311 lines
8.9 KiB
C
311 lines
8.9 KiB
C
/*
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* $Id$
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*/
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/*
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* Harbour Project source code:
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* The garbage collector for Harbour
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*
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* Copyright 1999 Ryszard Glab <rglab@imid.med.pl>
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* www - http://www.harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version, with one exception:
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*
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* The exception is that if you link the Harbour Runtime Library (HRL)
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* and/or the Harbour Virtual Machine (HVM) with other files to produce
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* an executable, this does not by itself cause the resulting executable
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* to be covered by the GNU General Public License. Your use of that
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* executable is in no way restricted on account of linking the HRL
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* and/or HVM code into it.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA (or visit
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* their web site at http://www.gnu.org/).
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*
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*/
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/* The Harbour implementation of codeblocks */
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#include "hbapi.h"
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#include "hbapiitm.h"
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#include "hbapierr.h"
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#include "hbvm.h"
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#include "error.ch"
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/* holder of memory block information */
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typedef struct HB_GARBAGE_
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{
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struct HB_GARBAGE_ *pNext; /* next memory block */
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struct HB_GARBAGE_ *pPrev; /* previous memory block */
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HB_GARBAGE_FUNC_PTR pFunc; /* cleanup function called before memory releasing */
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ULONG status; /* block status */
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} HB_GARBAGE, *HB_GARBAGE_PTR;
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/* status of memory block */
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#define HB_GC_UNLOCKED 0
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#define HB_GC_LOCKED 1 /* do not collect a memory block */
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#define HB_GC_NOTCHECKED 2 /* this item was not checked yet */
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#define HB_GC_CHECKING 4 /* this item is checked currently */
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/* pointer to memory block that will be checked in next step */
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static HB_GARBAGE_PTR s_pCurrBlock = NULL;
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/* memory blocks are stored in linked list with a loop */
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/* marks if block releasing is requested during garbage collecting */
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static BOOL s_bCollecting = FALSE;
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/* we may use a cache later */
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#define HB_GARBAGE_NEW( ulSize ) ( HB_GARBAGE_PTR )hb_xgrab( ulSize )
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#define HB_GARBAGE_FREE( pAlloc ) hb_xfree( (void *)(pAlloc) )
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/* allocates a memory block */
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void * hb_gcAlloc( ULONG ulSize, HB_GARBAGE_FUNC_PTR pCleanupFunc )
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{
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HB_GARBAGE_PTR pAlloc;
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pAlloc = HB_GARBAGE_NEW( ulSize + sizeof( HB_GARBAGE ) );
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if( pAlloc )
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{
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if( s_pCurrBlock )
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{
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/* add new block at the logical end of list */
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pAlloc->pNext = s_pCurrBlock;
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pAlloc->pPrev = s_pCurrBlock->pPrev;
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pAlloc->pPrev->pNext = pAlloc;
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s_pCurrBlock->pPrev = pAlloc;
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}
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else
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{
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s_pCurrBlock = pAlloc;
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s_pCurrBlock->pNext = s_pCurrBlock->pPrev = pAlloc;
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}
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pAlloc->pFunc = pCleanupFunc;
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pAlloc->status = HB_GC_UNLOCKED;
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return (void *)( pAlloc + 1 ); /* hide the internal data */
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}
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else
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return NULL;
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}
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/* release a memory block allocated with hb_gcAlloc() */
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void hb_gcFree( void *pBlock )
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{
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if( pBlock )
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{
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HB_GARBAGE_PTR pAlloc = ( HB_GARBAGE_PTR ) pBlock;
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--pAlloc;
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if( !( s_bCollecting && pAlloc == s_pCurrBlock ) )
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{
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/* Don't release the block that is a subject of collecting */
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pAlloc->pPrev->pNext = pAlloc->pNext;
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pAlloc->pNext->pPrev = pAlloc->pPrev;
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if( s_pCurrBlock == pAlloc )
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s_pCurrBlock = pAlloc->pNext;
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if( pAlloc->pPrev == pAlloc->pPrev && pAlloc == s_pCurrBlock )
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s_pCurrBlock = NULL; /* this was the last block */
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HB_GARBAGE_FREE( pAlloc );
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}
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}
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else
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{
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hb_errInternal( IE_XFREENULL, NULL, NULL, NULL );
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}
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}
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/* Lock a memory pointer so it will not be released if stored
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outside of harbour variables
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*/
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void *hb_gcLock( void *pBlock )
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{
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if( pBlock )
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{
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HB_GARBAGE_PTR pAlloc = ( HB_GARBAGE_PTR ) pBlock;
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--pAlloc;
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pAlloc->status |= HB_GC_LOCKED;
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}
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return pBlock;
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}
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/* Unlock a memory pointer so it can be released if there is no
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references inside of harbour variables
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*/
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void *hb_gcUnlock( void *pBlock )
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{
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if( pBlock )
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{
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HB_GARBAGE_PTR pAlloc = ( HB_GARBAGE_PTR ) pBlock;
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--pAlloc;
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pAlloc->status &= ~( ( ULONG ) HB_GC_LOCKED );
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}
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return pBlock;
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}
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/* Lock an item so it will not be released if stored
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outside of harbour variables
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*/
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void hb_gcLockItem( HB_ITEM_PTR pItem )
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{
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if( HB_IS_ARRAY( pItem ) )
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hb_gcLock( pItem->item.asArray.value );
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else if( HB_IS_BLOCK( pItem ) )
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hb_gcLock( pItem->item.asBlock.value );
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}
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/* Unlock an item so it can be released if there is no
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references inside of harbour variables
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*/
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void hb_gcUnlockItem( HB_ITEM_PTR pItem )
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{
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if( HB_IS_ARRAY( pItem ) )
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hb_gcUnlock( pItem->item.asArray.value );
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else if( HB_IS_BLOCK( pItem ) )
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hb_gcUnlock( pItem->item.asBlock.value );
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}
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/* Check a single memory block if it can be released
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* The block will be released if it is not locked and there is no
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* references for this block inside some harbour variable (local,
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* memvar or static)
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*/
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void hb_gcCollect( void )
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{
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if( s_pCurrBlock && !s_bCollecting )
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{
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void *pBlock = ( void * )( s_pCurrBlock + 1 ); /* change for real pointer */
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HB_GARBAGE_PTR pNext = s_pCurrBlock->pNext;
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s_pCurrBlock->status &= ~( (ULONG)HB_GC_NOTCHECKED );
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if( !( s_pCurrBlock->status & HB_GC_LOCKED ) )
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{
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if( !hb_vmIsLocalRef( pBlock ) )
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{
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if( !hb_memvarsIsMemvarRef( pBlock ) )
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{
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if( !hb_vmIsStaticRef( pBlock ) )
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{
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if( !hb_clsIsClassRef( pBlock ) )
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{
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/* It is possible that s_pCurrBlock will be requested
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* to release from a cleanup function - to prevent it
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* we have to use some flag.
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*/
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s_bCollecting = TRUE;
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if( s_pCurrBlock->pFunc )
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( s_pCurrBlock->pFunc )( ( void *)( s_pCurrBlock + 1 ) );
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s_pCurrBlock->pPrev->pNext = s_pCurrBlock->pNext;
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s_pCurrBlock->pNext->pPrev = s_pCurrBlock->pPrev;
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pNext = s_pCurrBlock->pNext;
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if( s_pCurrBlock == pNext && pNext->pPrev == pNext->pNext )
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pNext = NULL; /* this was the last block */
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HB_GARBAGE_FREE( s_pCurrBlock );
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s_bCollecting = FALSE;
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}
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}
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}
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}
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}
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s_pCurrBlock = pNext;
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}
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}
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/* Check all memory block if they can be released
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*/
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void hb_gcCollectAll( void )
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{
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if( s_pCurrBlock )
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{
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HB_GARBAGE_PTR pBlock = s_pCurrBlock;
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do
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{
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pBlock->status |= HB_GC_NOTCHECKED;
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pBlock = pBlock->pNext;
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} while (pBlock != s_pCurrBlock);
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do
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{
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hb_gcCollect();
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} while( s_pCurrBlock && (s_pCurrBlock->status & HB_GC_NOTCHECKED) );
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}
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}
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/* Check if passed item <pItem> contains a reference to passed
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* memory pointer <pBlock>
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* Returns TRUE if there is a reference (the pointer cannot be released)
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* or returns FALSE if the item doesn't refer the pointer.
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* Arrays are scanned recursively.
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*/
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BOOL hb_gcItemRef( HB_ITEM_PTR pItem, void *pBlock )
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{
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if( HB_IS_BYREF( pItem ) )
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{
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if( HB_IS_MEMVAR( pItem ) )
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pItem = hb_itemUnRef( pItem ); /* detached variable */
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else
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return FALSE; /* all items should be passed directly */
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}
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if( HB_IS_ARRAY( pItem ) )
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{
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/* NOTE: this checks for objects too */
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if( pItem->item.asArray.value == ( HB_BASEARRAY_PTR )pBlock )
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return TRUE;
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else
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{
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HB_GARBAGE_PTR pAlloc = ( HB_GARBAGE_PTR ) pItem->item.asArray.value;
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ULONG ulSize = pItem->item.asArray.value->ulLen;
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--pAlloc;
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pAlloc->status |= HB_GC_CHECKING;
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pItem = pItem->item.asArray.value->pItems;
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while( ulSize-- )
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{
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if( hb_gcItemRef( pItem, pBlock ) )
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{
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pAlloc->status &= ~( (ULONG) ( HB_GC_CHECKING ) );
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return TRUE;
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}
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else
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++pItem;
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}
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pAlloc->status &= ~( (ULONG) ( HB_GC_CHECKING ) );
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}
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}
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else if( HB_IS_BLOCK( pItem ) )
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{
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return ( pItem->item.asBlock.value == ( HB_CODEBLOCK_PTR )pBlock );
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}
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return FALSE;
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}
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/* service a single garbage collector step
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* Check a single memory block if it can be released
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*/
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HB_FUNC( HB_GCSTEP )
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{
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hb_gcCollect();
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}
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/* Check all memory blocks if they can be released
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*/
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HB_FUNC( HB_GCALL )
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{
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hb_gcCollectAll();
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}
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