnLock();
      th->SetComment();
      return 1997;
   } else            //we are in the main thread
      return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static method called via the thread timer to execute in the main
/// thread certain commands. This to avoid sophisticated locking and
/// possible deadlocking.
 
void TThread::XAction()
{
   TConditionImp *condimp = fgXActCondi->fConditionImp;
   TMutexImp *condmutex = fgXActCondi->GetMutex()->fMutexImp;
   condmutex->Lock();
 
   char const acts[] = "PRTF CUPD CANV CDEL PDCD METH ERRO";
   enum { kPRTF = 0, kCUPD = 5, kCANV = 10, kCDEL = 15,
          kPDCD = 20, kMETH = 25, kERRO = 30 };
   int iact = strstr(acts, fgXAct) - acts;
   TString cmd;
 
   switch (iact) {
 
      case kPRTF:
         printf("%s\n", (const char*)fgXArr[1]);
         fflush(stdout);
         break;
 
      case kERRO:
         {
            int level = (int)Longptr_t(fgXArr[1]);
            const char *location = (const char*)fgXArr[2];
            char *mess = (char*)fgXArr[3];
            if (level != kFatal)
               GetErrorHandler()(level, level >= gErrorAbortLevel, location, mess);
            else
               GetErrorHandler()(level, kTRUE, location, mess);
            delete [] mess;
         }
         break;
 
      case kCUPD:
         //((TCanvas *)fgXArr[1])->Update();
         union CastFromFuncToVoidPtr_t {
            void (*fFuncPtr)(void*);
            void* fVoidPtr;
         } castFromFuncToVoidPtr;
         castFromFuncToVoidPtr.fVoidPtr = fgXArr[2];
         (*castFromFuncToVoidPtr.fFuncPtr)(fgXArr[1]); // aka TCanvas::Update()
         break;
 
      case kCANV:
 
         switch(fgXAnb) { // Over TCanvas constructors
 
            case 2:
               //((TCanvas*)fgXArr[1])->Constructor();
               cmd.Form("((TCanvas *)0x%zx)->Constructor();",(size_t)fgXArr[1]);
               gROOT->ProcessLine(cmd.Data());
               break;
 
            case 5:
               //((TCanvas*)fgXArr[1])->Constructor(
               //                 (char*)fgXArr[2],
               //                 (char*)fgXArr[3],
               //                *((Int_t*)(fgXArr[4])));
               cmd.Form("((TCanvas *)0x%zx)->Constructor((char*)0x%zx,(char*)0x%zx,*((Int_t*)(0x%zx)));",(size_t)fgXArr[1],(size_t)fgXArr[2],(size_t)fgXArr[3],(size_t)fgXArr[4]);
               gROOT->ProcessLine(cmd.Data());
               break;
            case 6:
               //((TCanvas*)fgXArr[1])->Constructor(
               //                 (char*)fgXArr[2],
               //                 (char*)fgXArr[3],
               //                *((Int_t*)(fgXArr[4])),
               //                *((Int_t*)(fgXArr[5])));
               cmd.Form("((TCanvas *)0x%zx)->Constructor((char*)0x%zx,(char*)0x%zx,*((Int_t*)(0x%zx)),*((Int_t*)(0x%zx)));",(size_t)fgXArr[1],(size_t)fgXArr[2],(size_t)fgXArr[3],(size_t)fgXArr[4],(size_t)fgXArr[5]);
               gROOT->ProcessLine(cmd.Data());
               break;
 
            case 8:
               //((TCanvas*)fgXArr[1])->Constructor(
               //                 (char*)fgXArr[2],
               //                 (char*)fgXArr[3],
               //               *((Int_t*)(fgXArr[4])),
               //               *((Int_t*)(fgXArr[5])),
               //               *((Int_t*)(fgXArr[6])),
               //               *((Int_t*)(fgXArr[7])));
               cmd.Form("((TCanvas *)0x%zx)->Constructor((char*)0x%zx,(char*)0x%zx,*((Int_t*)(0x%zx)),*((Int_t*)(0x%zx)),*((Int_t*)(0x%zx)),*((Int_t*)(0x%zx)));",(size_t)fgXArr[1],(size_t)fgXArr[2],(size_t)fgXArr[3],(size_t)fgXArr[4],(size_t)fgXArr[5],(size_t)fgXArr[6],(size_t)fgXArr[7]);
               gROOT->ProcessLine(cmd.Data());
               break;
 
         }
         break;
 
      case kCDEL:
         //((TCanvas*)fgXArr[1])->Destructor();
         cmd.Form("((TCanvas *)0x%zx)->Destructor();",(size_t)fgXArr[1]);
         gROOT->ProcessLine(cmd.Data());
         break;
 
      case kPDCD:
         ((TVirtualPad*) fgXArr[1])->Divide( *((Int_t*)(fgXArr[2])),
                                  *((Int_t*)(fgXArr[3])),
                                  *((Float_t*)(fgXArr[4])),
                                  *((Float_t*)(fgXArr[5])),
                                  *((Int_t*)(fgXArr[6])));
         break;
      case kMETH:
         ((TMethodCall *) fgXArr[1])->Execute((void*)(fgXArr[2]),(const char*)(fgXArr[3]));
         break;
 
      default:
         ::Error("TThread::XAction", "wrong case");
   }
 
   fgXAct = nullptr;
   if (condimp) condimp->Signal();
   condmutex->UnLock();
}
 
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TThreadTimer                                                         //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
////////////////////////////////////////////////////////////////////////////////
/// Create thread timer.
 
TThreadTimer::TThreadTimer(Long_t ms) : TTimer(ms, kTRUE)
{
   gSystem->AddTimer(this);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Periodically execute the TThread::XAction() method in the main thread.
 
Bool_t TThreadTimer::Notify()
{
   if (TThread::fgXAct) { TThread::XAction(); }
   Reset();
 
   return kFALSE;
}
 
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
//  TThreadCleaner                                                      //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
////////////////////////////////////////////////////////////////////////////////
/// Call user clean up routines.
 
TThreadCleaner::~TThreadCleaner()
{
   TThread::CleanUp();
}