From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 25 Feb 2013 19:05:15 +0000 (-0500)
Subject: Add write metadata API to ust-ctl.h
X-Git-Url: http://git.efficios.com/?a=commitdiff_plain;h=c9023c9304149ee1a4134571fdc41fd5e2e2a1a9;p=lttng-ust.git

Add write metadata API to ust-ctl.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/lttng/ust-ctl.h b/include/lttng/ust-ctl.h
index ae4f3089..3171b315 100644
--- a/include/lttng/ust-ctl.h
+++ b/include/lttng/ust-ctl.h
@@ -146,6 +146,12 @@ void ustctl_destroy_channel(struct ustctl_consumer_channel *chan);
 
 int ustctl_send_channel_to_sessiond(int sock,
 		struct ustctl_consumer_channel *channel);
+
+int ustctl_write_metadata_to_channel(
+		struct ustctl_consumer_channel *channel,
+		const char *metadata_str,	/* NOT null-terminated */
+		size_t len);			/* metadata length */
+
 /*
  * Send a NULL stream to finish iteration over all streams of a given
  * channel.
diff --git a/liblttng-ust-ctl/ustctl.c b/liblttng-ust-ctl/ustctl.c
index d47a5b50..ff4a537b 100644
--- a/liblttng-ust-ctl/ustctl.c
+++ b/liblttng-ust-ctl/ustctl.c
@@ -30,6 +30,13 @@
 
 #include "../libringbuffer/backend.h"
 #include "../libringbuffer/frontend.h"
+#include "../liblttng-ust/wait.h"
+
+/*
+ * Number of milliseconds to retry before failing metadata writes on
+ * buffer full condition. (10 seconds)
+ */
+#define LTTNG_METADATA_TIMEOUT_MSEC	10000
 
 /*
  * Channel representation within consumer.
@@ -844,6 +851,50 @@ int ustctl_send_stream_to_sessiond(int sock,
 			0);
 }
 
+int ustctl_write_metadata_to_channel(
+		struct ustctl_consumer_channel *channel,
+		const char *metadata_str,	/* NOT null-terminated */
+		size_t len)			/* metadata length */
+{
+	struct lttng_ust_lib_ring_buffer_ctx ctx;
+	struct lttng_channel *chan = channel->chan;
+	const char *str = metadata_str;
+	int ret = 0, waitret;
+	size_t reserve_len, pos;
+
+	for (pos = 0; pos < len; pos += reserve_len) {
+		reserve_len = min_t(size_t,
+				chan->ops->packet_avail_size(chan->chan, chan->handle),
+				len - pos);
+		lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
+					 sizeof(char), -1, chan->handle);
+		/*
+		 * We don't care about metadata buffer's records lost
+		 * count, because we always retry here. Report error if
+		 * we need to bail out after timeout or being
+		 * interrupted.
+		 */
+		waitret = wait_cond_interruptible_timeout(
+			({
+				ret = chan->ops->event_reserve(&ctx, 0);
+				ret != -ENOBUFS || !ret;
+			}),
+			LTTNG_METADATA_TIMEOUT_MSEC);
+		if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
+			DBG("LTTng: Failure to write metadata to buffers (%s)\n",
+				waitret == -EINTR ? "interrupted" :
+					(ret == -ENOBUFS ? "timeout" : "I/O error"));
+			if (waitret == -EINTR)
+				ret = waitret;
+			goto end;
+		}
+		chan->ops->event_write(&ctx, &str[pos], reserve_len);
+		chan->ops->event_commit(&ctx);
+	}
+end:
+	return ret;
+}
+
 int ustctl_stream_close_wait_fd(struct ustctl_consumer_stream *stream)
 {
 	struct channel *chan;