218 lines
6.8 KiB
Java
218 lines
6.8 KiB
Java
/*
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* Best Fit Algorithm by David Weber
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* ITCS 3146
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* 11/9/2012
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*/
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import java.lang.reflect.Method;
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import java.util.*;
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public class WorstFitAlgorithm implements baseAlgorithm{
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int memoryBlock[];
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private Job[] jobArray = new Job[memoryManagement.JOBAMOUNT+10];
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ArrayList<Integer> indices;
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ArrayList<Integer> blocks;
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int memoryLocation;
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int worstSize; //The most suitable block size for the job
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int worstSizeIndex; //The most suitable block size starting index for the job
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public WorstFitAlgorithm(int memorySize)
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{
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//Initialize memory block to whatever the size is
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memoryBlock = new int[memorySize];
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blocks = new ArrayList(); //Dynamically resizable array list for allocation candidates (interleaved with index and memory size);
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indices = new ArrayList(); //Dynamically resizable array list for allocation candidates (interleaved with index and memory size);
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}
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public int getWorstIndex(int jobSize)
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{
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memoryLocation = 0;
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indices.clear();
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blocks.clear();
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synchronized(memoryBlock)
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{
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while (memoryLocation < this.memoryBlock.length)
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{
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if (memoryBlock[memoryLocation] != 0){
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memoryLocation++;
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continue;
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}
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int beginningLoc = memoryLocation;
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int free = 0;
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while (memoryLocation < this.memoryBlock.length && memoryBlock[memoryLocation] == 0)
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{
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memoryLocation++;
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free++;
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}
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if (free >= jobSize){
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//System.out.println("Found a block of size " + free + " at " + beginningLoc);
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blocks.add(free);
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indices.add(beginningLoc);
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}
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}
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}
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//System.out.println("Size of indices array: " + indices.size());
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//System.out.println("Size of sizes array: " + blocks.size());
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for(int i = 0; i < blocks.size(); i++)
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{
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//System.out.println("Index: " + indices.get(i));
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//System.out.println("Size: " + blocks.get(i));
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}
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int worstIndex = -1;
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int wSize = -1;
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if(!blocks.isEmpty())
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{
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wSize = blocks.get(0).intValue();
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}
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//GET WORST INDEX
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for(int i = 0; i < blocks.size(); i++)
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{
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//Get largest possible free block to allocate to
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if(blocks.get(i).intValue() >= wSize || blocks.get(i).intValue() > -1)
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{
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worstIndex = indices.get(i).intValue();
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}
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//"Worst fit"....same size as job size
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else if(blocks.get(i).intValue() == jobSize)
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{
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//"Worst" possible fit. You're done.
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//System.out.println("Worst Case");
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worstIndex = indices.get(i).intValue();
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}
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else
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{
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if(!blocks.isEmpty())
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{
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worstIndex = indices.get(i).intValue();
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}
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}
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}
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//System.out.println("bestIndex: " + bestIndex);
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//System.out.println("bSize: " + bSize);
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return worstIndex;
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}
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@Override
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public void allocate(int jobID, int jobSize, int jobTime)
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{
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try
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{
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Method deallocateMethod = this.getClass().getMethod("deallocate", new Class[]{int.class, int.class});
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worstSizeIndex = this.getWorstIndex(jobSize);
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if(jobSize > memoryBlock.length)
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{
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//System.out.println("Job is too large for current memory size");
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}
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if(worstSizeIndex == -1)
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{
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while(worstSizeIndex == -1)
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{
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//Compact and try again
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System.out.print("");
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this.compact();
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worstSizeIndex = this.getWorstIndex(jobSize);
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}
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}
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if(worstSizeIndex != -1)
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{
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//System.out.println("Phew");
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//System.out.println("The size of the job is: " + jobSize);
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//System.out.println("The worst size index is: " + worstSizeIndex);
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synchronized(memoryBlock)
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{
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for(int i = worstSizeIndex; i < jobSize + worstSizeIndex; i++)
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{
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//System.out.println("Writing jobID: " + jobID + " to position " + i + " in memory block!");
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this.memoryBlock[i] = jobID;
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}
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}
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//System.out.println("Successfully allocated! Starting job...");
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Job newJob = new Job(jobTime, jobID, jobSize, worstSizeIndex, deallocateMethod, this);
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//System.out.println("Job started!");
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jobArray[jobID] = newJob;
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//System.out.println("The size of the job array is: " + jobArray.length);
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newJob.start();
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//System.out.println("Job started!");
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}
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}
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catch (Exception e)
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{
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e.printStackTrace();
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System.exit(-1);
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}
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}
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/*
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* This method gathers all occupied memory and stores it contiguously in an array list of blocks.
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* After that, it rewrites the memoryBlock array by writing the memory in contiguous order, and then
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* filling in the rest of the memory with 0's
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*/
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public void compact()
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{
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ArrayList<Integer> takenBlocks = new ArrayList();
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memoryLocation = 0;
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//Gather allocated memory
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while(memoryLocation < this.memoryBlock.length && memoryBlock[memoryLocation] != 0)
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{
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takenBlocks.add(memoryBlock[memoryLocation]);
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memoryLocation++;
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}
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synchronized(memoryBlock)
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{
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for(int i = 0; i < takenBlocks.size(); i++)
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{
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this.memoryBlock[i] = takenBlocks.get(i).intValue();
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}
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}
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synchronized(memoryBlock)
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{
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for(int i = takenBlocks.size(); i < this.memoryBlock.length; i++)
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{
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this.memoryBlock[i] = 0;
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}
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}
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/*
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System.out.println("Successfully compacted!");
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if(takenBlocks.isEmpty())
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{
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System.out.println("Cannot compact!");
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}
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*/
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}
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@Override
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public void deallocate(int jobSize, int beginningLocation)
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{
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synchronized(memoryBlock)
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{
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for(int i = beginningLocation; i < jobSize + beginningLocation; i++)
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{
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memoryBlock[i] = 0;
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}
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}
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}
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}
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