/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ #pragma once #include #include #include #include #include #include #include #include /*! \file isc/refcount.h * \brief Implements a locked reference counter. * * These macros uses C11(-like) atomic functions to implement reference * counting. The isc_refcount_t type must not be accessed directly. */ ISC_LANG_BEGINDECLS typedef atomic_uint_fast32_t isc_refcount_t; #define ISC_REFCOUNT_INITIALIZER(a) (a) /** \def isc_refcount_init(ref, n) * \brief Initialize the reference counter. * \param[in] ref pointer to reference counter. * \param[in] n an initial number of references. * \return nothing. * * \warning No memory barrier are being imposed here. */ #define isc_refcount_init(target, value) atomic_init(target, value) /** \def isc_refcount_current(ref) * \brief Returns current number of references. * \param[in] ref pointer to reference counter. * \returns current value of reference counter. */ #define isc_refcount_current(target) atomic_load_acquire(target) /** \def isc_refcount_destroy(ref) * \brief a destructor that makes sure that all references were cleared. * \param[in] ref pointer to reference counter. * \returns nothing. */ #define isc_refcount_destroy(target) \ ISC_REQUIRE(isc_refcount_current(target) == 0) /** \def isc_refcount_increment0(ref) * \brief increases reference counter by 1. * \param[in] ref pointer to reference counter. * \returns previous value of reference counter. */ #define isc_refcount_increment0(target) \ ({ \ uint_fast32_t __v; \ __v = atomic_fetch_add_release(target, 1); \ INSIST(__v < UINT32_MAX); \ __v; \ }) /** \def isc_refcount_increment(ref) * \brief increases reference counter by 1. * \param[in] ref pointer to reference counter. * \returns previous value of reference counter. */ #define isc_refcount_increment(target) \ ({ \ uint_fast32_t __v; \ __v = atomic_fetch_add_release(target, 1); \ INSIST(__v > 0 && __v < UINT32_MAX); \ __v; \ }) /** \def isc_refcount_decrement(ref) * \brief decreases reference counter by 1. * \param[in] ref pointer to reference counter. * \returns previous value of reference counter. */ #define isc_refcount_decrement(target) \ ({ \ uint_fast32_t __v; \ __v = atomic_fetch_sub_acq_rel(target, 1); \ INSIST(__v > 0); \ __v; \ }) #define isc_refcount_decrementz(target) \ do { \ uint_fast32_t _refs = isc_refcount_decrement(target); \ ISC_INSIST(_refs == 1); \ } while (0) #define isc_refcount_decrement1(target) \ do { \ uint_fast32_t _refs = isc_refcount_decrement(target); \ ISC_INSIST(_refs > 1); \ } while (0) #define isc_refcount_decrement0(target) \ do { \ uint_fast32_t _refs = isc_refcount_decrement(target); \ ISC_INSIST(_refs > 0); \ } while (0) #define ISC__REFCOUNT_TRACE_DECL(name, stat) \ stat name##_t *name##__ref(name##_t *ptr, const char *func, \ const char *file, unsigned int line); \ stat void name##__unref(name##_t *ptr, const char *func, \ const char *file, unsigned int line); \ stat void name##__attach(name##_t *ptr, name##_t **ptrp, \ const char *func, const char *file, \ unsigned int line); \ stat void name##__detach(name##_t **ptrp, const char *func, \ const char *file, unsigned int line) #define ISC_REFCOUNT_BLANK #define ISC_REFCOUNT_TRACE_DECL(name) \ ISC__REFCOUNT_TRACE_DECL(name, ISC_REFCOUNT_BLANK) #define ISC_REFCOUNT_STATIC_TRACE_DECL(name) \ ISC__REFCOUNT_TRACE_DECL(name, static inline) #define ISC__REFCOUNT_TRACE_IMPL(name, destroy, stat) \ stat name##_t *name##__ref(name##_t *ptr, const char *func, \ const char *file, unsigned int line) { \ REQUIRE(ptr != NULL); \ uint_fast32_t refs = \ isc_refcount_increment(&ptr->references) + 1; \ fprintf(stderr, \ "%s:%s:%s:%u:t%u:%p->references = %" PRIuFAST32 "\n", \ __func__, func, file, line, isc_tid(), ptr, refs); \ return (ptr); \ } \ \ stat void name##__unref(name##_t *ptr, const char *func, \ const char *file, unsigned int line) { \ REQUIRE(ptr != NULL); \ uint_fast32_t refs = \ isc_refcount_decrement(&ptr->references) - 1; \ if (refs == 0) { \ isc_refcount_destroy(&ptr->references); \ destroy(ptr); \ } \ fprintf(stderr, \ "%s:%s:%s:%u:t%u:%p->references = %" PRIuFAST32 "\n", \ __func__, func, file, line, isc_tid(), ptr, refs); \ } \ stat void name##__attach(name##_t *ptr, name##_t **ptrp, \ const char *func, const char *file, \ unsigned int line) { \ REQUIRE(ptrp != NULL && *ptrp == NULL); \ uint_fast32_t refs = \ isc_refcount_increment(&ptr->references) + 1; \ fprintf(stderr, \ "%s:%s:%s:%u:t%u:%p->references = %" PRIuFAST32 "\n", \ __func__, func, file, line, isc_tid(), ptr, refs); \ *ptrp = ptr; \ } \ \ stat void name##__detach(name##_t **ptrp, const char *func, \ const char *file, unsigned int line) { \ REQUIRE(ptrp != NULL && *ptrp != NULL); \ name##_t *ptr = *ptrp; \ *ptrp = NULL; \ uint_fast32_t refs = \ isc_refcount_decrement(&ptr->references) - 1; \ if (refs == 0) { \ isc_refcount_destroy(&ptr->references); \ destroy(ptr); \ } \ fprintf(stderr, \ "%s:%s:%s:%u:t%u:%p->references = %" PRIuFAST32 "\n", \ __func__, func, file, line, isc_tid(), ptr, refs); \ } #define ISC_REFCOUNT_TRACE_IMPL(name, destroy) \ ISC__REFCOUNT_TRACE_IMPL(name, destroy, ISC_REFCOUNT_BLANK) #define ISC_REFCOUNT_STATIC_TRACE_IMPL(name, destroy) \ ISC__REFCOUNT_TRACE_IMPL(name, destroy, static inline) #define ISC__REFCOUNT_DECL(name, stat) \ stat name##_t *name##_ref(name##_t *ptr) __attribute__((unused)); \ stat void name##_unref(name##_t *ptr) __attribute__((unused)); \ stat void name##_attach(name##_t *ptr, name##_t **ptrp) \ __attribute__((unused)); \ stat void name##_detach(name##_t **ptrp) __attribute__((unused)) #define ISC_REFCOUNT_DECL(name) ISC__REFCOUNT_DECL(name, ISC_REFCOUNT_BLANK) #define ISC_REFCOUNT_STATIC_DECL(name) ISC__REFCOUNT_DECL(name, static inline) #define ISC__REFCOUNT_IMPL(name, destroy, stat) \ stat name##_t *name##_ref(name##_t *ptr) { \ REQUIRE(ptr != NULL); \ isc_refcount_increment(&ptr->references); \ return (ptr); \ } \ \ stat void name##_unref(name##_t *ptr) { \ REQUIRE(ptr != NULL); \ if (isc_refcount_decrement(&ptr->references) == 1) { \ isc_refcount_destroy(&ptr->references); \ destroy(ptr); \ } \ } \ stat void name##_attach(name##_t *ptr, name##_t **ptrp) { \ REQUIRE(ptrp != NULL && *ptrp == NULL); \ name##_ref(ptr); \ *ptrp = ptr; \ } \ \ stat void name##_detach(name##_t **ptrp) { \ REQUIRE(ptrp != NULL && *ptrp != NULL); \ name##_t *ptr = *ptrp; \ *ptrp = NULL; \ name##_unref(ptr); \ } #define ISC_REFCOUNT_IMPL(name, destroy) \ ISC__REFCOUNT_IMPL(name, destroy, ISC_REFCOUNT_BLANK) #define ISC_REFCOUNT_STATIC_IMPL(name, destroy) \ ISC__REFCOUNT_IMPL(name, destroy, static inline) ISC_LANG_ENDDECLS