protected async Task RemoveLeastRecentlyUsedCacheItemWhenOverMaxCacheSize(CancellationToken cancellationToken)
{
var cacheStore = await StateManager.GetOrAddAsync <IReliableDictionary <string, CachedItem> >(CacheStoreName);
var cacheStoreMetadata = await StateManager.GetOrAddAsync <IReliableDictionary <string, CacheStoreMetadata> >(CacheStoreMetadataName);
bool continueRemovingItems = true;
while (continueRemovingItems)
{
continueRemovingItems = false;
cancellationToken.ThrowIfCancellationRequested();
await RetryHelper.ExecuteWithRetry(StateManager, async (tx, cancelToken, state) =>
{
var metadata = await cacheStoreMetadata.TryGetValueAsync(tx, CacheStoreMetadataKey, LockMode.Update);
if (metadata.HasValue)
{
_log?.Invoke($"Size: {metadata.Value.Size} Max Size: {GetMaxSizeInBytes()}");
if (metadata.Value.Size > GetMaxSizeInBytes())
{
Func <string, Task <ConditionalValue <CachedItem> > > getCacheItem = async(string cacheKey) => await cacheStore.TryGetValueAsync(tx, cacheKey, LockMode.Update);
var linkedDictionaryHelper = new LinkedDictionaryHelper(getCacheItem, ByteSizeOffset);
var firstItemKey = metadata.Value.FirstCacheKey;
var firstCachedItem = (await getCacheItem(firstItemKey)).Value;
// Move item to last item if cached item is not expired
if (firstCachedItem.AbsoluteExpiration > _systemClock.UtcNow)
{
// remove cached item
var removeResult = await linkedDictionaryHelper.Remove(metadata.Value, firstCachedItem);
await ApplyChanges(tx, cacheStore, cacheStoreMetadata, removeResult);
// add to last
var addLastResult = await linkedDictionaryHelper.AddLast(removeResult.CacheStoreMetadata, firstItemKey, firstCachedItem, firstCachedItem.Value);
await ApplyChanges(tx, cacheStore, cacheStoreMetadata, addLastResult);
continueRemovingItems = addLastResult.CacheStoreMetadata.Size > GetMaxSizeInBytes();
}
else // Remove
{
_log?.Invoke($"Auto Removing: {metadata.Value.FirstCacheKey}");
var result = await linkedDictionaryHelper.Remove(metadata.Value, firstCachedItem);
await ApplyChanges(tx, cacheStore, cacheStoreMetadata, result);
await cacheStore.TryRemoveAsync(tx, metadata.Value.FirstCacheKey);
continueRemovingItems = result.CacheStoreMetadata.Size > GetMaxSizeInBytes();
}
}
}
});
await Task.Delay(TimeSpan.FromMilliseconds(100), cancellationToken);
}
}
public async Task SetCachedItemAsync(string key, byte[] value, TimeSpan?slidingExpiration, DateTimeOffset?absoluteExpiration)
{
if (slidingExpiration.HasValue)
{
var now = _systemClock.UtcNow;
absoluteExpiration = now.AddMilliseconds(slidingExpiration.Value.TotalMilliseconds);
}
var cacheStore = await StateManager.GetOrAddAsync <IReliableDictionary <string, CachedItem> >(CacheStoreName);
var cacheStoreMetadata = await StateManager.GetOrAddAsync <IReliableDictionary <string, CacheStoreMetadata> >(CacheStoreMetadataName);
await RetryHelper.ExecuteWithRetry(StateManager, async (tx, cancellationToken, state) =>
{
_log?.Invoke($"Set cached item called with key: {key} on partition id: {Partition?.PartitionInfo.Id}");
Func <string, Task <ConditionalValue <CachedItem> > > getCacheItem = async(string cacheKey) => await cacheStore.TryGetValueAsync(tx, cacheKey, LockMode.Update);
var linkedDictionaryHelper = new LinkedDictionaryHelper(getCacheItem, ByteSizeOffset);
var cacheStoreInfo = (await cacheStoreMetadata.TryGetValueAsync(tx, CacheStoreMetadataKey, LockMode.Update)).Value ?? new CacheStoreMetadata(0, null, null);
var existingCacheItem = (await getCacheItem(key)).Value;
var cachedItem = ApplyAbsoluteExpiration(existingCacheItem, absoluteExpiration) ?? new CachedItem(value, null, null, slidingExpiration, absoluteExpiration);
// empty linked dictionary
if (cacheStoreInfo.FirstCacheKey == null)
{
var metadata = new CacheStoreMetadata(value.Length + ByteSizeOffset, key, key);
await cacheStoreMetadata.SetAsync(tx, CacheStoreMetadataKey, metadata);
await cacheStore.SetAsync(tx, key, cachedItem);
}
else
{
var cacheMetadata = cacheStoreInfo;
// linked node already exists in dictionary
if (existingCacheItem != null)
{
var removeResult = await linkedDictionaryHelper.Remove(cacheStoreInfo, cachedItem);
cacheMetadata = removeResult.CacheStoreMetadata;
await ApplyChanges(tx, cacheStore, cacheStoreMetadata, removeResult);
}
// add to last
var addLastResult = await linkedDictionaryHelper.AddLast(cacheMetadata, key, cachedItem, value);
await ApplyChanges(tx, cacheStore, cacheStoreMetadata, addLastResult);
}
});
}