1 files changed, 138 insertions, 0 deletions
diff --git a/lib/isc/counter.c b/lib/isc/counter.c
new file mode 100644
index 000000000000..d7d187bbeee4
--- /dev/null
+++ b/lib/isc/counter.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2014  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*! \file */
+
+#include <config.h>
+
+#include <stddef.h>
+
+#include <isc/counter.h>
+#include <isc/magic.h>
+#include <isc/mem.h>
+#include <isc/util.h>
+
+#define COUNTER_MAGIC			ISC_MAGIC('C', 'n', 't', 'r')
+#define VALID_COUNTER(r)		ISC_MAGIC_VALID(r, COUNTER_MAGIC)
+
+struct isc_counter {
+	unsigned int	magic;
+	isc_mem_t	*mctx;
+	isc_mutex_t	lock;
+	unsigned int	references;
+	unsigned int	limit;
+	unsigned int	used;
+};
+
+isc_result_t
+isc_counter_create(isc_mem_t *mctx, int limit, isc_counter_t **counterp) {
+	isc_result_t result;
+	isc_counter_t *counter;
+
+	REQUIRE(counterp != NULL && *counterp == NULL);
+
+	counter = isc_mem_get(mctx, sizeof(*counter));
+	if (counter == NULL)
+		return (ISC_R_NOMEMORY);
+
+	result = isc_mutex_init(&counter->lock);
+	if (result != ISC_R_SUCCESS) {
+		isc_mem_put(mctx, counter, sizeof(*counter));
+		return (result);
+	}
+
+	counter->mctx = NULL;
+	isc_mem_attach(mctx, &counter->mctx);
+
+	counter->references = 1;
+	counter->limit = limit;
+	counter->used = 0;
+
+	counter->magic = COUNTER_MAGIC;
+	*counterp = counter;
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_counter_increment(isc_counter_t *counter) {
+	isc_result_t result = ISC_R_SUCCESS;
+
+	LOCK(&counter->lock);
+	counter->used++;
+	if (counter->limit != 0 && counter->used >= counter->limit)
+		result = ISC_R_QUOTA;
+	UNLOCK(&counter->lock);
+
+	return (result);
+}
+
+unsigned int
+isc_counter_used(isc_counter_t *counter) {
+	REQUIRE(VALID_COUNTER(counter));
+
+	return (counter->used);
+}
+
+void
+isc_counter_setlimit(isc_counter_t *counter, int limit) {
+	REQUIRE(VALID_COUNTER(counter));
+
+	LOCK(&counter->lock);
+	counter->limit = limit;
+	UNLOCK(&counter->lock);
+}
+
+void
+isc_counter_attach(isc_counter_t *source, isc_counter_t **targetp) {
+	REQUIRE(VALID_COUNTER(source));
+	REQUIRE(targetp != NULL && *targetp == NULL);
+
+	LOCK(&source->lock);
+	source->references++;
+	INSIST(source->references > 0);
+	UNLOCK(&source->lock);
+
+	*targetp = source;
+}
+
+static void
+destroy(isc_counter_t *counter) {
+	counter->magic = 0;
+	isc_mutex_destroy(&counter->lock);
+	isc_mem_putanddetach(&counter->mctx, counter, sizeof(*counter));
+}
+
+void
+isc_counter_detach(isc_counter_t **counterp) {
+	isc_counter_t *counter;
+	isc_boolean_t want_destroy = ISC_FALSE;
+
+	REQUIRE(counterp != NULL && *counterp != NULL);
+	counter = *counterp;
+	REQUIRE(VALID_COUNTER(counter));
+
+	*counterp = NULL;
+
+	LOCK(&counter->lock);
+	INSIST(counter->references > 0);
+	counter->references--;
+	if (counter->references == 0)
+		want_destroy = ISC_TRUE;
+	UNLOCK(&counter->lock);
+
+	if (want_destroy)
+		destroy(counter);
+}