139 lines
4.5 KiB
C++
139 lines
4.5 KiB
C++
// Filename: uniqueIdAllocator.cxx
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// Created by: schuyler 2003-03-13
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//
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////////////////////////////////////////////////////////////////////
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//
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// PANDA 3D SOFTWARE
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// Copyright (c) 2001, Disney Enterprises, Inc. All rights reserved
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//
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// All use of this software is subject to the terms of the Panda 3d
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// Software license. You should have received a copy of this license
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// along with this source code; you will also find a current copy of
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// the license at http://www.panda3d.org/license.txt .
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//
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// To contact the maintainers of this program write to
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// panda3d@yahoogroups.com .
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//
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////////////////////////////////////////////////////////////////////
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//
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#include "pandabase.h"
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#include "notify.h"
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#include "uniqueIdAllocator.h"
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////////////////////////////////////////////////////////////////////
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// Function:
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// Access:
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// Description: Create a free id pool in the range [min:max].
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////////////////////////////////////////////////////////////////////
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UniqueIdAllocator::
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UniqueIdAllocator(U32 min, U32 max)
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: _min(min), _max(max) {
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//cout<<"UniqueIdAllocator::UniqueIdAllocator("<<min<<", "<<max<<")"<<endl;
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_size=_max-_min+1; // +1 because min and max are inclusive.
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assert(_size); // size must be > 0.
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_table=new U32[_size];
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assert(_table); // This should be redundant if new throws an exception.
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for (U32 i=0; i<_size; ++i) {
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_table[i]=i+1;
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}
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_table[_size-1]=-1;
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_next_free=0;
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_last_free=_size-1;
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_free=_size;
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}
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////////////////////////////////////////////////////////////////////
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// Function:
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// Access:
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// Description:
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////////////////////////////////////////////////////////////////////
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UniqueIdAllocator::
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~UniqueIdAllocator() {
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//cout<<"UniqueIdAllocator::~UniqueIdAllocator()"<<endl;
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delete [] _table;
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}
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////////////////////////////////////////////////////////////////////
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// Function:
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// Access:
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// Description: Receive an id between _min and _max (that were passed
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// to the constructor). This code will succede or call
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// exit().
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////////////////////////////////////////////////////////////////////
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U32 UniqueIdAllocator::
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allocate() {
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if (_next_free==-1) {
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// ...all ids allocated.
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cerr<<"UniqueIdAllocator Error: all ids allocated."<<endl;
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// TODO:throw an exception rather than calling exit.
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exit(1);
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}
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// This next block is redundant with the one above it, but I'm leaving
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// the one above in place, in case anyone removes this next block.
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if (_free<=(_size>>2)) {
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// ...under 1/4 of the ids are free.
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cerr<<"UniqueIdAllocator Error: 75% of ids allocated."<<endl;
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// TODO:throw an exception rather than calling exit.
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exit(1);
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}
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U32 id=_min+_next_free;
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_next_free=_table[_next_free];
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assert(_table[id-_min]=-2); // this assignment is debug only.
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--_free;
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//cout<<"UniqueIdAllocator::allocate() returning "<<id<<endl;
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return id;
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}
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////////////////////////////////////////////////////////////////////
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// Function:
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// Access:
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// Description: Free an allocated index (index must be between _min
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// and _max that were passed to the constructor).
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////////////////////////////////////////////////////////////////////
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void UniqueIdAllocator::
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free(U32 index) {
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//cout<<"UniqueIdAllocator::free(index)"<<endl;
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assert(index>=_min); // Attempt to free out-of-range id.
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assert(index<=_max); // Attempt to free out-of-range id.
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index=index-_min;
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assert(_table[index]==-2); // Attempt to free non-allocated id.
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_table[index]=-1;
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_table[_last_free]=index;
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#if 0 //[
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// This is only necessary if the free pool is allowed to go empty.
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// Since we don't allow that, it is an optimization to comment
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// this out.
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if (_next_free==-1) {
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_next_free=index;
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}
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#endif //]
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_last_free=index;
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++_free;
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}
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////////////////////////////////////////////////////////////////////
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// Function:
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// Access:
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// Description: ...intended for debugging only.
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////////////////////////////////////////////////////////////////////
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void UniqueIdAllocator::
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printTo(ostream& os) const {
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os <<"[_next_free: "<<long(_next_free)
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<<"; _last_free: "<<long(_last_free)
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<<"; _size: "<<_size
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<<"; _free: "<<_free
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<<"; used: "<<_size-_free
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<<"; %used: "<<float(_size-_free)/_size // This differs the %used code above.
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<<";\n ";
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for (U32 i=0; i<_size; ++i) {
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os<<long(_table[i])<<", ";
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}
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os<<"]"<<endl;
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}
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