InfoMagic Source Code 1993 July/THE_SOURCE_CODE_CD_ROM.iso/gnu/nihcl-3.0/lib/SharedQueue.c

C/C++ Source or Header | 1990-05-19 | 4.7 KB | 183 lines

/* SharedQueue.c -- implementation of shared queues

    THIS SOFTWARE FITS THE DESCRIPTION IN THE U.S. COPYRIGHT ACT OF A
    "UNITED STATES GOVERNMENT WORK".  IT WAS WRITTEN AS A PART OF THE
    AUTHOR'S OFFICIAL DUTIES AS A GOVERNMENT EMPLOYEE.  THIS MEANS IT
    CANNOT BE COPYRIGHTED.  THIS SOFTWARE IS FREELY AVAILABLE TO THE
    PUBLIC FOR USE WITHOUT A COPYRIGHT NOTICE, AND THERE ARE NO
    RESTRICTIONS ON ITS USE, NOW OR SUBSEQUENTLY.

Author:
    K. E. Gorlen
    Bg. 12A, Rm. 2033
    Computer Systems Laboratory
    Division of Computer Research and Technology
    National Institutes of Health
    Bethesda, Maryland 20892
    Phone: [phone]
    uucp: uunet!nih-csl!kgorlen
    Internet: [e-mail]
    December, 1985

Function:

Class SharedQueue provides a queue that can be used for communication
between two separate processes.  Semaphores are used to block a process
if next() is called and there are no objects in the queue, or if
nextPut() is called and there is no space in the queue.

$Log:    SharedQueue.c,v $
 * Revision 3.0  90/05/20  00:21:20  kgorlen
 * Release for 1st edition.
 *
*/

#include "SharedQueue.h"
#include "nihclIO.h"

#define    THIS    SharedQueue
#define    BASE    Object
#define BASE_CLASSES BASE::desc()
#define MEMBER_CLASSES ArrayOb::desc(),Semaphore::desc(),Semaphore::desc()
#define VIRTUAL_BASE_CLASSES Object::desc()

DEFINE_CLASS(SharedQueue,2,"$Header: /afs/alw.nih.gov/unix/sun4_40c/usr/local/src/nihcl-3.0/share/lib/RCS/SharedQueue.c,v 3.0 90/05/20 00:21:20 kgorlen Rel $",NULL,NULL);

SharedQueue::SharedQueue(unsigned queueSize)
:
    queue(queueSize),
    valueAvailable(0),
    spaceAvailable(queueSize)
{
    readPosition = writePosition = 0;
}

SharedQueue::SharedQueue(const SharedQueue& q)
:
    queue(q.queue),
    valueAvailable(q.valueAvailable),
    spaceAvailable(q.spaceAvailable)
{
    readPosition = q.readPosition;
    writePosition = q.writePosition;
}

Object* SharedQueue::next()
{
    valueAvailable.wait();
    Object* ob = queue[readPosition];
    queue[readPosition++] = nil;
    if (readPosition >= queue.capacity()) readPosition = 0;
    spaceAvailable.signal();
    return ob;
}

Object* SharedQueue::nextPut(Object& ob)
{
    spaceAvailable.wait();
    queue[writePosition++] = &ob;
    if (writePosition >= queue.capacity()) writePosition = 0;
    valueAvailable.signal();
    return &ob;
}

unsigned SharedQueue::capacity() const    { return queue.capacity(); }

bool SharedQueue::isEmpty() const    { return valueAvailable.value() <= 0; }

unsigned SharedQueue::size() const    { return MAX(valueAvailable.value(),0); }

Object* SharedQueue::copy() const    { return deepCopy(); }

void SharedQueue::deepenShallowCopy()
{
    queue.deepenShallowCopy();
    valueAvailable.deepenShallowCopy();
    spaceAvailable.deepenShallowCopy();
}

void SharedQueue::dumpOn(ostream& strm) const
{
    strm << className() << "[\n";
    strm << "valueAvailable ";  valueAvailable.dumpOn(strm);
    strm << "spaceAvailable ";  spaceAvailable.dumpOn(strm);
    strm << "queue:\n";
    int i = readPosition;
    for (int n = valueAvailable.value(); n>0; n--) {
        queue[i++]->dumpOn(strm);
        if (i == queue.capacity()) i = 0;
    }
    strm << "]\n";
}

unsigned SharedQueue::hash() const    { return (unsigned)this; }

bool SharedQueue::isEqual(const Object& ob) const   { return isSame(ob); }

void SharedQueue::printOn(ostream& strm) const
{
    int i = readPosition;
    for (int n = valueAvailable.value(); n>0; n--) {
        if (i != readPosition) strm << '\n';
        queue[i++]->printOn(strm);
        if (i == queue.capacity()) i = 0;
    }
}

static unsigned sharedqueue_capacity;

SharedQueue::SharedQueue(OIOin& strm)
    : BASE(strm),
    queue((strm >> sharedqueue_capacity, sharedqueue_capacity)),
    valueAvailable(strm),
    spaceAvailable(strm)
{
    readPosition = 0;
    writePosition = valueAvailable.value();
    for (register int i =0; i<writePosition; i++) queue[i] = Object::readFrom(strm);
}

void SharedQueue::storer(OIOout& strm) const
{
    BASE::storer(strm);
    strm << queue.capacity();
    valueAvailable.storeMemberOn(strm);
    spaceAvailable.storeMemberOn(strm);
    register int i = readPosition;
    while (i != writePosition) {
        queue[i++]->storeOn(strm);
        if (i == queue.capacity()) i = 0;
    }
}

SharedQueue::SharedQueue(OIOifd& fd)
    : BASE(fd),
    queue((fd >> sharedqueue_capacity, sharedqueue_capacity)),
    valueAvailable(fd),
    spaceAvailable(fd)
{
    readPosition = 0;
    writePosition = valueAvailable.value();
    for (register int i=0; i < writePosition; i++)
      queue[i] = Object::readFrom(fd);
}

void SharedQueue::storer(OIOofd& fd) const
{
    BASE::storer(fd);
    fd << queue.capacity();
    valueAvailable.storeMemberOn(fd);
    spaceAvailable.storeMemberOn(fd);
    register int i = readPosition;
    while (i != writePosition) {
      queue[i++]->storeOn(fd);
      if (i == queue.capacity()) i = 0;
      };
}

int SharedQueue::compare(const Object&) const
{
    shouldNotImplement("compare");
    return 0;
}