DiskUnit.java

/*
 * DiskUnit.java
 *
 * Quick tests of Disk
 *
 * You must follow the coding standards distributed
 * on the class web page.
 *
 * (C) 2007,2010 Mike Dahlin
 *
 */
import java.util.concurrent.locks.Condition;
import java.io.FileNotFoundException;

public class DiskUnit implements DiskCallback{

  private static final int NUM = 100;

  boolean anyHaveError;
  private static final int INPROGRESS = 234;
  private static final int DONE_OK = 9234;
  private static final int DONE_ERROR = 22842;

  private static final boolean verbose = true;
  private static final boolean vverbose = false;


  int status[];
  int doneCount;
  
  SimpleLock lock;
  Condition resultAvailable;

  //-------------------------------------------------------
  // main() -- java DiskUnit to run this test
  //-------------------------------------------------------
  public static void main(String args[])
  {
    testWrites(true, (float)0.0);
    System.out.println("Wrote 0 to all");
    testWrites(false, (float)0.0);
    System.out.println("Wrote data to all");
    testReads(true);
    System.out.println("Read data from all");
    testWrites(true, (float)0.0);
    System.out.println("Wrote 0 to all");
    testWrites(false,  (float)0.1);
    System.out.println("Wrote data to some");
    testReads(false);    
    System.out.println("Read data from some");
    System.exit(0);
  }


  //-------------------------------------------------------
  // Issue a one write to each of a bunch of disk sectors
  // Expect all of the writes to have completed properly...
  //-------------------------------------------------------
  private static void testWrites(boolean writeZero, float errorPct)
  {

    DiskUnit du;
    Disk d = null;
    int ii;

    assert(NUM < Disk.NUM_OF_SECTORS);
    int ok;

    du = new DiskUnit();
    try{
      d = new Disk(du, errorPct);
    }
    catch(FileNotFoundException fnf){
      System.out.println("Unable to open disk file");
      System.exit(-1);
    }
    du.doClear();
    for(ii = 0; ii < NUM; ii++){
      //
      // Remember: Do not re-use buffer until
      // request completes!
      //
      byte b[] = new byte[Disk.SECTOR_SIZE];
      if(writeZero){
        setBuffer((byte)0, b);
      }
      else{
        setBuffer((byte)ii, b);
      }
      try{
        d.startRequest(Disk.WRITE, ii, ii, b);
      }
      catch(Exception e){
        System.out.println("Unexpected exception in startReq write" 
                           + e.toString() + " ii=" + ii);
        System.exit(-1);
      }
    }
    if(verbose){
      System.out.println("Writes started");
    }
    ok = du.check(); // All writes done
    if(verbose){
      System.out.println("Writes done");
    }
    if(ok < NUM && errorPct == 0){
      System.out.println("Fewer writes than expected " + ok);
      return;
    }
    if(ok == NUM && errorPct > 0){ // Make sure expected num writes nonzero
      System.out.println("More writes than expected " + ok);
      return;
    }
  }

  //-------------------------------------------------------
  // Issue a one read to each of a bunch of disk sectors
  //-------------------------------------------------------
  private static void testReads(boolean expectAll)
  {

    DiskUnit du;
    Disk d = null;
    int ii;

    assert(NUM < Disk.NUM_OF_SECTORS);
    int ok;

    du = new DiskUnit();
    try{
      d = new Disk(du, (float)0.0);
    }
    catch(FileNotFoundException fnf){
      System.out.println("Unable to open disk file");
      System.exit(-1);
    }

    du.doClear();
    for(ii = 0; ii < NUM; ii++){
      //
      // Remember: Do not re-use buffer until
      // request completes!
      //
      byte b[] = new byte[Disk.SECTOR_SIZE];
      setBuffer((byte)0, b);
      try{
        d.startRequest(Disk.READ, ii, ii, b);
      }
      catch(Exception f){
        System.out.println("Unexpected exception in startReq read");
        System.exit(-1);
      }
    }
    if(verbose){
      System.out.println("Reads started");
    }
    ok = du.check(); // All reads done
    if(verbose){
      System.out.println("Reads done");
    }
    if(expectAll && ok < NUM){
      System.out.println("Fewer reads than expected " + ok);
      System.exit(-1);
      return;
    }
    if(!expectAll && ok == NUM){
      System.out.println("More reads than expected " + ok);
      return;
    }
    return;
  }

  //-------------------------------------------------------
  // set Disk.SECTOR_SIZE bytes to specified value
  //-------------------------------------------------------
  private static void setBuffer(byte value, byte b[])
  {
    int ii;
    for(ii = 0; ii < Disk.SECTOR_SIZE; ii++){
      b[ii] = value;
    }
    return;
  }

  //-------------------------------------------------------
  // DiskUnit
  //-------------------------------------------------------
  private DiskUnit()
  {
    status = new int[NUM];
    this.lock = new SimpleLock();
    this.resultAvailable = lock.newCondition();
    doClear();
  }

  //-------------------------------------------------------
  // clear
  //-------------------------------------------------------
  public void doClear()
  {
    int ii;
    try{
      lock.lock();
      for(ii = 0; ii < NUM; ii++){
        status[ii] = INPROGRESS;
      }
      anyHaveError = false;
      doneCount = 0;
    }
    finally{
      lock.unlock();
    }
  }
  


  //-------------------------------------------------------
  // check
  //-------------------------------------------------------
  public int check()
  {
    try{
      lock.lock();
      while(!anyHaveError && doneCount < NUM){
        resultAvailable.awaitUninterruptibly();
      }
      return doneCount;
    }
    finally{
      lock.unlock();
    }
  }
  

  //-------------------------------------------------------
  // requesDone -- callback -- check writes for status
  // and check reads for 
  //-------------------------------------------------------
  public void requestDone(DiskResult result)
  {
    int sec;
    try{
      lock.lock();

      //
      // For this simple test, we have at most one outstanding request
      // per sector, so we can use sector number to know which
      // request this reply finishes.
      // Could use tag to match requests with replies instead
      //
      sec = result.getSectorNum();
      if(status[sec] == INPROGRESS){
        if(result.getStatus() == DiskResult.OK){
          if(vverbose){
            System.out.println("Request " + result.getSectorNum() + " done");
          }
          if(checkOK(result)){
            doneCount++;
            status[sec] = DONE_OK;
            if(doneCount == NUM){
              resultAvailable.signal();
            }
            return;
          }
          else{
            //
            // Expected case if writes did not complete
            //
            if(vverbose){
              System.out.println("Request " + result.getSectorNum() + " missing data");
            }
            status[sec] = DONE_ERROR;
            anyHaveError = true;
            resultAvailable.signal();
            return;
          }
        }
        else if(result.getStatus() == DiskResult.REAL_ERROR){
          System.out.println("UNEXPECTED ERROR: real IO error");
          System.exit(-1);
        }
        else{
          //
          // Fake error. Expected case
          //
          if(vverbose){
            System.out.println("Request " + result.getSectorNum() + " fake error");
          }
          status[sec] = DONE_ERROR;
          anyHaveError = true;
          resultAvailable.signal();
          return;
        }
      }
      System.out.println("UNEXPECTED ERROR: multiple returns for same entry");
      System.exit(-1);
      return;
    }
    finally{
      lock.unlock();
    }
  }


  //-------------------------------------------------------
  // check -- check for expected data in buffer if this is a read
  //-------------------------------------------------------
  private static boolean checkOK(DiskResult r)
  {
    int ii;
    int secNum;
    byte b[];

    if(r.getOperation() == Disk.WRITE){
      return true;
    }
    secNum = r.getSectorNum();
    b = r.getBuf();
    for(ii = 0; ii < Disk.SECTOR_SIZE; ii++){
      if(b[ii] != (byte)secNum){
        return false;
      }
    }
    return true;
  }
  

}