Coverage Report

Coverage Report - org.apache.ojb.odmg.locking.SerializableStrategy

Classes in this File

8.5

 package org.apache.ojb.odmg.locking;
 
 /* Copyright 2002-2005 The Apache Software Foundation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 
 import org.apache.ojb.odmg.TransactionImpl;
 
 import java.util.Collection;
 
 /**
  * The implementation of the Serializable Locking strategy.
  *
  * @author Thomas Mahler & David Dixon-Peugh
  */
 public class SerializableStrategy extends AbstractLockStrategy
 {
     /**
      * acquire a read lock on Object obj for Transaction tx.
      * @param tx the transaction requesting the lock
      * @param obj the Object to be locked
      * @return true if successful, else false
      *
      */
     public boolean readLock(TransactionImpl tx, Object obj)
     {
         LockEntry writer = getWriter(obj);
         Collection readers = getReaders(obj);
         if (writer == null)
         {
             // only one reader at a time
             if (readers.size() == 0)
             {
                 if (addReader(tx, obj))
                 {
                     readers = getReaders(obj);
                     if (readers.size() == 1)
                     {
                         return true;
                     }
                     else
                     {
                         removeReader(tx, obj);
                         return readLock(tx, obj);
                     }
                 }
                 else
                     return readLock(tx, obj);
             }
             else if ((readers.size() == 1) && (((LockEntry) readers.iterator().next()).isOwnedBy(tx)))
             {
                 // I'm the reader, thus I am allowed to read even more !
                 return true;
             }
         }
         else if (writer.isOwnedBy(tx))
         {
             return true;    // If I'm the writer, I can read.
         }
 
         return false;
     }
 
     /**
      * acquire a write lock on Object obj for Transaction tx.
      * @param tx the transaction requesting the lock
      * @param obj the Object to be locked
      * @return true if successful, else false
      *
      */
     public boolean writeLock(TransactionImpl tx, Object obj)
     {
         LockEntry writer = getWriter(obj);
         Collection readers = getReaders(obj);
         if (writer == null)
         {
             if (readers.size() == 0)
             {
                 if (setWriter(tx, obj))
                     return true;
                 else
                     return writeLock(tx, obj);
             }
 
             else if (readers.size() == 1)
             {
                 if (((LockEntry) readers.iterator().next()).isOwnedBy(tx))
                     return upgradeLock(tx, obj);
             }
         }
         else if (writer.isOwnedBy(tx))
         {
             return true;    // If I'm the writer, then I can write.
         }
         return false;
     }
 
     /**
      * acquire a lock upgrade (from read to write) lock on Object obj for Transaction tx.
      * @param tx the transaction requesting the lock
      * @param obj the Object to be locked
      * @return true if successful, else false
      *
      */
     public boolean upgradeLock(TransactionImpl tx, Object obj)
     {
         LockEntry writer = getWriter(obj);
         if (writer == null)
         {
             Collection readers = getReaders(obj);
             if (readers.size() == 1)
             {
                 LockEntry reader = (LockEntry) readers.iterator().next();
                 if (reader.isOwnedBy(tx))
                 {
                     if (upgradeLock(reader))
                         return true;
                     else
                         return upgradeLock(tx, obj);
                 }
             }
             else
             {
                 if (readers.size() == 0)
                 {
                     if (setWriter(tx, obj))
                         return true;
                     else
                         return upgradeLock(tx, obj);
                 }
             }
         }
         else if (writer.isOwnedBy(tx))
         {
             return true;    // If I already have Write, then I've upgraded.
         }
 
         return false;
     }
 
     /**
      * release a lock on Object obj for Transaction tx.
      * @param tx the transaction releasing the lock
      * @param obj the Object to be unlocked
      * @return true if successful, else false
      *
      */
     public boolean releaseLock(TransactionImpl tx, Object obj)
     {
         LockEntry writer = getWriter(obj);
         if (writer != null && writer.isOwnedBy(tx))
         {
             removeWriter(writer);
             return true;
         }
 
         if (hasReadLock(tx, obj))
         {
             removeReader(tx, obj);
             return true;
         }
         else
             return false;
 
     }
 
     /**
      * checks whether the specified Object obj is read-locked by Transaction tx.
      * @param tx the transaction
      * @param obj the Object to be checked
      * @return true if lock exists, else false
      */
     public boolean checkRead(TransactionImpl tx, Object obj)
     {
         if (hasReadLock(tx, obj))
         {
             return true;
         }
         LockEntry writer = getWriter(obj);
         if (writer != null && writer.isOwnedBy(tx))
         {
             return true;
         }
         else
             return false;
     }
 
     /**
      * checks whether the specified Object obj is write-locked by Transaction tx.
      * @param tx the transaction
      * @param obj the Object to be checked
      * @return true if lock exists, else false
      */
     public boolean checkWrite(TransactionImpl tx, Object obj)
     {
         LockEntry writer = getWriter(obj);
         return (writer != null && writer.isOwnedBy(tx));
     }
 }

1		package org.apache.ojb.odmg.locking;
2
3		/* Copyright 2002-2005 The Apache Software Foundation
4		*
5		* Licensed under the Apache License, Version 2.0 (the "License");
6		* you may not use this file except in compliance with the License.
7		* You may obtain a copy of the License at
8		*
9		* http://www.apache.org/licenses/LICENSE-2.0
10		*
11		* Unless required by applicable law or agreed to in writing, software
12		* distributed under the License is distributed on an "AS IS" BASIS,
13		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14		* See the License for the specific language governing permissions and
15		* limitations under the License.
16		*/
17
18
19		import org.apache.ojb.odmg.TransactionImpl;
20
21		import java.util.Collection;
22
23		/**
24		* The implementation of the Serializable Locking strategy.
25		*
26		* @author Thomas Mahler & David Dixon-Peugh
27		*/
28		public class SerializableStrategy extends AbstractLockStrategy
29		{
30		/**
31		* acquire a read lock on Object obj for Transaction tx.
32		* @param tx the transaction requesting the lock
33		* @param obj the Object to be locked
34		* @return true if successful, else false
35		*
36		*/
37		public boolean readLock(TransactionImpl tx, Object obj)
38		{
39		LockEntry writer = getWriter(obj);
40		Collection readers = getReaders(obj);
41		if (writer == null)
42		{
43		// only one reader at a time
44		if (readers.size() == 0)
45		{
46		if (addReader(tx, obj))
47		{
48		readers = getReaders(obj);
49		if (readers.size() == 1)
50		{
51		return true;
52		}
53		else
54		{
55		removeReader(tx, obj);
56		return readLock(tx, obj);
57		}
58		}
59		else
60		return readLock(tx, obj);
61		}
62		else if ((readers.size() == 1) && (((LockEntry) readers.iterator().next()).isOwnedBy(tx)))
63		{
64		// I'm the reader, thus I am allowed to read even more !
65		return true;
66		}
67		}
68		else if (writer.isOwnedBy(tx))
69		{
70		return true; // If I'm the writer, I can read.
71		}
72
73		return false;
74		}
75
76		/**
77		* acquire a write lock on Object obj for Transaction tx.
78		* @param tx the transaction requesting the lock
79		* @param obj the Object to be locked
80		* @return true if successful, else false
81		*
82		*/
83		public boolean writeLock(TransactionImpl tx, Object obj)
84		{
85		LockEntry writer = getWriter(obj);
86		Collection readers = getReaders(obj);
87		if (writer == null)
88		{
89		if (readers.size() == 0)
90		{
91		if (setWriter(tx, obj))
92		return true;
93		else
94		return writeLock(tx, obj);
95		}
96
97		else if (readers.size() == 1)
98		{
99		if (((LockEntry) readers.iterator().next()).isOwnedBy(tx))
100		return upgradeLock(tx, obj);
101		}
102		}
103		else if (writer.isOwnedBy(tx))
104		{
105		return true; // If I'm the writer, then I can write.
106		}
107		return false;
108		}
109
110		/**
111		* acquire a lock upgrade (from read to write) lock on Object obj for Transaction tx.
112		* @param tx the transaction requesting the lock
113		* @param obj the Object to be locked
114		* @return true if successful, else false
115		*
116		*/
117		public boolean upgradeLock(TransactionImpl tx, Object obj)
118		{
119		LockEntry writer = getWriter(obj);
120		if (writer == null)
121		{
122		Collection readers = getReaders(obj);
123		if (readers.size() == 1)
124		{
125		LockEntry reader = (LockEntry) readers.iterator().next();
126		if (reader.isOwnedBy(tx))
127		{
128		if (upgradeLock(reader))
129		return true;
130		else
131		return upgradeLock(tx, obj);
132		}
133		}
134		else
135		{
136		if (readers.size() == 0)
137		{
138		if (setWriter(tx, obj))
139		return true;
140		else
141		return upgradeLock(tx, obj);
142		}
143		}
144		}
145		else if (writer.isOwnedBy(tx))
146		{
147		return true; // If I already have Write, then I've upgraded.
148		}
149
150		return false;
151		}
152
153		/**
154		* release a lock on Object obj for Transaction tx.
155		* @param tx the transaction releasing the lock
156		* @param obj the Object to be unlocked
157		* @return true if successful, else false
158		*
159		*/
160		public boolean releaseLock(TransactionImpl tx, Object obj)
161		{
162		LockEntry writer = getWriter(obj);
163		if (writer != null && writer.isOwnedBy(tx))
164		{
165		removeWriter(writer);
166		return true;
167		}
168
169		if (hasReadLock(tx, obj))
170		{
171		removeReader(tx, obj);
172		return true;
173		}
174		else
175		return false;
176
177		}
178
179		/**
180		* checks whether the specified Object obj is read-locked by Transaction tx.
181		* @param tx the transaction
182		* @param obj the Object to be checked
183		* @return true if lock exists, else false
184		*/
185		public boolean checkRead(TransactionImpl tx, Object obj)
186		{
187		if (hasReadLock(tx, obj))
188		{
189		return true;
190		}
191		LockEntry writer = getWriter(obj);
192		if (writer != null && writer.isOwnedBy(tx))
193		{
194		return true;
195		}
196		else
197		return false;
198		}
199
200		/**
201		* checks whether the specified Object obj is write-locked by Transaction tx.
202		* @param tx the transaction
203		* @param obj the Object to be checked
204		* @return true if lock exists, else false
205		*/
206		public boolean checkWrite(TransactionImpl tx, Object obj)
207		{
208		LockEntry writer = getWriter(obj);
209		return (writer != null && writer.isOwnedBy(tx));
210		}
211		}