sirius.kernel.commons

Class RateLimit

java.lang.Object

sirius.kernel.commons.RateLimit

public class RateLimit
extends Object

Limits calls to specified rate. Can be either time based, or invocation based.

This method check() can be called frequently. It will however only return true after a certain amount of time has elapsed or after a number of calls where made. The mode depends on how the object was created.

As an example, this can be used in an inner loop if one wants to print out the current status every once in a while. Since writing to System.out is comparatively slow, it's a good idea to apply a rate limit:

 
 RateLimit limit = RateLimit.everyNthCall(1000);
 for(int i = 0; i < 100000; i++) {
     // ...smart computation here...
     if (limit.check()) {
          System.out.println(i);
     }
 }
 
 

Method Summary

Modifier and Type	Method and Description
boolean	check() Checks whether the rate limit constraints permit another call or not.
static RateLimit	everyNthCall(long n) Creates a new call based rate limit.
static RateLimit	nTimesPerInterval(long interval, TimeUnit unit, int permitsPerInterval) Creates a new time based rate limit which permits up to N calls per interval.
static RateLimit	timeInterval(long interval, TimeUnit unit) Creates a new time based rate limit.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

everyNthCall

public static RateLimit everyNthCall(long n)

Creates a new call based rate limit.

Calling check() on will only return true every n-th call and false otherwise.

Parameters:

n - the number of calls to skip (returning false) by check() before true is returned

Returns:

a new call based rate limit

timeInterval

public static RateLimit timeInterval(long interval,
                                     TimeUnit unit)

Creates a new time based rate limit.

Calling check() on will only return true every after the given amount of time has be passed since the last time it returned true. Returns false otherwise.

Parameters:

interval - the amount of time after a call to check() returns true again

unit - the unit for amount

Returns:

a new time based rate limit

nTimesPerInterval

public static RateLimit nTimesPerInterval(long interval,
                                          TimeUnit unit,
                                          int permitsPerInterval)

Creates a new time based rate limit which permits up to N calls per interval.

Calling check() on will only return true N times in every given interval, false otherwise.

Parameters:

interval - the amount of time after a call to check() returns true again

unit - the unit for amount

permitsPerInterval - the number of times to return true per interval

Returns:

a new time based rate limit

check

public boolean check()

Checks whether the rate limit constraints permit another call or not.

Returns:

true if the call or time based rate limiting permit another call, flfalse otherwise

toString

public String toString()

Overrides:

toString in class Object