[Libguestfs] [PATCH nbdkit INCOMPLETE 5/6] filters: Move rdelay/wdelay from file plugin to new delay filter.
Richard W.M. Jones
rjones at redhat.com
Sun Jan 14 12:11:20 UTC 2018
Previously the file plugin supported ‘rdelay’ and ‘wdelay’ parameters
for injecting delays (for testing) into read and write requests. This
moves the functionality to a new delay filter so that it can be used
with any plugin.
---
TODO | 3 -
configure.ac | 1 +
filters/Makefile.am | 1 +
filters/delay/Makefile.am | 62 +++++++++++++
filters/delay/delay.c | 167 ++++++++++++++++++++++++++++++++++
filters/delay/nbdkit-delay-filter.pod | 88 ++++++++++++++++++
plugins/file/file.c | 76 +---------------
plugins/file/nbdkit-file-plugin.pod | 14 +--
8 files changed, 327 insertions(+), 85 deletions(-)
diff --git a/TODO b/TODO
index 8eda0d7..3ec45fd 100644
--- a/TODO
+++ b/TODO
@@ -37,9 +37,6 @@ directed to qemu-nbd for these use cases.
Suggestions for filters
-----------------------
-* adding artificial delays (see wdelay/rdelay options in the file
- plugin)
-
* injecting artificial errors for testing clients
* copy-on-write, a popular feature in other servers
diff --git a/configure.ac b/configure.ac
index 4892dc4..9376a2e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -513,6 +513,7 @@ AC_CONFIG_FILES([Makefile
plugins/vddk/Makefile
plugins/xz/Makefile
filters/Makefile
+ filters/delay/Makefile
filters/offset/Makefile
src/Makefile
src/nbdkit.pc
diff --git a/filters/Makefile.am b/filters/Makefile.am
index 91fbe6c..e4b2942 100644
--- a/filters/Makefile.am
+++ b/filters/Makefile.am
@@ -31,4 +31,5 @@
# SUCH DAMAGE.
SUBDIRS = \
+ delay
offset
diff --git a/filters/delay/Makefile.am b/filters/delay/Makefile.am
new file mode 100644
index 0000000..5b20b69
--- /dev/null
+++ b/filters/delay/Makefile.am
@@ -0,0 +1,62 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+EXTRA_DIST = nbdkit-delay-filter.pod
+
+CLEANFILES = *~
+
+filterdir = $(libdir)/nbdkit/filters
+
+filter_LTLIBRARIES = nbdkit-delay-filter.la
+
+nbdkit_delay_filter_la_SOURCES = \
+ delay.c \
+ $(top_srcdir)/include/nbdkit-filter.h
+
+nbdkit_delay_filter_la_CPPFLAGS = \
+ -I$(top_srcdir)/include
+nbdkit_delay_filter_la_CFLAGS = \
+ $(WARNINGS_CFLAGS)
+nbdkit_delay_filter_la_LDFLAGS = \
+ -module -avoid-version -shared
+
+if HAVE_POD2MAN
+
+man_MANS = nbdkit-delay-filter.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-delay-filter.1: nbdkit-delay-filter.pod
+ $(POD2MAN) $(POD2MAN_ARGS) --section=1 --name=`basename $@ .1` $< $@.t && \
+ if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
+ mv $@.t $@
+
+endif
diff --git a/filters/delay/delay.c b/filters/delay/delay.c
new file mode 100644
index 0000000..24033cd
--- /dev/null
+++ b/filters/delay/delay.c
@@ -0,0 +1,167 @@
+/* nbdkit
+ * Copyright (C) 2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <time.h>
+
+#include <nbdkit-filter.h>
+
+static int rdelayms = 0; /* read delay (milliseconds) */
+static int wdelayms = 0; /* write delay (milliseconds) */
+
+static int
+parse_delay (const char *value)
+{
+ size_t len = strlen (value);
+ int r;
+
+ if (len > 2 && strcmp (&value[len-2], "ms") == 0) {
+ if (sscanf (value, "%d", &r) == 1)
+ return r;
+ else {
+ nbdkit_error ("cannot parse rdelay/wdelay milliseconds parameter: %s",
+ value);
+ return -1;
+ }
+ }
+ else {
+ if (sscanf (value, "%d", &r) == 1)
+ return r * 1000;
+ else {
+ nbdkit_error ("cannot parse rdelay/wdelay seconds parameter: %s",
+ value);
+ return -1;
+ }
+ }
+}
+
+static void
+delay (int ms)
+{
+ if (ms > 0) {
+ const struct timespec ts = {
+ .tv_sec = ms / 1000,
+ .tv_nsec = (ms * 1000000) % 1000000000
+ };
+ nanosleep (&ts, NULL);
+ }
+}
+
+static void
+read_delay (void)
+{
+ delay (rdelayms);
+}
+
+static void
+write_delay (void)
+{
+ delay (wdelayms);
+}
+
+/* Called for each key=value passed on the command line. */
+static int
+delay_config (const char *key, const char *value,
+ int (*next) (void *data, const char *key, const char *value),
+ void *data)
+{
+ if (strcmp (key, "rdelay") == 0) {
+ rdelayms = parse_delay (value);
+ if (rdelayms == -1)
+ return -1;
+ return 0;
+ }
+ else if (strcmp (key, "wdelay") == 0) {
+ wdelayms = parse_delay (value);
+ if (wdelayms == -1)
+ return -1;
+ return 0;
+ }
+ else
+ return next (data, key, value);
+}
+
+#define delay_config_help \
+ "rdelay=<NN>[ms] Read delay in seconds/milliseconds.\n" \
+ "wdelay=<NN>[ms] Write delay in seconds/milliseconds." \
+
+/* Read data. */
+static int
+delay_pread (void *handle, void *buf, uint32_t count, uint64_t offset,
+ int (*next) (void *data,
+ void *buf, uint32_t count, uint64_t offset),
+ void *data)
+{
+ read_delay ();
+ return next (data, buf, count, offset);
+}
+
+/* Write data. */
+static int
+delay_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
+ int (*next) (void *data,
+ const void *buf, uint32_t count, uint64_t offset),
+ void *data)
+{
+ write_delay ();
+ return next (data, buf, count, offset);
+}
+
+/* Zero data. */
+static int
+delay_zero (void *handle, uint32_t count, uint64_t offset, int may_trim,
+ int (*next) (void *data,
+ uint32_t count, uint64_t offset, int may_trim),
+ void *data)
+{
+ write_delay ();
+ return next (data, count, offset, may_trim);
+}
+
+static struct nbdkit_filter filter = {
+ .name = "delay",
+ .longname = "nbdkit delay filter",
+ .version = PACKAGE_VERSION,
+ .config = delay_config,
+ .config_help = delay_config_help,
+ .pread = delay_pread,
+ .pwrite = delay_pwrite,
+ .zero = delay_zero,
+};
+
+NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/delay/nbdkit-delay-filter.pod b/filters/delay/nbdkit-delay-filter.pod
new file mode 100644
index 0000000..10aba94
--- /dev/null
+++ b/filters/delay/nbdkit-delay-filter.pod
@@ -0,0 +1,88 @@
+=encoding utf8
+
+=head1 NAME
+
+nbdkit-delay-filter - nbdkit delay filter
+
+=head1 SYNOPSIS
+
+ nbdkit --filter=delay plugin rdelay=SECS wdelay=SECS [plugin-args...]
+
+ nbdkit --filter=delay plugin rdelay=<NN>ms wdelay=<NN>ms [plugin-args...]
+
+=head1 DESCRIPTION
+
+C<nbdkit-delay-filter> is a filter that delays read and write requests
+by some seconds or milliseconds. This is used to simulate a slow or
+remote server, or to test certain kinds of race conditions in Linux.
+
+=head1 PARAMETERS
+
+=over 4
+
+=item B<rdelay=SECS>
+
+=item B<rdelay=E<lt>NNE<gt>ms>
+
+The optional read delay in seconds or milliseconds.
+
+=item B<wdelay=SECS>
+
+=item B<wdelay=E<lt>NNE<gt>ms>
+
+The optional write delay in seconds or milliseconds.
+
+=back
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-filter(3)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright (C) 2018 Red Hat Inc.
+
+=head1 LICENSE
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+=over 4
+
+=item *
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+=item *
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+=item *
+
+Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+=back
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/plugins/file/file.c b/plugins/file/file.c
index 4a91251..1fe4191 100644
--- a/plugins/file/file.c
+++ b/plugins/file/file.c
@@ -40,7 +40,6 @@
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
-#include <time.h>
#include <errno.h>
#include <nbdkit-plugin.h>
@@ -50,8 +49,6 @@
#endif
static char *filename = NULL;
-static int rdelayms = 0; /* read delay (milliseconds) */
-static int wdelayms = 0; /* write delay (milliseconds) */
static void
file_unload (void)
@@ -59,56 +56,6 @@ file_unload (void)
free (filename);
}
-static int
-parse_delay (const char *value)
-{
- size_t len = strlen (value);
- int r;
-
- if (len > 2 && strcmp (&value[len-2], "ms") == 0) {
- if (sscanf (value, "%d", &r) == 1)
- return r;
- else {
- nbdkit_error ("cannot parse rdelay/wdelay milliseconds parameter: %s",
- value);
- return -1;
- }
- }
- else {
- if (sscanf (value, "%d", &r) == 1)
- return r * 1000;
- else {
- nbdkit_error ("cannot parse rdelay/wdelay seconds parameter: %s",
- value);
- return -1;
- }
- }
-}
-
-static void
-delay (int ms)
-{
- if (ms > 0) {
- const struct timespec ts = {
- .tv_sec = ms / 1000,
- .tv_nsec = (ms * 1000000) % 1000000000
- };
- nanosleep (&ts, NULL);
- }
-}
-
-static void
-read_delay (void)
-{
- delay (rdelayms);
-}
-
-static void
-write_delay (void)
-{
- delay (wdelayms);
-}
-
/* Called for each key=value passed on the command line. This plugin
* only accepts file=<filename>, which is required.
*/
@@ -122,15 +69,10 @@ file_config (const char *key, const char *value)
if (!filename)
return -1;
}
- else if (strcmp (key, "rdelay") == 0) {
- rdelayms = parse_delay (value);
- if (rdelayms == -1)
- return -1;
- }
- else if (strcmp (key, "wdelay") == 0) {
- wdelayms = parse_delay (value);
- if (wdelayms == -1)
- return -1;
+ else if (strcmp (key, "rdelay") == 0 ||
+ strcmp (key, "wdelay") == 0) {
+ nbdkit_error ("add --filter=delay on the command line");
+ return -1;
}
else {
nbdkit_error ("unknown parameter '%s'", key);
@@ -157,9 +99,7 @@ file_config_complete (void)
}
#define file_config_help \
- "file=<FILENAME> (required) The filename to serve.\n" \
- "rdelay=<NN>[ms] Read delay in seconds/milliseconds.\n" \
- "wdelay=<NN>[ms] Write delay in seconds/milliseconds." \
+ "file=<FILENAME> (required) The filename to serve." \
/* The per-connection handle. */
struct handle {
@@ -241,8 +181,6 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset)
{
struct handle *h = handle;
- read_delay ();
-
while (count > 0) {
ssize_t r = pread (h->fd, buf, count, offset);
if (r == -1) {
@@ -267,8 +205,6 @@ file_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset)
{
struct handle *h = handle;
- write_delay ();
-
while (count > 0) {
ssize_t r = pwrite (h->fd, buf, count, offset);
if (r == -1) {
@@ -292,8 +228,6 @@ file_zero (void *handle, uint32_t count, uint64_t offset, int may_trim)
#endif
int r = -1;
- write_delay ();
-
#ifdef FALLOC_FL_PUNCH_HOLE
if (may_trim) {
r = fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
diff --git a/plugins/file/nbdkit-file-plugin.pod b/plugins/file/nbdkit-file-plugin.pod
index a2d1e6a..016513a 100644
--- a/plugins/file/nbdkit-file-plugin.pod
+++ b/plugins/file/nbdkit-file-plugin.pod
@@ -31,21 +31,13 @@ This parameter is required.
=item B<rdelay=E<lt>NNE<gt>ms>
-Delay reads for C<SECS> seconds or C<NN> milliseconds.
-This is used to simulate a slow or remote server, or to
-test certain kinds of race conditions in Linux.
-
-The default is no delay.
-
=item B<wdelay=SECS>
=item B<wdelay=E<lt>NNE<gt>ms>
-Delay writes for C<SECS> seconds or C<NN> milliseconds.
-This is used to simulate a slow or remote server, or to
-test certain kinds of race conditions in Linux.
-
-The default is no delay.
+These plugin parameters have been moved to the
+L<nbdkit-delay-filter(1)> filter. Modify the command line to add
+I<--filter=delay> in order to use these parameters.
=back
--
2.15.1
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