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+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2011. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights 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;
+
+typedef union {
+ erts_atomic_t atmc;
+ ErtsThrQElement_t *ptr;
+} ErtsThrQPtr_t;
+
+struct ErtsThrQElement_t_ {
+ ErtsThrQPtr_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;
+
+#ifdef USE_THREADS
+
+typedef struct {
+ ErtsThrQElement_t marker;
+ erts_atomic_t last;
+ erts_atomic_t um_refc[2];
+ erts_atomic32_t um_refc_ix;
+ ErtsThrQLive_t live;
+#ifdef ERTS_SMP
+ erts_atomic32_t thr_prgr_clean_scheduled;
+#endif
+ 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 {
+ ErtsThrQPtr_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 {
+#ifdef ERTS_SMP
+ ErtsThrPrgrVal thr_progress;
+ int thr_progress_reached;
+#endif
+ 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;
+};
+
+#else /* !USE_THREADS */
+
+struct ErtsThrQ_t_ {
+ ErtsThrQInit_t init;
+ ErtsThrQElement_t *first;
+ ErtsThrQElement_t *last;
+ struct {
+ void *blk;
+ } q;
+};
+
+#endif
+
+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 ERTS_SMP
+ERTS_GLB_INLINE ErtsThrPrgrVal erts_thr_q_need_thr_progress(ErtsThrQ_t *q);
+#endif
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+#ifdef ERTS_SMP
+ERTS_GLB_INLINE ErtsThrPrgrVal
+erts_thr_q_need_thr_progress(ErtsThrQ_t *q)
+{
+ return q->head.next.thr_progress;
+}
+#endif
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#endif /* ERL_THR_QUEUE_H__ */