text: /* ---------------------------------------------------------------------------
   *
   * (c) The GHC Team, 2001-2005
   *
   * Accessing OS threads functionality in a (mostly) OS-independent
   * manner.
   *
   * --------------------------------------------------------------------------*/
  
  #include "Rts.h"
  #include <windows.h>
  #include "sm/OSMem.h"
  #if defined(THREADED_RTS)
  #include "RtsUtils.h"
  
  /* For reasons not yet clear, the entire contents of process.h is protected
   * by __STRICT_ANSI__ not being defined.
   */
  #undef __STRICT_ANSI__
  #include <process.h>
  
  
  /* Processor group info cache.  */
  static uint8_t* cpuGroupCache = NULL;
  /* Processor group cumulative summary cache.  */
  static uint32_t* cpuGroupCumulativeCache = NULL;
  /* Processor group dist cache.  */
  static uint8_t* cpuGroupDistCache = NULL;
  
  /* Win32 threads and synchronisation objects */
  
  /* A Condition is represented by a Win32 Event object;
   * a Mutex by a Mutex kernel object.
   *
   * ToDo: go through the defn and usage of these to
   * make sure the semantics match up with that of
   * the (assumed) pthreads behaviour. This is really
   * just a first pass at getting something compilable.
   */
  
  void
  initCondition( Condition* pCond )
  {
    HANDLE h =  CreateEvent(NULL,
                            FALSE,  /* auto reset */
                            FALSE,  /* initially not signalled */
                            NULL); /* unnamed => process-local. */
  
    if ( h == NULL ) {
        sysErrorBelch("initCondition: unable to create");
        stg_exit(EXIT_FAILURE);
    }
    *pCond = h;
    return;
  }
  
  void
  closeCondition( Condition* pCond )
  {
    if ( CloseHandle(*pCond) == 0 ) {
        sysErrorBelch("closeCondition: failed to close");
    }
    return;
  }
  
  bool
  broadcastCondition ( Condition* pCond )
  {
    PulseEvent(*pCond);
    return true;
  }
  
  bool
  signalCondition ( Condition* pCond )
  {
      if (SetEvent(*pCond) == 0) {
          sysErrorBelch("SetEvent");
          stg_exit(EXIT_FAILURE);
      }
      return true;
  }
  
  bool
  waitCondition ( Condition* pCond, Mutex* pMut )
  {
    RELEASE_LOCK(pMut);
    WaitForSingleObject(*pCond, INFINITE);
    /* Hmm..use WaitForMultipleObjects() ? */
    ACQUIRE_LOCK(pMut);
    return true;
  }
  
  void
  yieldThread()
  {
    SwitchToThread();
    return;
  }
  
  void
  shutdownThread()
  {
      ExitThread(0);
      barf("ExitThread() returned"); // avoid gcc warning
  }
  
  int
  createOSThread (OSThreadId* pId, char *name STG_UNUSED,
                  OSThreadProc *startProc, void *param)
  {
      HANDLE h;
      h = CreateThread ( NULL,  /* default security attributes */
                         0,
                         (LPTHREAD_START_ROUTINE)(void*)startProc,
                         param,
                         0,
                         pId);
  
      if (h == 0) {
          return 1;
      } else {
          // This handle leaks if we don't close it here.  Perhaps we
          // should try to keep it around to avoid needing OpenThread()
          // later.
          CloseHandle(h);
          return 0;
      }
  }
  
  OSThreadId
  osThreadId()
  {
    return GetCurrentThreadId();
  }
  
  bool
  osThreadIsAlive(OSThreadId id)
  {
      DWORD exit_code;
      HANDLE hdl;
      if (!(hdl = OpenThread(THREAD_QUERY_INFORMATION,FALSE,id))) {
          sysErrorBelch("osThreadIsAlive: OpenThread");
          stg_exit(EXIT_FAILURE);
      }
      if (!GetExitCodeThread(hdl, &exit_code)) {
          sysErrorBelch("osThreadIsAlive: GetExitCodeThread");
          stg_exit(EXIT_FAILURE);
      }
      CloseHandle(hdl);
      return (exit_code == STILL_ACTIVE);
  }
  
  #if defined(USE_CRITICAL_SECTIONS)
  void
  initMutex (Mutex* pMut)
  {
      InitializeCriticalSectionAndSpinCount(pMut,4000);
  }
  void
  closeMutex (Mutex* pMut)
  {
      DeleteCriticalSection(pMut);
  }
  #else
  void
  initMutex (Mutex* pMut)
  {
    HANDLE h = CreateMutex ( NULL,  /* default sec. attributes */
                             TRUE, /* not owned => initially signalled */
                             NULL
                             );
    *pMut = h;
    return;
  }
  void
  closeMutex (Mutex* pMut)
  {
      CloseHandle(*pMut);
  }
  #endif
  
  void
  newThreadLocalKey (ThreadLocalKey *key)
  {
      DWORD r;
      r = TlsAlloc();
      if (r == TLS_OUT_OF_INDEXES) {
          barf("newThreadLocalKey: out of keys");
      }
      *key = r;
  }
  
  void *
  getThreadLocalVar (ThreadLocalKey *key)
  {
      void *r;
      r = TlsGetValue(*key);
  #if defined(DEBUG)
      // r is allowed to be NULL - it can mean that either there was an
      // error or the stored value is in fact NULL.
      if (GetLastError() != NO_ERROR) {
          sysErrorBelch("getThreadLocalVar");
          stg_exit(EXIT_FAILURE);
      }
  #endif
      return r;
  }
  
  void
  setThreadLocalVar (ThreadLocalKey *key, void *value)
  {
      BOOL b;
      b = TlsSetValue(*key, value);
      if (!b) {
          sysErrorBelch("setThreadLocalVar");
          stg_exit(EXIT_FAILURE);
      }
  }
  
  void
  freeThreadLocalKey (ThreadLocalKey *key)
  {
      BOOL r;
      r = TlsFree(*key);
      if (r == 0) {
          DWORD dw = GetLastError();
          barf("freeThreadLocalKey failed: %lu", dw);
      }
  }
  
  
  static unsigned __stdcall
  forkOS_createThreadWrapper ( void * entry )
  {
      Capability *cap;
      cap = rts_lock();
      rts_evalStableIO(&cap, (HsStablePtr) entry, NULL);
      rts_unlock(cap);
      rts_done();
      return 0;
  }
  
  int
  forkOS_createThread ( HsStablePtr entry )
  {
      unsigned long pId;
      return (_beginthreadex ( NULL,  /* default security attributes */
                             0,
                             forkOS_createThreadWrapper,
                             (void*)entry,
                             0,
                             (unsigned*)&pId) == 0);
  }
  
  void freeThreadingResources (void)
  {
      if (cpuGroupCache)
      {
          stgFree(cpuGroupCache);
          cpuGroupCache = NULL;
      }
  
      if (cpuGroupCumulativeCache)
      {
          stgFree(cpuGroupCumulativeCache);
          cpuGroupCumulativeCache = NULL;
      }
  
      if (cpuGroupDistCache)
      {
          stgFree(cpuGroupDistCache);
          cpuGroupDistCache = NULL;
      }
  }
  
  /* Processor groups are not guaranteed to be uniformly distributed
     nor guaranteed to be filled before a next group is needed.
     The OS will assign processors to groups based on physical proximity
     and will never partially assign cores from one physical cpu to more
     than one group. If one has two 48 core CPUs then you'd end up with
     two groups of 48 logical cpus. Now add a 3rd CPU with 10 cores and
     the group it is assigned to depends where the socket is on the board.
  
     So we need to make a map of where the CPUs reside and how the groups are filled.
     Since groups are created at boot time by the kernel, we can cache this information.
  
     NOTE: This code does not support hot-swapping cores as it's caching the information.
     If you activate a new core you have to restart the program. This builds a
     simple lookup array for cpu -> group indexes. This gives O(1) lookup against
     O(n) space. But n is < 256 so we'll only use 256 bytes of extra memory. */
  
  static uint8_t
  getNumberOfProcessorsGroups (void)
  {
      /* Group count cache.  */
      static uint8_t n_groups = 0;
  
  
  #if defined(x86_64_HOST_ARCH)
      if (!n_groups)
      {
          n_groups = GetActiveProcessorGroupCount();
  
          IF_DEBUG(scheduler, debugBelch("[*] Number of processor groups detected: %u\n", n_groups));
      }
  #endif
  
      if (!n_groups)
      {
          n_groups = 1;
      }
  
      return n_groups;
  }
  
  #if defined(x86_64_HOST_ARCH)
  static uint8_t*
  getProcessorsDistribution (void)
  {
      if (cpuGroupDistCache)
      {
          return cpuGroupDistCache;
      }
  
      if (!cpuGroupDistCache)
      {
          uint8_t n_groups = getNumberOfProcessorsGroups();
          cpuGroupDistCache = stgMallocBytes(n_groups * sizeof(uint8_t), "getProcessorsDistribution");
          memset(cpuGroupDistCache, MAXIMUM_PROCESSORS, n_groups * sizeof(uint8_t));
  
          for (int i = 0; i < n_groups; i++)
          {
              cpuGroupDistCache[i] = GetActiveProcessorCount(i);
              IF_DEBUG(scheduler, debugBelch("[*] Number of active processors in group %u detected: %u\n", i, cpuGroupDistCache[i]));
          }
      }
  
      return cpuGroupDistCache;
  }
  #endif
  
  static uint32_t*
  getProcessorsCumulativeSum(void)
  {
      if (cpuGroupCumulativeCache)
      {
          return cpuGroupCumulativeCache;
      }
  
      if (!cpuGroupCumulativeCache)
      {
          uint8_t n_groups = getNumberOfProcessorsGroups();
          cpuGroupCumulativeCache = stgMallocBytes(n_groups * sizeof(uint32_t), "getProcessorsCumulativeSum");
          memset(cpuGroupCumulativeCache, 0, n_groups * sizeof(uint32_t));
  
  #if defined(x86_64_HOST_ARCH)
          uint8_t* proc_dist = getProcessorsDistribution();
          uint32_t cum_num_proc = 0;
          for (int i = 0; i < n_groups; i++)
          {
              cpuGroupCumulativeCache[i] = cum_num_proc;
              cum_num_proc += proc_dist[i];
              IF_DEBUG(scheduler, debugBelch("[*] Cumulative active processors for group %u: %u\n", i, cpuGroupCumulativeCache[i]));
          }
  #endif
      }
  
      return cpuGroupCumulativeCache;
  }
  
  /*
   Because processors can be distributed rather unpredictably inside
   processor groups, we need to keep track of which processors are in
   which group to be able to determine which mask to set and which bit
   in the mask to set.
  
   This can either be done by the typical trade-off: speed or
   memory usage. In this case I prioritize speed.
  
   This function will generate an array where each index is a processor
   and the value of the array the group it belongs to. This allows us to
   in constant time determine where a processor is.
   */
  static uint8_t*
  createProcessorGroupMap (void)
  {
      if (cpuGroupCache)
      {
          return cpuGroupCache;
      }
  
      uint32_t numProcs = getNumberOfProcessors();
  
      cpuGroupCache = stgMallocBytes(numProcs * sizeof(uint8_t), "createProcessorGroupMap");
      /* For 32bit Windows and 64bit older than Windows 7, create a default mapping. */
      memset(cpuGroupCache, 0, numProcs * sizeof(uint8_t));
  
  #if defined(x86_64_HOST_ARCH)
      uint8_t* proc_dist = getProcessorsDistribution();
  
      int totalProcs = 0;
      uint8_t nGroups = getNumberOfProcessorsGroups();
      int group;
      for (group = 0; group < nGroups; group++)
      {
          uint8_t nProc = proc_dist[group];
          memset(cpuGroupCache + totalProcs, group, nProc * sizeof(uint8_t));
          totalProcs += nProc;
      }
  
      IF_DEBUG(scheduler, debugBelch("[*] Processor group map created\n"));
  #endif
  
      return cpuGroupCache;
  }
  
  uint32_t
  getNumberOfProcessors (void)
  {
      static uint32_t nproc = 0;
  
  #if defined(x86_64_HOST_ARCH)
      if (!nproc)
      {
          nproc = GetActiveProcessorCount(ALL_PROCESSOR_GROUPS);
  
          if (nproc)
          {
              IF_DEBUG(scheduler, debugBelch("[*] Total number of active processors detected: %u\n", nproc));
              return nproc;
          }
  
          IF_DEBUG(scheduler, debugBelch("Could not determine Max number of logical processors.\n"
                                         "Falling back to old code which limits to 64 logical processors.\n"));
      }
  #endif
  
      /* This will return the maximum number of processes
         within one processor group. It's also slower
         so use it only when needed.  */
      if (nproc == 0) {
          SYSTEM_INFO si;
          GetSystemInfo(&si);
          nproc = si.dwNumberOfProcessors;
      }
  
      return nproc;
  }
  
  void
  setThreadAffinity (uint32_t n, uint32_t m) // cap N of M
  {
      ASSERT(n <= m);
  
      HANDLE hThread;
      DWORD_PTR *mask, r;  // 64-bit win is required to handle more than 32 procs
                           // and Windows 7+ required for more than 64 procs
      uint32_t n_proc, i, ix;
      uint8_t* proc_map      = createProcessorGroupMap();
      uint32_t n_groups      = getNumberOfProcessorsGroups();
      uint32_t* proc_cum     = getProcessorsCumulativeSum();
      n_proc                 = getNumberOfProcessors();
      hThread                = GetCurrentThread();
  
      ASSERT(proc_map         );
      ASSERT(proc_cum         );
      ASSERT(hThread          );
      ASSERT(n_groups      > 0);
      ASSERT(n_proc        > 0);
  
      mask = stgMallocBytes(n_groups * sizeof(DWORD_PTR), "setThreadAffinity");
      memset(mask, 0, n_groups * sizeof(DWORD_PTR));
  
      /* The mask for the individual groups are all 0 based
         so we need different masks for every group.  */
      int group;
      for (i = n; i < n_proc; i += m)
      {
          group = proc_map[i];
          ix = i - proc_cum[group];
          mask[group] |= 1 << ix;
      }
  
      for (i = 0; i < n_groups; i++)
      {
  #if defined(x86_64_HOST_ARCH)
          // If we support the new API, use it.
          if (mask[i] > 0)
          {
              GROUP_AFFINITY hGroup;
              ZeroMemory(&hGroup, sizeof(hGroup));
              hGroup.Mask = mask[i];
              hGroup.Group = i;
  
              if (!SetThreadGroupAffinity(hThread, &hGroup, NULL))
              {
                  sysErrorBelch("SetThreadGroupAffinity");
              }
  
              continue;
          }
  #endif
          // Fall-back methods. Only do it if there's a mask to set
          if (mask[i] > 0)
          {
              r = SetThreadAffinityMask(hThread, mask[i]);
              if (r == 0) {
                  stgFree(mask);
                  sysErrorBelch("SetThreadAffinity");
                  stg_exit(EXIT_FAILURE);
              }
          }
      }
  
      stgFree(mask);
  }
  
  typedef BOOL (WINAPI *PCSIO)(HANDLE);
  
  void
  interruptOSThread (OSThreadId id)
  {
      HANDLE hdl;
      PCSIO pCSIO;
      if (!(hdl = OpenThread(THREAD_TERMINATE,FALSE,id))) {
          sysErrorBelch("interruptOSThread: OpenThread");
          stg_exit(EXIT_FAILURE);
      }
      pCSIO = (PCSIO)(void*)GetProcAddress(GetModuleHandle(TEXT("Kernel32.dll")),
                                           "CancelSynchronousIo");
      if ( NULL != pCSIO ) {
          pCSIO(hdl);
      } else {
          // Nothing to do, unfortunately
      }
      CloseHandle(hdl);
  }
  
  void setThreadNode (uint32_t node)
  {
      if (osNumaAvailable())
      {
          uint64_t mask = 0;
          if (!GetNumaNodeProcessorMask(node, &mask) && !SetThreadAffinityMask(GetCurrentThread(), mask))
          {
              sysErrorBelch(
                  "setThreadNode: Error setting affinity of thread to NUMA node `%u': %lu.",
                  node, GetLastError());
              stg_exit(EXIT_FAILURE);
          }
      }
  }
  
  void releaseThreadNode (void)
  {
      if (osNumaAvailable())
      {
          PDWORD_PTR processMask = NULL;
          PDWORD_PTR systemMask = NULL;
          if (!GetProcessAffinityMask(GetCurrentProcess(),
                                      processMask,
                                      systemMask))
          {
              sysErrorBelch(
                  "releaseThreadNode: Error resetting affinity of thread: %lu",
                  GetLastError());
              stg_exit(EXIT_FAILURE);
          }
  
          if (!SetThreadAffinityMask(GetCurrentThread(), *processMask))
          {
              sysErrorBelch(
                  "releaseThreadNode: Error reseting NUMA affinity mask of thread: %lu.",
                  GetLastError());
              stg_exit(EXIT_FAILURE);
          }
  
      }
  }
  
  #else /* !defined(THREADED_RTS) */
  
  int
  forkOS_createThread ( HsStablePtr entry STG_UNUSED )
  {
      return -1;
  }
  
  void freeThreadingResources (void) { /* nothing */ }
  
  uint32_t getNumberOfProcessors (void)
  {
      return 1;
  }
  
  #endif /* !defined(THREADED_RTS) */
  
  KernelThreadId kernelThreadId (void)
  {
      DWORD tid = GetCurrentThreadId();
      return tid;
  }
  