// Accesses a data object from the cache.
// If the object was reclaimed for garbage collection,
// create a new data object at that index location.
public MemoryIndexedDocument this[string file]
{
get
{
// now look for that file in the cache
WeakReference weakRef;
if (!_cacheStorage.TryGetValue(file, out weakRef))
{
return(null);
}
// Obtain an instance of a data object from the cache of
// of weak reference objects.
MemoryIndexedDocument document =
weakRef.Target as MemoryIndexedDocument;
if (document == null)
{
// Object was reclaimed, so generate a new one.
document = new MemoryIndexedDocument(_documentSource, file);
weakRef.Target = document;
}
else
{
// Object was obtained with the weak reference.
}
return(document);
}
}
public override void AddDocument(string file, bool cacheIt,
bool warnOverride)
{
// load the document
MemoryIndexedDocument document =
new MemoryIndexedDocument(this, file);
// record the keys
//string[] keys = document.GetKeys();
ICollection <string> keys = document.GetKeys();
foreach (string key in keys)
{
if (warnOverride && _keyFileIndex.ContainsKey(key))
{
this.WriteMessage(MessageLevel.Warn,
String.Format("Entries for the key '{0}' occur in both '{1}' and '{2}'. The last entry will be used.",
key, _keyFileIndex[key], file));
}
_keyFileIndex[key] = file;
}
if (cacheIt)
{
this.CacheDocument(file, document);
}
document = null;
}
private MemoryIndexedDocument GetDocument(string key)
{
// look up the file corresponding to the key
string file;
if (_keyFileIndex.TryGetValue(key, out file))
{
// now look for that file in the cache
MemoryIndexedDocument document = _documentCache[file];
if (document == null)
{
// not in the cache, so load it
document = new MemoryIndexedDocument(this, file);
this.CacheDocument(file, document);
}
return(document);
}
else
{
// there is no such key
return(null);
}
}
private void CacheDocument(string file, MemoryIndexedDocument document)
{
if (_documentCache == null)
{
return;
}
// add it to the cache
_documentCache.Add(file, document);
}
public override XPathNavigator GetContent(string key)
{
XPathNavigator navigator = null;
MemoryIndexedDocument document = GetDocument(key);
if (document != null)
{
navigator = document.GetContent(key);
// Remove any strong reference to the document by setting it null
document = null;
}
return(navigator);
}
public void Add(string file, MemoryIndexedDocument document)
{
if (document == null)
{
return;
}
// if the cache is full, remove a document
if (_cacheStorage.Count >= _cacheSize)
{
string fileToUnload = _cacheQueue.Dequeue();
_cacheStorage.Remove(fileToUnload);
}
// add it to the cache
_cacheStorage.Add(file, new WeakReference(document, false));
_cacheQueue.Enqueue(file);
document = null;
}
