/// <inheritdoc />
public object Get(string key, Func <object> factory, TimeSpan?timeout, bool isSliding = false, string[] dependentFiles = null)
{
// see notes in HttpRuntimeAppCache
Lazy <object> result;
using (var lck = new UpgradeableReadLock(_locker))
{
result = MemoryCache.Get(key) as Lazy <object>;
if (result == null || SafeLazy.GetSafeLazyValue(result, true) == null) // get non-created as NonCreatedValue & exceptions as null
{
result = SafeLazy.GetSafeLazy(factory);
var policy = GetPolicy(timeout, isSliding, dependentFiles);
lck.UpgradeToWriteLock();
//NOTE: This does an add or update
MemoryCache.Set(key, result, policy);
}
}
//return result.Value;
var value = result.Value; // will not throw (safe lazy)
if (value is SafeLazy.ExceptionHolder eh)
{
eh.Exception.Throw(); // throw once!
}
return(value);
}
/// <inheritdoc />
public void Insert(string key, Func <object> factory, TimeSpan?timeout = null, bool isSliding = false, string[] dependentFiles = null)
{
InnerCache.Insert(key, () =>
{
var result = SafeLazy.GetSafeLazy(factory);
var value = result.Value; // force evaluation now - this may throw if cacheItem throws, and then nothing goes into cache
// do not store null values (backward compat), clone / reset to go into the cache
return(value == null ? null : CheckCloneableAndTracksChanges(value));
}, timeout, isSliding, dependentFiles);
}
/// <inheritdoc />
public object Get(string key, Func <object> factory)
{
var cached = InnerCache.Get(key, () =>
{
var result = SafeLazy.GetSafeLazy(factory);
var value = result.Value; // force evaluation now - this may throw if cacheItem throws, and then nothing goes into cache
// do not store null values (backward compat), clone / reset to go into the cache
return(value == null ? null : CheckCloneableAndTracksChanges(value));
});
return(CheckCloneableAndTracksChanges(cached));
}
/// <inheritdoc />
public override object Get(string key, Func <object> factory)
{
//no place to cache so just return the callback result
if (!TryGetContextItems(out var items))
{
return(factory());
}
key = GetCacheKey(key);
Lazy <object> result;
try
{
EnterWriteLock();
result = items[key] as Lazy <object>; // null if key not found
// cannot create value within the lock, so if result.IsValueCreated is false, just
// do nothing here - means that if creation throws, a race condition could cause
// more than one thread to reach the return statement below and throw - accepted.
if (result == null || SafeLazy.GetSafeLazyValue(result, true) == null) // get non-created as NonCreatedValue & exceptions as null
{
result = SafeLazy.GetSafeLazy(factory);
items[key] = result;
}
}
finally
{
ExitWriteLock();
}
// using GetSafeLazy and GetSafeLazyValue ensures that we don't cache
// exceptions (but try again and again) and silently eat them - however at
// some point we have to report them - so need to re-throw here
// this does not throw anymore
//return result.Value;
var value = result.Value; // will not throw (safe lazy)
if (value is SafeLazy.ExceptionHolder eh)
{
eh.Exception.Throw(); // throw once!
}
return(value);
}
/// <inheritdoc />
public void Insert(string key, Func <object> factory, TimeSpan?timeout = null, bool isSliding = false, string[] dependentFiles = null)
{
// NOTE - here also we must insert a Lazy<object> but we can evaluate it right now
// and make sure we don't store a null value.
var result = SafeLazy.GetSafeLazy(factory);
var value = result.Value; // force evaluation now
if (value == null)
{
return; // do not store null values (backward compat)
}
var policy = GetPolicy(timeout, isSliding, dependentFiles);
//NOTE: This does an add or update
MemoryCache.Set(key, result, policy);
}
/// <inheritdoc />
public object Get(string cacheKey, Func <object> getCacheItem)
{
var result = _items.GetOrAdd(cacheKey, k => SafeLazy.GetSafeLazy(getCacheItem));
var value = result.Value; // will not throw (safe lazy)
if (!(value is SafeLazy.ExceptionHolder eh))
{
return(value);
}
// and... it's in the cache anyway - so contrary to other cache providers,
// which would trick with GetSafeLazyValue, we need to remove by ourselves,
// in order NOT to cache exceptions
_items.TryRemove(cacheKey, out result);
eh.Exception.Throw(); // throw once!
return(null); // never reached
}