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Private implementation of the Apache MyFaces Trinidad project
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.myfaces.trinidadinternal.image.cache;
import java.util.Hashtable;
import org.apache.myfaces.trinidad.logging.TrinidadLogger;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.myfaces.trinidadinternal.agent.TrinidadAgent;
import org.apache.myfaces.trinidadinternal.image.ImageContext;
import org.apache.myfaces.trinidadinternal.image.encode.ImageEncoderManager;
/**
* Cache data structure
*
* @version $Name: $ ($Revision: adfrt/faces/adf-faces-impl/src/main/java/oracle/adfinternal/view/faces/image/cache/Cache.java#0 $) $Date: 10-nov-2005.19:05:58 $
*/
class Cache
{
public Cache()
{
_cache = new ConcurrentHashMap(_CACHE_SIZE);
}
public CacheEntry get(ImageContext context, Object key)
{
CacheEntry entry = _cache.get(key);
if (entry == null)
return null;
TrinidadAgent agent = context.getAgent();
//int encodings = ((Integer)agent.getCapability(
// AdfFacesAgent.CAP_IMAGE_ENCODINGS)).intValue();
boolean capGif = false;
Object capability = agent.getCapability(TrinidadAgent.CAP_GIF_TYPE_IMAGE);
if (capability == Boolean.TRUE)
capGif = true;
boolean capPng = false;
capability = agent.getCapability(TrinidadAgent.CAP_PNG_TYPE_IMAGE);
if (capability == Boolean.TRUE)
capPng = true;
if (_supportsEncoding(entry, capGif, capPng))
return entry;
while ((entry = entry.getNext()) != null)
{
if (_supportsEncoding(entry, capGif, capPng))
return entry;
}
return null;
}
public void put(ImageContext context, Object key, CacheEntry entry)
{
String baseName = _getBaseName(entry.getImageURI());
if (baseName != null)
_names.put(baseName.toLowerCase(), Boolean.TRUE);
synchronized (_cache)
{
// First check to see if we have already got an entry -
// perhaps for some other encoding
CacheEntry topEntry = _cache.get(key);
if (topEntry == null)
{
_cache.put(key, entry);
}
else
{
// If we have already got an entry, add the new entry to
// the list. If the new entry is a miss/retry entry,
// we explicitly add the new entry to the end of the list.
// This allows lookups of existing images to be found.
// Otherwise, just add the entry to the front of the list.
if (_isMissRetryEntry(entry))
{
CacheEntry nextEntry = null;
// Loop until there is no next entry
while ((nextEntry = topEntry.getNext()) != null)
topEntry = nextEntry;
// When we get to the end, tack on the new entry
// We reuse miss/retry entries - so never set the
// next pointer for these entries - see 2510160.
if (!_isMissRetryEntry(topEntry))
topEntry.setNext(entry);
}
else
{
entry.setNext(topEntry);
_cache.put(key, entry);
}
}
}
}
public void remove(
ImageContext context,
Object key,
CacheEntry entry)
{
synchronized (_cache)
{
CacheEntry topEntry = _cache.get(key);
if (topEntry == entry)
{
_cache.remove(key);
// If there is a next CacheEntry, put it back into the cache
CacheEntry nextEntry = entry.getNext();
if (nextEntry != null)
{
_cache.put(key, nextEntry);
// What the heck, null out the reference to the next entry
entry.setNext(null);
}
}
else if (topEntry != null)
{
// If the entry isn't the first entry in the list, check
// to see if the entry is somewhere in the middle of the
// list - if so, remove it.
CacheEntry nextEntry = null;
while ((nextEntry = topEntry.getNext()) != null)
{
if (nextEntry == entry)
{
// Remove the entry from the list
topEntry.setNext(entry.getNext());
// What the heck, null out the reference to the next entry
entry.setNext(null);
}
topEntry = nextEntry;
}
}
}
}
public synchronized String getUniqueName(String baseName)
{
baseName = _filterName(baseName);
String lowerBaseName = baseName.toLowerCase();
// Try to find a unique name
for (int i = 0; i < Integer.MAX_VALUE; i++)
{
String name = (i == 0) ? lowerBaseName : lowerBaseName + "-" + i;
synchronized (_names)
{
if (!_names.containsKey(name))
{
// Add a placeholder into the inverse name cache to reserve
// this name
_names.put(name, Boolean.TRUE);
return (i == 0) ? baseName : baseName + "-" + i;
}
}
}
// We should never get here - we should always get a unique name above!
_LOG.severe("CANNOT_GET_UNIQUE_NAME");
return null;
}
// Frees up the unique name for reuse.
public synchronized void releaseUniqueName(String uniqueName)
{
_names.remove(uniqueName.toLowerCase());
}
// Filters the specified name to a valid file name. We strip out
// characters that we suspect might cause problems for the file
// system. For example, the name may be based on a label which
// contains special characters (like '/').
private String _filterName(String name)
{
StringBuffer buffer = null;
int length = name.length();
for (int i = 0; i < length; i++)
{
char c = name.charAt(i);
if (_isValidCharacter(c))
{
if (buffer != null)
buffer.append(c);
}
else
{
if (buffer == null)
{
buffer = new StringBuffer(length);
buffer.append(name.substring(0, i));
}
buffer.append(_getValidCharacter(c));
}
}
// If we have transformed the name, return the new name
if (buffer != null)
return buffer.toString();;
return name;
}
// Tests whether the specified character can be used as part of
// a file name (and URL). We pretty much just allow ascii alphanumerics.
private boolean _isValidCharacter(char c)
{
return
((c >= 0x41) && (c < 0x5b)) || // A-Z
((c >= 0x61) && (c < 0x7b)) || // a-z
((c >= 0x30) && (c < 0x3a)) || // 0-9
(c == 0x5F) || // underscore
(c == 0x2D); // dash
}
// Returns a valid character to use in place of the specified character
// We just return an Ascii character, based on the hexadecimal
// representation of the character. This results in meaningless but
// valid file names.
private char _getValidCharacter(char c)
{
// Convert space to underline
if (c == 0x20)
return 0x5f;
// Convert to hexidecimal string
String hex = Integer.toHexString(c);
// To keep names short, just pick off the last character - it's the
// most variable digit.
return hex.charAt(hex.length() - 1);
}
// Gets the base name from the uri.
private String _getBaseName(String uri)
{
if (uri == null)
return null;
// The base name is everything from the first '/' to the last '.'.
// Everything before the first '/' is the locale. Everything
// after the last '.' is the extension
int startIndex = uri.indexOf('/');
int endIndex = uri.indexOf('.');
assert(endIndex != -1);
return uri.substring((startIndex == -1) ? 0 : startIndex + 1, endIndex);
}
// Tests whether the specified entry uses a supported encoding.
private boolean _supportsEncoding(
CacheEntry entry,
//int encodings,
boolean capGif,
boolean capPng
)
{
// Miss/retry entries are always supported.
if (_isMissRetryEntry(entry))
return true;
String encoding = entry.getEncoding();
return (((encoding == ImageEncoderManager.GIF_TYPE) && (capGif)) ||
//((AdfFacesAgent.IMAGE_ENCODINGS_CAP_GIF & encodings) != 0)) ||
((encoding == ImageEncoderManager.PNG_TYPE) && (capPng)));
//((AdfFacesAgent.IMAGE_ENCODINGS_CAP_PNG & encodings) != 0)));
}
// Test whether the entry is a special miss/retry entry.
// We consider an entry with a null URI to be a miss/retry
// entry. This is a bit obscure, but what the heck...
private static boolean _isMissRetryEntry(CacheEntry entry)
{
return (entry.getImageURI() == null);
}
// Hashtable of CacheKeys to CacheEntrys
private ConcurrentHashMap _cache;
// List of base names.
// =-=ags We use a Hashtable so that lookups are quick. However,
// this probably should just be a sorted list and do a binary
// search, since we don't care about the value, just the key.
// -= Simon Lessard =-
// FIXME: Hashtale is synchronized (thus slow). If thread safety is not
// required, HashMap would be better,
private Hashtable _names =
new Hashtable(_NAMES_SIZE);
private static final int _CACHE_SIZE = 101;
// Default size for names cache
private static final int _NAMES_SIZE = 101;
static private final TrinidadLogger _LOG =
TrinidadLogger.createTrinidadLogger(Cache.class);
}