DeadObject.cpp

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/******************************************************************************/
/* REXX Kernel                                                DeadObject.c  */
/*                                                                            */
/* Primitive DeadObject management code                                       */
/*                                                                            */
/******************************************************************************/
 
#include <stdlib.h>
#include <string.h>
#include "RexxCore.h"
#include "RexxMemory.hpp"
#include "Interpreter.hpp"
 
void DeadObjectPool::dumpMemoryProfile(FILE *outFile)
/******************************************************************************/
/* Function:  Dump statistics for this dead object pool.                      */
/******************************************************************************/
{
#ifdef MEMPROFILE                      /* doing memory profiling            */
    fprintf(outFile, "Statistics for Dead Object Pool %s\n, id");
    fprintf(outFile, "    Total memory allocations:  %d\n", allocationCount);
    fprintf(outFile, "    Unsuccessful requests:  %d\n", allocationMisses);
    fprintf(outFile, "    Successful requests:  %d\n", allocationHits);
    fprintf(outFile, "    Objects added back to the pool\n", allocationReclaim);
#endif
}
 
 
DeadObject *DeadObjectPool::findBestFit(size_t length)
/******************************************************************************/
/* Function:  Find an object that is the best fit for a requested length.     */
/* To get the best fit, we either want an object that fits well enough that   */
/* we don't need to create a trailing dead object from the remainder, OR      */
/* we return the largest possible object so that we can create the largest    */
/* possible remainder object.                                                 */
/******************************************************************************/
{
    DeadObject *newObject = anchor.next;
    DeadObject *largest = NULL;
    size_t largestSize = 0;
    size_t deadLength = newObject->getObjectSize();
 
    for (; deadLength != 0; deadLength = newObject->getObjectSize()) {
        if (deadLength >= length) {
            /* if within an allocation unit of the request size (which should */
            /* be common, since we round to a higher boundary for */
            /* large allocations), use this block */
            if ((deadLength - length) < VeryLargeObjectGrain) {
                newObject->remove();
                logHit();
                return newObject;
            }
            /* keep track of the largest block.  We want to */
            /* suballocate that if we can't find a good fit. */
            else if (deadLength > largestSize) {
                largestSize = deadLength;
                largest = newObject;
            }
        }
        newObject = newObject->next;
    }
    /* we didn't find a close fit, so use the largest that will */
    /* work, if we found one. */
    if (largest != NULL) {
        logHit();
        largest->remove();
    }
    else {
        logMiss();
    }
    return largest;
}
 
 
DeadObject *DeadObjectPool::findSmallestFit(size_t minSize)
/******************************************************************************/
/* Function:  Find the smallest object in the pool that will hold the length. */
/******************************************************************************/
{
    DeadObject *newObject = anchor.next;
    DeadObject *smallest = NULL;
    size_t smallestSize = MaximumObjectSize;
 
    while (newObject->isReal()) {
        size_t deadLength = newObject->getObjectSize();
        /* does this fit the request size? */
        if (deadLength >= minSize && deadLength < smallestSize) {
            /* remember this for the end. */
            smallestSize = deadLength;
            smallest = newObject;
            /* did we get an exact fit?  No need to look at any */
            /* others then. */
            if (deadLength == minSize) {
                break;
            }
        }
        newObject = newObject->next;
    }
    /* if we found a fit, remove the block and return it. */
    if (smallest != NULL) {
        smallest->remove();
        logHit();
    }
    else {
        logMiss();
    }
    return smallest;
}
 
 
void DeadObjectPool::addSortedBySize(DeadObject *obj)
/******************************************************************************/
/* Function:  Add an object to the pool sorted by size (ascending order).     */
/******************************************************************************/
{
//  checkObjectOverlap(obj);
//  checkObjectGrain(obj);
    /* we start with the first element in the chain as the */
    /* insertion point.  If the chain is empty, we'll terminate the */
    /* loop immediately and use the anchor as the insertion point, */
    /* which gives us the result we want. */
    DeadObject *insertPoint = anchor.next;
    size_t size = obj->getObjectSize();
 
    while (insertPoint->isReal()) {
        /* if the current block is larger than the one we're */
        /* inserting, we've found our spot. */
        if (insertPoint->getObjectSize() >= size) {
            break;
        }
        insertPoint = insertPoint->next;
    }
    /* insert this at the given point */
    insertPoint->insertBefore(obj);
}
 
 
void DeadObjectPool::addSortedByLocation(DeadObject *obj)
/******************************************************************************/
/* Function:  Add an object to the pool sorted by address (ascending order).  */
/******************************************************************************/
{
//  checkObjectOverlap(obj);
//  checkObjectGrain(obj);
    /* we start with the first element in the chain as the */
    /* insertion point.  If the chain is empty, we'll terminate the */
    /* loop immediately and use the anchor as the insertion point, */
    /* which gives us the result we want. */
    DeadObject *insertPoint = anchor.next;
 
    while (insertPoint->isReal()) {
        /* if the current block's address is larger than the one we're */
        /* inserting, we've found our spot. */
        if (insertPoint > obj) {
            break;
        }
        insertPoint = insertPoint->next;
    }
    /* insert this at the given point */
    insertPoint->insertBefore(obj);
}
 
 
void DeadObjectPool::checkObjectGrain(DeadObject *obj)
/******************************************************************************/
/* Function:  Debug validity check of object added to a dead pool.            */
/******************************************************************************/
{
    if (!IsObjectGrained(obj))
    {
        Interpreter::logicError("Object aligned on improper boundary");
    }
}
 
void DeadObjectPool::checkObjectOverlap(DeadObject *obj)
/******************************************************************************/
/* Function:  Debug validity check of object added to a dead pool.            */
/******************************************************************************/
{
    DeadObject *check = anchor.next;
 
    while (check != NULL && check->isReal()) {
        if (check->overlaps(obj)) {
            printf("Object at %p for length %zu overlaps object at %p for length %zu\n", obj, obj->getObjectSize(), check, check->getObjectSize());
            Interpreter::logicError("Overlapping dead objects added to the cache.");
        }
        check = check->next;
    }
}