Bucket (bucket4j-core 4.0.1 API)

All Known Subinterfaces:

LocalBucket

All Known Implementing Classes:

AbstractBucket, GridBucket, LockFreeBucket, SynchronizedBucket
```
public interface Bucket
```
Performs rate limiting using algorithm based on top of ideas of Token Bucket.
Use following links for further details:
- Basic example of usage
- Advanced examples of usage

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`addTokens(long tokensToAdd)` Add `tokensToAdd` to bucket.
`AsyncBucket`	`asAsync()` Returns asynchronous view of this bucket.
`AsyncScheduledBucket`	`asAsyncScheduler()` Returns asynchronous view of this bucket that allows to use bucket as async scheduler.
`BlockingBucket`	`asScheduler()` Returns the `BlockingBucket` view of this bucket, that provides operations which are able to block caller thread.
`BucketState`	`createSnapshot()` Creates the copy of internal state.
`long`	`getAvailableTokens()` Returns amount of available tokens in this bucket.
`boolean`	`isAsyncModeSupported()` Describes whether or not this bucket supports asynchronous mode.
`void`	`replaceConfiguration(BucketConfiguration newConfiguration)` Replaces configuration of this bucket instance.
`Bucket`	`toListenable(BucketListener listener)` Returns new copy of this bucket instance decorated by `listener`.
`boolean`	`tryConsume(long numTokens)` Tries to consume a specified number of tokens from this bucket.
`ConsumptionProbe`	`tryConsumeAndReturnRemaining(long numTokens)` Tries to consume a specified number of tokens from this bucket.
`long`	`tryConsumeAsMuchAsPossible()` Tries to consume as much tokens from this bucket as available at the moment of invocation.
`long`	`tryConsumeAsMuchAsPossible(long limit)` Tries to consume as much tokens from bucket as available in the bucket at the moment of invocation, but tokens which should be consumed is limited by `limit`.

- Method Detail
  - asScheduler
```
BlockingBucket asScheduler()
```
    Returns the BlockingBucket view of this bucket, that provides operations which are able to block caller thread.
    
    Returns:
    
    the view to bucket that can be used as scheduler
  - isAsyncModeSupported
```
boolean isAsyncModeSupported()
```
    Describes whether or not this bucket supports asynchronous mode.
    If asynchronous mode is not supported any attempt to call asAsync() will fail with UnsupportedOperationException
    
    Returns:
    
    true if this extension supports asynchronous mode.
  - asAsync
```
AsyncBucket asAsync()
```
    Returns asynchronous view of this bucket.
    If asynchronous mode is not supported by particular extension behind this bucket, then any attempt to call this method will fail with UnsupportedOperationException.
    
    Returns:
    
    Asynchronous view of this bucket.
    
    Throws:
    
    UnsupportedOperationException - if particular extension behind the bucket does not support asynchronous mode.
  - asAsyncScheduler
```
AsyncScheduledBucket asAsyncScheduler()
```
    Returns asynchronous view of this bucket that allows to use bucket as async scheduler.
    If asynchronous mode is not supported by particular extension behind this bucket, then any attempt to call this method will fail with UnsupportedOperationException.
    
    Returns:
    
    Asynchronous view of this bucket that allows to use bucket as async scheduler.
    
    Throws:
    
    UnsupportedOperationException - if particular extension behind the bucket does not support asynchronous mode.
  - tryConsume
```
boolean tryConsume(long numTokens)
```
    Tries to consume a specified number of tokens from this bucket.
    
    Parameters:
    
    numTokens - The number of tokens to consume from the bucket, must be a positive number.
    
    Returns:
    
    true if the tokens were consumed, false otherwise.
  - tryConsumeAndReturnRemaining
```
ConsumptionProbe tryConsumeAndReturnRemaining(long numTokens)
```
    Tries to consume a specified number of tokens from this bucket.
    
    Parameters:
    
    numTokens - The number of tokens to consume from the bucket, must be a positive number.
    
    Returns:
    
    ConsumptionProbe which describes both result of consumption and tokens remaining in the bucket after consumption.
  - tryConsumeAsMuchAsPossible
```
long tryConsumeAsMuchAsPossible()
```
    Tries to consume as much tokens from this bucket as available at the moment of invocation.
    
    Returns:
    
    number of tokens which has been consumed, or zero if was consumed nothing.
  - tryConsumeAsMuchAsPossible
```
long tryConsumeAsMuchAsPossible(long limit)
```
    Tries to consume as much tokens from bucket as available in the bucket at the moment of invocation, but tokens which should be consumed is limited by limit.
    
    Parameters:
    
    limit - maximum number of tokens to consume, should be positive.
    
    Returns:
    
    number of tokens which has been consumed, or zero if was consumed nothing.
  - addTokens
```
void addTokens(long tokensToAdd)
```
    Add tokensToAdd to bucket. Resulted count of tokens are calculated by following formula:
```
newTokens = Math.min(capacity, currentTokens + tokensToAdd)
```
    in other words resulted number of tokens never exceeds capacity independent of tokensToAdd.
    Example of usage
    The "compensating transaction" is one of obvious use case, when any piece of code consumed tokens from bucket, tried to do something and failed, the "addTokens" will be helpful to return tokens back to bucket:
```
      Bucket wallet;
      ...
      if(wallet.tryConsume(50)) {// get 50 cents from wallet
         try {
             buyCocaCola();
         } catch(NoCocaColaException e) {
             // return money to wallet
             wallet.addTokens(50);
         }
      };
 
```
    Parameters:
    
    tokensToAdd - number of tokens to add
  - getAvailableTokens
```
long getAvailableTokens()
```
    Returns amount of available tokens in this bucket.
    This method designed to be used only for monitoring and testing, you should never use this method for business cases, because available tokens can be changed by concurrent transactions for case of multithreaded/multi-process environment.
    
    Returns:
    
    amount of available tokens
  - replaceConfiguration
```
void replaceConfiguration(BucketConfiguration newConfiguration)
```
    Replaces configuration of this bucket instance.
    Rules of reconfiguration:
    - New configuration can be applied if and only if it describes same count of bandwidths which already configured, else IncompatibleConfigurationException will be thrown. In other words you must not try to reduce or increase count of bandwidths, it is impossible to create bucket with one bandwidth and reconfigure to use two bandwidths and vice-versa.
    - If new configuration defines capacity which greater than current available tokens, then current available tokens stay unchanged.
    - If new configuration defines capacity which lesser than current available tokens, then current available tokens will be reduced to capacity. For example: if bandwidth at moment of reconfiguration has 90 tokens, and new capacity is 70 tokens then available tokens will be reduced from 90 to 70 according to new rules.
    Parameters:
    
    newConfiguration - the new configuration for this bucket
    
    Throws:
    
    IncompatibleConfigurationException - if newConfiguration incompatible with previous configuration
  - createSnapshot
```
BucketState createSnapshot()
```
    Creates the copy of internal state.
    This method is designed to be used only for monitoring and testing, you should never use this method for business cases.
    
    Returns:
    
    snapshot of internal state
  - toListenable
```
Bucket toListenable(BucketListener listener)
```
    Returns new copy of this bucket instance decorated by listener. See javadocs for BucketListener in order to understand semantic of listener.
    
    Parameters:
    
    listener - the listener of bucket events.
    
    Returns:
    
    new bucket instance decorated by listener

Interface Bucket

Method Summary

Method Detail

asScheduler

isAsyncModeSupported

asAsync

asAsyncScheduler

tryConsume

tryConsumeAndReturnRemaining

tryConsumeAsMuchAsPossible

tryConsumeAsMuchAsPossible

addTokens

Example of usage

getAvailableTokens

replaceConfiguration

createSnapshot

toListenable