private bool TryGetCachedWithWait <TResult>(string cacheKey, IDataCacheStore cache, out TResult cachedResult)
{
int nextWaitMs = 20;
int totalWaitMs = 0;
// Use Sleep() instead of locks to avoid lock complexity.
// This should not happen very often so performance is secondary.
while (totalWaitMs < maxWaitForOtherThreadExec.TotalMilliseconds)
{
if (TryGetCached(cacheKey, cache, out cachedResult))
{
return(true);
}
// Wait a while and hope for executing thread to finish
Thread.Sleep(nextWaitMs);
totalWaitMs += nextWaitMs;
nextWaitMs = Math.Min(2 * nextWaitMs, 200);
if (totalWaitMs + nextWaitMs > maxWaitForOtherThreadExec.TotalMilliseconds)
{
nextWaitMs = (int)maxWaitForOtherThreadExec.TotalMilliseconds - totalWaitMs;
}
}
return(TryGetCached(cacheKey, cache, out cachedResult));
}
/// <summary>
/// Initializes a new instance of the <see cref="DataCacheHandler"/> class. Enables
/// possibility to change actual storage of cached items. Default is DataCacheStore.
/// </summary>
/// <param name="theDataCache">
/// Storage of the actual data. It must be available
/// a little longer than the keys in DataTimeOutCache.
/// </param>
/// <param name="theDataTimeOutCache">
/// One value stored for each DataCache value. These
/// values has expire set to data expire time.
/// </param>
/// <param name="theFetchFlagCache">
/// Cache for marking that fetching of data has been started by using the exec function.
/// </param>
/// <param name="theFailCountCache">
/// Cache for counting the number of fails per resource.
/// </param>
public DataCacheHandler(IDataCacheStore theDataCache, IDataCacheStore theDataTimeOutCache, IDataCacheStore theFetchFlagCache, IDataCacheStore theFailCountCache)
{
_dataCache = theDataCache;
_dataTimeoutCache = theDataTimeOutCache;
_fetchFlagCache = theFetchFlagCache;
_failCountCache = theFailCountCache;
GetAppSettings();
}
/// <summary>
/// Initializes a new instance of the <see cref="DataCacheHandler"/> class. Creating a new bucket of
/// cache items. This is accomplished by using another prefix for storing cached items.
/// </summary>
/// <param name="cachePrefix">
/// The cache key prefix.
/// </param>
public DataCacheHandler(string cachePrefix)
{
_dataCache = new DataCacheStore(cachePrefix + ":", cachePrefix + ":");
_dataTimeoutCache = new DataCacheStore(cachePrefix + "Timeout:", cachePrefix + ":");
_fetchFlagCache = new DataCacheStore(cachePrefix + "FetchFlag:", cachePrefix + ":");
_failCountCache = new DataCacheStore(cachePrefix + "FailCount:", cachePrefix + ":");
GetAppSettings();
}
private static TResult GetCachedOrDefault <TResult>(string cacheKey, IDataCacheStore cache, TResult defaultResult)
{
object item;
if (cache.TryGetValue(cacheKey, out item))
{
if (item is TResult result)
{
return(result);
}
}
return(defaultResult);
}
private static bool TryGetCached <TResult>(string cacheKey, IDataCacheStore cache, out TResult cachedResult)
{
TResult defaultDummy = default(TResult);
var result = GetCachedOrDefault(cacheKey, cache, defaultDummy);
if (!Equals(result, defaultDummy))
{
// Not default, so return from cache
cachedResult = result;
return(true);
}
cachedResult = defaultDummy;
return(false);
}
