From 1a759c83278fcdae11ee5da8318b646b9d47129c Mon Sep 17 00:00:00 2001
From: Daniel Gustafsson <dgustafsson@postgresql.org>
Date: Tue, 25 Mar 2025 17:53:33 +0100
Subject: psql: Make default \watch interval configurable

The default interval for \watch to wait between executing queries,
when executed without a specified interval, was hardcoded to two
seconds.  This adds the new variable WATCH_INTERVAL which is used
to set the default interval, making it configurable for the user.
This makes \watch the first command which has a user configurable
default setting.

Author: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Masahiro Ikeda <ikedamsh@oss.nttdata.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-by: Greg Sabino Mullane <htamfids@gmail.com>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://postgr.es/m/B2FD26B4-8F64-4552-A603-5CC3DF1C7103@yesql.se
---
 src/bin/psql/variables.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

(limited to 'src/bin/psql/variables.c')

diff --git a/src/bin/psql/variables.c b/src/bin/psql/variables.c
index 59956028918..5150eb0532b 100644
--- a/src/bin/psql/variables.c
+++ b/src/bin/psql/variables.c
@@ -7,6 +7,8 @@
  */
 #include "postgres_fe.h"
 
+#include <math.h>
+
 #include "common.h"
 #include "common/logging.h"
 #include "variables.h"
@@ -179,6 +181,74 @@ ParseVariableNum(const char *value, const char *name, int *result)
 	}
 }
 
+/*
+ * Try to interpret "value" as a double value, and if successful store it in
+ * *result. If unsuccessful, *result isn't clobbered. "name" is the variable
+ * which is being assigned, the value of which is only used to produce a good
+ * error message. Pass NULL as the name to suppress the error message.  The
+ * value must be within the range [min,max] in order to be considered valid.
+ *
+ * Returns true, with *result containing the interpreted value, if "value" is
+ * syntactically valid, else false (with *result unchanged).
+ */
+bool
+ParseVariableDouble(const char *value, const char *name, double *result, double min, double max)
+{
+	char	   *end;
+	double		dblval;
+
+	/*
+	 * Empty-string input has historically been treated differently by strtod
+	 * on various platforms, so handle that by specifically checking for it.
+	 */
+	if ((value == NULL) || (*value == '\0'))
+	{
+		if (name)
+			pg_log_error("invalid input syntax for \"%s\"", name);
+		return false;
+	}
+
+	errno = 0;
+	dblval = strtod(value, &end);
+	if (errno == 0 && *end == '\0' && end != value)
+	{
+		if (dblval < min)
+		{
+			if (name)
+				pg_log_error("invalid value \"%s\" for \"%s\": must be greater than %.2f",
+							 value, name, min);
+			return false;
+		}
+		else if (dblval > max)
+		{
+			if (name)
+				pg_log_error("invalid value \"%s\" for \"%s\": must be less than %.2f",
+							 value, name, max);
+		}
+		*result = dblval;
+		return true;
+	}
+
+	/*
+	 * Cater for platforms which treat values which aren't zero, but that are
+	 * too close to zero to have full precision, by checking for zero or real
+	 * out-of-range values.
+	 */
+	else if ((errno = ERANGE) &&
+			 (dblval == 0.0 || dblval >= HUGE_VAL || dblval <= -HUGE_VAL))
+	{
+		if (name)
+			pg_log_error("\"%s\" is out of range for \"%s\"", value, name);
+		return false;
+	}
+	else
+	{
+		if (name)
+			pg_log_error("invalid value \"%s\" for \"%s\"", value, name);
+		return false;
+	}
+}
+
 /*
  * Print values of all variables.
  */
-- 
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