* TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
* dynamically with the userspace rcu reclamation library.
*
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
* Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
*
* This library is free software; you can redistribute it and/or
#include <stdlib.h>
#include <pthread.h>
-#include <compiler.h>
-#include <arch.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+#include <urcu/uatomic_arch.h>
+#include <urcu/list.h>
+#include <urcu/system.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
/*
* Number of entries in the per-thread defer queue. Must be power of 2.
#define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
/*
- * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
- */
-#define _LOAD_SHARED(p) ACCESS_ONCE(p)
-
-/*
- * Load a data from shared memory, doing a cache flush if required.
- */
-#define LOAD_SHARED(p) \
- ({ \
- smp_rmc(); \
- _LOAD_SHARED(p); \
- })
-
-/*
- * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
- */
-#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
-
-/*
- * Store v into x, where x is located in shared memory. Performs the required
- * cache flush after writing. Returns v.
+ * Typically, data is aligned at least on the architecture size.
+ * Use lowest bit to indicate that the current callback is changing.
+ * Assumes that (void *)-2L is not used often. Used to encode non-aligned
+ * functions and non-aligned data using extra space.
+ * We encode the (void *)-2L fct as: -2L, fct, data.
+ * We encode the (void *)-2L data as: -2L, fct, data.
+ * Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
*/
-#define STORE_SHARED(x, v) \
- ({ \
- _STORE_SHARED(x, v); \
- smp_wmc(); \
- (v); \
- })
+#define DQ_FCT_BIT (1 << 0)
+#define DQ_IS_FCT_BIT(x) ((unsigned long)(x) & DQ_FCT_BIT)
+#define DQ_SET_FCT_BIT(x) \
+ (x = (void *)((unsigned long)(x) | DQ_FCT_BIT))
+#define DQ_CLEAR_FCT_BIT(x) \
+ (x = (void *)((unsigned long)(x) & ~DQ_FCT_BIT))
+#define DQ_FCT_MARK ((void *)(~DQ_FCT_BIT))
/*
* This code section can only be included in LGPL 2.1 compatible source code.
#define rcu_assert(args...)
#endif
+/*
+ * defer queue.
+ * Contains pointers. Encoded to save space when same callback is often used.
+ * When looking up the next item:
+ * - if DQ_FCT_BIT is set, set the current callback to DQ_CLEAR_FCT_BIT(ptr)
+ * - next element contains pointer to data.
+ * - else if item == DQ_FCT_MARK
+ * - set the current callback to next element ptr
+ * - following next element contains pointer to data.
+ * - else current element contains data
+ */
struct defer_queue {
unsigned long head; /* add element at head */
+ void *last_fct_in; /* last fct pointer encoded */
unsigned long tail; /* next element to remove at tail */
+ void *last_fct_out; /* last fct pointer encoded */
void **q;
+ /* registry information */
+ unsigned long last_head;
+ struct cds_list_head list; /* list of thread queues */
};
-extern struct defer_queue __thread defer_queue;
-
-extern void rcu_defer_barrier_thread(void);
-
-/*
- * not signal-safe.
- */
-static inline void _rcu_defer_queue(void *p)
-{
- unsigned long head, tail;
-
- /*
- * Head is only modified by ourself. Tail can be modified by reclamation
- * thread.
- */
- head = defer_queue.head;
- tail = LOAD_SHARED(defer_queue.tail);
-
- /*
- * If queue is full, empty it ourself.
- */
- if (unlikely(head - tail >= DEFER_QUEUE_SIZE)) {
- assert(head - tail == DEFER_QUEUE_SIZE);
- rcu_defer_barrier_thread();
- assert(head - LOAD_SHARED(defer_queue.tail) == 0);
- }
-
- smp_wmb(); /* Publish new pointer before write q[] */
- _STORE_SHARED(defer_queue.q[head & DEFER_QUEUE_MASK], p);
- smp_wmb(); /* Write q[] before head. */
- STORE_SHARED(defer_queue.head, head + 1);
+#ifdef __cplusplus
}
+#endif
#endif /* _URCU_DEFER_STATIC_H */
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