Added a ring buffer log target to store the last N log messages.

The log target can be used via log alarms and show alarms.
Why? This feature was proposed/requested at
http://openbsc.osmocom.org/trac/wiki/Tasks/ErrorLogTarget
All messages use the same amount of space, prioritizing simplicity.

1 files changed, 98 insertions, 0 deletions

diff --git a/src/loggingrb.c b/src/loggingrb.c
new file mode 100644
index 00000000..b206fded
--- /dev/null
+++ b/src/loggingrb.c
@@ -0,0 +1,98 @@
+/* Ringbuffer-backed logging support code */
+
+/* (C) 2012-2013 by Katerina Barone-Adesi
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*! \addtogroup logging
+ *  @{
+ */
+
+/*! \file loggingrb.c */
+
+#include <osmocom/core/strrb.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/loggingrb.h>
+
+static void _rb_output(struct log_target *target,
+			  unsigned int level, const char *log)
+{
+	osmo_strrb_add(target->tgt_rb.rb, log);
+}
+
+/*! \brief Return the number of log strings in the osmo_strrb-backed target.
+ *  \param[in] target The target to search.
+ *
+ *  \return The number of log strings in the osmo_strrb-backed target.
+ */
+size_t log_target_rb_used_size(struct log_target const *target)
+{
+	return osmo_strrb_elements(target->tgt_rb.rb);
+}
+
+/*! \brief Return the capacity of the osmo_strrb-backed target.
+ *  \param[in] target The target to search.
+ *
+ * Note that this is the capacity (aka max number of messages).
+ * It is not the number of unused message slots.
+ *  \return The number of log strings in the osmo_strrb-backed target.
+ */
+size_t log_target_rb_avail_size(struct log_target const *target)
+{
+	struct osmo_strrb *rb = target->tgt_rb.rb;
+	return rb->size - 1;
+}
+
+/*! \brief Return the nth log entry in a target.
+ *  \param[in] target The target to search.
+ *  \param[in] logindex The index of the log entry/error message.
+ *
+ *  \return A pointer to the nth message, or NULL if logindex is invalid.
+ */
+const char *log_target_rb_get(struct log_target const *target, size_t logindex)
+{
+	return osmo_strrb_get_nth(target->tgt_rb.rb, logindex);
+}
+
+/*! \brief Create a new logging target for ringbuffer-backed logging.
+ *  \param[in] size The capacity (number of messages) of the logging target.
+ *  \returns A log target in case of success, NULL in case of error.
+ */
+struct log_target *log_target_create_rb(size_t size)
+{
+	struct log_target *target;
+	struct osmo_strrb *rb;
+
+	target = log_target_create();
+	if (!target)
+		return NULL;
+
+	rb = osmo_strrb_create(target, size + 1);
+	if (!rb) {
+		log_target_destroy(target);
+		return NULL;
+	}
+
+	target->tgt_rb.rb = rb;
+	target->type = LOG_TGT_TYPE_STRRB;
+	target->output = _rb_output;
+
+	return target;
+}
+
+/* @} */