token-bucket: New library for generic rate-limiting.

This commit converts two rate-limiters in the tree to use the library.
I intend to use the library elsewhere in the future.

Signed-off-by: Ben Pfaff <blp@nicira.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/lib/token-bucket.h b/lib/token-bucket.h
new file mode 100644
index 00000000..ef2b1ae7
--- /dev/null
+++ b/lib/token-bucket.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2012 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TOKEN_BUCKET_H
+#define TOKEN_BUCKET_H 1
+
+#include <limits.h>
+#include <stdbool.h>
+
+struct token_bucket {
+    /* Configuration settings. */
+    unsigned int rate;          /* Tokens added per millisecond. */
+    unsigned int burst;         /* Max cumulative tokens credit. */
+
+    /* Current status. */
+    unsigned int tokens;        /* Current number of tokens. */
+    long long int last_fill;    /* Last time tokens added. */
+};
+
+#define TOKEN_BUCKET_INIT(RATE, BURST) { RATE, BURST, 0, LLONG_MIN }
+
+void token_bucket_init(struct token_bucket *,
+                       unsigned int rate, unsigned int burst);
+void token_bucket_set(struct token_bucket *,
+                       unsigned int rate, unsigned int burst);
+bool token_bucket_withdraw(struct token_bucket *, unsigned int n);
+void token_bucket_wait(struct token_bucket *, unsigned int n);
+
+#endif /* token-bucket.h */