MAR-125: Support log rate limiting.

Much like Linux's ratelimit. Allow for message bursts of some size,
count messages as they pass. Drop messages once the burst size was
exceeded within a given interval. Next interval resets the count.

Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>

diff --git a/drivers/Makefile b/drivers/Makefile
index 8eae6d1f4254238ee19fa7f13a875f3f8a0388f6..036732d4622964a9e49157e5c10d898d36f543d8 100644 (file)
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -46,6 +46,7 @@ TAP-OBJS  += tapdisk-disktype.o
 TAP-OBJS  += tapdisk-syslog.o
 TAP-OBJS  += tapdisk-stats.o
 TAP-OBJS  += tapdisk-storage.o
+TAP-OBJS  += tapdisk-loglimit.o
 TAP-OBJS  += io-optimize.o
 TAP-OBJS  += lock.o
 

diff --git a/drivers/tapdisk-loglimit.c b/drivers/tapdisk-loglimit.c
new file mode 100644 (file)
index 0000000..0752a46
--- /dev/null
+++ b/drivers/tapdisk-loglimit.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2011, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Simple log rate limiting. Allow for bursts, then drop messages
+ * until some interval expired.
+ */
+
+#include "tapdisk-loglimit.h"
+#include "compiler.h"
+#include "list.h"
+
+void
+tapdisk_loglimit_init(td_loglimit_t *rl, int burst, int interval)
+{
+       rl->burst    = burst;
+       rl->interval = interval;
+
+       rl->count    = 0;
+       rl->dropped  = 0;
+
+       gettimeofday(&rl->ts, NULL);
+}
+
+static void
+timeradd_ms(struct timeval *tv, long ms)
+{
+       tv->tv_usec += ms * 1000;
+       if (tv->tv_usec > 1000000) {
+               tv->tv_sec  += tv->tv_usec / 1000000;
+               tv->tv_usec %= 1000000;
+       }
+}
+
+static void
+tapdisk_loglimit_update(td_loglimit_t *rl, struct timeval *now)
+{
+       struct timeval next = rl->ts;
+       int expired;
+
+       timeradd_ms(&next, rl->interval);
+
+       if (timercmp(&next, now, <)) {
+               rl->count = 0;
+               rl->ts    = *now;
+       }
+}
+
+static void
+tapdisk_loglimit_update_now(td_loglimit_t *rl)
+{
+       struct timeval now;
+
+       gettimeofday(&now, NULL);
+
+       tapdisk_loglimit_update(rl, &now);
+}
+
+int
+tapdisk_loglimit_pass(td_loglimit_t *rl)
+{
+       if (!rl->interval)
+               return 1; /* unlimited */
+
+       if (unlikely(rl->count >= rl->burst)) {
+
+               tapdisk_loglimit_update_now(rl);
+
+               if (rl->count >= rl->burst) {
+                       rl->dropped++;
+                       return 0;
+               }
+       }
+
+       rl->count++;
+       return 1;
+}

diff --git a/drivers/tapdisk-loglimit.h b/drivers/tapdisk-loglimit.h
new file mode 100644 (file)
index 0000000..6d756c5
--- /dev/null
+++ b/drivers/tapdisk-loglimit.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2011, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __TAPDISK_LOGLIMIT_H__
+#define __TAPDISK_LOGLIMIT_H__
+
+#include <sys/time.h>
+#include "list.h"
+
+typedef struct td_loglimit td_loglimit_t;
+
+struct td_loglimit {
+       int burst;
+       int interval;
+
+       int count;
+       int dropped;
+
+       struct timeval ts;
+};
+
+void tapdisk_loglimit_init(td_loglimit_t *rl, int burst, int interval);
+
+int tapdisk_loglimit_pass(td_loglimit_t *);
+
+#endif /* __TAPDISK_LOGLIMIT_H__ */