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-rw-r--r--lock_free_queue.c157
-rw-r--r--lock_free_queue.h44
-rw-r--r--lock_free_queue_test.c48
3 files changed, 141 insertions, 108 deletions
diff --git a/lock_free_queue.c b/lock_free_queue.c
index e3e128f..a21d1ce 100644
--- a/lock_free_queue.c
+++ b/lock_free_queue.c
@@ -1,7 +1,7 @@
/*
* File : lock_free_queue.c
* Author : Jérémy Zurcher <jeremy@asynk.ch>
- * Date : 01/11/09
+ * Date : 2009/11/01
* License : stolen from http://www.cs.rochester.edu/~scott/papers/1996_PODC_queues.pdf
*/
@@ -14,87 +14,102 @@
/* CMPXCHG8B m64 Compare EDX:EAX with m64. If equal, set ZF and load ECX:EBX into m64. Else, clear ZF and load m64 into EDX:EAX. */
static inline unsigned int compare_and_swap(volatile unsigned long long *mem,
volatile unsigned long long old,
- volatile unsigned long long new) {
- char result;
- __asm__ __volatile__("lock; cmpxchg8b %0; setz %1;"
+ volatile unsigned long long new)
+{
+ char result;
+ __asm__ __volatile__("lock; cmpxchg8b %0; setz %1;"
: "=m"(*mem), "=q"(result)
- : "m"(*mem), "d" ((unsigned long)(old>>32)), "a" ((unsigned long)old),
- "c" ((unsigned long)(new>>32)), "b" ((unsigned long)new)
+ : "m"(*mem), "d" ((unsigned long)(old>>32)), "a" ((unsigned long)old)
+ , "c" ((unsigned long)(new>>32)), "b" ((unsigned long)new)
: "memory");
- return (int)result;
+ return (int)result;
}
-void init( lfq_t *q ) {
- node_t *node = (node_t*)malloc(sizeof(node_t));
- node->next.split.ptr = NULL;
- node->next.split.count = 0;
- q->head.split.ptr = q->tail.split.ptr = node;
- q->head.split.count = q->tail.split.count = 0;
+void init(lfq_t *q)
+{
+ node_t *node = (node_t*)malloc(sizeof(node_t));
+ node->next.split.ptr = NULL;
+ node->next.split.count = 0;
+ q->head.split.ptr = q->tail.split.ptr = node;
+ q->head.split.count = q->tail.split.count = 0;
}
-void enqueue( lfq_t *q, void *data ) {
- node_t *node;
- pointer_t tail;
- pointer_t next;
- pointer_t tmp;
+void enqueue(lfq_t *q, void *data)
+{
+ node_t *node;
+ pointer_t tail;
+ pointer_t next;
+ pointer_t tmp;
- node = (node_t*)malloc(sizeof(node_t));
- node->data = data;
- node->next.split.ptr = NULL;
- /* node->next.split.count = 0; */
- for(;;) {
- tail.concat = q->tail.concat; /* copy tail pointer */
- next.concat = tail.split.ptr->next.concat; /* copy next pointer */
- if (tail.concat == q->tail.concat) { /* tail is still consistent */
- if (next.split.ptr == NULL) { /* next is still the last node */
- /* if tail->next is the same as next, link node at the end of the list */
- tmp.split.ptr = node;
- tmp.split.count = next.split.count+1;
- if ( compare_and_swap( &tail.split.ptr->next.concat, next.concat, tmp.concat ) ) break;
- } else {
- /* try to swing tail to the next node, if q-> tail is still tail => next is ok */
- tmp.split.ptr = next.split.ptr;
- tmp.split.count = tail.split.count+1;
- compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
- }
- }
- }
- /* try to swing tail to the next node, may have been done by a concurrent push */
- tmp.split.ptr = node;
- tmp.split.count = tail.split.count+1;
- compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
+ node = (node_t*)malloc(sizeof(node_t));
+ node->data = data;
+ node->next.split.ptr = NULL;
+ /* node->next.split.count = 0; */
+ for(;;)
+ {
+ tail.concat = q->tail.concat; /* copy tail pointer */
+ next.concat = tail.split.ptr->next.concat; /* copy next pointer */
+ if (tail.concat == q->tail.concat)
+ { /* tail is still consistent */
+ if (next.split.ptr == NULL)
+ { /* next is still the last node */
+ /* if tail->next is the same as next, link node at the end of the list */
+ tmp.split.ptr = node;
+ tmp.split.count = next.split.count+1;
+ if ( compare_and_swap( &tail.split.ptr->next.concat, next.concat, tmp.concat ) ) break;
+ }
+ else
+ {
+ /* try to swing tail to the next node, if q-> tail is still tail => next is ok */
+ tmp.split.ptr = next.split.ptr;
+ tmp.split.count = tail.split.count+1;
+ compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
+ }
+ }
+ }
+ /* try to swing tail to the next node, may have been done by a concurrent push */
+ tmp.split.ptr = node;
+ tmp.split.count = tail.split.count+1;
+ compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
}
-void* dequeue( lfq_t *q ) {
- void *data;
- pointer_t head;
- pointer_t tail;
- node_t *next;
- pointer_t tmp;
-
- for(;;) {
+void* dequeue(lfq_t *q)
+{
+ void *data;
+ pointer_t head;
+ pointer_t tail;
+ node_t *next;
+ pointer_t tmp;
+
+ for(;;)
+ {
head.concat = q->head.concat;
tail.concat = q->tail.concat;
next = (node_t *)head.split.ptr;
- if (head.concat == q->head.concat) {
- if (head.split.ptr == tail.split.ptr) { /* still consistent */
- if (next->next.split.ptr == NULL) { /* queue empty */
- return NULL;
- }
- /* new node has been linked, but tail is behind, should advance it */
- tmp.split.ptr = next->next.split.ptr;
- tmp.split.count = tail.split.count+1;
- compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
- } else {
- data = next->data;
- /* try to swing head to the next node */
- tmp.split.ptr = next->next.split.ptr;
- tmp.split.count = head.split.count+1;
- if( compare_and_swap( &q->head.concat, head.concat, tmp.concat ) ) break;
- }
- }
- }
- free((void*)head.split.ptr);
- return data;
+ if (head.concat == q->head.concat)
+ {
+ if (head.split.ptr == tail.split.ptr)
+ { /* still consistent */
+ if (next->next.split.ptr == NULL)
+ { /* queue empty */
+ return NULL;
+ }
+ /* new node has been linked, but tail is behind, should advance it */
+ tmp.split.ptr = next->next.split.ptr;
+ tmp.split.count = tail.split.count+1;
+ compare_and_swap( &q->tail.concat, tail.concat, tmp.concat );
+ }
+ else
+ {
+ data = next->data;
+ /* try to swing head to the next node */
+ tmp.split.ptr = next->next.split.ptr;
+ tmp.split.count = head.split.count+1;
+ if( compare_and_swap( &q->head.concat, head.concat, tmp.concat ) ) break;
+ }
+ }
+ }
+ free((void*)head.split.ptr);
+ return data;
}
diff --git a/lock_free_queue.h b/lock_free_queue.h
index 14a2cae..0bce83e 100644
--- a/lock_free_queue.h
+++ b/lock_free_queue.h
@@ -1,31 +1,47 @@
/*
* File : lock_free_queue.h
* Author : Jérémy Zurcher <jeremy@asynk.ch>
- * Date : 01/11/09
+ * Date : 2009/11/01
* License : stolen from http://www.cs.rochester.edu/~scott/papers/1996_PODC_queues.pdf
*/
+#ifndef _LOCK_FREE_QUEUE_H_
+#define _LOCK_FREE_QUEUE_H_
+
+# ifdef __cplusplus
+extern "C" {
+# endif /* __cplusplus */
+
struct node;
-typedef union pointer {
- struct {
+typedef union pointer
+{
+ struct
+ {
volatile struct node *ptr;
volatile unsigned int count;
- } split;
- volatile unsigned long long concat;
+ } split;
+ volatile unsigned long long concat;
} pointer_t;
-typedef struct node {
- void *data;
- pointer_t next;
+typedef struct node
+{
+ void *data;
+ pointer_t next;
} node_t;
-typedef struct queue {
- pointer_t head;
- pointer_t tail;
+typedef struct queue
+{
+ pointer_t head;
+ pointer_t tail;
} lfq_t;
-void init( lfq_t *q );
-void enqueue( lfq_t *q, void *data );
-void* dequeue( lfq_t *q );
+void init(lfq_t *q);
+void enqueue(lfq_t *q, void *data);
+void* dequeue(lfq_t *q);
+
+# ifdef __cplusplus
+}
+# endif /* __cplusplus */
+# endif /* _LOCK_FREE_QUEUE_H_ */
diff --git a/lock_free_queue_test.c b/lock_free_queue_test.c
index 3a067d7..157c984 100644
--- a/lock_free_queue_test.c
+++ b/lock_free_queue_test.c
@@ -1,7 +1,7 @@
/*
* File : lock_free_queue_test.c
* Author : Jérémy Zurcher <jeremy@asynk.ch>
- * Date : 01/11/09
+ * Date : 2009/11/01
* License :
*
* Permission is hereby granted, free of charge, to any person obtaining
@@ -11,10 +11,10 @@
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
- *
+ *
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
- *
+ *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
@@ -29,31 +29,33 @@
#include "stdlib.h"
#include "lock_free_queue.h"
-int main(int argc, char *argv[]) {
- lfq_t q;
- node_t *it;
- int data[10];
- int i;
+int main(int argc, char *argv[])
+{
+ lfq_t q;
+ node_t *it;
+ int data[10];
+ int i;
+
+ for(i=0; i<10; i++) data[i]=i;
+ for(i=0; i<10; i++) printf("data[i] :%d (%X)\n",data[i],(unsigned int)&data[i]);
- for(i=0; i<10; i++) data[i]=i;
- for(i=0; i<10; i++) printf("data[i] :%d (%X)\n",data[i],(unsigned int)&data[i]);
-
- init( &q);
- for(i=0; i<10; i++) enqueue( &q, (void*)&data[i] );
+ init( &q);
+ for(i=0; i<10; i++) enqueue( &q, (void*)&data[i] );
- it = (node_t*)q.head.split.ptr;
- while(it!=NULL) {
+ it = (node_t*)q.head.split.ptr;
+ while(it!=NULL)
+ {
if(it->data>0)printf("data : %X %d\n",(unsigned int)it->data,*((int*)it->data));
it = (node_t*)it->next.split.ptr;
- }
-
- for(i=0; i<5; i++) printf("unqueue %X\n",(unsigned int)dequeue( &q ));
- it = (node_t*)q.head.split.ptr;
- while(it!=NULL) {
+ }
+
+ for(i=0; i<5; i++) printf("unqueue %X\n",(unsigned int)dequeue( &q ));
+ it = (node_t*)q.head.split.ptr;
+ while(it!=NULL)
+ {
if(it->data>0)printf("data : %X %d\n",(unsigned int)it->data,*((int*)it->data));
it = (node_t*)it->next.split.ptr;
- }
-
+ }
- return EXIT_SUCCESS;
+ return EXIT_SUCCESS;
}
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