1 cananian 1.1.2.1 // CommitRecord.java, created Fri Oct 27 16:59:59 2000 by cananian
2 cananian 1.1.2.1 // Copyright (C) 2000 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.Runtime.Transactions;
5 cananian 1.1.2.1
6 cananian 1.1.2.1 /**
7 cananian 1.1.2.2 * A <code>CommitRecord</code> keeps track of the status of a transaction.
8 cananian 1.1.2.2 * It is initialized in the <code>WAITING</code> state and can be updated
9 cananian 1.1.2.2 * exactly once to either COMMITTED or ABORTED. Transactions can be nested;
10 cananian 1.1.2.2 * therefore <code>CommitRecord</code>s can be dependent on other commit
11 cananian 1.1.2.2 * records.
12 cananian 1.1.2.1 *
13 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
14 cananian 1.3 * @version $Id: CommitRecord.java,v 1.3 2003/07/21 21:21:58 cananian Exp $
15 cananian 1.1.2.1 */
16 cananian 1.1.2.1 public class CommitRecord {
17 cananian 1.1.2.2 // enumerated constants
18 cananian 1.1.2.4 public final static int WAITING=0;
19 cananian 1.1.2.4 public final static int COMMITTED=1;
20 cananian 1.1.2.4 public final static int ABORTED=2;
21 cananian 1.1.2.2 // fields.
22 cananian 1.1.2.2 /** The commit record that this is dependent on, if any. */
23 cananian 1.1.2.2 public final CommitRecord parent;
24 cananian 1.1.2.2 /** The 'state' of this record: initialized to WAITING, and
25 cananian 1.1.2.2 * write-once to either COMMITTED or ABORTED. */
26 cananian 1.1.2.4 private int state = WAITING;
27 cananian 1.1.2.3
28 cananian 1.1.2.3 /** Constructor method. */
29 cananian 1.1.2.3 public static CommitRecord newTransaction(CommitRecord parent) {
30 cananian 1.1.2.3 return new CommitRecord(parent, 0);
31 cananian 1.1.2.3 }
32 cananian 1.1.2.3 /** Returns a new commit record suitable for retrying this transaction.
33 cananian 1.1.2.3 * @exception TransactionAbortException if this transaction has been
34 cananian 1.1.2.3 * retried too many times.
35 cananian 1.1.2.3 */
36 cananian 1.1.2.3 public final CommitRecord retryTransaction()
37 cananian 1.1.2.3 throws TransactionAbortException {
38 cananian 1.3 if (retry_count > 2 && parent!=null)
39 cananian 1.3 throw new TransactionAbortException(parent);
40 cananian 1.1.2.3 try {
41 cananian 1.1.2.3 Thread.sleep(retry_count); // sleep for a few milliseconds.
42 cananian 1.1.2.3 } catch (InterruptedException ex) { /* wake up */ }
43 cananian 1.1.2.3 return new CommitRecord(this.parent, retry_count+1);
44 cananian 1.1.2.3 }
45 cananian 1.1.2.3 public final void commitTransaction() throws TransactionAbortException {
46 cananian 1.1.2.3 if (this.commit()!=COMMITTED)
47 cananian 1.1.2.3 throw new TransactionAbortException(this);
48 cananian 1.1.2.3 }
49 cananian 1.1.2.3
50 cananian 1.1.2.3 /** Private constructor. */
51 cananian 1.1.2.3 private CommitRecord(CommitRecord parent, int retry_count) {
52 cananian 1.1.2.2 this.parent = parent;
53 cananian 1.1.2.3 this.retry_count = retry_count;
54 cananian 1.1.2.2 }
55 cananian 1.1.2.3 /** Keep track of how many times this transaction's been retried. */
56 cananian 1.1.2.3 private final int retry_count;
57 cananian 1.1.2.2
58 cananian 1.1.2.2 /** Returns the 'state' of this record (including dependencies) */
59 cananian 1.1.2.4 public int state() { return state(this); }
60 cananian 1.1.2.4
61 cananian 1.1.2.2 /** 'StateP' procedure from write-up. */
62 cananian 1.1.2.4 public static native int state(CommitRecord c);
63 cananian 1.1.2.4
64 cananian 1.1.2.2 /** Abort this (sub)transaction, if possible.
65 cananian 1.1.2.2 * @return the final state of the (sub)transaction.
66 cananian 1.1.2.2 */
67 cananian 1.1.2.4 public int abort() { return abort(this); }
68 cananian 1.1.2.2 /** Commit this (sub)transaction, if possible.
69 cananian 1.1.2.2 * @return the final state of the (sub)transaction.
70 cananian 1.1.2.2 */
71 cananian 1.1.2.4 public int commit() { return commit(this); }
72 cananian 1.1.2.4
73 cananian 1.1.2.2 /** Abort a transaction, if possible.
74 cananian 1.1.2.2 * @return the final state of the (sub)transaction.
75 cananian 1.1.2.2 */
76 cananian 1.1.2.4 public static native int abort(CommitRecord c);
77 cananian 1.1.2.4
78 cananian 1.1.2.2 /** Commit a transaction, if possible.
79 cananian 1.1.2.2 * @return the final state of the (sub)transaction.
80 cananian 1.1.2.2 */
81 cananian 1.1.2.4 public static native int commit(CommitRecord c);
82 cananian 1.2 }