1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/vmalloc.c	Sat Oct 30 20:54:36 2010 -0700
     1.3 @@ -0,0 +1,256 @@
     1.4 +/*
     1.5 + *  Copyright 2009 OpenSourceCodeStewardshipFoundation.org
     1.6 + *  Licensed under GNU General Public License version 2
     1.7 + *
     1.8 + * Author: seanhalle@yahoo.com
     1.9 + *
    1.10 + * Created on November 14, 2009, 9:07 PM
    1.11 + */
    1.12 +
    1.13 +#include <malloc.h>
    1.14 +
    1.15 +#include "VMS.h"
    1.16 +
    1.17 +/*Helper function
    1.18 + *Insert a newly generated free chunk into the first spot on the free list.
    1.19 + * The chunk is cast as a MallocProlog, so the various pointers in it are
    1.20 + * accessed with C's help -- and the size of the prolog is easily added to
    1.21 + * the pointer when a chunk is returned to the app -- so C handles changes
    1.22 + * in pointer sizes among machines.
    1.23 + *
    1.24 + *The list head is a normal MallocProlog struct -- identified by its
    1.25 + * prevChunkInFreeList being NULL -- the only one.
    1.26 + *
    1.27 + *The end of the list is identified by next chunk being NULL, as usual.
    1.28 + */
    1.29 +void inline
    1.30 +add_chunk_to_free_list( MallocProlog *chunk, MallocProlog *listHead )
    1.31 + { 
    1.32 +   chunk->nextChunkInFreeList     = listHead->nextChunkInFreeList;
    1.33 +   if( chunk->nextChunkInFreeList != NULL ) //if not last in free list
    1.34 +      chunk->nextChunkInFreeList->prevChunkInFreeList = chunk;
    1.35 +   chunk->prevChunkInFreeList     = listHead;
    1.36 +   listHead->nextChunkInFreeList  = chunk;
    1.37 + }
    1.38 +
    1.39 +
    1.40 +/*This is sequential code, meant to only be called from the Master, not from
    1.41 + * any slave VPs.
    1.42 + *Search down list, checking size by the nextHigherInMem pointer, to find
    1.43 + * first chunk bigger than size needed.
    1.44 + *Shave off the extra and make it into a new free-list element, hook it in
    1.45 + * then return the address of the found element plus size of prolog.
    1.46 + *
    1.47 + *Will find a
    1.48 + */
    1.49 +void *
    1.50 +VMS__malloc( int32 sizeRequested )
    1.51 + { MallocProlog *foundElem = NULL, *currElem, *newElem;
    1.52 +   int32         amountExtra, foundElemIsTopOfHeap, sizeConsumed,sizeOfFound;
    1.53 +
    1.54 +      //step up the size to be aligned at 16-byte boundary, prob better ways
    1.55 +   sizeRequested = ((sizeRequested + 16) >> 4) << 4;
    1.56 +   currElem = (_VMSMasterEnv->freeListHead)->nextChunkInFreeList;
    1.57 +
    1.58 +   while( currElem != NULL )
    1.59 +    {    //check if size of currElem is big enough
    1.60 +      sizeOfFound=(int32)((char*)currElem->nextHigherInMem -(char*)currElem);
    1.61 +      amountExtra = sizeOfFound - sizeRequested - sizeof(MallocProlog);
    1.62 +      if( amountExtra > 0 )
    1.63 +       {    //found it, get out of loop
    1.64 +         foundElem = currElem;
    1.65 +         currElem = NULL;
    1.66 +       }
    1.67 +      else
    1.68 +         currElem = currElem->nextChunkInFreeList;
    1.69 +    }
    1.70 +
    1.71 +   if( foundElem == NULL )
    1.72 +    { PRINT_ERROR("\nmalloc failed\n")
    1.73 +      return NULL;  //indicates malloc failed
    1.74 +    }
    1.75 +      //Using a kludge to identify the element that is the top chunk in the
    1.76 +      // heap -- saving top-of-heap addr in head's nextHigherInMem -- and
    1.77 +      // save addr of start of heap in head's nextLowerInMem
    1.78 +      //Will handle top of Heap specially
    1.79 +   foundElemIsTopOfHeap = foundElem->nextHigherInMem ==
    1.80 +                          _VMSMasterEnv->freeListHead->nextHigherInMem;
    1.81 +
    1.82 +      //before shave off and try to insert new elem, remove found elem
    1.83 +      //note, foundElem will never be the head, so always has valid prevChunk
    1.84 +   foundElem->prevChunkInFreeList->nextChunkInFreeList =
    1.85 +                                              foundElem->nextChunkInFreeList;
    1.86 +   if( foundElem->nextChunkInFreeList != NULL )
    1.87 +    { foundElem->nextChunkInFreeList->prevChunkInFreeList =
    1.88 +                                              foundElem->prevChunkInFreeList;
    1.89 +    }
    1.90 +   foundElem->prevChunkInFreeList = NULL;//indicates elem currently allocated
    1.91 +   
    1.92 +      //if enough, turn extra into new elem & insert it
    1.93 +   if( amountExtra > 64 )
    1.94 +    {    //make new elem by adding to addr of curr elem then casting
    1.95 +      sizeConsumed = sizeof(MallocProlog) + sizeRequested;
    1.96 +      newElem = (MallocProlog *)( (char *)foundElem + sizeConsumed );
    1.97 +      newElem->nextHigherInMem   = foundElem->nextHigherInMem;
    1.98 +      newElem->nextLowerInMem    = foundElem;
    1.99 +      foundElem->nextHigherInMem = newElem;
   1.100 +      
   1.101 +      if( ! foundElemIsTopOfHeap )
   1.102 +       {    //there is no next higher for top of heap, so can't write to it
   1.103 +         newElem->nextHigherInMem->nextLowerInMem = newElem;
   1.104 +       }
   1.105 +      add_chunk_to_free_list( newElem, _VMSMasterEnv->freeListHead );
   1.106 +    }
   1.107 +   else
   1.108 +    {
   1.109 +      sizeConsumed = sizeOfFound;
   1.110 +    }
   1.111 +  _VMSMasterEnv->amtOfOutstandingMem += sizeConsumed;
   1.112 +
   1.113 +      //skip over the prolog by adding its size to the pointer return
   1.114 +   return (void *)((char *)foundElem + sizeof(MallocProlog));
   1.115 + }
   1.116 +
   1.117 +
   1.118 +/*This is sequential code -- only to be called from the Master
   1.119 + * When free, subtract the size of prolog from pointer, then cast it to a
   1.120 + * MallocProlog.  Then check the nextLower and nextHigher chunks to see if
   1.121 + * one or both are also free, and coalesce if so, and if neither free, then
   1.122 + * add this one to free-list.
   1.123 + */
   1.124 +void
   1.125 +VMS__free( void *ptrToFree )
   1.126 + { MallocProlog *elemToFree, *nextLowerElem, *nextHigherElem;
   1.127 +   int32         lowerExistsAndIsFree, higherExistsAndIsFree, sizeOfElem;
   1.128 +
   1.129 +   if( ptrToFree < _VMSMasterEnv->freeListHead->nextLowerInMem ||
   1.130 +       ptrToFree > _VMSMasterEnv->freeListHead->nextHigherInMem )
   1.131 +    {    //outside the range of data owned by VMS's malloc, so do nothing
   1.132 +      return;
   1.133 +    }
   1.134 +      //subtract size of prolog to get pointer to prolog, then cast
   1.135 +   elemToFree = (MallocProlog *)((char *)ptrToFree - sizeof(MallocProlog));
   1.136 +   sizeOfElem =(int32)((char*)elemToFree->nextHigherInMem-(char*)elemToFree);
   1.137 +   _VMSMasterEnv->amtOfOutstandingMem -= sizeOfElem;
   1.138 +
   1.139 +   nextLowerElem  = elemToFree->nextLowerInMem;
   1.140 +   nextHigherElem = elemToFree->nextHigherInMem;
   1.141 +
   1.142 +   if( nextHigherElem == NULL )
   1.143 +      higherExistsAndIsFree = FALSE;
   1.144 +   else //okay exists, now check if in the free-list by checking back ptr
   1.145 +      higherExistsAndIsFree = (nextHigherElem->prevChunkInFreeList != NULL);
   1.146 +    
   1.147 +   if( nextLowerElem == NULL )
   1.148 +      lowerExistsAndIsFree = FALSE;
   1.149 +   else //okay, it exists, now check if it's free
   1.150 +      lowerExistsAndIsFree = (nextLowerElem->prevChunkInFreeList != NULL);
   1.151 +    
   1.152 +
   1.153 +      //now, know what exists and what's free
   1.154 +   if( lowerExistsAndIsFree )
   1.155 +    { if( higherExistsAndIsFree )
   1.156 +       {    //both exist and are free, so coalesce all three
   1.157 +            //First, remove higher from free-list
   1.158 +         nextHigherElem->prevChunkInFreeList->nextChunkInFreeList =
   1.159 +                                         nextHigherElem->nextChunkInFreeList;
   1.160 +         if( nextHigherElem->nextChunkInFreeList != NULL ) //end-of-list?
   1.161 +            nextHigherElem->nextChunkInFreeList->prevChunkInFreeList =
   1.162 +                                         nextHigherElem->prevChunkInFreeList;
   1.163 +            //Now, fix-up sequence-in-mem list -- by side-effect, this also
   1.164 +            // changes size of the lower elem, which is still in free-list
   1.165 +         nextLowerElem->nextHigherInMem = nextHigherElem->nextHigherInMem;
   1.166 +         if( nextHigherElem->nextHigherInMem !=
   1.167 +             _VMSMasterEnv->freeListHead->nextHigherInMem )
   1.168 +            nextHigherElem->nextHigherInMem->nextLowerInMem = nextLowerElem;
   1.169 +            //notice didn't do anything to elemToFree -- it simply is no
   1.170 +            // longer reachable from any of the lists.  Wonder if could be a
   1.171 +            // security leak because left valid addresses in it,
   1.172 +            // but don't care for now.
   1.173 +       }
   1.174 +      else
   1.175 +       {    //lower is the only of the two that exists and is free,
   1.176 +            //In this case, no adjustment to free-list, just change mem-list.
   1.177 +            // By side-effect, changes size of the lower elem
   1.178 +         nextLowerElem->nextHigherInMem = elemToFree->nextHigherInMem;
   1.179 +         if( elemToFree->nextHigherInMem !=
   1.180 +             _VMSMasterEnv->freeListHead->nextHigherInMem )
   1.181 +            elemToFree->nextHigherInMem->nextLowerInMem = nextLowerElem;
   1.182 +       }
   1.183 +    }
   1.184 +   else
   1.185 +    {    //lower either doesn't exist or isn't free, so check higher
   1.186 +      if( higherExistsAndIsFree )
   1.187 +       {    //higher exists and is the only of the two free
   1.188 +            //First, in free-list, replace higher elem with the one to free
   1.189 +         elemToFree->nextChunkInFreeList=nextHigherElem->nextChunkInFreeList;
   1.190 +         elemToFree->prevChunkInFreeList=nextHigherElem->prevChunkInFreeList;
   1.191 +         elemToFree->prevChunkInFreeList->nextChunkInFreeList = elemToFree;
   1.192 +         if( elemToFree->nextChunkInFreeList != NULL ) // end-of-list?
   1.193 +            elemToFree->nextChunkInFreeList->prevChunkInFreeList =elemToFree;
   1.194 +            //Now chg mem-list. By side-effect, changes size of elemToFree
   1.195 +         elemToFree->nextHigherInMem = nextHigherElem->nextHigherInMem;
   1.196 +         if( elemToFree->nextHigherInMem !=
   1.197 +             _VMSMasterEnv->freeListHead->nextHigherInMem )
   1.198 +            elemToFree->nextHigherInMem->nextLowerInMem = elemToFree;
   1.199 +       }
   1.200 +      else
   1.201 +       {    //neither lower nor higher is availabe to coalesce so add to list
   1.202 +            // this makes prev chunk ptr non-null, which indicates it's free
   1.203 +         elemToFree->nextChunkInFreeList =
   1.204 +                            _VMSMasterEnv->freeListHead->nextChunkInFreeList;
   1.205 +         _VMSMasterEnv->freeListHead->nextChunkInFreeList = elemToFree;
   1.206 +         if( elemToFree->nextChunkInFreeList != NULL ) // end-of-list?
   1.207 +            elemToFree->nextChunkInFreeList->prevChunkInFreeList =elemToFree;
   1.208 +         elemToFree->prevChunkInFreeList = _VMSMasterEnv->freeListHead;
   1.209 +       }
   1.210 +    }
   1.211 +
   1.212 + }
   1.213 +
   1.214 +
   1.215 +/*Designed to be called from the main thread outside of VMS, during init
   1.216 + */
   1.217 +MallocProlog *
   1.218 +VMS__create_free_list()
   1.219 + { MallocProlog *freeListHead, *firstChunk;
   1.220 +
   1.221 +      //Note, this is running in the main thread -- all increases in malloc
   1.222 +      // mem and all frees of it must be done in this thread, with the
   1.223 +      // thread's original stack available
   1.224 +   freeListHead = malloc( sizeof(MallocProlog) );
   1.225 +   firstChunk   = malloc( MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE );
   1.226 +   if( firstChunk == NULL ) {printf("malloc error\n"); exit(1);}
   1.227 +
   1.228 +   freeListHead->prevChunkInFreeList = NULL;
   1.229 +      //Use this addr to free the heap when cleanup
   1.230 +   freeListHead->nextLowerInMem      = firstChunk;
   1.231 +      //to identify top-of-heap elem, compare this addr to elem's next higher
   1.232 +   freeListHead->nextHigherInMem     = (char *)firstChunk +
   1.233 +                                          MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE;
   1.234 +   freeListHead->nextChunkInFreeList = firstChunk;
   1.235 +
   1.236 +   firstChunk->nextChunkInFreeList   = NULL;
   1.237 +   firstChunk->prevChunkInFreeList   = freeListHead;
   1.238 +      //next Higher has to be set to top of chunk, so can calc size in malloc
   1.239 +   firstChunk->nextHigherInMem       = (char *)firstChunk +
   1.240 +                                          MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE;
   1.241 +   firstChunk->nextLowerInMem        = NULL; //identifies as bott of heap
   1.242 +
   1.243 +   return freeListHead;
   1.244 + }
   1.245 +
   1.246 +
   1.247 +/*Designed to be called from the main thread outside of VMS, during cleanup
   1.248 + */
   1.249 +void
   1.250 +VMS_ext__free_free_list( MallocProlog *freeListHead )
   1.251 + {    
   1.252 +      //stashed a ptr to the one and only bug chunk malloc'd from OS in the
   1.253 +      // free list head's next lower in mem pointer
   1.254 +   free( freeListHead->nextLowerInMem );
   1.255 +
   1.256 +   //don't free the head -- it'll be in an array eventually -- free whole
   1.257 +   // array when all the free lists linked from it have already been freed
   1.258 + }
   1.259 +