fix: remove while loop for setbit & getbit (#2687)

Constant time `setbit` and `getbit` in the bloom filter - was hitting performance issues when using a 30mb bloom filter

Author: dozyio

packages/utils/benchmark/filter/bloom-filter.cjs

@@ -0,0 +1,26 @@
+/* eslint-disable no-console */
+const Benchmark = require('benchmark')
+
+const suite = new Benchmark.Suite('bloom-filter')
+
+const bits = [8, 64, 512, 4096, 32768, 262144, 2097152, 251658240]
+
+bits.forEach((bit) => {
+  suite.add(`Loop ${bit}bits`, () => {
+    let pos = 0
+    let shift = bit
+    while (shift > 7) {
+      pos++
+      shift -= 8
+    }
+  })
+
+  suite.add(`Math Ops ${bit}bits`, () => {
+    _ = Math.floor(bit / 8)
+    _ = bit % 8
+  })
+})
+
+suite
+  .on('cycle', (event) => console.log(String(event.target)))
+  .run({ async: true })

packages/utils/package.json

@@ -178,6 +178,7 @@
   "devDependencies": {
     "@types/netmask": "^2.0.5",
     "aegir": "^44.0.1",
+    "benchmark": "^2.1.4",
     "delay": "^6.0.0",
     "it-all": "^3.0.6",
     "it-drain": "^3.0.7",

packages/utils/src/filters/bloom-filter.ts

@@ -78,25 +78,17 @@ export class BloomFilter implements Filter {
   }
 
   setbit (bit: number): void {
-    let pos = 0
-    let shift = bit
-    while (shift > 7) {
-      pos++
-      shift -= 8
-    }
+    const pos = Math.floor(bit / 8)
+    const shift = bit % 8
 
     let bitfield = this.buffer[pos]
     bitfield |= (0x1 << shift)
     this.buffer[pos] = bitfield
   }
 
   getbit (bit: number): boolean {
-    let pos = 0
-    let shift = bit
-    while (shift > 7) {
-      pos++
-      shift -= 8
-    }
+    const pos = Math.floor(bit / 8)
+    const shift = bit % 8
 
     const bitfield = this.buffer[pos]
     return (bitfield & (0x1 << shift)) !== 0