* [lttng-dev] [PATCH babeltrace] Fix: lttng-live flush when output to file
@ 2016-04-19 22:42 Mathieu Desnoyers
2016-04-20 21:03 ` Jérémie Galarneau
0 siblings, 1 reply; 2+ messages in thread
From: Mathieu Desnoyers @ 2016-04-19 22:42 UTC (permalink / raw)
When the standard output is redirected to a file, we need to flush the
output between each packet, otherwise the stream buffering may keep us
from seeing events for a while in a low-throughput trace.
While we are there, document that lttng-live does now support the
--output option in babeltrace 1.x.
Fixes #1010
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
doc/babeltrace.1 | 3 ++-
formats/lttng-live/lttng-live-comm.c | 13 ++++++++++++-
formats/lttng-live/lttng-live-plugin.c | 6 ++++++
formats/lttng-live/lttng-live.h | 7 +++++++
4 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/doc/babeltrace.1 b/doc/babeltrace.1
index f783105..cee9f7b 100644
--- a/doc/babeltrace.1
+++ b/doc/babeltrace.1
@@ -100,7 +100,8 @@ babeltrace-log(1), lttng(1), lttng-ust(3), lttng-sessiond(8)
.SH "BUGS"
.PP
-No known bugs at this point.
+The lttng-live plugin does not honor the the "--output" command line
+option.
If you encounter any issues or usability problem, please report it on
our mailing list <lttng-dev at lists.lttng.org> to help improve this
diff --git a/formats/lttng-live/lttng-live-comm.c b/formats/lttng-live/lttng-live-comm.c
index cea50ff..729df6f 100644
--- a/formats/lttng-live/lttng-live-comm.c
+++ b/formats/lttng-live/lttng-live-comm.c
@@ -246,7 +246,7 @@ void print_session_list(GPtrArray *session_list, const char *path)
for (i = 0; i < session_list->len; i++) {
relay_session = g_ptr_array_index(session_list, i);
- fprintf(stdout, "%s/host/%s/%s (timer = %u, "
+ fprintf(LTTNG_LIVE_OUTPUT_FP, "%s/host/%s/%s (timer = %u, "
"%u stream(s), %u client(s) connected)\n",
path, relay_session->hostname,
relay_session->name, relay_session->timer,
@@ -649,6 +649,17 @@ retry:
ret = -1;
goto end;
}
+
+ /*
+ * Flush the output between attempt to grab a packet, thus
+ * ensuring we flush at least at the periodical timer period.
+ * This is useful when the output is redirected to a file.
+ */
+ if (fflush(LTTNG_LIVE_OUTPUT_FP) < 0) {
+ perror("fflush");
+ goto error;
+ }
+
cmd.cmd = htobe32(LTTNG_VIEWER_GET_PACKET);
cmd.data_size = htobe64(sizeof(rq));
cmd.cmd_version = htobe32(0);
diff --git a/formats/lttng-live/lttng-live-plugin.c b/formats/lttng-live/lttng-live-plugin.c
index bf71b2b..771801c 100644
--- a/formats/lttng-live/lttng-live-plugin.c
+++ b/formats/lttng-live/lttng-live-plugin.c
@@ -292,6 +292,12 @@ struct bt_trace_descriptor *lttng_live_open_trace(const char *path, int flags,
pos->parent.rw_table = NULL;
pos->parent.event_cb = NULL;
pos->parent.trace = &pos->trace_descriptor;
+ /*
+ * Since we do *everything* in this function, we are skipping
+ * the output plugin handling that is part of Babeltrace 1.x.
+ * Therefore, don't expect the --output cmd line option to work.
+ * This limits the output of lttng-live to stderr and stdout.
+ */
if (lttng_live_open_trace_read(path) < 0) {
goto error;
}
diff --git a/formats/lttng-live/lttng-live.h b/formats/lttng-live/lttng-live.h
index 553cd34..e00a51e 100644
--- a/formats/lttng-live/lttng-live.h
+++ b/formats/lttng-live/lttng-live.h
@@ -32,6 +32,13 @@
#define LTTNG_LIVE_MAJOR 2
#define LTTNG_LIVE_MINOR 4
+/*
+ * The lttng-live output file pointer is currently hardcoded to stdout,
+ * and is expected to be hardcoded to this by fflush() performed between
+ * each packet.
+ */
+#define LTTNG_LIVE_OUTPUT_FP stdout
+
struct lttng_live_ctx {
char traced_hostname[MAXNAMLEN];
char session_name[MAXNAMLEN];
--
2.1.4
^ permalink raw reply [flat|nested] 2+ messages in thread
* [lttng-dev] [PATCH babeltrace] Fix: lttng-live flush when output to file
2016-04-19 22:42 [lttng-dev] [PATCH babeltrace] Fix: lttng-live flush when output to file Mathieu Desnoyers
@ 2016-04-20 21:03 ` Jérémie Galarneau
0 siblings, 0 replies; 2+ messages in thread
From: Jérémie Galarneau @ 2016-04-20 21:03 UTC (permalink / raw)
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 4355 bytes --]
Merged in master and stable-1.3. Thanks!
Jérémie
On Tue, Apr 19, 2016 at 6:42 PM, Mathieu Desnoyers
<mathieu.desnoyers at efficios.com> wrote:
> When the standard output is redirected to a file, we need to flush the
> output between each packet, otherwise the stream buffering may keep us
> from seeing events for a while in a low-throughput trace.
>
> While we are there, document that lttng-live does now support the
> --output option in babeltrace 1.x.
>
> Fixes #1010
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> ---
> doc/babeltrace.1 | 3 ++-
> formats/lttng-live/lttng-live-comm.c | 13 ++++++++++++-
> formats/lttng-live/lttng-live-plugin.c | 6 ++++++
> formats/lttng-live/lttng-live.h | 7 +++++++
> 4 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/doc/babeltrace.1 b/doc/babeltrace.1
> index f783105..cee9f7b 100644
> --- a/doc/babeltrace.1
> +++ b/doc/babeltrace.1
> @@ -100,7 +100,8 @@ babeltrace-log(1), lttng(1), lttng-ust(3), lttng-sessiond(8)
> .SH "BUGS"
>
> .PP
> -No known bugs at this point.
> +The lttng-live plugin does not honor the the "--output" command line
> +option.
>
> If you encounter any issues or usability problem, please report it on
> our mailing list <lttng-dev at lists.lttng.org> to help improve this
> diff --git a/formats/lttng-live/lttng-live-comm.c b/formats/lttng-live/lttng-live-comm.c
> index cea50ff..729df6f 100644
> --- a/formats/lttng-live/lttng-live-comm.c
> +++ b/formats/lttng-live/lttng-live-comm.c
> @@ -246,7 +246,7 @@ void print_session_list(GPtrArray *session_list, const char *path)
>
> for (i = 0; i < session_list->len; i++) {
> relay_session = g_ptr_array_index(session_list, i);
> - fprintf(stdout, "%s/host/%s/%s (timer = %u, "
> + fprintf(LTTNG_LIVE_OUTPUT_FP, "%s/host/%s/%s (timer = %u, "
> "%u stream(s), %u client(s) connected)\n",
> path, relay_session->hostname,
> relay_session->name, relay_session->timer,
> @@ -649,6 +649,17 @@ retry:
> ret = -1;
> goto end;
> }
> +
> + /*
> + * Flush the output between attempt to grab a packet, thus
> + * ensuring we flush at least at the periodical timer period.
> + * This is useful when the output is redirected to a file.
> + */
> + if (fflush(LTTNG_LIVE_OUTPUT_FP) < 0) {
> + perror("fflush");
> + goto error;
> + }
> +
> cmd.cmd = htobe32(LTTNG_VIEWER_GET_PACKET);
> cmd.data_size = htobe64(sizeof(rq));
> cmd.cmd_version = htobe32(0);
> diff --git a/formats/lttng-live/lttng-live-plugin.c b/formats/lttng-live/lttng-live-plugin.c
> index bf71b2b..771801c 100644
> --- a/formats/lttng-live/lttng-live-plugin.c
> +++ b/formats/lttng-live/lttng-live-plugin.c
> @@ -292,6 +292,12 @@ struct bt_trace_descriptor *lttng_live_open_trace(const char *path, int flags,
> pos->parent.rw_table = NULL;
> pos->parent.event_cb = NULL;
> pos->parent.trace = &pos->trace_descriptor;
> + /*
> + * Since we do *everything* in this function, we are skipping
> + * the output plugin handling that is part of Babeltrace 1.x.
> + * Therefore, don't expect the --output cmd line option to work.
> + * This limits the output of lttng-live to stderr and stdout.
> + */
> if (lttng_live_open_trace_read(path) < 0) {
> goto error;
> }
> diff --git a/formats/lttng-live/lttng-live.h b/formats/lttng-live/lttng-live.h
> index 553cd34..e00a51e 100644
> --- a/formats/lttng-live/lttng-live.h
> +++ b/formats/lttng-live/lttng-live.h
> @@ -32,6 +32,13 @@
> #define LTTNG_LIVE_MAJOR 2
> #define LTTNG_LIVE_MINOR 4
>
> +/*
> + * The lttng-live output file pointer is currently hardcoded to stdout,
> + * and is expected to be hardcoded to this by fflush() performed between
> + * each packet.
> + */
> +#define LTTNG_LIVE_OUTPUT_FP stdout
> +
> struct lttng_live_ctx {
> char traced_hostname[MAXNAMLEN];
> char session_name[MAXNAMLEN];
> --
> 2.1.4
>
--
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com
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