From edb93a7c280ef134ded39a2d1b12fe614b1501b0 Mon Sep 17 00:00:00 2001
From: Andrew Hayworth <andrew.hayworth@getbraintree.com>
Date: Tue, 27 Oct 2015 21:46:25 +0000
Subject: [PATCH] MINOR: cli: ability to set per-server maxconn

This commit adds support for setting a per-server maxconn from the stats
socket. The only really notable part of this commit is that we need to
check if maxconn == minconn before changing things, as this indicates
that we are NOT using dynamic maxconn. When we are not using dynamic
maxconn, we should update maxconn/minconn in lockstep.
---
 doc/management.txt |  5 +++++
 src/dumpstats.c    | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/doc/management.txt b/doc/management.txt
index d67988b42..a53a953a3 100644
--- a/doc/management.txt
+++ b/doc/management.txt
@@ -1356,6 +1356,11 @@ set maxconn frontend <frontend> <value>
   delayed until the threshold is reached. The frontend might be specified by
   either its name or its numeric ID prefixed with a sharp ('#').
 
+set maxconn server <backend/server> <value>
+  Dynamically change the specified server's maxconn setting. Any positive
+  value is allowed including zero, but setting values larger than the global
+  maxconn does not make much sense.
+
 set maxconn global <maxconn>
   Dynamically change the global maxconn setting within the range defined by the
   initial global maxconn setting. If it is increased and connections were
diff --git a/src/dumpstats.c b/src/dumpstats.c
index e80e45c91..b83dfb80b 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -1646,6 +1646,38 @@ static int stats_sock_parse_request(struct stream_interface *si, char *line)
 
 				return 1;
 			}
+			else if (strcmp(args[2], "server") == 0) {
+				struct server *sv;
+				int v;
+
+				sv = expect_server_admin(s, si, args[3]);
+				if (!sv)
+					return 1;
+
+				if (!*args[4]) {
+					appctx->ctx.cli.msg = "Integer value expected.\n";
+					appctx->st0 = STAT_CLI_PRINT;
+					return 1;
+				}
+
+				v = atoi(args[4]);
+				if (v < 0) {
+					appctx->ctx.cli.msg = "Value out of range.\n";
+					appctx->st0 = STAT_CLI_PRINT;
+					return 1;
+				}
+
+				if (sv->maxconn == sv->minconn) { // static maxconn
+					sv->maxconn = sv->minconn = v;
+				} else { // dynamic maxconn
+					sv->maxconn = v;
+				}
+
+				if (may_dequeue_tasks(sv, sv->proxy))
+					process_srv_queue(sv);
+
+				return 1;
+			}
 			else if (strcmp(args[2], "global") == 0) {
 				int v;
 
@@ -1681,7 +1713,7 @@ static int stats_sock_parse_request(struct stream_interface *si, char *line)
 				return 1;
 			}
 			else {
-				appctx->ctx.cli.msg = "'set maxconn' only supports 'frontend' and 'global'.\n";
+				appctx->ctx.cli.msg = "'set maxconn' only supports 'frontend', 'server', and 'global'.\n";
 				appctx->st0 = STAT_CLI_PRINT;
 				return 1;
 			}