Fix resolver test: prefetch disabled

The previous test had two problems:
1. It wasn't written specifically for testing what it was supposed to:
prefetch disabled.
2. It could fail in some circunstances if the computer's load is too
high, due to sleeps not taking parallel tests and cpu load into account.

The new test is testing prefetch disabled as follows:
1. It asks for a txt record for a given domain and takes note of the
record's TTL (which is 10).
2. It sleeps for (TTL - 5) = 5 seconds, having a window of 5 seconds to
issue new queries before the record expires from cache.
3. Three(3) queries are executed in a row, with a interval of 1 second
between them, and for each query we verify that the TTL in response is
less than the previous one, thus ensuring that prefetch is disabled (if
it were enabled this record would have been refreshed already and TTL
would be >= the first TTL).

Having a window of 5 seconds to perform 3 queries with a interval of 1
second between them gives the test a reasonable amount of time
to not suffer from a machine with heavy load.

(cherry picked from commit dd524cc893c12c777eeb4505bec031c6e4c7baa9)

diff --git a/bin/tests/system/resolver/tests.sh b/bin/tests/system/resolver/tests.sh
index 4e63125084ee0eb0d4f59e80ecd23234a2910358..ee886fd0b29b40184d8e00d3b76e5e478ff6590e 100755 (executable)
--- a/bin/tests/system/resolver/tests.sh
+++ b/bin/tests/system/resolver/tests.sh
@@ -491,25 +491,26 @@ n=`expr $n + 1`
 echo_i "check prefetch disabled (${n})"
 ret=0
 $DIG $DIGOPTS @10.53.0.7 fetch.example.net txt > dig.out.1.${n} || ret=1
-ttl1=`awk '/"A" "short" "ttl"/ { print $2 - 2 }' dig.out.1.${n}`
+ttl1=`awk '/"A" "short" "ttl"/ { print $2 }' dig.out.1.${n}`
+delay=$((ttl1 - 5))
 # sleep so we are in expire range
-sleep ${ttl1:-0}
-# look for ttl = 1, allow for one miss at getting zero ttl
-zerotonine="0 1 2 3 4 5 6 7 8 9"
-for i in $zerotonine $zerotonine $zerotonine $zerotonine
-do
+sleep ${delay:-0}
+tmp_ttl=$ttl1
+# fetch record and ensure its ttl is in range 0 < ttl < tmp_ttl
+# since prefetch is disabled, updated ttl must be a lower value than
+# the previous one.
+for i in 0 1 3; do
        $DIG $DIGOPTS @10.53.0.7 fetch.example.net txt > dig.out.2.${n} || ret=1
        ttl2=`awk '/"A" "short" "ttl"/ { print $2 }' dig.out.2.${n}`
-       test ${ttl2:-2} -eq 1 && break
-       $PERL -e 'select(undef, undef, undef, 0.05);'
+        # check that prefetch has not occured
+        if [ $ttl2 -ge $tmp_ttl ]; then
+                ret=1
+                break
+        fi
+        tmp_ttl=$ttl2
+       $PERL -e 'select(undef, undef, undef, 1);'
 done
-test ${ttl2:-2} -eq 1 || ret=1
-# delay so that any prefetched record will have a lower ttl than expected
-sleep 3
-# check that prefetch has not occured
-$DIG $DIGOPTS @10.53.0.7 fetch.example.net txt > dig.out.3.${n} || ret=1
-ttl=`awk '/"A" "short" "ttl"/ { print $2 - 2 }' dig.out.3.${n}`
-test ${ttl:-0} -eq ${ttl1:-1} || ret=1
+
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`