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/*
*
* Copyright 2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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 GRPC_CORE_LIB_SUPPORT_MPSCQ_H
#define GRPC_CORE_LIB_SUPPORT_MPSCQ_H
#include <grpc/support/atm.h>
#include <stddef.h>
// Multiple-producer single-consumer lock free queue, based upon the
// implementation from Dmitry Vyukov here:
// http://www.1024cores.net/home/lock-free-algorithms/queues/intrusive-mpsc-node-based-queue
// List node (include this in a data structure at the top, and add application
// fields after it - to simulate inheritance)
typedef struct gpr_mpscq_node { gpr_atm next; } gpr_mpscq_node;
// Actual queue type
typedef struct gpr_mpscq {
gpr_atm head;
// make sure head & tail don't share a cacheline
char padding[GPR_CACHELINE_SIZE];
gpr_mpscq_node *tail;
gpr_mpscq_node stub;
} gpr_mpscq;
void gpr_mpscq_init(gpr_mpscq *q);
void gpr_mpscq_destroy(gpr_mpscq *q);
// Push a node
void gpr_mpscq_push(gpr_mpscq *q, gpr_mpscq_node *n);
// Pop a node (returns NULL if no node is ready - which doesn't indicate that
// the queue is empty!!)
gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q);
#endif /* GRPC_CORE_LIB_SUPPORT_MPSCQ_H */
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