From eaef17bcaf8b28de19856a31a0e77ee917dbe51e Mon Sep 17 00:00:00 2001
From: preciz <barna.kovacs@tutanota.com>
Date: Fri, 12 Jun 2026 19:33:28 +0200
Subject: [PATCH] Optimize Keyword.pop/3, pop!/2, and pop_lazy/3
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Eliminate redundant list traversal by calling :lists.keyfind + delete_key
directly instead of going through fetch/2 + delete/2.

The old code performed 3 traversals when the key was present:
1. :lists.keyfind (inside fetch)
2. :lists.keymember (inside delete — redundant)
3. delete_key (inside delete)

The new code performs 2 traversals:
1. :lists.keyfind (find the value)
2. delete_key (remove all matching entries)

Benchmark shows ~1.15x speedup on avg (noisy system)
---
 lib/elixir/lib/keyword.ex | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/elixir/lib/keyword.ex b/lib/elixir/lib/keyword.ex
index f6f57e8b7ce..984838066c5 100644
--- a/lib/elixir/lib/keyword.ex
+++ b/lib/elixir/lib/keyword.ex
@@ -1342,9 +1342,9 @@ defmodule Keyword do
   """
   @spec pop(t, key, default) :: {value | default, t}
   def pop(keywords, key, default \\ nil) when is_list(keywords) and is_atom(key) do
-    case fetch(keywords, key) do
-      {:ok, value} -> {value, delete(keywords, key)}
-      :error -> {default, keywords}
+    case :lists.keyfind(key, 1, keywords) do
+      {^key, value} -> {value, delete_key(keywords, key)}
+      false -> {default, keywords}
     end
   end
 
@@ -1369,9 +1369,9 @@ defmodule Keyword do
   @doc since: "1.10.0"
   @spec pop!(t, key) :: {value, t}
   def pop!(keywords, key) when is_list(keywords) and is_atom(key) do
-    case fetch(keywords, key) do
-      {:ok, value} -> {value, delete(keywords, key)}
-      :error -> raise KeyError, key: key, term: keywords
+    case :lists.keyfind(key, 1, keywords) do
+      {^key, value} -> {value, delete_key(keywords, key)}
+      false -> raise KeyError, key: key, term: keywords
     end
   end
 
@@ -1434,9 +1434,9 @@ defmodule Keyword do
   @spec pop_lazy(t, key, (-> value)) :: {value, t}
   def pop_lazy(keywords, key, fun)
       when is_list(keywords) and is_atom(key) and is_function(fun, 0) do
-    case fetch(keywords, key) do
-      {:ok, value} -> {value, delete(keywords, key)}
-      :error -> {fun.(), keywords}
+    case :lists.keyfind(key, 1, keywords) do
+      {^key, value} -> {value, delete_key(keywords, key)}
+      false -> {fun.(), keywords}
     end
   end