[OSSTEST PATCH 07/16] cri-getconfig: Provide debugging for get_psql_cmd

[Ian Jackson <ian.jackson@eu.citrix.com>]

This allows us to execute only the first <some number> SQL
invocations.  The first non-executed one is dumped, instead, by having
get_psql_command print a rune involving ./mg-debug-fail (which the
caller will then execute).

The locking makes things work roughly-correctly if get_psql_cmd is run
in multiple processes at once: it is not defined exactly which
invocations get which counter values, but they will all work properly
and get exactly one counter value each.

If set -x is in force, turn it off for get_psql_cmd: our perl rune is
uninteresting to see repeated ad infinitum in debugging output.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
 cri-getconfig |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/cri-getconfig b/cri-getconfig
index 973f1c0..7b75700 100644
--- a/cri-getconfig
+++ b/cri-getconfig
@@ -41,6 +41,22 @@ getrepos() {
 }
 
 get_psql_cmd () {
+	# To use this:
+	#  on each test run, rm -f t.psql-counter
+	#  and set OSSTEST_PSQL_ONLY_DO to an integer
+	if [ "x$OSSTEST_PSQL_ONLY_DO" != x ]; then
+		local f=t.psql-counter
+		psql_counter=$( with-lock-ex -w $f.lock bash -ec '
+			psql_counter=$(cat '$f' || echo 0)
+			echo $(( $psql_counter + 1 )) >'$f'.tmp
+			mv -f '$f'.tmp '$f'
+			echo $psql_counter' )
+		if ! [ $psql_counter -lt $OSSTEST_PSQL_ONLY_DO ]; then
+			printf './mg-debug-fail '
+		fi
+	fi
+
+	set +x
 	perl -we '
 	use Osstest;
 	use Osstest::Executive;
-- 
1.7.10.4