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diff --git a/src/rate_limiter.h b/src/rate_limiter.h
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+/*
+    Copyright 2014 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs 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 General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INC_BINDFS_RATE_LIMITER_H
+#define INC_BINDFS_RATE_LIMITER_H
+
+#include <string.h>
+#include <pthread.h>
+
+/* When we are idle, we allow some time to be "credited" to the next writer.
+ * Otherwise, the short pause between requests would "go to waste", lowering
+ * the throughput when there is only one requester. */
+const double rate_limiter_idle_credit;
+
+typedef struct RateLimiter {
+    double rate;  /* bytes / second */
+    double (*clock)();
+    double last_modified;
+    double accumulated_sleep_time;
+    pthread_mutex_t mutex;
+} RateLimiter;
+
+double gettimeofday_clock();
+
+/* 0 on success, error number on error. */
+void rate_limiter_init(RateLimiter* limiter, double rate, double (*clock)());
+/* Blocks until the rate limiter clears `size` units. */
+void rate_limiter_wait(RateLimiter* limiter, size_t size);
+/* Updates the rate limiter like `rate_limiter_wait` but does not actually
+ * sleep. Returns the time that the caller is expected to sleep. */
+double rate_limiter_wait_nosleep(RateLimiter* limiter, size_t size);
+/* Destroys the rate limiter. No wait_for_permit calls may be active. */
+void rate_limiter_destroy(RateLimiter* limiter);
+
+#endif