tlibthrd.cxx

安装 H323需要的pwlib库

 *
 * Revision 1.13  1999/03/16 10:30:37  robertj
 * Added missing PThread::WaitForTermination function.
 *
 * Revision 1.12  1999/01/12 12:09:51  robertj
 * Removed redundent member variable, was in common.
 * Fixed BSD threads compatibility.
 *
 * Revision 1.11  1999/01/11 12:05:56  robertj
 * Fixed some more race conditions in threads.
 *
 * Revision 1.10  1999/01/11 03:42:26  robertj
 * Fixed problem with destroying thread automatically.
 *
 * Revision 1.9  1999/01/09 03:37:28  robertj
 * Fixed problem with closing thread waiting on semaphore.
 * Improved efficiency of mutex to use pthread functions directly.
 *
 * Revision 1.8  1999/01/08 01:31:03  robertj
 * Support for pthreads under FreeBSD
 *
 * Revision 1.7  1998/12/15 12:41:07  robertj
 * Fixed signal handling so can now ^C a pthread version.
 *
 * Revision 1.6  1998/11/05 09:45:04  robertj
 * Removed StartImmediate option in thread construction.
 *
 * Revision 1.5  1998/09/24 04:12:25  robertj
 * Added open software license.
 *
 */

#include <ptlib/socket.h>
#include <sched.h>	// for sched_yield
#include <pthread.h>
#include <sys/resource.h>

#ifdef P_RTEMS
#define	SUSPEND_SIG SIGALRM
#include <sched.h>
#else
#define	SUSPEND_SIG SIGVTALRM
#endif

#ifdef P_MACOSX
#include <mach/mach.h>
#include <mach/thread_policy.h>
#include <sys/param.h>
#include <sys/sysctl.h>
// going to need the main thread for adjusting relative priority
static pthread_t baseThread;
#endif

#ifdef P_HAS_SEMAPHORES_XPG6
#include "semaphore.h"
#endif

int PX_NewHandle(const char *, int);


#define PAssertPTHREAD(func, args) \
  { \
    unsigned threadOpRetry = 0; \
    while (PAssertThreadOp(func args, threadOpRetry, #func, __FILE__, __LINE__)); \
  }

static BOOL PAssertThreadOp(int retval,
                            unsigned & retry,
                            const char * funcname,
                            const char * file,
                            unsigned line)
{
  if (retval == 0) {
    PTRACE_IF(2, retry > 0, "PWLib\t" << funcname << " required " << retry << " retries!");
    return FALSE;
  }

  if (errno == EINTR || errno == EAGAIN) {
    if (++retry < 1000) {
#if defined(P_RTEMS)
      sched_yield();
#else
      usleep(10000); // Basically just swap out thread to try and clear blockage
#endif
      return TRUE;   // Return value to try again
    }
    // Give up and assert
  }

  PAssertFunc(file, line, NULL, psprintf("Function %s failed", funcname));
  return FALSE;
}


PDECLARE_CLASS(PHouseKeepingThread, PThread)
  public:
    PHouseKeepingThread()
      : PThread(1000, NoAutoDeleteThread, NormalPriority, "Housekeeper")
      { closing = FALSE; Resume(); }

    void Main();
    void SetClosing() { closing = TRUE; }

  protected:
    BOOL closing;
};


static pthread_mutex_t MutexInitialiser = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  CondInitialiser  = PTHREAD_COND_INITIALIZER;


#define new PNEW


void PHouseKeepingThread::Main()
{
  PProcess & process = PProcess::Current();

  while (!closing) {
    PTimeInterval delay = process.timers.Process();

    int fd = process.timerChangePipe[0];

    P_fd_set read_fds = fd;
    P_timeval tval = delay;
    if (::select(fd+1, read_fds, NULL, NULL, tval) == 1) {
      BYTE ch;
      ::read(fd, &ch, 1);
    }

    process.PXCheckSignals();
  }
}


void PProcess::SignalTimerChange()
{
  if (housekeepingThread == NULL) {
#if PMEMORY_CHECK
    BOOL oldIgnoreAllocations = PMemoryHeap::SetIgnoreAllocations(TRUE);
#endif
    housekeepingThread = new PHouseKeepingThread;
#if PMEMORY_CHECK
    PMemoryHeap::SetIgnoreAllocations(oldIgnoreAllocations);
#endif
  }

  BYTE ch;
  write(timerChangePipe[1], &ch, 1);
}


void PProcess::Construct()
{
#ifndef P_RTEMS
  // get the file descriptor limit
  struct rlimit rl;
  PAssertOS(getrlimit(RLIMIT_NOFILE, &rl) == 0);
  maxHandles = rl.rlim_cur;
  PTRACE(4, "PWLib\tMaximum per-process file handles is " << maxHandles);

  ::pipe(timerChangePipe);
#else
  maxHandles = 500; // arbitrary value
  socketpair(AF_INET,SOCK_STREAM,0,timerChangePipe);
#endif

  // initialise the housekeeping thread
  housekeepingThread = NULL;

#ifdef P_MACOSX
    // records the main thread for priority adjusting
    baseThread = pthread_self();
#endif

  CommonConstruct();
}


BOOL PProcess::SetMaxHandles(int newMax)
{
#ifndef P_RTEMS
  // get the current process limit
  struct rlimit rl;
  PAssertOS(getrlimit(RLIMIT_NOFILE, &rl) == 0);

  // set the new current limit
  rl.rlim_cur = newMax;
  if (setrlimit(RLIMIT_NOFILE, &rl) == 0) {
    PAssertOS(getrlimit(RLIMIT_NOFILE, &rl) == 0);
    maxHandles = rl.rlim_cur;
    if (maxHandles == newMax) {
      PTRACE(2, "PWLib\tNew maximum per-process file handles set to " << maxHandles);
      return TRUE;
    }
  }
#endif // !P_RTEMS

  PTRACE(1, "PWLib\tCannot set per-process file handle limit to "
         << newMax << " (is " << maxHandles << ") - check permissions");
  return FALSE;
}


PProcess::~PProcess()
{
  PreShutdown();

  // Don't wait for housekeeper to stop if Terminate() is called from it.
  if (housekeepingThread != NULL && PThread::Current() != housekeepingThread) {
    housekeepingThread->SetClosing();
    SignalTimerChange();
    housekeepingThread->WaitForTermination();
    delete housekeepingThread;
  }
  CommonDestruct();

  PTRACE(5, "PWLib\tDestroyed process " << this);
}


//////////////////////////////////////////////////////////////////////////////

PThread::PThread()
{
  // see InitialiseProcessThread()
}


void PThread::InitialiseProcessThread()
{
  autoDelete          = FALSE;

  PX_origStackSize    = 0;
  PX_threadId         = pthread_self();
  PX_priority         = NormalPriority;
  PX_suspendCount     = 0;

#ifndef P_HAS_SEMAPHORES
  PX_waitingSemaphore = NULL;
  PX_WaitSemMutex = MutexInitialiser;
#endif

  PX_suspendMutex = MutexInitialiser;

#ifdef P_RTEMS
  PAssertOS(socketpair(AF_INET,SOCK_STREAM,0,unblockPipe) == 0);
#else
  PAssertOS(::pipe(unblockPipe) == 0);
#endif

  ((PProcess *)this)->activeThreads.DisallowDeleteObjects();
  ((PProcess *)this)->activeThreads.SetAt((unsigned)PX_threadId, this);

  traceBlockIndentLevel = 0;
}


PThread::PThread(PINDEX stackSize,
                 AutoDeleteFlag deletion,
                 Priority priorityLevel,
                 const PString & name)
  : threadName(name)
{
  autoDelete = (deletion == AutoDeleteThread);

  PAssert(stackSize > 0, PInvalidParameter);
  PX_origStackSize = stackSize;
  PX_threadId = 0;
  PX_priority = priorityLevel;
  PX_suspendCount = 1;

#ifndef P_HAS_SEMAPHORES
  PX_waitingSemaphore = NULL;
  PX_WaitSemMutex = MutexInitialiser;
#endif

  PX_suspendMutex = MutexInitialiser;

#ifdef P_RTEMS
  PAssertOS(socketpair(AF_INET,SOCK_STREAM,0,unblockPipe) == 0);
#else
  PAssertOS(::pipe(unblockPipe) == 0);
#endif
  PX_NewHandle("Thread unblock pipe", PMAX(unblockPipe[0], unblockPipe[1]));

  // new thread is actually started the first time Resume() is called.
  PX_firstTimeStart = TRUE;

  traceBlockIndentLevel = 0;

  PTRACE(5, "PWLib\tCreated thread " << this << ' ' << threadName);
}


PThread::~PThread()
{
  if (PX_threadId != 0 && PX_threadId != pthread_self())
    Terminate();

  PAssertPTHREAD(::close, (unblockPipe[0]));
  PAssertPTHREAD(::close, (unblockPipe[1]));

#ifndef P_HAS_SEMAPHORES
  pthread_mutex_destroy(&PX_WaitSemMutex);
#endif

#ifdef P_NETBSD
  // If the mutex was not locked, the unlock will fail */
  pthread_mutex_trylock(&PX_suspendMutex);
#endif
  pthread_mutex_unlock(&PX_suspendMutex);
  pthread_mutex_destroy(&PX_suspendMutex);

  if (this != &PProcess::Current())
    PTRACE(5, "PWLib\tDestroyed thread " << this << ' ' << threadName);
}


void PThread::Restart()
{
  if (!IsTerminated())
    return;

  pthread_attr_t threadAttr;
  pthread_attr_init(&threadAttr);
  pthread_attr_setdetachstate(&threadAttr, PTHREAD_CREATE_DETACHED);

#if defined(P_LINUX)

  // Set a decent (256K) stack size that won't eat all virtual memory
  pthread_attr_setstacksize(&threadAttr, 16*PTHREAD_STACK_MIN);

  /*
    Set realtime scheduling if our effective user id is root (only then is this
    allowed) AND our priority is Highest.
      As far as I can see, we could use either SCHED_FIFO or SCHED_RR here, it
    doesn't matter.
      I don't know if other UNIX OSs have SCHED_FIFO and SCHED_RR as well.

    WARNING: a misbehaving thread (one that never blocks) started with Highest
    priority can hang the entire machine. That is why root permission is 
    neccessary.
  */
  if ((geteuid() == 0) && (PX_priority == HighestPriority))
    PAssertPTHREAD(pthread_attr_setschedpolicy, (&threadAttr, SCHED_FIFO));
#elif defined(P_RTEMS)
  pthread_attr_setstacksize(&threadAttr, 2*PTHREAD_MINIMUM_STACK_SIZE);
  pthread_attr_setinheritsched(&threadAttr, PTHREAD_EXPLICIT_SCHED);
  pthread_attr_setschedpolicy(&threadAttr, SCHED_OTHER);
  struct sched_param sched_param;
  sched_param.sched_priority = 125; /* set medium priority */
  pthread_attr_setschedparam(&threadAttr, &sched_param);
#endif

  PAssertPTHREAD(pthread_create, (&PX_threadId, &threadAttr, PX_ThreadStart, this));

#ifdef P_MACOSX
  if (PX_priority == HighestPriority) {
    PTRACE(1, "set thread to have the highest priority (MACOSX)");
    SetPriority(HighestPriority);
  }
#endif
}


void PX_SuspendSignalHandler(int)
{
  PThread * thread = PThread::Current();
  if (thread == NULL)
    return;

  BOOL notResumed = TRUE;
  while (notResumed) {
    BYTE ch;
    notResumed = ::read(thread->unblockPipe[0], &ch, 1) < 0 && errno == EINTR;
#if !( defined(P_NETBSD) && defined(P_NO_CANCEL) )
    pthread_testcancel();
#endif
  }
}


void PThread::Suspend(BOOL susp)
{
  PAssertPTHREAD(pthread_mutex_lock, (&PX_suspendMutex));

  // Check for start up condition, first time Resume() is called
  if (PX_firstTimeStart) {
    if (susp)
      PX_suspendCount++;
    else {
      if (PX_suspendCount > 0)
        PX_suspendCount--;
      if (PX_suspendCount == 0) {
        PX_firstTimeStart = FALSE;
        Restart();
      }
    }

    PAssertPTHREAD(pthread_mutex_unlock, (&PX_suspendMutex));
    return;
  }

#if defined(P_MACOSX) && (P_MACOSX <= 55)
  // Suspend - warn the user with an Assertion
  PAssertAlways("Cannot suspend threads on Mac OS X due to lack of pthread_kill()");
#else
  if (pthread_kill(PX_threadId, 0) == 0) {

    // if suspending, then see if already suspended
    if (susp) {
      PX_suspendCount++;
      if (PX_suspendCount == 1) {
        if (PX_threadId != pthread_self()) {
          signal(SUSPEND_SIG, PX_SuspendSignalHandler);
          pthread_kill(PX_threadId, SUSPEND_SIG);
        }
        else {
          PAssertPTHREAD(pthread_mutex_unlock, (&PX_suspendMutex));
          PX_SuspendSignalHandler(SUSPEND_SIG);
          return;  // Mutex already unlocked
        }
      }
    }

    // if resuming, then see if to really resume
    else if (PX_suspendCount > 0) {
      PX_suspendCount--;
      if (PX_suspendCount == 0) 
        PXAbortBlock();
    }
  }

  PAssertPTHREAD(pthread_mutex_unlock, (&PX_suspendMutex));
#endif // P_MACOSX
}


void PThread::Resume()
{
  Suspend(FALSE);
}


BOOL PThread::IsSuspended() const
{
  if (PX_firstTimeStart)
    return TRUE;

  if (IsTerminated())
    return FALSE;

  PAssertPTHREAD(pthread_mutex_lock, ((pthread_mutex_t *)&PX_suspendMutex));
  BOOL suspended = PX_suspendCount != 0;
  PAssertPTHREAD(pthread_mutex_unlock, ((pthread_mutex_t *)&PX_suspendMutex));
  return suspended;
}


void PThread::SetAutoDelete(AutoDeleteFlag deletion)