dce.c

Solaris环境下的数据挖掘算法：birch聚类算法。该算法适用于对大量数据的挖掘。

    }
  } else
    perror("shmctl");
}

#if defined(SHARED_KEYS)
int SharedMemory::destroyAll()
{
  key_t maxKey = ShmKeyTableKey + 500;
  if (shmKeyTable)
    maxKey = shmKeyTable->shmNextKey + 100;

  for(key_t key = ShmKeyTableKey; key < maxKey; key++) {
    int id;
    if ((id = shmget(key, 0, SHM_R | SHM_W)) < 0) {
      if (errno != ENOENT)
        perror("shmget");
    } else {
#ifdef DEBUG
      cerr << "%%  Removing shared memory segment " << id << endl;
#endif
      if (shmctl(id, IPC_RMID, 0) < 0)
	perror("semctl");
    }
  }

  if (shmKeyTable)
    shmKeyTable->shmNextKey = SharedMemoryBase;

  return 0;
}

key_t SharedMemory::newKey()
{
  if (!shmKeyTable)
    attachTable();
  assert(shmKeyTable);
  key_t key = shmKeyTable->shmNextKey++;
#ifdef DEBUG
  cerr << "Next shared memory key is " << key << endl;
#endif
  return key;
}
#endif

#if defined(PRIVATE_KEYS)
key_t SharedMemory::newKey()
{
  return IPC_PRIVATE;
}
#endif

#define RELEASE(sem) sems->release(1, sem)
#define ACQUIRE(sem) sems->acquire(1, sem)

IOBuffer::IOBuffer(int size) :
	size(size), sems(0), shmem(0)
{
  semKey = Semaphore::newKey();
  shmKey = SharedMemory::newKey();
}

IOBuffer::~IOBuffer()
{
  delete sems;
  delete shmem;
}

void IOBuffer::attach()
{
  // attach to semaphores

  int status;
  sems = new SemaphoreV(semKey, status, 3);
  assert(status >= 0);
  
  // attach to shared memory segment

  char *buf = 0;
  int created = 0;
  shmem = new SharedMemory(shmKey, size + 7 * sizeof(int), buf, created);
  assert(shmem && buf);
  comm = (CommBuffer *)buf;
  if (created)
    init();
}

void IOBuffer::init()
{
  assert(comm && sems);

  comm->size = shmem->getSize() - 7 * sizeof(int);
  assert(comm->size == size);
  comm->bytes = 0;
  comm->head = 0;
  comm->tail = 0;
  comm->atEOF = 0;
  comm->wReserve = 0;
  comm->rReserve = 0;
  sems->setValue(1, lock);
  sems->setValue(0, hasData);
  sems->setValue(1, hasSpace);
}

int IOBuffer::reserveW(int minUnits, int maxUnits, int bytes,
		       int &n, char *&buf)
{
  if (!minUnits)
    minUnits = 1;
  if (!maxUnits)
    maxUnits = 1;

  assert(comm && sems);
  assert(minUnits > 0 && maxUnits >= minUnits && bytes > 0);

  while(1) {
    ACQUIRE(hasSpace);                  // wait until space available
    ACQUIRE(lock);
    int space = comm->size - comm->bytes - comm->wReserve;
    if (!space) {                       // false alarm, no space?
      RELEASE(lock);
      continue;
    }

    int b = (maxUnits * bytes < space ? maxUnits * bytes : space);
    b = (b < comm->size - comm->tail ? b : comm->size - comm->tail);
    n = b / bytes;
    assert(n > 0);
    if (n < minUnits) {                 // too little space?
#ifdef DEBUG
      cerr << "reserveW asking for " << minUnits << " units, got only "
	   << n << endl;
#endif
      RELEASE(lock);
      continue;
    }

    buf = &comm->buf[comm->tail];
    b = n * bytes;
#ifdef DEBUG
    cerr << "%%  Reserved " << b << " bytes to buffer at "
         << comm->tail << ", now " << comm->wReserve << "/"
	 << comm->bytes << " bytes" << endl;
#endif
    comm->tail += b;
    if (comm->tail >= comm->size)
      comm->tail -= comm->size;
    assert(comm->tail >= 0 && comm->tail < comm->size);
    comm->wReserve += b;
    if (comm->bytes + comm->wReserve < comm->size)
      RELEASE(hasSpace);                // still space left
    RELEASE(lock);
    break;
  }

  return 0;
}

int IOBuffer::reserveR(int minUnits, int maxUnits, int bytes,
		       int &n, char *&buf)
{
  if (!minUnits)
    minUnits = 1;
  if (!maxUnits)
    maxUnits = 1;

  assert(comm && sems);
  assert(minUnits > 0 && maxUnits >= minUnits && bytes > 0);

  ACQUIRE(lock);
  if (!comm->bytes && comm->atEOF) {
    n = 0;
    buf = 0;
    RELEASE(lock);
    return 0;
  }
  RELEASE(lock);

  while(1) {
    ACQUIRE(hasData);                   // wait until data available
    ACQUIRE(lock);
    int data = comm->bytes - comm->rReserve;
    if (!data) {                        // false alarm, no data?
      int eof = comm->atEOF;
      RELEASE(lock);
      if (eof) {
	n = 0;
	buf = 0;
	break;
      }
      continue;
    }

    int b = (maxUnits * bytes < data ? maxUnits * bytes : data);
    b = (b < comm->size - comm->head ? b : comm->size - comm->head);
    n = b / bytes;
    assert(n > 0);
    if (!comm->atEOF && n < minUnits) { // too little data?
#ifdef DEBUG
      cerr << "reserveR asking for " << minUnits << " units, got only "
	   << n << endl;
#endif
      RELEASE(lock);
      continue;
    }

    buf = &comm->buf[comm->head];
    b = n * bytes;
#ifdef DEBUG
    cerr << "%%  Reserved " << b << " bytes from buffer at "
         << comm->head << ", now " << comm->rReserve << "/"
	 << comm->bytes << " bytes" << endl;
#endif
    comm->head += b;
    if (comm->head >= comm->size)
      comm->head -= comm->size;
    assert(comm->head >= 0 && comm->head < comm->size);
    comm->rReserve += b;
    if (comm->bytes - comm->rReserve > 0)
      RELEASE(hasData);                 // still data left
    RELEASE(lock);
    break;
  }

  return 0;
}

int IOBuffer::releaseW(int origUnits, int units, int bytes)
{
  assert(origUnits > 0 && units >= 0 && bytes > 0);
  ACQUIRE(lock);
  assert(comm->wReserve >= origUnits * bytes);
  comm->wReserve -= origUnits * bytes;  // move bytes from reserved state
  comm->bytes += units * bytes;         // .. to actual state
#ifdef DEBUG
  cerr << "%%  Released " << units * bytes << " of "
       << origUnits * bytes << " bytes as written" << endl;
#endif
  RELEASE(lock);
  RELEASE(hasData);                     // notify reader that data is available
  return 0;
}

int IOBuffer::releaseR(int units, int bytes)
{
  if (!units)
    return 0;
  assert(units > 0 && bytes > 0);
  ACQUIRE(lock);
  assert(comm->rReserve >= units * bytes);
  comm->rReserve -= units * bytes;      // move bytes from reserved state
  comm->bytes -= units * bytes;         // .. to actual state
#ifdef DEBUG
  cerr << "%%  Released " << units * bytes << " bytes as read" << endl;
#endif
  RELEASE(lock);
  RELEASE(hasSpace);                    // notify writer that space exists
  return 0;
}

int IOBuffer::write(char *buf, int bytes)
{
  assert(comm && sems);
  assert(comm->wReserve == 0);

  int left = bytes;
  while(left > 0) {
    ACQUIRE(hasSpace);                  // wait until space available
    ACQUIRE(lock);
    int space = comm->size - comm->bytes;
    if (!space) {                       // false alarm, no space?
      RELEASE(lock);
      continue;
    }

    int b = (left < space ? left : space);
#ifdef DEBUG
    cerr << "%%  Writing " << b << " bytes to buffer at "
         << comm->tail << ", now " << comm->bytes << " bytes" << endl;
#endif
    int atend = (b < comm->size - comm->tail ? b : comm->size - comm->tail);
    int atbeg = b - atend;
    if (atend) {
      memcpy(&comm->buf[comm->tail], &buf[bytes - left], atend);
      comm->tail += atend;
      if (comm->tail >= comm->size)     // wrap around the buffer?
	comm->tail -= comm->size;
    }      
    if (atbeg) {
      memcpy(comm->buf, &buf[bytes - left + atend], atbeg);
      comm->tail = atbeg;
    }
    assert(comm->tail >= 0 && comm->tail < comm->size);
    left -= b;
    comm->bytes += b;
    if (comm->bytes < comm->size)
      RELEASE(hasSpace);                // still space left
    RELEASE(lock);
    RELEASE(hasData);                   // notify reader that data is available
  }

  return bytes;
}

int IOBuffer::read(char *buf, int bytes)
{
  assert(comm && sems);
  assert(comm->rReserve == 0);

  ACQUIRE(lock);
  if (!comm->bytes && comm->atEOF) {
    RELEASE(lock);
    return 0;
  }
  RELEASE(lock);

  int left = bytes;
  while(left > 0) {
    ACQUIRE(hasData);                   // wait until data available
    ACQUIRE(lock);
    int data = comm->bytes;
    if (!data) {                        // false alarm, no data?
      int eof = comm->atEOF;
      RELEASE(lock);
      if (eof)
	break;
      continue;
    }

    int b = (left < data ? left : data);
#ifdef DEBUG
    cerr << "%%  Reading " << b << " bytes from buffer at "
         << comm->head << ", now " << comm->bytes << " bytes" << endl;
#endif
    int atend = (b < comm->size - comm->head ? b : comm->size - comm->head);
    int atbeg = b - atend;
    if (atend) {
      memcpy(&buf[bytes - left], &comm->buf[comm->head], atend);
      comm->head += atend;
      if (comm->head >= comm->size)     // wrap around the buffer?
	comm->head -= comm->size;
    }
    if (atbeg) {
      memcpy(&buf[bytes - left + atend], comm->buf, atbeg);
      comm->head = atbeg;
    }
    assert(comm->head >= 0 && comm->head < comm->size);
    left -= b;
    comm->bytes -= b;
    if (comm->bytes > 0)
      RELEASE(hasData);                 // still data left
    RELEASE(lock);
    RELEASE(hasSpace);                  // notify writer that space exists
  }

  return bytes - left;
}

void IOBuffer::setEOF()
{
  ACQUIRE(lock);
  assert(comm->wReserve == 0); 
  comm->atEOF = 1;
  RELEASE(lock);
  RELEASE(hasData);
}