/// <summary>Removes all items from the <see cref="Cache"/> object.</summary>
public void Clear()
{
_rwl.AcquireWriterLock(LOCK_TIMEOUT_MSECS);
try
{
if (_data.Count > 0)
{
foreach (object key in _data.Keys)
{
if (key != null)
{
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
element.IsCollectable = true;
}
}
}
_data.Clear();
}
}
finally
{
_rwl.ReleaseWriterLock();
}
}
/// <summary>Removes the specified item from the <see cref="Cache"/> object.</summary>
/// <param name="key">The cache key of the item to remove.</param>
/// <returns>The item removed from the cache. If the value in the key parameter is not found, returns a null reference.</returns>
public object Remove(object key)
{
if (key != null)
{
_rwl.AcquireWriterLock(LOCK_TIMEOUT_MSECS);
try
{
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
object value = element.Value;
element.IsCollectable = true;
_data.Remove(key);
return(value);
}
}
finally
{
_rwl.ReleaseWriterLock();
}
}
else
{
throw new ArgumentNullException("key");
}
return(null);
}
/// <summary>
/// Inserts an item into the <see cref="Cache"/> object with a specified lifetime using a cache key to reference its location.
/// </summary>
/// <param name="key">The cache key used to reference the item.</param>
/// <param name="value">The object to be inserted into the cache.</param>
/// <param name="lifetime">The lifetime of the inserted item (i.e. is it expendable or not).</param>
public void Insert(object key, object value, CacheItemLifetime lifetime)
{
if (key != null)
{
_rwl.AcquireWriterLock(LOCK_TIMEOUT_MSECS);
try
{
// remove any existing item for this key
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
element.IsCollectable = true;
_data.Remove(key);
}
// add new item
element = new CacheCollectionElement(value, lifetime);
_data[key] = element;
}
finally
{
_rwl.ReleaseWriterLock();
}
}
else
{
throw new ArgumentNullException("key");
}
}
/// <summary>Compresses the <see cref="Cache"/>, removing references to collected items (if any).</summary>
/// <returns>The count of live items in the <see cref="Cache"/>.</returns>
private int Purge()
{
int liveItemCount = 0;
_rwl.AcquireWriterLock(LOCK_TIMEOUT_MSECS);
try
{
// if no items in Cache, we're done...
if (_data.Count > 0)
{
// check to see if the data for any elements has been collected
ArrayList collected = new ArrayList();
foreach (object key in _data.Keys)
{
if (key != null)
{
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
if (element.IsCollected)
{
collected.Add(key);
}
}
}
}
// remove collected elements from the cache
if (collected.Count > 0)
{
foreach (object key in collected)
{
_data.Remove(key);
}
}
// the Cache item count should now only refer to live, accessible items...
liveItemCount = _data.Count;
}
}
finally
{
_rwl.ReleaseWriterLock();
}
return(liveItemCount);
}
/// <summary>Retrieves the specified item from the <see cref="Cache"/> object.</summary>
/// <param name="key">The cache key of the item to retrieve.</param>
/// <returns>The retrieved cache item, or a null reference if the key is not found.</returns>
public object Get(object key)
{
if (key != null)
{
_rwl.AcquireReaderLock(LOCK_TIMEOUT_MSECS);
try
{
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
if (!element.IsCollected)
{
return(element.Value);
}
else
{
// we're modifying the collection so upgrade to writer lock
LockCookie lockCookie = _rwl.UpgradeToWriterLock(LOCK_TIMEOUT_MSECS);
_data.Remove(key);
// done -- downgrade to reader lock
_rwl.DowngradeFromWriterLock(ref lockCookie);
}
}
}
finally
{
// ReleaseLock is used in lieu of ReleaseWriterLock/ReleaseReaderLock due to the lock upgrade logic.
// Since we don't need to support nested locks here this should be OK...
_rwl.ReleaseLock();
}
}
else
{
throw new ArgumentNullException("key");
}
return(null);
}
/// <summary>
/// Inserts an item into the <see cref="Cache"/> object with a specified lifetime using a cache key to reference its location.
/// </summary>
/// <param name="key">The cache key used to reference the item.</param>
/// <param name="value">The object to be inserted into the cache.</param>
/// <param name="lifetime">The lifetime of the inserted item (i.e. is it expendable or not).</param>
public void Insert(object key, object value, CacheItemLifetime lifetime)
{
if (key != null)
{
_rwl.AcquireWriterLock(LOCK_TIMEOUT_MSECS);
try
{
// remove any existing item for this key
CacheCollectionElement element = _data[key] as CacheCollectionElement;
if (element != null)
{
element.IsCollectable = true;
_data.Remove(key);
}
// add new item
element = new CacheCollectionElement(value, lifetime);
_data[key] = element;
}
finally
{
_rwl.ReleaseWriterLock();
}
}
else
{
throw new ArgumentNullException("key");
}
}
