FailureDetector (Pinot Broker 1.0.0 API)

All Known Implementing Classes:

BaseExponentialBackoffRetryFailureDetector, ConnectionFailureDetector, NoOpFailureDetector
```
@Private
@Evolving
@ThreadSafe
public interface FailureDetector
```
The FailureDetector detects unhealthy servers based on the query responses. When it detects an unhealthy server, it will notify the listener via a callback, and schedule a delay to retry the unhealthy server later via another callback.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface FailureDetector.Listener
Listener for the failure detector.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Set<String>`	`getUnhealthyServers()`	Returns all the unhealthy servers.
`void`	`init(org.apache.pinot.spi.env.PinotConfiguration config, org.apache.pinot.common.metrics.BrokerMetrics brokerMetrics)`	Initializes the failure detector.
`void`	`markServerHealthy(String instanceId)`	Marks a server as healthy.
`void`	`markServerUnhealthy(String instanceId)`	Marks a server as unhealthy.
`void`	`notifyQueryFinished(QueryResponse queryResponse)`	Notifies the failure detector that a query is finished (COMPLETED, FAILED or TIMED_OUT).
`void`	`notifyQuerySubmitted(QueryResponse queryResponse)`	Notifies the failure detector that a query is submitted.
`void`	`register(FailureDetector.Listener listener)`	Registers a listener to the failure detector.
`void`	`start()`	Starts the failure detector.
`void`	`stop()`	Stops the failure detector.

- Method Detail
  - init
```
void init(org.apache.pinot.spi.env.PinotConfiguration config,
          org.apache.pinot.common.metrics.BrokerMetrics brokerMetrics)
```
    Initializes the failure detector.
  - register
```
void register(FailureDetector.Listener listener)
```
    Registers a listener to the failure detector.
  - start
```
void start()
```
    Starts the failure detector. Listeners should be registered before starting the failure detector.
  - notifyQuerySubmitted
```
void notifyQuerySubmitted(QueryResponse queryResponse)
```
    Notifies the failure detector that a query is submitted.
  - notifyQueryFinished
```
void notifyQueryFinished(QueryResponse queryResponse)
```
    Notifies the failure detector that a query is finished (COMPLETED, FAILED or TIMED_OUT).
  - markServerHealthy
```
void markServerHealthy(String instanceId)
```
    Marks a server as healthy.
  - markServerUnhealthy
```
void markServerUnhealthy(String instanceId)
```
    Marks a server as unhealthy.
  - getUnhealthyServers
```
Set<String> getUnhealthyServers()
```
    Returns all the unhealthy servers.
  - stop
```
void stop()
```
    Stops the failure detector.