// $Id: KrPool.C,v 1.1 2000/03/10 16:15:11 ben Exp $

#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <Kr/KrPool.h>

const uint	KrPool::BUFLEN;
const uint	KrPool::DATALEN;

KrPool::Buf*	KrPool::_freeList = NULL;
uint		KrPool::_allocSize = 65536;
uint		KrPool::_numBufs = 0;
int		KrPool::_maxBufs = -1;

#define KRPOOL_MAXBUFS 10000 // 2.5Mb

struct KrPool::Buf*
KrPool::alloc()
{
    Buf* b = _freeList;
    if (!b) {
	int numBufs = (_allocSize / BUFLEN);

	// Memory safety valve. By default, KRPOOL_MAXBUFS bufs
	// are allowed to be allocated. This can be overridden with
	// the "KRPOOL_MAXMEM" environment variable, which specifies
	// the maximum memory in bytes allowed. A value of zero
	// means "unlimited".
	
	_numBufs += numBufs;
	
	if (_maxBufs == -1) {
	    _maxBufs = KRPOOL_MAXBUFS; // default value
	    
	    const char* maxMemStr = ::getenv("KRPOOL_MAXMEM");
	    if (maxMemStr) {
		int maxMem = ::strtol(maxMemStr, NULL, 0);
		if (maxMem >= 0 && maxMem < LONG_MAX)
		    _maxBufs = maxMem / BUFLEN;
	    }
	}

//cerr << "KrPool::alloc _numBufs = " << _numBufs << endl;

// $$$ turn off max pool size, may as well let this grow openendedly
//	if (_maxBufs && _numBufs > (unsigned) _maxBufs)
//	    krFatalError(krFormat("exhausted KrPool limit of %dKb",
//		_maxBufs * BUFLEN / 1024));

	// Allocate one less Buf than space would allow, so we can find
	// a starting address for the Bufs that is buf-aligned.
	
// $$$ Turns out the memory-alignment feature isn't used and can be turned off
//	b = (Buf*)(((long int)::malloc(_allocSize) + BUFLEN - 1)
//	    & ~(BUFLEN - 1));
	
	b = (Buf*)::malloc(_allocSize);

	// Now break off the memory into Buf-sized chunks, and
	// add them to the freelist.
    
	while (numBufs--) {
	    b->_next = _freeList;
	    _freeList = b++;
	}
    
	b = _freeList;
    }
    
    _freeList = b->_next;
    return b;
}

void
KrPool::free(Buf* b)
{
#ifdef DEBUG
    ::memset(b, 0, BUFLEN);
#endif
    b->_next = _freeList;
    _freeList = b;
}

void
KrPool::freeChain(Buf* b)
{
    Buf* start = b;
    while (b->_next)
	b = b->_next;
    b->_next = _freeList;
    _freeList = start;
}