internal void Update(long number)
{
switch (this.aggType)
{
case AggregationType.LongSumIncomingDelta:
{
Interlocked.Add(ref this.runningValue.AsLong, number);
break;
}
case AggregationType.LongSumIncomingCumulative:
{
Interlocked.Exchange(ref this.runningValue.AsLong, number);
break;
}
case AggregationType.LongGauge:
{
Interlocked.Exchange(ref this.runningValue.AsLong, number);
break;
}
case AggregationType.Histogram:
case AggregationType.HistogramSumCount:
{
this.Update((double)number);
break;
}
}
// There is a race with Snapshot:
// Update() updates the value
// Snapshot snapshots the value
// Snapshot sets status to NoCollectPending
// Update sets status to CollectPending -- this is not right as the Snapshot
// already included the updated value.
// In the absence of any new Update call until next Snapshot,
// this results in exporting an Update even though
// it had no update.
// TODO: For Delta, this can be mitigated
// by ignoring Zero points
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
internal void TakeSnapshot(bool outputDelta)
{
switch (this.aggType)
{
case AggregationType.LongSumIncomingDelta:
case AggregationType.LongSumIncomingCumulative:
{
if (outputDelta)
{
long initValue = Interlocked.Read(ref this.runningValue.AsLong);
this.snapshotValue.AsLong = initValue - this.deltaLastValue.AsLong;
this.deltaLastValue.AsLong = initValue;
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
// Check again if value got updated, if yes reset status.
// This ensures no Updates get Lost.
if (initValue != Interlocked.Read(ref this.runningValue.AsLong))
{
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
}
else
{
this.snapshotValue.AsLong = Interlocked.Read(ref this.runningValue.AsLong);
}
break;
}
case AggregationType.DoubleSumIncomingDelta:
case AggregationType.DoubleSumIncomingCumulative:
{
if (outputDelta)
{
// TODO:
// Is this thread-safe way to read double?
// As long as the value is not -ve infinity,
// the exchange (to 0.0) will never occur,
// but we get the original value atomically.
double initValue = Interlocked.CompareExchange(ref this.runningValue.AsDouble, 0.0, double.NegativeInfinity);
this.snapshotValue.AsDouble = initValue - this.deltaLastValue.AsDouble;
this.deltaLastValue.AsDouble = initValue;
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
// Check again if value got updated, if yes reset status.
// This ensures no Updates get Lost.
if (initValue != Interlocked.CompareExchange(ref this.runningValue.AsDouble, 0.0, double.NegativeInfinity))
{
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
}
else
{
// TODO:
// Is this thread-safe way to read double?
// As long as the value is not -ve infinity,
// the exchange (to 0.0) will never occur,
// but we get the original value atomically.
this.snapshotValue.AsDouble = Interlocked.CompareExchange(ref this.runningValue.AsDouble, 0.0, double.NegativeInfinity);
}
break;
}
case AggregationType.LongGauge:
{
this.snapshotValue.AsLong = Interlocked.Read(ref this.runningValue.AsLong);
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
// Check again if value got updated, if yes reset status.
// This ensures no Updates get Lost.
if (this.snapshotValue.AsLong != Interlocked.Read(ref this.runningValue.AsLong))
{
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
break;
}
case AggregationType.DoubleGauge:
{
// TODO:
// Is this thread-safe way to read double?
// As long as the value is not -ve infinity,
// the exchange (to 0.0) will never occur,
// but we get the original value atomically.
this.snapshotValue.AsDouble = Interlocked.CompareExchange(ref this.runningValue.AsDouble, 0.0, double.NegativeInfinity);
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
// Check again if value got updated, if yes reset status.
// This ensures no Updates get Lost.
if (this.snapshotValue.AsDouble != Interlocked.CompareExchange(ref this.runningValue.AsDouble, 0.0, double.NegativeInfinity))
{
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
break;
}
case AggregationType.Histogram:
{
lock (this.histogramBuckets.LockObject)
{
this.snapshotValue.AsLong = this.runningValue.AsLong;
this.histogramBuckets.SnapshotSum = this.histogramBuckets.RunningSum;
if (outputDelta)
{
this.runningValue.AsLong = 0;
this.histogramBuckets.RunningSum = 0;
}
for (int i = 0; i < this.histogramBuckets.RunningBucketCounts.Length; i++)
{
this.histogramBuckets.SnapshotBucketCounts[i] = this.histogramBuckets.RunningBucketCounts[i];
if (outputDelta)
{
this.histogramBuckets.RunningBucketCounts[i] = 0;
}
}
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
}
break;
}
case AggregationType.HistogramSumCount:
{
lock (this.histogramBuckets.LockObject)
{
this.snapshotValue.AsLong = this.runningValue.AsLong;
this.histogramBuckets.SnapshotSum = this.histogramBuckets.RunningSum;
if (outputDelta)
{
this.runningValue.AsLong = 0;
this.histogramBuckets.RunningSum = 0;
}
this.MetricPointStatus = MetricPointStatus.NoCollectPending;
}
break;
}
}
}
internal void Update(double number)
{
switch (this.aggType)
{
case AggregationType.DoubleSumIncomingDelta:
{
double initValue, newValue;
do
{
initValue = this.runningValue.AsDouble;
newValue = initValue + number;
}while (initValue != Interlocked.CompareExchange(ref this.runningValue.AsDouble, newValue, initValue));
break;
}
case AggregationType.DoubleSumIncomingCumulative:
{
Interlocked.Exchange(ref this.runningValue.AsDouble, number);
break;
}
case AggregationType.DoubleGauge:
{
Interlocked.Exchange(ref this.runningValue.AsDouble, number);
break;
}
case AggregationType.Histogram:
{
int i;
for (i = 0; i < this.histogramBuckets.ExplicitBounds.Length; i++)
{
// Upper bound is inclusive
if (number <= this.histogramBuckets.ExplicitBounds[i])
{
break;
}
}
lock (this.histogramBuckets.LockObject)
{
this.runningValue.AsLong++;
this.histogramBuckets.RunningSum += number;
this.histogramBuckets.RunningBucketCounts[i]++;
}
break;
}
case AggregationType.HistogramSumCount:
{
lock (this.histogramBuckets.LockObject)
{
this.runningValue.AsLong++;
this.histogramBuckets.RunningSum += number;
}
break;
}
}
// There is a race with Snapshot:
// Update() updates the value
// Snapshot snapshots the value
// Snapshot sets status to NoCollectPending
// Update sets status to CollectPending -- this is not right as the Snapshot
// already included the updated value.
// In the absence of any new Update call until next Snapshot,
// this results in exporting an Update even though
// it had no update.
// TODO: For Delta, this can be mitigated
// by ignoring Zero points
this.MetricPointStatus = MetricPointStatus.CollectPending;
}
