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bloomfilter/v0 package

Overview

Package bloomfilter ports the classic Bloom filter data structure to gno.land: a fixed-size bit array plus k independent hash functions that let you test set membership with zero false negatives and a small, bounded false-positive rate — without ever storing the actual items.

Membership is checked via double hashing (Kirsch–Mitzenmacher): two base hashes h1, h2 are combined as h1 + i*h2 to derive k bit positions per item, avoiding the cost of k independent hash functions.

Add is a crossing function per the gno 0.9 interrealm convention (it takes `cur realm` as its first parameter); MightContain and Stats are read-only.

Functions

Add

func Add(cur realm, item string)

Add inserts `item` into the filter. Crossing function: any caller (user or realm) may add, matching this demo's open-membership model.

Param

Command

# WARNING: This command is running in an INSECURE mode.
# It is strongly recommended to use a hardware device for signing
# and avoid trusting any computer connected to the internet,
# as your private keys could be exposed.

gnokey maketx call -pkgpath "gno.land/r/moul/x/daily/bloomfilter/v0" -func "Add" -args $'' -gas-fee 1000000ugnot -gas-wanted 1_000_000_000 -send "" -chainid "gnoland-1" -remote "https://rpc.gno.land" ADDRESSgnokey query -remote "https://rpc.gno.land" auth/accounts/ADDRESS
gnokey maketx call -pkgpath "gno.land/r/moul/x/daily/bloomfilter/v0" -func "Add" -args $'' -gas-fee 1000000ugnot -gas-wanted 1_000_000_000 -send "" -broadcast=false ADDRESS > call.tx
gnokey sign -tx-path call.tx -chainid "gnoland-1" -account-number ACCOUNTNUMBER -account-sequence SEQUENCENUMBER ADDRESS
gnokey broadcast -remote "https://rpc.gno.land" call.tx

FalsePositiveRatePercent

func FalsePositiveRatePercent() float64

FalsePositiveRatePercent estimates the current false-positive rate, in percent, as (bitsSet/m)^k — the standard Bloom filter approximation once bits are randomly distributed. Computed with plain integer/float math to avoid depending on math.Exp/Pow availability.

Command

gnokey query vm/qeval -remote "https://rpc.gno.land" -data "gno.land/r/moul/x/daily/bloomfilter/v0.FalsePositiveRatePercent()"

Result

MightContain

func MightContain(item string) bool

MightContain reports whether `item` was possibly added before. A false (definitely-not-a-member) answer is always correct; a true answer can occasionally be a false positive, never a false negative.

Param

Command

gnokey query vm/qeval -remote "https://rpc.gno.land" -data "gno.land/r/moul/x/daily/bloomfilter/v0.MightContain()"

Result

Render

func Render(path string) string

Render draws the filter's current stats and recently-added items as Markdown for gnoweb.

Param

Command

gnokey query vm/qeval -remote "https://rpc.gno.land" -data "gno.land/r/moul/x/daily/bloomfilter/v0.Render()"

Result

Stats

func Stats() (int, int, int, int)

Stats returns the raw counters backing the Render view and FalsePositiveRatePercent: (itemsAdded, bitsSet, totalBits, hashCount).

Command

gnokey query vm/qeval -remote "https://rpc.gno.land" -data "gno.land/r/moul/x/daily/bloomfilter/v0.Stats()"

Result