From 5524b8ed3819f6764c09eaa85d8f68b955f79d9d Mon Sep 17 00:00:00 2001
From: "Stephen R. van den Berg" <srb@cuci.nl>
Date: Wed, 8 Aug 2018 15:37:09 +0200
Subject: [PATCH] pgsql: Avoid excessive latency on frequent ping()s.
---
lib/modules/Sql.pmod/pgsql.h | 1 +
lib/modules/Sql.pmod/pgsql.pike | 11 +++++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/lib/modules/Sql.pmod/pgsql.h b/lib/modules/Sql.pmod/pgsql.h
index 67d8301899..e2fb97ef9f 100644
--- a/lib/modules/Sql.pmod/pgsql.h
+++ b/lib/modules/Sql.pmod/pgsql.h
@@ -30,6 +30,7 @@
#define QUERYTIMEOUT 4095 // Queries running longer than this number
// of seconds are canceled automatically
#define PORTALBUFFERSIZE (32*1024) // Approximate buffer per portal
+#define MINPINGINTERVAL 4 // minimum seconds between ping()s
#define BACKOFFDELAY 1
#define PGSQL_DEFAULT_PORT 5432
diff --git a/lib/modules/Sql.pmod/pgsql.pike b/lib/modules/Sql.pmod/pgsql.pike
index d968066088..948a6707f9 100644
--- a/lib/modules/Sql.pmod/pgsql.pike
+++ b/lib/modules/Sql.pmod/pgsql.pike
@@ -80,6 +80,7 @@ private int portalbuffersize = PORTALBUFFERSIZE;
private int timeout = QUERYTIMEOUT;
private array connparmcache;
private int reconnected;
+private int lastping = time(1);
protected string _sprintf(int type) {
string res;
@@ -253,9 +254,15 @@ protected void create(void|string host, void|string database,
//! @seealso
//! @[is_open()]
/*semi*/final int ping() {
+ int t, ret;
waitauthready();
- return is_open()
- && !catch(proxy.c->start()->sendcmd(FLUSHSEND)) ? !!reconnected : -1;
+ if ((ret = is_open())
+ // Pinging more frequently than MINPINGINTERVAL seconds
+ // is suppressed to avoid artificial TCP-ACK latency
+ && (t = time(1)) - lastping > MINPINGINTERVAL
+ && (ret = !catch(proxy.c->start()->sendcmd(FLUSHSEND))))
+ lastping = t;
+ return ret ? !!reconnected : -1;
}
//! Cancels all currently running queries in this session.
--
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