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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2011-2018. All Rights Reserved.
*
* 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.
*
* %CopyrightEnd%
*/
/*
* Description: Lock-free queue for communication between threads.
*
* Currently only a many-to-one version has been,
* implemented, i.e., many threads can enqueue but
* only one thread can dequeue at a time. It doesn't
* have to be the same thread dequeuing every time, but
* synchronization so that only one thread dequeues
* at a time has to be provided by other means.
*
* When/If the need for a many-to-many queue arises,
* this implementation can relatively easy be extended
* to support that too.
*
* Usage instructions can be found in erts_thr_queue.c
*
* Author: Rickard Green
*/
#ifndef ERL_THR_QUEUE_H__
#define ERL_THR_QUEUE_H__
#include "sys.h"
#include "erl_threads.h"
#include "erl_alloc.h"
#include "erl_thr_progress.h"
typedef enum {
ERTS_THR_Q_LIVE_UNDEF,
ERTS_THR_Q_LIVE_SHORT,
ERTS_THR_Q_LIVE_LONG
} ErtsThrQLive_t;
#define ERTS_THR_Q_INIT_DEFAULT \
{ \
{ \
ERTS_THR_Q_LIVE_UNDEF, \
ERTS_THR_Q_LIVE_SHORT \
}, \
NULL, \
NULL, \
1 \
}
typedef struct ErtsThrQ_t_ ErtsThrQ_t;
typedef struct {
struct {
ErtsThrQLive_t queue;
ErtsThrQLive_t objects;
} live;
void *arg;
void (*notify)(void *);
int auto_finalize_dequeue;
} ErtsThrQInit_t;
typedef struct ErtsThrQElement_t_ ErtsThrQElement_t;
typedef struct ErtsThrQElement_t ErtsThrQPrepEnQ_t;
struct ErtsThrQElement_t_ {
erts_atomic_t next;
union {
erts_atomic_t atmc;
void *ptr;
} data;
};
typedef struct {
ErtsThrQElement_t *start;
ErtsThrQElement_t *end;
} ErtsThrQFinDeQ_t;
typedef enum {
ERTS_THR_Q_CLEAN,
ERTS_THR_Q_NEED_THR_PRGR,
ERTS_THR_Q_DIRTY,
} ErtsThrQCleanState_t;
typedef struct {
ErtsThrQElement_t marker;
erts_atomic_t last;
erts_atomic_t um_refc[2];
erts_atomic32_t um_refc_ix;
ErtsThrQLive_t live;
erts_atomic32_t thr_prgr_clean_scheduled;
void *arg;
void (*notify)(void *);
} ErtsThrQTail_t;
struct ErtsThrQ_t_ {
/*
* This structure needs to be cache line aligned for best
* performance.
*/
union {
/* Modified by threads enqueuing */
ErtsThrQTail_t data;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(ErtsThrQTail_t))];
} tail;
/*
* Everything below this point is *only* accessed by the
* thread dequeuing.
*/
struct {
erts_atomic_t head;
ErtsThrQLive_t live;
ErtsThrQElement_t *first;
ErtsThrQElement_t *unref_end;
int clean_reached_head_count;
struct {
int automatic;
ErtsThrQElement_t *start;
ErtsThrQElement_t *end;
} deq_fini;
struct {
ErtsThrPrgrVal thr_progress;
int thr_progress_reached;
int um_refc_ix;
ErtsThrQElement_t *unref_end;
} next;
int used_marker;
void *arg;
void (*notify)(void *);
} head;
struct {
int finalizing;
ErtsThrQLive_t live;
void *blk;
} q;
};
void erts_thr_q_init(void);
void erts_thr_q_initialize(ErtsThrQ_t *, ErtsThrQInit_t *);
ErtsThrQCleanState_t erts_thr_q_finalize(ErtsThrQ_t *);
ErtsThrQ_t *erts_thr_q_create(ErtsThrQInit_t *);
ErtsThrQCleanState_t erts_thr_q_destroy(ErtsThrQ_t *);
ErtsThrQCleanState_t erts_thr_q_clean(ErtsThrQ_t *);
ErtsThrQCleanState_t erts_thr_q_inspect(ErtsThrQ_t *, int);
ErtsThrQPrepEnQ_t *erts_thr_q_prepare_enqueue(ErtsThrQ_t *);
void erts_thr_q_enqueue_prepared(ErtsThrQ_t *, void *, ErtsThrQPrepEnQ_t *);
void erts_thr_q_enqueue(ErtsThrQ_t *, void *);
void * erts_thr_q_dequeue(ErtsThrQ_t *);
int erts_thr_q_get_finalize_dequeue_data(ErtsThrQ_t *,
ErtsThrQFinDeQ_t *);
void erts_thr_q_append_finalize_dequeue_data(ErtsThrQFinDeQ_t *,
ErtsThrQFinDeQ_t *);
int erts_thr_q_finalize_dequeue(ErtsThrQFinDeQ_t *);
void erts_thr_q_finalize_dequeue_state_init(ErtsThrQFinDeQ_t *);
#ifdef USE_LTTNG_VM_TRACEPOINTS
int erts_thr_q_length_dirty(ErtsThrQ_t *);
#endif
ERTS_GLB_INLINE ErtsThrPrgrVal erts_thr_q_need_thr_progress(ErtsThrQ_t *q);
#if ERTS_GLB_INLINE_INCL_FUNC_DEF
ERTS_GLB_INLINE ErtsThrPrgrVal
erts_thr_q_need_thr_progress(ErtsThrQ_t *q)
{
return q->head.next.thr_progress;
}
#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
#endif /* ERL_THR_QUEUE_H__ */
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