From b7b2fe14a868efb1727975537ad88deccf3fde7b Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Tue, 14 Apr 2026 12:45:23 +0300
Subject: [PATCH] all: This code is in time out (fixes #21319)

---
 vlib/math/big/bench/bench_edigits.v | 85 +++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 vlib/math/big/bench/bench_edigits.v

diff --git a/vlib/math/big/bench/bench_edigits.v b/vlib/math/big/bench/bench_edigits.v
new file mode 100644
index 000000000..dcd71fc90
--- /dev/null
+++ b/vlib/math/big/bench/bench_edigits.v
@@ -0,0 +1,85 @@
+module main
+
+import benchmark
+import math
+import math.big
+import os
+import strconv
+
+// Regression benchmark for issue #21319.
+// It mirrors the external edigits workload without printing every line,
+// so the timing stays focused on `math.big`.
+const default_n = 250_001
+const one = big.one_int
+const ten = big.c10
+
+fn main() {
+	mut n := default_n
+	if os.args.len > 1 {
+		n = strconv.atoi(os.args[1]) or { default_n }
+	}
+	mut clock := benchmark.start()
+	k := binary_search(n)
+	clock.measure('k=${k}')
+	mut p, q := sum_terms(0, k - 1)
+	clock.measure('sum_terms p.bit_len=${p.bit_len()} q.bit_len=${q.bit_len()}')
+	p += q
+	a := ten.pow(u32(n - 1))
+	clock.measure('pow 10^${n - 1}')
+	answer := p * a / q
+	clock.measure('division answer.bit_len=${answer.bit_len()}')
+	s := answer.str()
+	clock.measure('str digits=${s.len}')
+	if s.len != n {
+		eprintln('unexpected digit count: got ${s.len}, want ${n}')
+		return
+	}
+	println(last_line(s, n))
+}
+
+fn sum_terms(a int, b int) (big.Integer, big.Integer) {
+	if b == a + 1 {
+		return one, big.integer_from_int(b)
+	}
+	mid := (a + b) / 2
+	p_left, q_left := sum_terms(a, mid)
+	p_right, q_right := sum_terms(mid, b)
+	return p_left * q_right + p_right, q_left * q_right
+}
+
+fn binary_search(n int) int {
+	mut a := 0
+	mut b := 1
+	for !test_k(n, b) {
+		a = b
+		b *= 2
+	}
+	for b - a > 1 {
+		m := (a + b) / 2
+		if test_k(n, m) {
+			b = m
+		} else {
+			a = m
+		}
+	}
+	return b
+}
+
+fn test_k(n int, k int) bool {
+	if k < 0 {
+		return false
+	}
+	ln_k_factorial := k * (math.log(k) - 1) + 0.5 * math.log(math.tau)
+	log_10_k_factorial := ln_k_factorial / math.ln10
+	return log_10_k_factorial >= n + 50
+}
+
+fn last_line(s string, n int) string {
+	chunk_len := if n % 10 == 0 { 10 } else { n % 10 }
+	start := n - chunk_len
+	mut line := s[start..n]
+	for line.len < 10 {
+		line += ' '
+	}
+	return '${line}\t:${n}'
+}
-- 
2.39.5