ApiErrorExponentialBackoff (Telegram Api 66.1 API)

java.lang.Object
- org.telegram.mtproto.backoff.ApiErrorExponentialBackoff

```
public class ApiErrorExponentialBackoff
extends Object
```
Implementation of BackOff that increases the back off period for each retry attempt using a randomization function that grows exponentially.
nextBackOffMillis() is calculated using the following formula:
```
 randomized_interval =
 retry_interval * (random value in range [1 - randomization_factor, 1 + randomization_factor])
 
```
In other words nextBackOffMillis() will range between the randomization factor percentage below and above the retry interval. For example, using 2 seconds as the base retry interval and 0.5 as the randomization factor, the actual back off period used in the next retry attempt will be between 1 and 3 seconds.

Note: max_interval caps the retry_interval and not the randomized_interval.

Example: The default retry_interval is .5 seconds, default randomization_factor is 0.5, default multiplier is 1.5 and the default max_interval is 1 minute. For 10 tries the sequence will be (values in seconds) and assuming we go over the max_elapsed_time on the 10th try:
```
 request#     retry_interval     randomized_interval

 1             0.5                [0.25,   0.75]
 2             0.75               [0.375,  1.125]
 3             1.125              [0.562,  1.687]
 4             1.687              [0.8435, 2.53]
 5             2.53               [1.265,  3.795]
 6             3.795              [1.897,  5.692]
 7             5.692              [2.846,  8.538]
 8             8.538              [4.269, 12.807]
 9            12.807              [6.403, 19.210]
 10           19.210              maxElapsedTimeMillis
 
```
Implementation is not thread-safe.
Since:

1.15

Author:

Ravi Mistry

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class ApiErrorExponentialBackoff.Builder
Builder for ApiErrorExponentialBackoff.

Nested Classes
Modifier and Type	Class and Description
`static class`	`ApiErrorExponentialBackoff.Builder` Builder for `ApiErrorExponentialBackoff`.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DEFAULT_INITIAL_INTERVAL_MILLIS` The default initial interval value in milliseconds (0.5 seconds).
`static int`	`DEFAULT_MAX_ELAPSED_TIME_MILLIS` The default maximum elapsed time in milliseconds (5 minutes).
`static int`	`DEFAULT_MAX_INTERVAL_MILLIS` The default maximum back off time in milliseconds (30 sec).
`static double`	`DEFAULT_MULTIPLIER` The default multiplier value (1.5 which is 50% increase per back off).
`static double`	`DEFAULT_RANDOMIZATION_FACTOR` The default randomization factor (0.5 which results in a random period ranging between 50% below and 50% above the retry interval).

Constructor Summary

Constructors
Modifier	Constructor and Description
	`ApiErrorExponentialBackoff()` Creates an instance of ExponentialBackOffPolicy using default values.
`protected`	`ApiErrorExponentialBackoff(ApiErrorExponentialBackoff.Builder builder)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`getCurrentIntervalMillis()` Returns the current retry interval in milliseconds.
`long`	`getElapsedTimeMillis()` Returns the elapsed time in milliseconds since an `ApiErrorExponentialBackoff` instance is created and is reset when `reset()` is called.
`int`	`getInitialIntervalMillis()` Returns the initial retry interval in milliseconds.
`int`	`getMaxElapsedTimeMillis()` Returns the maximum elapsed time in milliseconds.
`int`	`getMaxIntervalMillis()` Returns the maximum value of the back off period in milliseconds.
`double`	`getMultiplier()` Returns the value to multiply the current interval with for each retry attempt.
`double`	`getRandomizationFactor()` Returns the randomization factor to use for creating a range around the retry interval.
`long`	`nextBackOffMillis()`
`void`	`reset()` Sets the interval back to the initial retry interval and restarts the timer.

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

- Field Detail
  - DEFAULT_INITIAL_INTERVAL_MILLIS
```
public static final int DEFAULT_INITIAL_INTERVAL_MILLIS
```
    The default initial interval value in milliseconds (0.5 seconds).
    
    See Also:
    
    Constant Field Values
  - DEFAULT_RANDOMIZATION_FACTOR
```
public static final double DEFAULT_RANDOMIZATION_FACTOR
```
    The default randomization factor (0.5 which results in a random period ranging between 50% below and 50% above the retry interval).
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MULTIPLIER
```
public static final double DEFAULT_MULTIPLIER
```
    The default multiplier value (1.5 which is 50% increase per back off).
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_INTERVAL_MILLIS
```
public static final int DEFAULT_MAX_INTERVAL_MILLIS
```
    The default maximum back off time in milliseconds (30 sec).
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_ELAPSED_TIME_MILLIS
```
public static final int DEFAULT_MAX_ELAPSED_TIME_MILLIS
```
    The default maximum elapsed time in milliseconds (5 minutes).
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - ApiErrorExponentialBackoff
```
public ApiErrorExponentialBackoff()
```
    Creates an instance of ExponentialBackOffPolicy using default values.
    To override the defaults use ApiErrorExponentialBackoff.Builder.
    - initialIntervalMillis defaults to DEFAULT_INITIAL_INTERVAL_MILLIS
    - randomizationFactor defaults to DEFAULT_RANDOMIZATION_FACTOR
    - multiplier defaults to DEFAULT_MULTIPLIER
    - maxIntervalMillis defaults to DEFAULT_MAX_INTERVAL_MILLIS
    - maxElapsedTimeMillis defaults in DEFAULT_MAX_ELAPSED_TIME_MILLIS
  - ApiErrorExponentialBackoff
```
protected ApiErrorExponentialBackoff(ApiErrorExponentialBackoff.Builder builder)
```
    Parameters:
    
    builder - builder
- Method Detail
  - reset
```
public final void reset()
```
    Sets the interval back to the initial retry interval and restarts the timer.
  - nextBackOffMillis
```
public long nextBackOffMillis()
```
    This method calculates the next back off interval using the formula: randomized_interval = retry_interval +/- (randomization_factor * retry_interval)
    
    Subclasses may override if a different algorithm is required.
  - getInitialIntervalMillis
```
public final int getInitialIntervalMillis()
```
    Returns the initial retry interval in milliseconds.
  - getRandomizationFactor
```
public final double getRandomizationFactor()
```
    Returns the randomization factor to use for creating a range around the retry interval.
    A randomization factor of 0.5 results in a random period ranging between 50% below and 50% above the retry interval.
  - getCurrentIntervalMillis
```
public final int getCurrentIntervalMillis()
```
    Returns the current retry interval in milliseconds.
  - getMultiplier
```
public final double getMultiplier()
```
    Returns the value to multiply the current interval with for each retry attempt.
  - getMaxIntervalMillis
```
public final int getMaxIntervalMillis()
```
    Returns the maximum value of the back off period in milliseconds. Once the current interval reaches this value it stops increasing.
  - getMaxElapsedTimeMillis
```
public final int getMaxElapsedTimeMillis()
```
    Returns the maximum elapsed time in milliseconds.
    If the time elapsed since an ApiErrorExponentialBackoff instance is created goes past the max_elapsed_time then the method nextBackOffMillis() starts returning this value. The elapsed time can be reset by calling reset().
  - getElapsedTimeMillis
```
public final long getElapsedTimeMillis()
```
    Returns the elapsed time in milliseconds since an ApiErrorExponentialBackoff instance is created and is reset when reset() is called.
    The elapsed time is computed using System.nanoTime().

Class ApiErrorExponentialBackoff

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_INITIAL_INTERVAL_MILLIS

DEFAULT_RANDOMIZATION_FACTOR

DEFAULT_MULTIPLIER

DEFAULT_MAX_INTERVAL_MILLIS

DEFAULT_MAX_ELAPSED_TIME_MILLIS

Constructor Detail

ApiErrorExponentialBackoff

ApiErrorExponentialBackoff

Method Detail

reset

nextBackOffMillis

getInitialIntervalMillis

getRandomizationFactor

getCurrentIntervalMillis

getMultiplier

getMaxIntervalMillis

getMaxElapsedTimeMillis

getElapsedTimeMillis