Session daemon health check support

[lttng-tools.git] / src / bin / lttng-sessiond / health.c

diff --git a/src/bin/lttng-sessiond/health.c b/src/bin/lttng-sessiond/health.c
new file mode 100644 (file)
index 0000000..58f804e
--- /dev/null
+++ b/src/bin/lttng-sessiond/health.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <common/error.h>
+
+#include "health.h"
+
+/*
+ * Check health of a specific health state counter.
+ *
+ * Return 0 if health is bad or else 1.
+ */
+int health_check_state(struct health_state *state)
+{
+       int ret;
+       uint64_t current;
+       uint64_t last;
+
+       assert(state);
+
+       current = uatomic_read(&state->current);
+       last = uatomic_read(&state->last);
+
+       /*
+        * Here are the conditions for a bad health. Current state set to 0 or the
+        * current state is the same as the last one and we are NOT waiting for a
+        * poll() call.
+        */
+       if (current == 0 || (current == last && HEALTH_IS_IN_CODE(current))) {
+               ret = 0;
+               goto error;
+       }
+
+       /* All good */
+       ret = 1;
+
+error:
+       DBG("Health state current %" PRIu64 ", last %" PRIu64 ", ret %d",
+                       current, last, ret);
+
+       /* Exchange current state counter into last one */
+       uatomic_xchg(&state->last, state->current);
+       return ret;
+}