/*** *heapmin.c - Minimize the heap * * Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved. * *Purpose: * Minimize the heap freeing as much memory as possible back * to the OS. * *Revision History: * 08-28-89 JCR Module created. * 11-06-89 JCR Improved, partitioned * 11-13-89 GJF Added MTHREAD support, also fixed copyright * 12-14-89 GJF Couple of bug fixes, some tuning, cleaned up the * formatting a bit and changed header file name to * heap.h * 12-20-89 GJF Removed references to plastdesc * 03-11-90 GJF Replaced _cdecl with _CALLTYPE1, added #include * and removed #include . * 03-29-90 GJF Made _heapmin_region() and _free_partial_region() * _CALLTYPE4. * 07-24-90 SBM Compiles cleanly with -W3 (tentatively removed * unreferenced labels and unreachable code), removed * '32' from API names * 09-28-90 GJF New-style function declarators. Also, rewrote expr. * to avoid using cast as lvalue. * 12-04-90 SRW Changed to include instead of * 12-06-90 SRW Added _CRUISER_ and _WIN32 conditionals. * 12-28-90 SRW Added cast of void * to char * for Mips C Compiler * 03-05-91 GJF Changed strategy for rover - old version available * by #define-ing _OLDROVER_. * 04-06-93 SKS Replace _CRTAPI* with __cdecl * 03-03-94 GJF Changed references to _GETEMPTY macro to calls to * the __getempty function. Added graceful handling for * failure of the call to __getempty in _heapmin_region. * However, failure in _free_partial_region will still * result in termination via _heap_abort (very difficult * to handle any other way, very unlikely to occur). * 02-07-95 GJF Merged in Mac version. Removed obsolete _OLDROVER_ * support. * 04-30-95 GJF Spliced on winheap version. * 03-07-96 GJF Added support for small-block heap. * 05-22-97 RDK New small-block heap scheme implemented. * 09-26-97 BWT Remove POSIX * 12-17-97 GJF Exception-safe locking. * 09-30-98 GJF Bypass all small-block heap code when __sbh_initialized * is 0. * 11-19-98 GJF Merged in VC++ 5.0 small-block heap support. * 05-01-99 PML Disable small-block heap for Win64. * 05-17-99 PML Remove all Macintosh support. * 06-22-99 GJF Removed old small-block heap from static libs. * *******************************************************************************/ #ifdef WINHEAP #include #include #include #include #include #include #include /*** *_heapmin() - Minimize the heap * *Purpose: * Minimize the heap freeing as much memory as possible back * to the OS. * *Entry: * (void) * *Exit: * * 0 = no error has occurred * -1 = an error has occurred (errno is set) * *Exceptions: * *******************************************************************************/ int __cdecl _heapmin(void) { #ifndef _WIN64 if ( __active_heap == __V6_HEAP ) { #ifdef _MT _mlock( _HEAP_LOCK ); __try { #endif __sbh_heapmin(); #ifdef _MT } __finally { _munlock( _HEAP_LOCK ); } #endif } #ifdef CRTDLL else if ( __active_heap == __V5_HEAP ) { /* * Minimize the small-block heap by calling _sbh_decommit_pages() * with a big enough count to ensure every page which can be * decommitted, is. */ #ifdef _MT _mlock( _HEAP_LOCK ); __try { #endif __old_sbh_decommit_pages( 2 * _OLD_PAGES_PER_COMMITMENT ); #ifdef _MT } __finally { _munlock( _HEAP_LOCK ); } #endif } #endif /* CRTDLL */ #endif /* ndef _WIN64 */ if ( HeapCompact( _crtheap, 0 ) == 0 ) { if ( GetLastError() == ERROR_CALL_NOT_IMPLEMENTED ) { _doserrno = ERROR_CALL_NOT_IMPLEMENTED; errno = ENOSYS; } return -1; } else { return 0; } } #else /* ndef WINHEAP */ #include #include #include #include #include #include static int __cdecl _heapmin_region(int, void *, _PBLKDESC); static void __cdecl _free_partial_region(_PBLKDESC, unsigned, int); /*** *_heapmin() - Minimize the heap * *Purpose: * Minimize the heap freeing as much memory as possible back * to the OS. * *Entry: * (void) * *Exit: * 0 = no error has occurred * -1 = an error has occurred (errno is set) * *Exceptions: * *******************************************************************************/ int __cdecl _heapmin(void) { REG1 int index; _PBLKDESC pdesc; REG2 _PBLKDESC pdesc2; void * regend; int region_min_count = 0; /* * Lock the heap */ _mlock(_HEAP_LOCK); /* * Coalesce the heap (should return NULL) */ if ( _heap_search((unsigned)_HEAP_COALESCE) != NULL ) _heap_abort(); /* * Loop through the region descriptor table freeing as much * memory to the OS as possible. */ for ( index=0 ; index < _HEAP_REGIONMAX ; index++ ) { if ( _heap_regions[index]._regbase == NULL ) continue; /* region entry is empty */ /* * Get the entry that contains the last address of * the region (allocated so far, that is). */ regend = (char *) _heap_regions[index]._regbase + _heap_regions[index]._currsize - 1; if ( _heap_findaddr(regend, &pdesc) != _HEAPFIND_WITHIN ) _heap_abort(); /* last address not within a block */ /* * See if the containing block is free */ if ( !(_IS_FREE(pdesc)) ) continue; /* block is not free */ /* * Region ends with a free block, go free as much mem * as possible. */ region_min_count += _heapmin_region(index, regend, pdesc); } /* region loop */ /* * By minimizing the heap, we've likely invalidated the rover and * may have produced contiguous dummy blocks so: * * (1) reset the rover * (2) coalesce contiguous dummy blocks */ if ( region_min_count ) { /* * Set proverdesc to pfirstdesc */ _heap_desc.proverdesc = _heap_desc.pfirstdesc; for ( pdesc = _heap_desc.pfirstdesc ; pdesc != &_heap_desc.sentinel ; pdesc = pdesc->pnextdesc ) { /* * Check and remove consecutive dummy blocks */ if ( _IS_DUMMY(pdesc) ) { for ( pdesc2 = pdesc->pnextdesc ; _IS_DUMMY(pdesc2) ; pdesc2 = pdesc->pnextdesc ) { /* * coalesce the dummy blocks */ pdesc->pnextdesc = pdesc2->pnextdesc; _PUTEMPTY(pdesc2); } /* dummy loop */ } /* if */ } /* heap loop */ } /* region_min_count */ /* * Good return */ /* goodrtn: unreferenced label to be removed */ /* * Release the heap lock */ _munlock(_HEAP_LOCK); return(0); } /*** *_heapmin_region() - Minimize a region * *Purpose: * Free as much of a region back to the OS as possible. * *Entry: * int index = index of the region in the region table * void * regend = last valid address in region * pdesc = pointer to the last block of memory in the region * (it has already been determined that this block is free) * *Exit: * int 1 = minimized region * 0 = no change to region * *Exceptions: * *******************************************************************************/ static int __cdecl _heapmin_region ( int index, void * regend, REG1 _PBLKDESC pdesc ) { unsigned size; REG2 _PBLKDESC pnew; /* * Init some variables * * regend = 1st address AFTER region * size = amount of free memory at end of current region */ regend = (char *) regend + 1; /* "regend++" give compiler error... */ size = ((char *)regend - (char *)_ADDRESS(pdesc)); /* * See if there's enough free memory to release to the OS. * (NOTE: Need more than a page since we may need a back pointer.) */ if ( size <= _PAGESIZE_ ) return(0); /* 0 = no change to region */ /* * We're going to free some memory to the OS. See if the * free block crosses the end of the region and, if so, * split up the block appropriately. */ if ( (_MEMSIZE(pdesc) - size) != 0 ) { /* * The free block spans the end of the region. * Divide it up. */ /* * Get an empty descriptor */ if ( (pnew = __getempty()) == NULL ) return(0); pnew->pblock = regend; /* init block pointer */ * (_PBLKDESC*)regend = pnew; /* init back pointer */ _SET_FREE(pnew); /* set the block free */ pnew->pnextdesc = pdesc->pnextdesc; /* link it in */ pdesc->pnextdesc = pnew; } /* * At this point, we have a free block of memory that goes * up to (but not exceeding) the end of the region. * * pdesc = descriptor of the last free block in region * size = amount of free mem at end of region (i.e., _MEMSIZE(pdesc)) * regend = 1st address AFTER end of region */ /* * See if we should return the whole region of only part of it. */ if ( _ADDRESS(pdesc) == _heap_regions[index]._regbase ) { /* * Whole region is free, return it to OS */ _heap_free_region(index); /* * Put a dummy block in the heap to hold space for * the memory we just freed up. */ _SET_DUMMY(pdesc); } else { /* * Whole region is NOT free, return part of it to OS */ _free_partial_region(pdesc, size, index); } /* * Exit paths */ return(1); /* 1 = minimized region */ } /*** *_free_partial_region() - Free part of a region to the OS * *Purpose: * Free a portion of a region to the OS * *Entry: * pdesc = descriptor of last free block in region * size = amount of free mem at end of region (i.e., _MEMSIZE(pdesc)) * index = index of region * *Exit: * *Exceptions: * *******************************************************************************/ static void __cdecl _free_partial_region ( REG1 _PBLKDESC pdesc, unsigned size, int index ) { unsigned left; void * base; REG2 _PBLKDESC pnew; /* * Init a few variables. */ left = (size & (_PAGESIZE_-1)); base = (char *)_ADDRESS(pdesc); /* * We return memory to the OS in page multiples. If the * free block is not page aligned, we'll insert a new free block * to fill in the difference. */ if ( left != 0 ) { /* * The block is not a multiple of pages so we need * to adjust variables accordingly. */ size -= left; base = (char *)base + left; } /* * Return the free pages to the OS. */ if (!VirtualFree(base, size, MEM_DECOMMIT)) _heap_abort(); /* * Adjust the region table entry */ _heap_regions[index]._currsize -= size; /* * Adjust the heap according to whether we released the whole * free block or not. (Don't worry about consecutive dummies, * we'll coalesce them later.) * * base = address of block we just gave back to OS * size = size of block we gave back to OS * left = size of block we did NOT give back to OS */ if ( left == 0 ) { /* * The free block was released to the OS in its * entirety. Make the free block a dummy place holder. */ _SET_DUMMY(pdesc); } else { /* * Did NOT release the whole free block to the OS. * There's a block of free memory we want to leave * in the heap. Insert a dummy entry after it. */ if ( (pnew = __getempty()) == NULL ) _heap_abort(); pnew->pblock = (char *)base; _SET_DUMMY(pnew); pnew->pnextdesc = pdesc->pnextdesc; pdesc->pnextdesc = pnew; } } #endif /* WINHEAP */