+static double get_drop_probability (void) /* {{{ */
+{
+ long pos;
+ long size;
+ long wql;
+
+ pthread_mutex_lock (&write_lock);
+ wql = write_queue_length;
+ pthread_mutex_unlock (&write_lock);
+
+ if (wql < write_limit_low)
+ return (0.0);
+ if (wql >= write_limit_high)
+ return (1.0);
+
+ pos = 1 + wql - write_limit_low;
+ size = 1 + write_limit_high - write_limit_low;
+
+ return (((double) pos) / ((double) size));
+} /* }}} double get_drop_probability */
+
+static _Bool check_drop_value (void) /* {{{ */
+{
+ static cdtime_t last_message_time = 0;
+ static pthread_mutex_t last_message_lock = PTHREAD_MUTEX_INITIALIZER;
+
+ double p;
+ double q;
+ int status;
+
+ if (write_limit_high == 0)
+ return (0);
+
+ p = get_drop_probability ();
+ if (p == 0.0)
+ return (0);
+
+ status = pthread_mutex_trylock (&last_message_lock);
+ if (status == 0)
+ {
+ cdtime_t now;
+
+ now = cdtime ();
+ if ((now - last_message_time) > TIME_T_TO_CDTIME_T (1))
+ {
+ last_message_time = now;
+ ERROR ("plugin_dispatch_values: Low water mark "
+ "reached. Dropping %.0f%% of metrics.",
+ 100.0 * p);
+ }
+ pthread_mutex_unlock (&last_message_lock);
+ }
+
+ if (p == 1.0)
+ return (1);
+
+ q = cdrand_d ();
+ if (q > p)
+ return (1);
+ else
+ return (0);
+} /* }}} _Bool check_drop_value */
+