private EventCounter GetOrAdd(T key, long customSize)
{
EventCounter c;
lock (syncLock) {
keysToCounters.TryGetValue(key, out c);
if (c == null)
{
if (customSize < 0)
{
customSize = 0;
}
//Increment global counter first, so cleanup routine makes enough room
bytesUsed += itemSize + customSize;
if (byteCeiling > 0 && bytesUsed >= byteCeiling)
{
Cleanup(CleanupMode.MakeRoom);
}
c = new EventCounter(granularity, (int)_trackingDuration.Ticks / granularity);
c.CustomSize = customSize;
keysToCounters.Add(key, c);
countersToKeys.Add(c, key);
}
else if (customSize >= 0 && c.CustomSize != customSize)
{
bytesUsed += customSize - c.CustomSize;
}
}
return(c);
}
/// <summary>
/// Increment the counter for the given item. Pings cleanup as well.
/// </summary>
/// <param name="key"></param>
/// <param name="customSize"> Sets the custom size offset for the specified key (used for cleanup purposes). If -1, existing value will remain unchanged. </param>
public void Increment(T key, long customSize)
{
EventCounter c = GetOrAdd(key, customSize);
if (precision == EventCountingStrategy.ThreadingPrecision.Fast)
{
c.Increment();
}
else
{
c.IncrementExact();
}
PingCleanup();
}
/// <summary>
/// Performs cleanup on the dictionaries in either MakeRoom or Maintenance mode. Returns true if the goal was achieved, false if the cleanup was canceled because another cleanup was executing concurrently.
/// </summary>
/// <param name="mode"></param>
private bool Cleanup(CleanupMode mode)
{
if (mode == CleanupMode.MakeRoom && byteCeiling < 1)
{
return(true); //We don't perform minimal cleanups unless a ceiling is specified.
}
//We have to track removed items so we can fire events later.
List <KeyValuePair <T, int> > removed = CounterRemoved != null ? new List <KeyValuePair <T, int> >() : null;
//We have to weak lock method-level, because otherwise a background thread could be cleaning when GetOrAdd is called, and we could have a deadlock
//With syncLock locked in GetOrAdd, waiting on cleanupLock, and Cleanup locked on cleanupLock, waiting on GetOrAdd.
//If we didn't have any method-level lock, we'd waste resources with simultaneous cleanup runs.
//sortLock is redundant with cleanupLock, but remains in case I decide to pull the method level lock
if (!Monitor.TryEnter(cleanupLock))
{
return(false); //Failed to lock, another thread is cleaning.
}
try {
//In high precision, we lock the entire long-running process
if (precision == EventCountingStrategy.ThreadingPrecision.Accurate)
{
Monitor.Enter(syncLock);
}
try {
EventCounter[] counters;
//In fast mode, only lock for the copy and delete. We can sort outside after taking a snapshot.
//We wont remove newly added ones, but thats ok.
lock (syncLock) {
if (mode == CleanupMode.MakeRoom && bytesUsed < byteCeiling)
{
return(true); //Nothing to do, there is still room
}
counters = new EventCounter[countersToKeys.Count];
countersToKeys.Keys.CopyTo(counters, 0); //Clone
}
//Lock for sorting so we have synchronized access to a.sortValue
lock (sortLock) {
//Pause values
for (int i = 0; i < counters.Length; i++)
{
counters[i].sortValue = counters[i].GetValue();
}
//Sort lowest counters to the top using Quicksort
Array.Sort <EventCounter>(counters, delegate(EventCounter a, EventCounter b) {
return(a.sortValue - b.sortValue);
});
}
//Go back into lock
lock (syncLock) {
long removedBytes = 0;
long goal = byteCeiling / 10; //10% is our goal if we are removing minimally.
//Remove items
for (int i = 0; i < counters.Length; i++)
{
EventCounter c = counters[i];
if (mode == CleanupMode.MakeRoom && removedBytes >= goal)
{
return(true); //Done, we hit our goal!
}
if (mode == CleanupMode.Maintenance && c.sortValue > 0)
{
return(true); //Done, We hit the end of the zeros
}
if (mode == CleanupMode.Maintenance && c.GetValue() > 0)
{
continue; //Skip counters that incremented while we were working.
}
//Look up key
T key;
countersToKeys.TryGetValue(c, out key);
if (key.Equals(default(T)))
{
continue; //Skip counters that have already been removed
}
//Remove counter
countersToKeys.Remove(c);
keysToCounters.Remove(key);
//Increment our local byte removal counter
removedBytes += c.CustomSize + itemSize;
//Decrement global counter
bytesUsed = bytesUsed - c.CustomSize - itemSize;
//store removed keys
if (removed != null)
{
removed.Add(new KeyValuePair <T, int>(key, c.GetValue()));
}
}
}
} finally {
if (precision == EventCountingStrategy.ThreadingPrecision.Accurate)
{
Monitor.Exit(syncLock);
}
}
} finally {
Monitor.Exit(cleanupLock);
//Fire CounterRemoved event (may still be in syncLock)!
if (removed != null && this.CounterRemoved != null)
{
foreach (KeyValuePair <T, int> p in removed)
{
CounterRemoved(this, p.Key, p.Value);
}
}
}
return(true);
}
