/**
* Wicket's default implementation just uses the cacheKey to retrieve the markup from the cache.
* More sophisticated implementations may call a container method to e.g. ignore the cached markup
* under certain situations.
*
* @param cacheKey If null, than the cache will be ignored
* @param container
* @return null, if not found or to enforce reloading the markup
*/
protected Markup getMarkupFromCache(final String cacheKey, final MarkupContainer container) {
if (cacheKey != null) {
String locationString = markupKeyCache.get(cacheKey);
if (locationString != null) {
return markupCache.get(locationString);
}
}
return null;
}
/**
* @param resourceStream
* @return True if the markup is cached
*/
private boolean isMarkupCached(final MarkupResourceStream resourceStream) {
if (resourceStream != null) {
String key = resourceStream.getCacheKey();
if (key != null) {
String locationString = markupKeyCache.get(key);
if ((locationString != null) && (markupCache.get(locationString) != null)) {
return true;
}
}
}
return false;
}
/**
* Note that this method will be called from a "cleanup" thread which might not have a thread
* local application.
*/
@Override
public final IMarkupFragment removeMarkup(final String cacheKey) {
Args.notNull(cacheKey, "cacheKey");
if (log.isDebugEnabled()) {
log.debug("Removing from cache: " + cacheKey);
}
// Remove the markup from the cache
String locationString = markupKeyCache.get(cacheKey);
IMarkupFragment markup = (locationString != null ? markupCache.get(locationString) : null);
if (markup == null) {
return null;
}
// Found an entry: actual markup or Markup.NO_MARKUP. Null values are not possible
// because of ConcurrentHashMap.
markupCache.remove(locationString);
if (log.isDebugEnabled()) {
log.debug("Removed from cache: " + locationString);
}
// If a base markup file has been removed from the cache then
// the derived markup should be removed as well.
removeMarkupWhereBaseMarkupIsNoLongerInTheCache();
// And now remove all watcher entries associated with markup
// resources no longer in the cache.
// Note that you can not use Application.get() since removeMarkup() will be called from a
// ModificationWatcher thread which has no associated Application.
IModificationWatcher watcher = application.getResourceSettings().getResourceWatcher(false);
if (watcher != null) {
Iterator<IModifiable> iter = watcher.getEntries().iterator();
while (iter.hasNext()) {
IModifiable modifiable = iter.next();
if (modifiable instanceof MarkupResourceStream) {
if (!isMarkupCached((MarkupResourceStream) modifiable)) {
iter.remove();
if (log.isDebugEnabled()) {
log.debug("Removed from watcher: " + modifiable);
}
}
}
}
}
return markup;
}
/**
* Load markup from an IResourceStream and add an {@link IChangeListener}to the {@link
* ModificationWatcher} so that if the resource changes, we can remove it from the cache
* automatically and subsequently reload when needed.
*
* @param container The original requesting markup container
* @param markupResourceStream The markup stream to load and begin to watch
* @param enforceReload The cache will be ignored and all, including inherited markup files, will
* be reloaded. Whatever is in the cache, it will be ignored
* @return The markup in the stream
*/
private final Markup loadMarkupAndWatchForChanges(
final MarkupContainer container,
final MarkupResourceStream markupResourceStream,
final boolean enforceReload) {
// @TODO the following code sequence looks very much like in loadMarkup. Can it be
// optimized?
final String cacheKey = markupResourceStream.getCacheKey();
if (cacheKey != null) {
if (enforceReload == false) {
// get the location String
String locationString = markupResourceStream.locationAsString();
if (locationString == null) {
// set the cache key as location string, because location string
// couldn't be resolved.
locationString = cacheKey;
}
Markup markup = markupCache.get(locationString);
if (markup != null) {
markupKeyCache.put(cacheKey, locationString);
return markup;
}
}
// Watch file in the future
final IModificationWatcher watcher =
application.getResourceSettings().getResourceWatcher(true);
if (watcher != null) {
watcher.add(
markupResourceStream,
new IChangeListener() {
@Override
public void onChange() {
if (log.isDebugEnabled()) {
log.debug("Remove markup from watcher: " + markupResourceStream);
}
// Remove the markup from the cache. It will be reloaded
// next time when the markup is requested.
watcher.remove(markupResourceStream);
removeMarkup(cacheKey);
}
});
}
}
if (log.isDebugEnabled()) {
log.debug("Loading markup from " + markupResourceStream);
}
return loadMarkup(container, markupResourceStream, enforceReload);
}
/**
* Put the markup into the cache if cacheKey is not null and the cache does not yet contain the
* cacheKey. Return the markup stored in the cache if cacheKey is present already.
*
* <p>More sophisticated implementations may call a container method to e.g. cache it per
* container instance.
*
* @param locationString If {@code null} then ignore the cache
* @param container The container this markup is for.
* @param markup
* @return markup The markup provided, except if the cacheKey already existed in the cache, then
* the markup from the cache is provided.
*/
protected Markup putIntoCache(
final String locationString, final MarkupContainer container, Markup markup) {
if (locationString != null) {
if (markupCache.containsKey(locationString) == false) {
// The default cache implementation is a ConcurrentHashMap. Thus neither the key nor
// the value can be null.
if (markup == null) {
markup = Markup.NO_MARKUP;
}
markupCache.put(locationString, markup);
} else {
// We don't lock the cache while loading a markup. Thus it may
// happen that the very same markup gets loaded twice (the first
// markup being loaded, but not yet in the cache, and another
// request requesting the very same markup). Since markup
// loading in avg takes less than 100ms, it is not really an
// issue. For consistency reasons however, we should always use
// the markup loaded first which is why it gets returned.
markup = markupCache.get(locationString);
}
}
return markup;
}
