Module cuckoo_filter

Description
Data Types
Function Index
Function Details

High-performance, concurrent, and mutable Cuckoo Filter implemented using atomics for Erlang and Elixir.

Description

High-performance, concurrent, and mutable Cuckoo Filter implemented using atomics for Erlang and Elixir.

Data Types

option()

option() = {fingerprint_size, 4 | 8 | 16 | 32 | 64} | {bucket_size, pos_integer()} | {max_evictions, non_neg_integer()} | {hash_function, fun((binary()) -> non_neg_integer())}

Function Index

add/2	Equivalent to `add(Filter, Data, infinity)`.
add/3	Adds data to the filter.
capacity/1	Returns the maximum capacity of the filter.
contains/2	Checks if data is in the filter.
delete/2	Equivalent to `delete(Filter, Data, infinity)`.
delete/3	Deletes data from the filter.
export/1	Returns all buckets in the filter as a binary.
import/2	Imports filter data from a binary created using `export/1`.
new/1	Equivalent to `new(Capacity, [])`.
new/2	Creates a new cuckoo filter with the given capacity and options.
size/1	Returns number of items in the filter.

Function Details

add/2

add(Filter::cuckoo_filter(), Data::term()) -> ok | {error, not_enough_space}

Equivalent to add(Filter, Data, infinity).

add/3

add(Filter::cuckoo_filter(), Data::term(), LockTimeout::timeout()) -> ok | {error, not_enough_space | timeout}

Adds data to the filter.

Returns ok if the insertion was successful, but could return {error, not_enough_space}, when the filter is nearing its capacity.

When LockTimeout is given, it could return {error, timeout}, if it can not acquire the lock within LockTimeout milliseconds.

capacity/1

capacity(Cuckoo_filter::cuckoo_filter()) -> pos_integer()

Returns the maximum capacity of the filter.

contains/2

contains(Filter::cuckoo_filter(), Data::term()) -> boolean()

Checks if data is in the filter.

delete/2

delete(Filter::cuckoo_filter(), Data::term()) -> ok | {error, not_found}

Equivalent to delete(Filter, Data, infinity).

delete/3

delete(Filter::cuckoo_filter(), Data::term(), LockTimeout::timeout()) -> ok | {error, not_found | timeout}

Deletes data from the filter.

Returns ok if the deletion was successful, and returns {error, not_found} if the element could not be found in the filter.

When LockTimeout is given, it could return {error, timeout}, if it can not acquire the lock within LockTimeout milliseconds.

Note: A cuckoo filter can only delete items that are known to be inserted before. Deleting of non inserted items might lead to deletion of another random element.

export/1

export(Filter::cuckoo_filter()) -> binary()

Returns all buckets in the filter as a binary.

Returned binary can be used to reconstruct the filter again, using import/2 function.

import/2

import(Filter::cuckoo_filter(), Data::binary()) -> ok | {error, invalid_data_size}

Imports filter data from a binary created using export/1.

Returns ok if the import was successful, but could return {ok, invalid_data_size} if the size of the given binary does not match the size of the filter.

new/1

new(Capacity::pos_integer()) -> cuckoo_filter()

Equivalent to new(Capacity, []).

new/2

new(Capacity::pos_integer(), Opts::options()) -> cuckoo_filter()

Creates a new cuckoo filter with the given capacity and options

Note that the actual capacity might be higher than the given capacity, because internally number of buckets in a cuckoo filter must be a power of 2.

Possible options are:

{fingerprint_size, FingerprintSize}
FingerprintSize can be one of 4, 8, 16, 32, and 64 bits. Default fingerprint size is 16 bits.
{bucket_size, BucketSize}

BucketSize must be a non negative integer, and the default value is 4. Higher bucket sizes can reduce insert time considerably since it reduces the number of relocations of existing fingerprints in occupied buckets, but it increases the lookup time, and false positive rate.

{max_evictions, MaxEvictions}

MaxEvictions indicates the maximum number of relocation attemps before giving up when inserting a new element.

{hash_function, HashFunction}

You can specify a custom hash function that accepts a binary as argument and returns hash value as an integer.

size/1

size(Cuckoo_filter::cuckoo_filter()) -> non_neg_integer()

Returns number of items in the filter.

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