| 1 | /*
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| 2 | * Rick van der Zwet
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| 3 | * 0433373
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| 4 | * Java programming assigment 1.2
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| 5 | * Licence: BSD
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| 6 | * $Id: RWProblem.java 270 2007-10-13 13:45:29Z rick $
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| 7 | */
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| 8 | import java.util.Random;
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| 9 |
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| 10 |
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| 11 | class ReadProcess extends Process
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| 12 | {
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| 13 | public ReadProcess(int number, Database database)
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| 14 | {
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| 15 | super(number, database);
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| 16 | }
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| 17 |
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| 18 | public void run ()
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| 19 | {
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| 20 | message("Started as READ");
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| 21 | database.get_readlock();
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| 22 | message("Read: " + database.read());
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| 23 | sleep();
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| 24 | database.release_writelock();
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| 25 | message("Ended");
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| 26 | }
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| 27 | }
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| 28 |
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| 29 | class WriteProcess extends Process
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| 30 | {
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| 31 | public WriteProcess(int number, Database database)
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| 32 | {
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| 33 | super(number, database);
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| 34 | }
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| 35 |
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| 36 | public void run ()
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| 37 | {
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| 38 | message("Started as WRITE");
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| 39 | database.get_writelock();
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| 40 | database.write(Integer.toString(id));
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| 41 | sleep();
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| 42 | message("Wrote his Id");
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| 43 | database.release_writelock();
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| 44 | message("Ended");
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| 45 | }
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| 46 | }
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| 47 |
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| 48 | class Process extends Thread
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| 49 | {
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| 50 | protected int id;
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| 51 | protected Database database;
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| 52 |
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| 53 | Process (int number, Database d)
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| 54 | {
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| 55 | this.id = number;
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| 56 | database = d;
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| 57 | }
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| 58 |
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| 59 | protected void sleep ()
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| 60 | {
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| 61 | int sleeptime;
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| 62 | sleeptime = (int) (Math.random () * 1000);
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| 63 | try
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| 64 | {
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| 65 | Thread.sleep( sleeptime );
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| 66 | }
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| 67 | catch ( InterruptedException e) { }
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| 68 | }
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| 69 |
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| 70 | protected void message (String text)
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| 71 | {
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| 72 | System.out.println("[" + id + "] " + text);
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| 73 | }
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| 74 | }
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| 75 |
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| 76 | public class RWProblem
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| 77 | {
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| 78 | public static void main (String args[])
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| 79 | {
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| 80 | Database database;
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| 81 | int N = 100; //processes
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| 82 | int i; //loop counter
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| 83 | Random write = new Random();
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| 84 |
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| 85 | database = new Database();
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| 86 | Process [] process = new Process [N];
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| 87 |
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| 88 | for( i = 0; i < N; i++)
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| 89 | {
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| 90 | if (write.nextBoolean())
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| 91 | {
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| 92 | process[i] = new WriteProcess (i, database);
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| 93 | }
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| 94 | else {
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| 95 | process[i] = new ReadProcess (i, database);
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| 96 | }
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| 97 | process[i].start();
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| 98 | }
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| 99 | }
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| 100 | }
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