| /* |
| * Copyright 2009-2015 Samy Al Bahra. |
| * All rights reserved. |
| * |
| * 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 CK_BACKOFF_H |
| #define CK_BACKOFF_H |
| |
| #include <ck_cc.h> |
| #include <ck_pr.h> |
| |
| #ifndef CK_BACKOFF_CEILING |
| #define CK_BACKOFF_CEILING ((1 << 20) - 1) |
| #endif |
| |
| #define CK_BACKOFF_INITIALIZER (1 << 9) |
| |
| typedef unsigned int ck_backoff_t; |
| |
| /* |
| * This is a exponential back-off implementation. |
| */ |
| CK_CC_INLINE static void |
| ck_backoff_eb(unsigned int *c) |
| { |
| unsigned int i, ceiling; |
| |
| ceiling = *c; |
| for (i = 0; i < ceiling; i++) |
| ck_pr_barrier(); |
| |
| *c = ceiling <<= ceiling < CK_BACKOFF_CEILING; |
| return; |
| } |
| |
| #endif /* CK_BACKOFF_H */ |