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package com.sun.faces.application.resource;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletContext;
import com.sun.faces.config.WebConfiguration;
import com.sun.faces.config.WebConfiguration.WebContextInitParameter;
import com.sun.faces.util.FacesLogger;
import com.sun.faces.util.Util;
import com.sun.faces.util.MultiKeyConcurrentHashMap;
/**
* <p>
* This is the caching mechanism for caching ResourceInfo instances to
* offset the cost of looking up the resource.
* </p>
*
* <p>
* This cache uses a background thread to check for modifications to the underlying
* webapp or JAR files containing resources. This check is periodic, configurable
* via context init param <code>com.sun.faces.resourceUpdateCheckPeriod</code>. Through
* this config option, the cache can also be made static or completely disabled.
* If the value of of this option is <code>0</code>, then no check will be made
* making the cache static. If value of this option is <code>less than 0</code>,
* then no caching will be perfomed. Otherwise, the value of the option will
* be the number of minutes between modification checks.
* </p>
*/
public class ResourceCache {
private static final Logger LOGGER = FacesLogger.RESOURCE.getLogger();
/**
* The <code>ResourceInfo<code> cache.
*/
private MultiKeyConcurrentHashMap<String,ResourceInfoCheckPeriodProxy> resourceCache;
/**
* Resource check period in minutes.
*/
private long checkPeriod;
// ------------------------------------------------------------ Constructors
/**
* Constructs a new ResourceCache.
*/
public ResourceCache() {
WebConfiguration config = WebConfiguration.getInstance();
assert (config != null);
ServletContext sc = config.getServletContext();
long period = getCheckPeriod(config);
checkPeriod = ((period != -1) ? period * 1000L * 60L : -1);
resourceCache = new MultiKeyConcurrentHashMap<String,ResourceInfoCheckPeriodProxy>(30);
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE,
"ResourceCache constructed for {0}. Check period is {1} minutes.",
new Object[] { getServletContextIdentifier(sc), checkPeriod });
}
}
// ---------------------------------------------------------- Public Methods
/**
* Add the {@link ResourceInfo} to the internal cache.
*
* @param info resource metadata
*
* @return previous value associated with specified key, or null
* if there was no mapping for key
*/
public ResourceInfo add(ResourceInfo info) {
Util.notNull("info", info);
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE,
"Caching ResourceInfo: {0}",
info.toString());
}
ResourceInfoCheckPeriodProxy proxy =
resourceCache.putIfAbsent(info.name,
info.libraryName,
info.localePrefix,
new ResourceInfoCheckPeriodProxy(info, checkPeriod));
return ((proxy != null) ? proxy.getResourceInfo() : null);
}
/**
* @param name the resource name
* @param libraryName the library name
* @param localePrefix the locale prefix
* @return the {@link ResourceInfo} associated with <code>key<code>
* if any.
*/
public ResourceInfo get(String name, String libraryName, String localePrefix) {
Util.notNull("name", name);
ResourceInfoCheckPeriodProxy proxy =
resourceCache.get(name, libraryName, localePrefix);
if (proxy != null && proxy.needsRefreshed()) {
resourceCache.remove(name, libraryName, localePrefix);
return null;
} else {
return ((proxy != null) ? proxy.getResourceInfo() : null);
}
}
/**
* <p>Empty the cache.</p>
*/
public void clear() {
resourceCache.clear();
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Cache Cleared");
}
}
// --------------------------------------------------------- Private Methods
private Long getCheckPeriod(WebConfiguration webConfig) {
String val = webConfig.getOptionValue(WebContextInitParameter.ResourceUpdateCheckPeriod);
try {
return (Long.parseLong(val));
} catch (NumberFormatException nfe) {
return Long.parseLong(WebContextInitParameter.ResourceUpdateCheckPeriod.getDefaultValue());
}
}
private static String getServletContextIdentifier(ServletContext context) {
if (context.getMajorVersion() == 2 && context.getMinorVersion() < 5) {
return context.getServletContextName();
} else {
return context.getContextPath();
}
}
// ---------------------------------------------------------- Nested Classes
private static final class ResourceInfoCheckPeriodProxy {
private ResourceInfo resourceInfo;
private Long checkTime;
// -------------------------------------------------------- Constructors
public ResourceInfoCheckPeriodProxy(ResourceInfo resourceInfo,
long checkPeriod) {
this.resourceInfo = resourceInfo;
if (checkPeriod != -1L) {
if (!(resourceInfo.getHelper() instanceof ClasspathResourceHelper)) {
checkTime = System.currentTimeMillis() + checkPeriod;
}
}
}
private boolean needsRefreshed() {
return (checkTime != null
&& (checkTime < System.currentTimeMillis()));
}
private ResourceInfo getResourceInfo() {
return resourceInfo;
}
} // END ResourceInfoCheckPeriodProxy
} // END ResourceCache