Re: [Libguestfs] [PATCH nbdkit v3 3/3] retry: Add a test of this filter.
On 9/19/19 10:26 AM, Richard W.M. Jones wrote:
We use a custom sh plugin to test retries are working.
---
tests/Makefile.am | 8 +++
tests/test-retry-reopen-fail.sh | 108 ++++++++++++++++++++++++++++++++
tests/test-retry.sh | 97 ++++++++++++++++++++++++++++
3 files changed, 213 insertions(+)
+++ b/tests/test-retry-reopen-fail.sh
+
+# Create a custom plugin which will test retrying.
+nbdkit -v -U - --filter=retry \
+ sh - \
+ --run 'qemu-img convert $nbd retry-reopen-fail.img'
<<'EOF'
+case "$1" in
+ open)
+ # Count how many times the connection is (re-)opened.
+ i=`cat retry-reopen-fail-open-count`
$() is nicer than ``, but even better is just:
read i retry-reopen-fail-open-count
+ ((i++))
+ echo $i > retry-reopen-fail-open-count
Potentially racy if more than one thread tries to do this - but sh
plugins don't default to parallel and you aren't requesting parallel
mode, so we are safe due to serialization. But maybe worth a comment?
+ if [ $i -eq 2 ]; then
+ echo "EIO open failed" >&2
+ exit 1
+ fi
+ ;;
+ pread)
+ # Fail 3 times then succeed, and count how long it takes.
+ i=`cat retry-reopen-fail-count`
same thing about using 'read'
+
+# In this test we should see 4 failures:
+# pread FAILS
+# retry and wait 2 seconds
+# open FAILS
+# retry and wait 4 seconds
+# open succeeds
+# pread FAILS
+# retry and wait 8 seconds
+# pread FAILS
+# retry and wait 16 seconds
+# pread succeeds
+
+# The minimum time for the test should be 2+4+8+16 = 30 seconds.
+start_t=`stat -c '%Z' retry-reopen-fail-start`
+end_t=`date +'%s'`
+if [ $((end_t - start_t)) -lt 30 ]; then
+ echo "$0: test ran too quickly"
+ exit 1
+fi
Slows down 'make check'; is there any way we can scale it to be slightly
faster, such as using a smaller retry interval than just 1 second as our
starting point?
+
+# Check the handle was opened 5 times.
+retry_open_count=`cat retry-reopen-fail-open-count`
Another potential 'read' spot.
+if [ $retry_open_count -ne 5 ]; then
+ echo "$0: retry-reopen-fail-open-count ($retry_open_count) != 5"
+ exit 1
+fi
diff --git a/tests/test-retry.sh b/tests/test-retry.sh
new file mode 100755
index 0000000..47d6e23
--- /dev/null
+++ b/tests/test-retry.sh
+touch retry-start
+
+# Create a custom plugin which will test retrying.
+nbdkit -v -U - --filter=retry \
+ sh - \
+ --run 'qemu-img convert $nbd retry.img' <<'EOF'
+case "$1" in
+ open)
+ # Count how many times the connection is (re-)opened.
+ i=`cat retry-open-count`
and more in this file
+
+# The minimum time for the test should be 2+4+8 = 14 seconds.
+start_t=`stat -c '%Z' retry-start`
+end_t=`date +'%s'`
I'm not sure how portable this will be to non-Linux, but we'll deal with
that when someone complains. It may also be an issue if filesystem time
is skewed in relation to system date.
Bash includes $SECONDS which auto-increments at 1-second intervals,
would testing that be more reliable than stat/date?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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