From: Willy Tarreau <w@1wt.eu>
Date: Sun, 15 Sep 2024 21:05:50 +0000 (+0200)
Subject: OPTIM: vars: remove the unneeded lock in vars_prune_*
X-Git-Tag: v3.1-dev8~28
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=aad6b771dd270680e3cf1850fa47fbfc8d0f1538;p=thirdparty%2Fhaproxy.git

OPTIM: vars: remove the unneeded lock in vars_prune_*

vars_prune() and vars_prune_all() take the variable lock while purging
all variables from a head. However this is not needed:
  - proc scope variables are only purged during deinit, hence no lock
    is needed ;
  - all other scopes are attached to entities bound to a single thread
    so no lock is needed either.

Removing the lock saves about 0.5% CPU on variables-intensive setups,
but above all simplify the code, so let's do it.
---

diff --git a/src/vars.c b/src/vars.c
index 0e2029de77..772ae34022 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -203,11 +203,10 @@ void vars_prune(struct vars *vars, struct session *sess, struct stream *strm)
 	struct var *var, *tmp;
 	unsigned int size = 0;
 
-	vars_wrlock(vars);
 	list_for_each_entry_safe(var, tmp, &vars->head, l) {
 		size += var_clear(var, 1);
 	}
-	vars_wrunlock(vars);
+
 	var_accounting_diff(vars, sess, strm, -size);
 }
 
@@ -219,11 +218,9 @@ void vars_prune_per_sess(struct vars *vars)
 	struct var *var, *tmp;
 	unsigned int size = 0;
 
-	vars_wrlock(vars);
 	list_for_each_entry_safe(var, tmp, &vars->head, l) {
 		size += var_clear(var, 1);
 	}
-	vars_wrunlock(vars);
 
 	if (var_sess_limit)
 		_HA_ATOMIC_SUB(&vars->size, size);