Sampler (filter-service-metrics 1.13 1.13 API)

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
```
@FunctionalInterface
public interface Sampler<T>
```
Sampler is responsible for deciding if a particular trace should be "sampled", i.e. whether the overhead of tracing will occur and/or if a trace will be reported to the collection tier.
Zipkin v1 uses before-the-fact sampling. This means that the decision to keep or drop the trace is made before any work is measured, or annotations are added. As such, the input parameter to zipkin v1 samplers is the trace ID (lower 64-bits under the assumption all bits are random).
The instrumentation sampling decision happens once, at the root of the trace, and is propagated downstream. For this reason, the algorithm needn't be consistent based on trace ID.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods Deprecated Methods
Modifier and Type	Method and Description
`static <T> Sampler<T>`	`always()` Returns a sampler that will always return `true`.
`boolean`	`isSampled(T object)` Returns `true` if a request should be recorded.
`static <T> Sampler<T>`	`never()` Returns a sampler that will always return `false`.
`static <T> Sampler<T>`	`of(String specification)` Returns a `Sampler` that is configured as specified in the given `specification` string.
`static <T> Sampler<T>`	`random(double probability)` Returns a probabilistic sampler which samples at the specified `probability` between `0.0` and `1.0`.
`static <T> Sampler<T>`	`rateLimited(int samplesPerSecond)` Deprecated. Use `rateLimiting(int)`.
`static <T> Sampler<T>`	`rateLimiting(int samplesPerSecond)` Returns a rate-limiting sampler which rate-limits up to the specified `samplesPerSecond`.

- Method Detail
  - random
```
static <T> Sampler<T> random(double probability)
```
    Returns a probabilistic sampler which samples at the specified probability between 0.0 and 1.0.
    
    Parameters:
    
    probability - the probability expressed as a floating point number between 0.0 and 1.0.
  - rateLimiting
```
static <T> Sampler<T> rateLimiting(int samplesPerSecond)
```
    Returns a rate-limiting sampler which rate-limits up to the specified samplesPerSecond.
    
    Parameters:
    
    samplesPerSecond - an integer between 0 and
  - rateLimited
```
@Deprecated
static <T> Sampler<T> rateLimited(int samplesPerSecond)
```
    Deprecated. Use rateLimiting(int).
    
    Returns a rate-limiting sampler which rate-limits up to the specified samplesPerSecond.
    
    Parameters:
    
    samplesPerSecond - an integer between 0 and
  - always
```
static <T> Sampler<T> always()
```
    Returns a sampler that will always return true.
  - never
```
static <T> Sampler<T> never()
```
    Returns a sampler that will always return false.
  - of
```
static <T> Sampler<T> of(String specification)
```
    Returns a Sampler that is configured as specified in the given specification string. The specification string must be formatted in one of the following formats:
    - "always"
      
      Returns the Sampler that always samples.
    - "never"
      
      Returns the Sampler that never samples.
    - "random=<probability>" where probability is a floating point number between 0.0 and 1.0
      
      Returns a probabilistic Sampler which samples at the specified probability.
      
      e.g. "random=0.05" to sample at 5% probability
    - "rate-limit=<samples_per_sec>" where samples_per_sec is a non-negative integer
      
      Returns a rate-limiting Sampler which rate-limits up to the specified samples per second.
      
      e.g. "rate-limit=10" to sample 10 samples per second at most
  - isSampled
```
boolean isSampled(T object)
```
    Returns true if a request should be recorded.
    
    Parameters:
    
    object - the object to be decided on, can be ignored

Interface Sampler<T>

Method Summary

Method Detail

random

rateLimiting

rateLimited

always

never

of

isSampled