private static void UpdateTimestamp(ConcurrentLruRegexCacheNode result)
{
var timestamp = Stopwatch.GetTimestamp();
var resultTimestamp = result.Timestamp;
// here we want to avoid updating this using Interlocked on a highly
// used query, so we limit it to once per 10,000 ticks, which should
// still be good enough if we need to start evicting
if (timestamp - resultTimestamp > 10_000)//if our snapshot is over 10,000 ticks old
{
//If we fail this interlocked operation, it means that some other thread already updated the timestamp
Interlocked.CompareExchange(ref result.Timestamp, timestamp, resultTimestamp);
}
}
private Regex GetUnlikely(string pattern)
{
var result = new ConcurrentLruRegexCacheNode(
pattern, _neverCompile ? RegexOptions.None : RegexOptions.Compiled)
{
Timestamp = Stopwatch.GetTimestamp()
};
var res = _regexCache.GetOrAdd(pattern, result);
if (res != result) // someone else created it
{
return(res.RegexLazy.Value);
}
//We have reached the capacity and we will now clear 25% of the cache
var currentCount = Interlocked.Increment(ref _count);
if (currentCount >= _capacity)
{
ClearOldItems();
}
return(res.RegexLazy.Value);
}