/// <summary>
/// Attempts to get a value from cache.
/// If it is found in cache, return true, and the value.
/// If it is not found in cache, return false, and use the valueFactory callback to generate and return the value.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="value">The value.</param>
/// <param name="valueFactory">A callback that can create the value.</param>
/// <returns>
/// True if the value came from cache, otherwise false.
/// </returns>
/// <exception cref="System.ArgumentNullException">valueFactory</exception>
public bool TryGetOrAdd(TKey key, out TValue value, Func <TKey, TValue> valueFactory)
{
if (valueFactory == null)
{
throw new ArgumentNullException(nameof(valueFactory));
}
Func <TKey, LastAccessedEntry> factory = k =>
{
TValue val = valueFactory(key);
return(LastAccessedEntry.Create(val));
};
LastAccessedEntry lastAccessed;
bool cameFromCache = _cache.TryGetOrAdd(key, out lastAccessed, factory);
if (!cameFromCache)
{
IncrementCacheSize( );
}
else
{
lastAccessed.LastAccess = DateTime.UtcNow.Ticks;
}
value = lastAccessed.Value;
return(cameFromCache);
}
/// <summary>
/// Adds or updates the specified key/value pair.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="value">The value.</param>
/// <returns>
/// True if the specified key/value pair was added;
/// False if the specified key/value pair was updated.
/// </returns>
public bool Add(TKey key, TValue value)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
bool added = _cache.Add(key, LastAccessedEntry.Create(value));
if (added)
{
IncrementCacheSize( );
}
return(added);
}