add generic rate limiting implementation

src/pulsecore/ratelimit.c

@@ -0,0 +1,75 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2009 Lennart Poettering
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2 of the
+  License, or (at your option) any later version.
+
+  PulseAudio 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 Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <pulsecore/rtclock.h>
+#include <pulsecore/log.h>
+#include <pulsecore/mutex.h>
+
+#include "ratelimit.h"
+
+static pa_static_mutex mutex;
+
+/* Modelled after Linux' lib/ratelimit.c by Dave Young
+ * <hidave.darkstar@gmail.com>, which is licensed GPLv2. */
+
+pa_bool_t pa_ratelimit_test(pa_ratelimit *r) {
+    pa_usec_t now;
+    pa_mutex *m;
+
+    now = pa_rtclock_usec();
+
+    m = pa_static_mutex_get(&mutex, FALSE, FALSE);
+    pa_mutex_lock(m);
+
+    pa_assert(r);
+    pa_assert(r->interval > 0);
+    pa_assert(r->burst > 0);
+
+    if (r->begin <= 0 ||
+        r->begin + r->interval < now) {
+
+        if (r->n_missed > 0)
+            pa_log_warn("%u events suppressed", r->n_missed);
+
+        r->begin = now;
+
+        /* Reset counters */
+        r->n_printed = 0;
+        r->n_missed = 0;
+        goto good;
+    }
+
+    if (r->n_printed <= r->burst)
+        goto good;
+
+    r->n_missed++;
+    pa_mutex_unlock(m);
+    return FALSE;
+
+good:
+    r->n_printed++;
+    pa_mutex_unlock(m);
+    return TRUE;
+}