AbstractBackoff (Apache HttpClient 5.4.1 API)

java.lang.Object
- org.apache.hc.client5.http.impl.classic.AbstractBackoff

All Implemented Interfaces:

BackoffManager

Direct Known Subclasses:

AIMDBackoffManager, ExponentialBackoffManager, LinearBackoffManager
```
public abstract class AbstractBackoff
extends Object
implements BackoffManager
```
AbstractBackoff is an abstract class that provides a common implementation for managing backoff behavior in HttpClient connection pool. Subclasses should implement the specific backoff algorithms by overriding the abstract methods.
This class provides common functionality for maintaining the route-wise backoff and probe timestamps, as well as the cool-down period for each backoff attempt.
It also contains the basic structure of the backOff and probe methods, which use the route-wise timestamps to determine if the backoff or probe should be applied, and then call the specific algorithm implementation for calculating the new pool size.

Since:

5.3

Constructor Summary

Constructors
Constructor and Description
`AbstractBackoff(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPerRoute)` Constructs a new ExponentialBackoffManager with the specified connection pool control.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`backOff(HttpRoute route)` Reduces the number of maximum allowed connections for the specified route based on the exponential backoff algorithm.
`protected abstract int`	`getBackedOffPoolSize(int curr)` Calculates the new pool size after applying the exponential backoff algorithm.
`protected AtomicReference<Double>`	`getBackoffFactor()` Returns the backoff factor as an AtomicReference of Double.
`protected AtomicInteger`	`getCap()` Returns the cap on the maximum number of connections per route as an AtomicInteger.
`protected org.apache.hc.core5.pool.ConnPoolControl<HttpRoute>`	`getConnPerRoute()` Returns the connection pool control for managing the maximum number of connections per route.
`protected AtomicReference<org.apache.hc.core5.util.TimeValue>`	`getCoolDown()` Returns the cool down period between backoff and probe operations as an AtomicReference of TimeValue.
`protected Map<HttpRoute,Instant>`	`getLastRouteBackoffs()` Returns the map containing the last backoff times for each HttpRoute.
`protected Map<HttpRoute,Instant>`	`getLastRouteProbes()` Returns the map containing the last probe times for each HttpRoute.
`long`	`getLastUpdate(Map<HttpRoute,Long> updates, HttpRoute route)` Retrieves the last update timestamp for the specified route from the provided updates map.
`protected AtomicInteger`	`getTimeInterval()` Returns the time interval between backoff and probe operations as an AtomicInteger.
`void`	`probe(HttpRoute route)` Increases the number of maximum allowed connections for the specified route after a successful connection has been established.
`void`	`setCoolDown(org.apache.hc.core5.util.TimeValue coolDown)` Sets the cool-down time value for adjustments in pool sizes for a given host.
`void`	`setPerHostConnectionCap(int cap)` Sets the per-host connection cap.

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

- Constructor Detail
  - AbstractBackoff
```
public AbstractBackoff(org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> connPerRoute)
```
    Constructs a new ExponentialBackoffManager with the specified connection pool control.
    
    Parameters:
    
    connPerRoute - the connection pool control to be used for managing connections
    
    Throws:
    
    IllegalArgumentException - if connPerRoute is null
- Method Detail
  - backOff
```
public void backOff(HttpRoute route)
```
    Reduces the number of maximum allowed connections for the specified route based on the exponential backoff algorithm.
    
    Specified by:
    
    backOff in interface BackoffManager
    
    Parameters:
    
    route - the HttpRoute for which the backoff needs to be applied
  - getBackedOffPoolSize
```
protected abstract int getBackedOffPoolSize(int curr)
```
    Calculates the new pool size after applying the exponential backoff algorithm. The new pool size is calculated using the formula: floor(curr / (1 + growthRate) ^ t), where curr is the current pool size, growthRate is the exponential growth rate, and t is the time interval.
    
    Parameters:
    
    curr - the current pool size
    
    Returns:
    
    the new pool size after applying the backoff
  - probe
```
public void probe(HttpRoute route)
```
    Increases the number of maximum allowed connections for the specified route after a successful connection has been established.
    
    Specified by:
    
    probe in interface BackoffManager
    
    Parameters:
    
    route - the HttpRoute for which the probe needs to be applied
  - getLastUpdate
```
public long getLastUpdate(Map<HttpRoute,Long> updates,
                          HttpRoute route)
```
    Retrieves the last update timestamp for the specified route from the provided updates map.
    
    Parameters:
    
    updates - the map containing update timestamps for HttpRoutes
    
    route - the HttpRoute for which the last update timestamp is needed
    
    Returns:
    
    the last update timestamp for the specified route or 0L if not present in the map
  - setPerHostConnectionCap
```
public void setPerHostConnectionCap(int cap)
```
    Sets the per-host connection cap.
    
    Parameters:
    
    cap - the per-host connection cap to be set
    
    Throws:
    
    IllegalArgumentException - if the cap is not positive
  - setCoolDown
```
public void setCoolDown(org.apache.hc.core5.util.TimeValue coolDown)
```
    Sets the cool-down time value for adjustments in pool sizes for a given host. This time value allows enough time for the adjustments to take effect before further adjustments are made. The cool-down time value must be positive and not null.
    
    Parameters:
    
    coolDown - the TimeValue representing the cool-down period between adjustments
    
    Throws:
    
    IllegalArgumentException - if the provided cool-down time value is null or non-positive
  - getConnPerRoute
```
protected org.apache.hc.core5.pool.ConnPoolControl<HttpRoute> getConnPerRoute()
```
    Returns the connection pool control for managing the maximum number of connections per route.
    
    Returns:
    
    the connection pool control instance
  - getLastRouteProbes
```
protected Map<HttpRoute,Instant> getLastRouteProbes()
```
    Returns the map containing the last probe times for each HttpRoute.
    
    Returns:
    
    the map of HttpRoute to Instant representing the last probe times
  - getLastRouteBackoffs
```
protected Map<HttpRoute,Instant> getLastRouteBackoffs()
```
    Returns the map containing the last backoff times for each HttpRoute.
    
    Returns:
    
    the map of HttpRoute to Instant representing the last backoff times
  - getCoolDown
```
protected AtomicReference<org.apache.hc.core5.util.TimeValue> getCoolDown()
```
    Returns the cool down period between backoff and probe operations as an AtomicReference of TimeValue.
    
    Returns:
    
    the AtomicReference containing the cool down period
  - getBackoffFactor
```
protected AtomicReference<Double> getBackoffFactor()
```
    Returns the backoff factor as an AtomicReference of Double.
    
    Returns:
    
    the AtomicReference containing the backoff factor
  - getCap
```
protected AtomicInteger getCap()
```
    Returns the cap on the maximum number of connections per route as an AtomicInteger.
    
    Returns:
    
    the AtomicInteger containing the cap value
  - getTimeInterval
```
protected AtomicInteger getTimeInterval()
```
    Returns the time interval between backoff and probe operations as an AtomicInteger.
    
    Returns:
    
    the AtomicInteger containing the time interval

Class AbstractBackoff

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AbstractBackoff

Method Detail

backOff

getBackedOffPoolSize

probe

getLastUpdate

setPerHostConnectionCap

setCoolDown

getConnPerRoute

getLastRouteProbes

getLastRouteBackoffs

getCoolDown

getBackoffFactor

getCap

getTimeInterval