IBM Mainframe Forum

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.List;

import com.ibm.jzos.DfSort;
import com.ibm.jzos.RcException;
import com.ibm.jzos.ZFile;

/**
 * This example creates an instance of {@link DfSort} to sort an existing Dataset
 * and read the sort output into Java.
 * <p>
 * Arguments (supplied as key=value pairs):
 * <dl>
 * <dt>sortin=&lt;dsn&gt;</dt>
 * <dd>The name of a RECFM=F dataset to sort.  Supplied to DFSORT as SORTIN.</dd>
 * <dt>[encoding=&lt;codepage&gt;]</dt>
 * <dd>The character set of the SORTIN dataset.  If not supplied, binary data is assumed.</dd>
 * <dt>[shareas=&lt;yes | no&gt;]</dt>
 * <dd>Determines that address space for DFSORT.  If yes, DFSORT will run in the same address
 * space as the JVM.  If no, it will run in a separate address space.</dd>
 * <dt>[loglevel=&lt;n&gt;]</dt>
 * <dd>Sets the logging level for the child process and prints the resulting
 * child process output is written to System.err.  The valid levels are those defined
 * in the ZUtil.LOG_* constants.</dd>
 * </dl>
 * <p>
 * Features illustrated:
 * <ul>
 * <li>Specify an existing RECFM=F existing dataset as input (SORTIN) to DFSORT
 * <li>Sort the records in Ascending order
 * <li>Read the DFSORT (SORTOUT) results and process in Java
 * </ul>
 */
public class DfSortFixedDatasetToJava {

   public static void main(String[] args) throws Exception {
      DfSortArguments dfsortArgs = new DfSortArguments(args);
      if ((dfsortArgs.getSortinDataset() == null)) {
          System.err.println("Usage: " + DfSortFixedDatasetToJava.class.getName() + " sortin=<dsn> [encoding=<codepage>] [shareas=<yes|NO>]");
          System.err.println("Where:");
          System.err.println("\tsortin is a RECFM=F dataset");
          System.err.println("\tencoding is the source character set.  If not supplied, raw bytes are processed.");
          System.err.println("\tshareas = yes: DFSORT executes in the same address space as the JVM");
          System.exit(4);
       }

      DsInfo inDs = dfsortArgs.getSortinDataset();
      if (!inDs.isFixedRecfm()) {
         System.err.println("Dataset " + inDs.getFullyQualifiedDsn() + " is not RECFM=F");
         System.exit(8);
      }

      doSort(dfsortArgs);
      
   }

   private static void doSort(DfSortArguments dfsortArgs) throws Exception {
      DsInfo inDs = dfsortArgs.getSortinDataset();
      
      DfSort dfSort = new DfSort();
      
      if (dfsortArgs.getLogLevel() != -1) {
         dfSort.setLoggingLevel(dfsortArgs.getLogLevel());
      }

      //Direct DFSORT to get its input (SORTIN) from the supplied dataset.
      dfSort.addAllocation("alloc fi(sortin) da("+inDs.getFullyQualifiedDsn()+") reuse shr msg(2)");

      //Direct DFSORT to write output the the output named pipe.
      dfSort.setOutputStreamRecLen(inDs.getLrecl());
      
      //For this example, we sort the entire record (starting in column 1 for
      //a length of lrecl.  The data is treated as character data (CH) and the
      //results are in ascending order (A)
      dfSort.addControlStatement("SORT FIELDS=(1,"+inDs.getLrecl()+",CH,A)");
      
      //Specify whether the DFSORT child process should be run in a separate address space.
      //This allows multiple DFSORT processes to run simultaneously as each instance of
      //the DFSORT DDs (SORTIN, SORTOUT, etc...) will be in their own address space.
      dfSort.setSameAddressSpace(dfsortArgs.isSameAddressSpace());
      
      //Kick off the sort.
      long startTime = System.currentTimeMillis();
      dfSort.execute();
      
      //Once the child starts, open a BufferedInputStream on the child process' stdout
      //and read the sort result.
      
      BufferedInputStream bis = new BufferedInputStream(dfSort.getChildStdoutStream());
      byte[] bytes = new byte[inDs.getLrecl()];
      int recordCount = 0;
      while (readRecord(bis,bytes)) {
         //Process data
         if (dfsortArgs.getEncoding() != null) {
            String line = new String(bytes,dfsortArgs.getEncoding());
            //Process encoded string...
         } else {
            //Process raw bytes...
         }
         recordCount++;
      }
      bis.close();
   
      //Wait for dfSort to finish and check the result
      int rc =0;
      try {
         rc = dfSort.getReturnCode();
      } catch (RcException rce) {
         System.out.println("Caught RcException: " + rce.getMessage());
         rc = -1;
      }
      long runtime = System.currentTimeMillis() - startTime;

      if (rc != 0 || dfsortArgs.getLogLevel() >= 0) {
         List stderrLines = dfSort.getStderrLines();
         for (Iterator i=stderrLines.iterator(); i.hasNext(); ) {
            System.err.println(i.next());
         }
      }

      System.out.println("RC=" + rc + " TIME=" + runtime + " RECORD COUNT=" + recordCount + " "
            + DfSortFixedDatasetToJava.class.getName());      
      
   }

   /*
    * Read exactly bytesToRead from the underlying stream (this call may block).  Throw
    * an IOException if EOF is encountered before all of the bytes are read.
    */
   private static boolean readRecord(InputStream is, byte[] bytes) throws IOException {
      int offset = 0;
      int bytesToRead = bytes.length;
      int c = is.read();
      if (c == -1) {
         return false;
      } else {
         bytes[offset++] = (byte) c;
         --bytesToRead;
      }
      
      while (bytesToRead > 0) {
         int bytesRead = is.read(bytes, offset, bytesToRead);
         if (bytesRead == -1) {
            throw new IOException("EOF encountered before all record bytes read");
         }
         bytesToRead -= bytesRead;
         offset += bytesRead;
      }
      return true;
   }

}