org.forgerock.bloomfilter

Enum ConcurrencyStrategy

java.lang.Object

java.lang.Enum<ConcurrencyStrategy>

org.forgerock.bloomfilter.ConcurrencyStrategy

All Implemented Interfaces:

Serializable, Comparable<ConcurrencyStrategy>

public enum ConcurrencyStrategy
extends Enum<ConcurrencyStrategy>

Strategy that determines how thread-safety of bloom filters should be managed. Different strategies have different trade-offs in terms of memory usage and read or write performance.

Enum Constant Summary

Enum Constants

Enum Constant and Description
ATOMIC Uses atomic compare-and-set (CAS) instructions to implement BloomFilter operations over AtomicLongArrays.
COPY_ON_WRITE Treats Bloom Filters as effectively immutable objects and creates a copy when applying updates before atomically swapping with the original.
SYNCHRONIZED Fully synchronizes all accesses to the bloom filter.

Method Summary

Modifier and Type	Method and Description
static ConcurrencyStrategy	valueOf(String name) Returns the enum constant of this type with the specified name.
static ConcurrencyStrategy[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

COPY_ON_WRITE

public static final ConcurrencyStrategy COPY_ON_WRITE

Treats Bloom Filters as effectively immutable objects and creates a copy when applying updates before atomically swapping with the original. This strategy optimises read (mightContain) performance at the cost of significantly more expensive write (add/addAll) times and increased garbage collection pressure due to the temporary copies that are created. This is the recommended strategy if read performance is critical. Writing batching can be used to mitigate the poor write performance (even exceeding the synchronized strategy) and somewhat mitigate the additional garbage creation.

SYNCHRONIZED

public static final ConcurrencyStrategy SYNCHRONIZED

Fully synchronizes all accesses to the bloom filter. For scalable and rolling bloom filters, each bucket in the chain is synchronized individually, allowing a finer level of locking. This strategy provides a reasonable compromise between read and write performance when read performance is not critical. Additionally, this strategy creates significantly less garbage collection pressure than the copy-on-write strategy as it modifies bloom filters in-place.

ATOMIC

public static final ConcurrencyStrategy ATOMIC

Uses atomic compare-and-set (CAS) instructions to implement BloomFilter operations over AtomicLongArrays. This strategy offers excellent performance for reads and writes with less garbage collection pressure than the Copy on Write strategy and comparable performance to that strategy even with write batching.

Method Detail

values

public static ConcurrencyStrategy[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (ConcurrencyStrategy c : ConcurrencyStrategy.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static ConcurrencyStrategy valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null