Add libevent

[netatalk.git] / libevent / ratelim-internal.h

diff --git a/libevent/ratelim-internal.h b/libevent/ratelim-internal.h
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+/*
+ * Copyright (c) 2009-2010 Niels Provos and Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 _RATELIM_INTERNAL_H_
+#define _RATELIM_INTERNAL_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "event2/util.h"
+
+/** A token bucket is an internal structure that tracks how many bytes we are
+ * currently willing to read or write on a given bufferevent or group of
+ * bufferevents */
+struct ev_token_bucket {
+       /** How many bytes are we willing to read or write right now? These
+        * values are signed so that we can do "defecit spending" */
+       ev_ssize_t read_limit, write_limit;
+       /** When was this bucket last updated?  Measured in abstract 'ticks'
+        * relative to the token bucket configuration. */
+       ev_uint32_t last_updated;
+};
+
+/** Configuration info for a token bucket or set of token buckets. */
+struct ev_token_bucket_cfg {
+       /** How many bytes are we willing to read on average per tick? */
+       size_t read_rate;
+       /** How many bytes are we willing to read at most in any one tick? */
+       size_t read_maximum;
+       /** How many bytes are we willing to write on average per tick? */
+       size_t write_rate;
+       /** How many bytes are we willing to write at most in any one tick? */
+       size_t write_maximum;
+
+       /* How long is a tick?  Note that fractions of a millisecond are
+        * ignored. */
+       struct timeval tick_timeout;
+
+       /* How long is a tick, in milliseconds?  Derived from tick_timeout. */
+       unsigned msec_per_tick;
+};
+
+/** The current tick is 'current_tick': add bytes to 'bucket' as specified in
+ * 'cfg'. */
+int ev_token_bucket_update(struct ev_token_bucket *bucket,
+    const struct ev_token_bucket_cfg *cfg,
+    ev_uint32_t current_tick);
+
+/** In which tick does 'tv' fall according to 'cfg'?  Note that ticks can
+ * overflow easily; your code needs to handle this. */
+ev_uint32_t ev_token_bucket_get_tick(const struct timeval *tv,
+    const struct ev_token_bucket_cfg *cfg);
+
+/** Adjust 'bucket' to respect 'cfg', and note that it was last updated in
+ * 'current_tick'.  If 'reinitialize' is true, we are changing the
+ * configuration of 'bucket'; otherwise, we are setting it up for the first
+ * time.
+ */
+int ev_token_bucket_init(struct ev_token_bucket *bucket,
+    const struct ev_token_bucket_cfg *cfg,
+    ev_uint32_t current_tick,
+    int reinitialize);
+
+int bufferevent_remove_from_rate_limit_group_internal(struct bufferevent *bev,
+    int unsuspend);
+
+/** Decrease the read limit of 'b' by 'n' bytes */
+#define ev_token_bucket_decrement_read(b,n)    \
+       do {                                    \
+               (b)->read_limit -= (n);         \
+       } while (0)
+/** Decrease the write limit of 'b' by 'n' bytes */
+#define ev_token_bucket_decrement_write(b,n)   \
+       do {                                    \
+               (b)->write_limit -= (n);        \
+       } while (0)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif