10:58 p.m.
In the delay filter, all we need to do is pass through cache
operations, but with an added delay (well, technically, this isn't
enabled until a later patch flips the default for .can_cache to
pass-through).
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
filters/delay/nbdkit-delay-filter.pod | 9 ++++++++-
filters/delay/delay.c | 27 ++++++++++++++++++++++++++-
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/filters/delay/nbdkit-delay-filter.pod
b/filters/delay/nbdkit-delay-filter.pod
index 2e2ac74..730cea4 100644
--- a/filters/delay/nbdkit-delay-filter.pod
+++ b/filters/delay/nbdkit-delay-filter.pod
@@ -11,7 +11,7 @@ nbdkit-delay-filter - nbdkit delay filter
nbdkit --filter=delay plugin [plugin-args ...]
delay-read=(SECS|NNms) delay-write=(SECS|NNms)
delay-zero=(SECS|NNms) delay-trim=(SECS|NNms)
- delay-extents=(SECS|NNms)
+ delay-extents=(SECS|NNms) delay-cache=(SECS|NNms)
=head1 DESCRIPTION
@@ -71,6 +71,13 @@ Delay trim/discard operations by C<SECS> seconds or C<NN>
milliseconds.
Delay block status (extents) operations by C<SECS> seconds or C<NN>
milliseconds.
+=item B<delay-cache=>SECS
+
+=item B<delay-cache=>NNB<ms>
+
+Delay advisory cache operations by C<SECS> seconds or C<NN>
+milliseconds.
+
=item B<wdelay=>SECS
=item B<wdelay=>NNB<ms>
diff --git a/filters/delay/delay.c b/filters/delay/delay.c
index 862af93..486a24e 100644
--- a/filters/delay/delay.c
+++ b/filters/delay/delay.c
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2018 Red Hat Inc.
+ * Copyright (C) 2018-2019 Red Hat Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
@@ -47,6 +47,7 @@ static int delay_write_ms = 0; /* write delay (milliseconds) */
static int delay_zero_ms = 0; /* zero delay (milliseconds) */
static int delay_trim_ms = 0; /* trim delay (milliseconds) */
static int delay_extents_ms = 0;/* extents delay (milliseconds) */
+static int delay_cache_ms = 0; /* cache delay (milliseconds) */
static int
parse_delay (const char *key, const char *value)
@@ -116,6 +117,12 @@ extents_delay (void)
delay (delay_extents_ms);
}
+static void
+cache_delay (void)
+{
+ delay (delay_cache_ms);
+}
+
/* Called for each key=value passed on the command line. */
static int
delay_config (nbdkit_next_config *next, void *nxdata,
@@ -167,6 +174,12 @@ delay_config (nbdkit_next_config *next, void *nxdata,
return -1;
return 0;
}
+ else if (strcmp (key, "delay-cache") == 0) {
+ delay_cache_ms = parse_delay (key, value);
+ if (delay_cache_ms == -1)
+ return -1;
+ return 0;
+ }
else
return next (nxdata, key, value);
}
@@ -178,6 +191,7 @@ delay_config (nbdkit_next_config *next, void *nxdata,
"delay-zero=<NN>[ms] Zero delay in seconds/milliseconds.\n"
\
"delay-trim=<NN>[ms] Trim delay in seconds/milliseconds.\n"
\
"delay-extents=<NN>[ms] Extents delay in
seconds/milliseconds.\n" \
+ "delay-cache=<NN>[ms] Cache delay in seconds/milliseconds.\n"
\
"wdelay=<NN>[ms] Write, zero and trim delay in
secs/msecs."
/* Read data. */
@@ -231,6 +245,16 @@ delay_extents (struct nbdkit_next_ops *next_ops, void *nxdata,
return next_ops->extents (nxdata, count, offset, flags, extents, err);
}
+/* Cache. */
+static int
+delay_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, uint32_t flags,
+ int *err)
+{
+ cache_delay ();
+ return next_ops->cache (nxdata, count, offset, flags, err);
+}
+
static struct nbdkit_filter filter = {
.name = "delay",
.longname = "nbdkit delay filter",
@@ -242,6 +266,7 @@ static struct nbdkit_filter filter = {
.zero = delay_zero,
.trim = delay_trim,
.extents = delay_extents,
+ .cache = delay_cache,
};
NBDKIT_REGISTER_FILTER(filter)
--
2.20.1