ReservoirCell

java.lang.Object
- io.opentelemetry.sdk.metrics.internal.exemplar.ReservoirCell

```
class ReservoirCell
extends java.lang.Object
```
A Reservoir cell pre-allocated memories for Exemplar data.
We only allocate new objects during collection. This class should NOT cause allocations during sampling or within the synchronous metric hot-path.
Allocations are acceptable in the getAndResetDouble(Attributes) and getAndResetLong(Attributes) collection methods.

Field Summary

Fields
Modifier and Type	Field	Description
`private Attributes`	`attributes`
`private Clock`	`clock`
`private double`	`doubleValue`
`private long`	`longValue`
`private long`	`recordTime`
`private SpanContext`	`spanContext`

Constructor Summary

Constructors
Constructor Description

ReservoirCell(Clock clock)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private static Attributes`	`filtered(Attributes original, Attributes metricPoint)`	Returns filtered attributes for exemplars.
`(package private) DoubleExemplarData`	`getAndResetDouble(Attributes pointAttributes)`	Retrieve the cell's `ExemplarData`.
`(package private) LongExemplarData`	`getAndResetLong(Attributes pointAttributes)`	Retrieve the cell's `ExemplarData`.
`private void`	`offerMeasurement(Attributes attributes, Context context)`
`(package private) void`	`recordDoubleMeasurement(double value, Attributes attributes, Context context)`	Record the long measurement to the cell.
`(package private) void`	`recordLongMeasurement(long value, Attributes attributes, Context context)`	Record the long measurement to the cell.
`(package private) void`	`reset()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

clock
```
private final Clock clock
```

attributes

@Nullable
private Attributes attributes

spanContext
```
private SpanContext spanContext
```

recordTime
```
private long recordTime
```

longValue
```
private long longValue
```

doubleValue
```
private double doubleValue
```

Constructor Detail
- ReservoirCell
```
ReservoirCell(Clock clock)
```

Method Detail

recordLongMeasurement
```
void recordLongMeasurement(long value,
                           Attributes attributes,
                           Context context)
```
Record the long measurement to the cell.
Must be used in tandem with getAndResetLong(Attributes). recordDoubleMeasurement(double, Attributes, Context) and getAndResetDouble(Attributes) must not be used when a cell is recording longs.

recordDoubleMeasurement
```
void recordDoubleMeasurement(double value,
                             Attributes attributes,
                             Context context)
```
Record the long measurement to the cell.
Must be used in tandem with getAndResetDouble(Attributes). recordLongMeasurement(long, Attributes, Context) and getAndResetLong(Attributes) must not be used when a cell is recording longs.

offerMeasurement

private void offerMeasurement(Attributes attributes,
                              Context context)

getAndResetLong
```
@Nullable
LongExemplarData getAndResetLong(Attributes pointAttributes)
```
Retrieve the cell's ExemplarData.
Must be used in tandem with recordLongMeasurement(long, Attributes, Context).

getAndResetDouble
```
@Nullable
DoubleExemplarData getAndResetDouble(Attributes pointAttributes)
```
Retrieve the cell's ExemplarData.
Must be used in tandem with recordDoubleMeasurement(double, Attributes, Context).

reset
```
void reset()
```

filtered

private static Attributes filtered(Attributes original,
                                   Attributes metricPoint)

Returns filtered attributes for exemplars.