private boolean isHigh() {
return (_callTrackerStats.getCallCount() >= adjustedMinCallCount()
&& (_latency >= _config.getHighLatency()
|| _callTrackerStats.getErrorRate() >= _config.getHighErrorRate()))
|| (_callTrackerStats.getOutstandingCount() >= _config.getMinOutstandingCount()
&& _outstandingLatency >= _config.getHighOutstanding());
}
private boolean isLow() {
return _callTrackerStats.getCallCount() >= adjustedMinCallCount()
&& _latency <= _config.getLowLatency()
&& _callTrackerStats.getErrorRate() <= _config.getLowErrorRate()
&& (_callTrackerStats.getOutstandingCount() < _config.getMinOutstandingCount()
|| _outstandingLatency <= _config.getLowOutstanding());
}
/**
* checks if the stats that we used to compute drop rate is stale or not. Stale meaning, we use a
* certain interval (configured to be 5 seconds) to count the number of calls, latency, etc during
* that 5 seconds. So every 5 seconds we'll want to refresh the window of interval for counting.
*
* <p>So if it's stale, we'll call CallTrackerImpl to refresh the window
*
* @param now
*/
private void checkStale(long now) {
if (_callTrackerStats.stale(now)) {
// this code is a bit strange at first i.e. why it's not _callTrackerStats =
// _callTracker.getCallStats();
// but instead it's just _callTracker.getCallStats(); even though getCallStats returns a new
// Object.
// but this is fine because getCallStats() will eventually call Tracker.rolloverStats() which
// has a listener!
// the listener is actually {@see DegraderImpl.rollOverStats(CallTracker.CallStats)} which
// will update
// _callTrackerStats with the new stats. So we're fine.
_callTracker.getCallStats();
}
}
public synchronized Stats getStats() {
checkStale(_clock.currentTimeMillis());
return new Stats(
_dropRate,
_computedDropRate,
_countTotal.get(),
_noOverrideDropCountTotal.get(),
_droppedCountTotal.get(),
_lastNotDroppedTime.get(),
_callTrackerStats.getInterval(),
_callTrackerStats.getIntervalEndTime(),
_lastIntervalDroppedRate,
_callTrackerStats.getCallCount(),
_latency,
_callTrackerStats.getErrorRate(),
_outstandingLatency,
_callTrackerStats.getOutstandingCount(),
_callTrackerStats.getErrorTypeCountsTotal());
}
private void snapLatency() {
CallTracker.CallStats stats = _callTrackerStats;
switch (_config._latencyToUse) {
case PCT50:
_latency = stats.getCallTimeStats().get50Pct();
break;
case PCT90:
_latency = stats.getCallTimeStats().get90Pct();
break;
case PCT95:
_latency = stats.getCallTimeStats().get95Pct();
break;
case PCT99:
_latency = stats.getCallTimeStats().get99Pct();
break;
case AVERAGE:
_latency = Math.round(stats.getCallTimeStats().getAverage());
break;
default:
throw new IllegalArgumentException(
"Latency to use " + _config._latencyToUse + " is unknown");
}
}
private void snapOutstandingLatency() {
CallTracker.CallStats stats = _callTrackerStats;
_outstandingLatency = stats.getOutstandingStartTimeAvg();
}
private synchronized void rolloverStats(CallTracker.CallStats stats) {
_callTrackerStats = stats;
snapLatency();
snapOutstandingLatency();
if (_config.isLogEnabled()) {
log.info(_config.getName() + " " + _callTrackerStats);
}
long countTotal = _countTotal.get();
long noOverrideDropCountTotal = _noOverrideDropCountTotal.get();
long droppedCountTotal = _droppedCountTotal.get();
long dropped = droppedCountTotal - _lastIntervalDroppedCountTotal;
long count = countTotal - _lastIntervalCountTotal;
double lastIntervalDroppedRate = count == 0 ? 0.0 : (double) dropped / (double) count;
double oldDropRate = _computedDropRate;
double newDropRate = oldDropRate;
if (oldDropRate < _config.getMaxDropRate() && isHigh()) {
newDropRate = Math.min(_config.getMaxDropRate(), oldDropRate + _config.getUpStep());
} else if (oldDropRate > 0.0 && isLow()) {
newDropRate = Math.max(0.0, oldDropRate - _config.getDownStep());
}
if (oldDropRate != newDropRate) {
if (log.isWarnEnabled()) {
log.warn(
_config.getName()
+ " ComputedDropRate "
+ (oldDropRate > newDropRate ? "decreased" : "increased")
+ " from "
+ oldDropRate
+ " to "
+ newDropRate
+ ", OverrideDropRate="
+ _config.getOverrideDropRate()
+ ", AdjustedMinCallCount="
+ adjustedMinCallCount()
+ ", CallCount="
+ _callTrackerStats.getCallCount()
+ ", Latency="
+ _latency
+ ", ErrorRate="
+ stats.getErrorRate()
+ ", OutstandingLatency="
+ _outstandingLatency
+ ", OutstandingCount="
+ stats.getOutstandingCount()
+ ", CountTotal="
+ countTotal
+ ", NoOverrideDropCountTotal="
+ noOverrideDropCountTotal
+ ", DroppedCountTotal="
+ droppedCountTotal
+ ", LastIntervalDroppedRate="
+ lastIntervalDroppedRate);
}
} else {
if (_config.isLogEnabled() && log.isInfoEnabled()) {
log.info(
_config.getName()
+ " ComputedDropRate="
+ newDropRate
+ ", OverrideDropRate="
+ _config.getOverrideDropRate()
+ ", AdjustedMinCallCount="
+ adjustedMinCallCount()
+ ", CallCount="
+ _callTrackerStats.getCallCount()
+ ", Latency="
+ _latency
+ ", ErrorRate="
+ stats.getErrorRate()
+ ", OutstandingLatency="
+ _outstandingLatency
+ ", OutstandingCount="
+ stats.getOutstandingCount()
+ ", CountTotal="
+ countTotal
+ ", NoOverrideDropCountTotal="
+ noOverrideDropCountTotal
+ ", DroppedCountTotal="
+ droppedCountTotal
+ ", LastIntervalDroppedRate="
+ lastIntervalDroppedRate);
} else if (log.isDebugEnabled()) {
log.debug(
_config.getName()
+ " ComputedDropRate="
+ newDropRate
+ ", OverrideDropRate="
+ _config.getOverrideDropRate()
+ ", AdjustedMinCallCount="
+ adjustedMinCallCount()
+ ", CallCount="
+ _callTrackerStats.getCallCount()
+ ", Latency="
+ _latency
+ ", ErrorRate="
+ stats.getErrorRate()
+ ", OutstandingLatency="
+ _outstandingLatency
+ ", OutstandingCount="
+ stats.getOutstandingCount()
+ ", CountTotal="
+ countTotal
+ ", NoOverrideDropCountTotal="
+ noOverrideDropCountTotal
+ ", DroppedCountTotal="
+ droppedCountTotal
+ ", LastIntervalDroppedRate="
+ lastIntervalDroppedRate);
}
}
_lastIntervalCountTotal = countTotal;
_lastIntervalDroppedCountTotal = droppedCountTotal;
_lastIntervalDroppedRate = lastIntervalDroppedRate;
setComputedDropRate(newDropRate);
}