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1 package com.daffodilwoods.daffodildb.utils;
2
3 import com.daffodilwoods.database.resource.DException;
4 import java.util.*;
5
6 public class Lock{
7 public int locker;
8 public int lockCount;
9 ArrayList waitList;
10 public Lock() throws DException{
11 waitList = new ArrayList();
12 }
13
14
18 public synchronized void lock(int i) throws DException {
19 while(true){
20 if(locker==0){
21 locker=i;
22 waitList.remove(new Integer  (i));
23 return;
24 }
25 else if(locker==i && waitList.size() < 1 ) {
26 lockCount++;
27 return;
28 }
29 if( !waitList.contains( new Integer (i) ) )
30 waitList.add(new Integer (i));
31
32 try{
33 wait();
34 }catch(Exception e ){e.printStackTrace();};
35 }
36 }
37
38 public String showWaitList()throws DException{
39 StringBuffer sb = new StringBuffer ();
40 sb.append(this.hashCode());
41 if( waitList.size() > 0 ){
42 sb.append(" : ");
43 for (int i = 0; i < waitList.size(); i++) {
44 sb.append( waitList.get(i) );
45 sb.append(", ");
46 }
47 }
48 return sb.toString();
49 }
50
51 public synchronized void unLock() throws DException {
52 if(lockCount>0)
53 lockCount--;
54 else{
55 locker=0;
56 notifyAll();
57 }
58 }
59 }
60 |
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