User: biorn_steedom
Date: 01/03/26 04:40:33
Modified: src/main/org/jboss/util LRUCachePolicy.java
Log:
Small fixes in case an application is not deployed, to avoid a NPE.
Thanks to Dan Christopherson ([EMAIL PROTECTED]).
Revision Changes Path
1.8 +56 -53 jboss/src/main/org/jboss/util/LRUCachePolicy.java
Index: LRUCachePolicy.java
===================================================================
RCS file: /cvsroot/jboss/jboss/src/main/org/jboss/util/LRUCachePolicy.java,v
retrieving revision 1.7
retrieving revision 1.8
diff -u -r1.7 -r1.8
--- LRUCachePolicy.java 2000/12/18 10:27:57 1.7
+++ LRUCachePolicy.java 2001/03/26 12:40:33 1.8
@@ -12,9 +12,9 @@
* Implementation of a Least Recently Used cache policy.
*
* @author Simone Bordet ([EMAIL PROTECTED])
- * @version $Revision: 1.7 $
+ * @version $Revision: 1.8 $
*/
-public class LRUCachePolicy
+public class LRUCachePolicy
implements CachePolicy
{
// Constants -----------------------------------------------------
@@ -44,15 +44,15 @@
* Creates a LRU cache policy object with zero cache capacity.
* @see #init
*/
- public LRUCachePolicy()
- {
+ public LRUCachePolicy()
+ {
}
/**
- * Creates a LRU cache policy object with the specified minimum
+ * Creates a LRU cache policy object with the specified minimum
* and maximum capacity.
* @see #init
*/
- public LRUCachePolicy(int min, int max)
+ public LRUCachePolicy(int min, int max)
{
if (min < 2 || min > max) {throw new IllegalArgumentException("Illegal
cache capacities");}
m_minCapacity = min;
@@ -68,7 +68,7 @@
* @see #start
* @see #destroy
*/
- public void init() throws Exception
+ public void init() throws Exception
{
m_map = new HashMap();
m_list = createList();
@@ -81,7 +81,7 @@
* @see #init
* @see #stop
*/
- public void start() throws Exception
+ public void start() throws Exception
{
}
/**
@@ -90,29 +90,32 @@
* @see #start
* @see #destroy
*/
- public void stop()
+ public void stop()
{
- flush();
+ if (m_list != null)
+ {
+ flush();
+ }
}
/**
* Destroys the cache that is now unusable. <br>
- * To have it working again it must be re-{@link #init}ialized and
+ * To have it working again it must be re-{@link #init}ialized and
* re-{@link #start}ed.
* @see #init
*/
- public void destroy()
+ public void destroy()
{
}
- public Object get(Object key)
+ public Object get(Object key)
{
- if (key == null)
+ if (key == null)
{
throw new IllegalArgumentException("Requesting an object using
a null key");
}
LRUCacheEntry value = (LRUCacheEntry)m_map.get(key);
- if (value != null)
+ if (value != null)
{
m_list.promote(value);
return value.m_object;
@@ -123,53 +126,53 @@
return null;
}
}
- public Object peek(Object key)
+ public Object peek(Object key)
{
- if (key == null)
+ if (key == null)
{
throw new IllegalArgumentException("Requesting an object using
a null key");
}
-
+
LRUCacheEntry value = (LRUCacheEntry)m_map.get(key);
- if (value == null)
+ if (value == null)
{
return null;
}
- else
+ else
{
return value.m_object;
}
}
- public void insert(Object key, Object o)
+ public void insert(Object key, Object o)
{
if (o == null) {throw new IllegalArgumentException("Cannot insert a
null object in the cache");}
if (key == null) {throw new IllegalArgumentException("Cannot insert an
object in the cache with null key");}
Object obj = m_map.get(key);
- if (obj == null)
+ if (obj == null)
{
m_list.demote();
LRUCacheEntry entry = createCacheEntry(key, o);
m_list.promote(entry);
m_map.put(key, entry);
}
- else
+ else
{
throw new IllegalStateException("Attempt to put in the cache
an object that is already there");
}
}
- public void remove(Object key)
+ public void remove(Object key)
{
if (key == null) {throw new IllegalArgumentException("Removing an
object using a null key");}
Object value = m_map.get(key);
- if (value != null)
+ if (value != null)
{
m_list.remove((LRUCacheEntry)value);
}
else {} // Do nothing, the object isn't in the cache list
m_map.remove(key);
}
- public void flush()
+ public void flush()
{
LRUCacheEntry entry = null;
while ((entry = m_list.m_tail) != null)
@@ -188,24 +191,24 @@
*/
protected LRUList createList() {return new LRUList();}
/**
- * Callback method called when the cache algorithm ages out of the cache
+ * Callback method called when the cache algorithm ages out of the cache
* the given entry. <br>
* The implementation here is removing the given entry from the cache.
*/
- protected void ageOut(LRUCacheEntry entry)
+ protected void ageOut(LRUCacheEntry entry)
{
remove(entry.m_key);
}
/**
* Callback method called when a cache miss happens.
*/
- protected void cacheMiss()
+ protected void cacheMiss()
{
}
- /**
+ /**
* Factory method for cache entries
*/
- protected LRUCacheEntry createCacheEntry(Object key, Object value)
+ protected LRUCacheEntry createCacheEntry(Object key, Object value)
{
return new LRUCacheEntry(key, value);
}
@@ -216,7 +219,7 @@
/**
* Double queued list used to store cache entries.
*/
- public class LRUList
+ public class LRUList
{
/** The maximum capacity of the cache list */
public int m_maxCapacity;
@@ -235,7 +238,7 @@
/**
* Creates a new double queued list.
*/
- protected LRUList()
+ protected LRUList()
{
m_head = null;
m_tail = null;
@@ -243,21 +246,21 @@
}
/**
* Promotes the cache entry <code>entry</code> to the last used
position
- * of the list. <br>
+ * of the list. <br>
* If the object is already there, does nothing.
* @param entry the object to be promoted, cannot be null
* @see #demote
* @throws IllegalStateException if this method is called with a full
cache
*/
- protected void promote(LRUCacheEntry entry)
+ protected void promote(LRUCacheEntry entry)
{
if (entry == null) {throw new IllegalArgumentException("Trying
to promote a null object");}
if (m_capacity < 1) {throw new IllegalStateException("Can't
work with capacity < 1");}
entry.m_time = System.currentTimeMillis();
- if (entry.m_prev == null)
+ if (entry.m_prev == null)
{
- if (entry.m_next == null)
+ if (entry.m_next == null)
{
// entry is new or there is only the head
if (m_count == 0) // cache is empty
@@ -268,7 +271,7 @@
entryAdded(entry);
}
else if (m_count == 1 && m_head == entry) {}
// there is only the head and I want to promote it, do nothing
- else if (m_count < m_capacity)
+ else if (m_count < m_capacity)
{
entry.m_prev = null;
entry.m_next = m_head;
@@ -277,7 +280,7 @@
++m_count;
entryAdded(entry);
}
- else if (m_count < m_maxCapacity)
+ else if (m_count < m_maxCapacity)
{
entry.m_prev = null;
entry.m_next = m_head;
@@ -291,9 +294,9 @@
}
else {throw new IllegalStateException("Attempt
to put a new cache entry on a full cache");}
}
- else {} // entry is the head, do nothing
+ else {} // entry is the head, do nothing
}
- else
+ else
{
if (entry.m_next == null) // entry is the tail
{
@@ -322,33 +325,33 @@
* If the cache is not full, does nothing.
* @see #promote
*/
- protected void demote()
+ protected void demote()
{
if (m_capacity < 1) {throw new IllegalStateException("Can't
work with capacity < 1");}
if (m_count > m_maxCapacity) {throw new
IllegalStateException("Cache list entries number (" + m_count + ") > than the maximum
allowed (" + m_maxCapacity + ")");}
- if (m_count == m_maxCapacity)
+ if (m_count == m_maxCapacity)
{
LRUCacheEntry entry = m_tail;
-
+
// the entry will be removed by ageOut
- ageOut(entry);
+ ageOut(entry);
}
else {} // cache is not full, do nothing
}
/**
* Removes from the cache list the specified entry.
- */
- protected void remove(LRUCacheEntry entry)
+ */
+ protected void remove(LRUCacheEntry entry)
{
if (entry == null) {throw new IllegalArgumentException("Cannot
remove a null entry from the cache");}
if (m_count < 1) {throw new IllegalStateException("Trying to
remove an entry from an empty cache");}
entry.m_key = entry.m_object = null;
- if (m_count == 1)
+ if (m_count == 1)
{
m_head = m_tail = null;
}
- else
+ else
{
if (entry.m_prev == null) // the head
{
@@ -387,7 +390,7 @@
*/
protected void capacityChanged(int oldCapacity) {}
- public String toString()
+ public String toString()
{
String s = Integer.toHexString(super.hashCode());
s += " size: " + m_count;
@@ -398,11 +401,11 @@
return s;
}
}
-
+
/**
* Double linked cell used as entry in the cache list.
*/
- public class LRUCacheEntry
+ public class LRUCacheEntry
{
/** Reference to the next cell in the list */
public LRUCacheEntry m_next;
@@ -415,7 +418,7 @@
/** The timestamp of the creation */
public long m_time;
/**
- * Creates a new double linked cell, storing the object we
+ * Creates a new double linked cell, storing the object we
* want to cache and the key that is used to retrieve it.
*/
protected LRUCacheEntry(Object key, Object object)
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