original files of m241

components/ip_net2-6.9/ipntp/include/isc/refcount.h

@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2004-2007, 2009  Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (C) 2001, 2003  Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: refcount.h,v 1.1.2.1 2015-04-01 02:13:20 lyang3 Exp $ */
+
+#ifndef ISC_REFCOUNT_H
+#define ISC_REFCOUNT_H 1
+
+#include <isc/atomic.h>
+#include <isc/lang.h>
+#include <isc/mutex.h>
+#include <isc/platform.h>
+#include <isc/types.h>
+#include <isc/util.h>
+
+/*! \file isc/refcount.h
+ * \brief Implements a locked reference counter.
+ *
+ * These functions may actually be
+ * implemented using macros, and implementations of these macros are below.
+ * The isc_refcount_t type should not be accessed directly, as its contents
+ * depend on the implementation.
+ */
+
+ISC_LANG_BEGINDECLS
+
+/*
+ * Function prototypes
+ */
+
+/*
+ * isc_result_t
+ * isc_refcount_init(isc_refcount_t *ref, unsigned int n);
+ *
+ * Initialize the reference counter.  There will be 'n' initial references.
+ *
+ * Requires:
+ *	ref != NULL
+ */
+
+/*
+ * void
+ * isc_refcount_destroy(isc_refcount_t *ref);
+ *
+ * Destroys a reference counter.
+ *
+ * Requires:
+ *	ref != NULL
+ *	The number of references is 0.
+ */
+
+/*
+ * void
+ * isc_refcount_increment(isc_refcount_t *ref, unsigned int *targetp);
+ * isc_refcount_increment0(isc_refcount_t *ref, unsigned int *targetp);
+ *
+ * Increments the reference count, returning the new value in targetp if it's
+ * not NULL.  The reference counter typically begins with the initial counter
+ * of 1, and will be destroyed once the counter reaches 0.  Thus,
+ * isc_refcount_increment() additionally requires the previous counter be
+ * larger than 0 so that an error which violates the usage can be easily
+ * caught.  isc_refcount_increment0() does not have this restriction.
+ *
+ * Requires:
+ *	ref != NULL.
+ */
+
+/*
+ * void
+ * isc_refcount_decrement(isc_refcount_t *ref, unsigned int *targetp);
+ *
+ * Decrements the reference count,  returning the new value in targetp if it's
+ * not NULL.
+ *
+ * Requires:
+ *	ref != NULL.
+ */
+
+
+/*
+ * Sample implementations
+ */
+#ifdef ISC_PLATFORM_USETHREADS
+#ifdef ISC_PLATFORM_HAVEXADD
+
+#define ISC_REFCOUNT_HAVEATOMIC 1
+
+typedef struct isc_refcount {
+	isc_int32_t refs;
+} isc_refcount_t;
+
+#define isc_refcount_destroy(rp) REQUIRE((rp)->refs == 0)
+#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
+
+#define isc_refcount_increment0(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		isc_int32_t prev;				\
+		prev = isc_atomic_xadd(&(rp)->refs, 1);		\
+		if (_tmp != NULL)				\
+			*_tmp = prev + 1;			\
+	} while (0)
+
+#define isc_refcount_increment(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		isc_int32_t prev;				\
+		prev = isc_atomic_xadd(&(rp)->refs, 1);		\
+		REQUIRE(prev > 0);				\
+		if (_tmp != NULL)				\
+			*_tmp = prev + 1;			\
+	} while (0)
+
+#define isc_refcount_decrement(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		isc_int32_t prev;				\
+		prev = isc_atomic_xadd(&(rp)->refs, -1);	\
+		REQUIRE(prev > 0);				\
+		if (_tmp != NULL)				\
+			*_tmp = prev - 1;			\
+	} while (0)
+
+#else  /* ISC_PLATFORM_HAVEXADD */
+
+typedef struct isc_refcount {
+	int refs;
+	isc_mutex_t lock;
+} isc_refcount_t;
+
+/*% Destroys a reference counter. */
+#define isc_refcount_destroy(rp)			\
+	do {						\
+		REQUIRE((rp)->refs == 0);		\
+		DESTROYLOCK(&(rp)->lock);		\
+	} while (0)
+
+#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
+
+/*% Increments the reference count, returning the new value in targetp if it's not NULL. */
+#define isc_refcount_increment0(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		LOCK(&(rp)->lock);				\
+		++((rp)->refs);					\
+		if (_tmp != NULL)				\
+			*_tmp = ((rp)->refs);			\
+		UNLOCK(&(rp)->lock);				\
+	} while (0)
+
+#define isc_refcount_increment(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		LOCK(&(rp)->lock);				\
+		REQUIRE((rp)->refs > 0);			\
+		++((rp)->refs);					\
+		if (_tmp != NULL)				\
+			*_tmp = ((rp)->refs);			\
+		UNLOCK(&(rp)->lock);				\
+	} while (0)
+
+/*% Decrements the reference count,  returning the new value in targetp if it's not NULL. */
+#define isc_refcount_decrement(rp, tp)				\
+	do {							\
+		unsigned int *_tmp = (unsigned int *)(tp);	\
+		LOCK(&(rp)->lock);				\
+		REQUIRE((rp)->refs > 0);			\
+		--((rp)->refs);					\
+		if (_tmp != NULL)				\
+			*_tmp = ((rp)->refs);			\
+		UNLOCK(&(rp)->lock);				\
+	} while (0)
+
+#endif /* ISC_PLATFORM_HAVEXADD */
+#else  /* ISC_PLATFORM_USETHREADS */
+
+typedef struct isc_refcount {
+	int refs;
+} isc_refcount_t;
+
+#define isc_refcount_destroy(rp) REQUIRE((rp)->refs == 0)
+#define isc_refcount_current(rp) ((unsigned int)((rp)->refs))
+
+#define isc_refcount_increment0(rp, tp)					\
+	do {								\
+		unsigned int *_tmp = (unsigned int *)(tp);		\
+		int _n = ++(rp)->refs;					\
+		if (_tmp != NULL)					\
+			*_tmp = _n;					\
+	} while (0)
+
+#define isc_refcount_increment(rp, tp)					\
+	do {								\
+		unsigned int *_tmp = (unsigned int *)(tp);		\
+		int _n;							\
+		REQUIRE((rp)->refs > 0);				\
+		_n = ++(rp)->refs;					\
+		if (_tmp != NULL)					\
+			*_tmp = _n;					\
+	} while (0)
+
+#define isc_refcount_decrement(rp, tp)					\
+	do {								\
+		unsigned int *_tmp = (unsigned int *)(tp);		\
+		int _n;							\
+		REQUIRE((rp)->refs > 0);				\
+		_n = --(rp)->refs;					\
+		if (_tmp != NULL)					\
+			*_tmp = _n;					\
+	} while (0)
+
+#endif /* ISC_PLATFORM_USETHREADS */
+
+isc_result_t
+isc_refcount_init(isc_refcount_t *ref, unsigned int n);
+
+ISC_LANG_ENDDECLS
+
+#endif /* ISC_REFCOUNT_H */