base/bif/cardinality-counter.bif.bro

GLOBAL

Functions to create and manipulate probabilistic cardinality counters.

Namespace:GLOBAL
Source File:/scripts/base/bif/cardinality-counter.bif.bro

Summary

Functions

hll_cardinality_add: function Adds an element to a HyperLogLog cardinality counter.
hll_cardinality_copy: function Copy a HLL cardinality counter.
hll_cardinality_estimate: function Estimate the current cardinality of an HLL cardinality counter.
hll_cardinality_init: function Initializes a probabilistic cardinality counter that uses the HyperLogLog algorithm.
hll_cardinality_merge_into: function Merges a HLL cardinality counter into another.

Detailed Interface

Functions

hll_cardinality_add
Type:function (handle: opaque of cardinality, elem: any) : bool

Adds an element to a HyperLogLog cardinality counter.

Handle:the HLL handle.
Elem:the element to add.
Returns:true on success.

See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_init, hll_cardinality_copy

hll_cardinality_copy
Type:function (handle: opaque of cardinality) : opaque of cardinality

Copy a HLL cardinality counter.

Handle:cardinality counter to copy.
Returns:copy of handle.

See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_init

hll_cardinality_estimate
Type:function (handle: opaque of cardinality) : double

Estimate the current cardinality of an HLL cardinality counter.

Handle:the HLL handle.
Returns:the cardinality estimate. Returns -1.0 if the counter is empty.

See also: hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_init, hll_cardinality_copy

hll_cardinality_init
Type:function (err: double, confidence: double) : opaque of cardinality

Initializes a probabilistic cardinality counter that uses the HyperLogLog algorithm.

Err:the desired error rate (e.g. 0.01).
Confidence:the desired confidence for the error rate (e.g., 0.95).
Returns:a HLL cardinality handle.

See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_copy

hll_cardinality_merge_into
Type:function (handle1: opaque of cardinality, handle2: opaque of cardinality) : bool

Merges a HLL cardinality counter into another.

Note

The same restrictions as for Bloom filter merging apply, see bloomfilter_merge.

Handle1:the first HLL handle, which will contain the merged result.
Handle2:the second HLL handle, which will be merged into the first.
Returns:true on success.

See also: hll_cardinality_estimate, hll_cardinality_add, hll_cardinality_init, hll_cardinality_copy


Copyright 2016, The Bro Project. Last updated on December 13, 2017. Created using Sphinx 1.5.2.