| /* |
| * QEMU Object Model. |
| * |
| * Based on ideas by Avi Kivity <avi@redhat.com> |
| * |
| * Copyright (C) 2009, 2015 Red Hat Inc. |
| * |
| * Authors: |
| * Luiz Capitulino <lcapitulino@redhat.com> |
| * |
| * This work is licensed under the terms of the GNU LGPL, version 2.1 or later. |
| * See the COPYING.LIB file in the top-level directory. |
| * |
| * QObject Reference Counts Terminology |
| * ------------------------------------ |
| * |
| * - Returning references: A function that returns an object may |
| * return it as either a weak or a strong reference. If the reference |
| * is strong, you are responsible for calling QDECREF() on the reference |
| * when you are done. |
| * |
| * If the reference is weak, the owner of the reference may free it at |
| * any time in the future. Before storing the reference anywhere, you |
| * should call QINCREF() to make the reference strong. |
| * |
| * - Transferring ownership: when you transfer ownership of a reference |
| * by calling a function, you are no longer responsible for calling |
| * QDECREF() when the reference is no longer needed. In other words, |
| * when the function returns you must behave as if the reference to the |
| * passed object was weak. |
| */ |
| #ifndef QOBJECT_H |
| #define QOBJECT_H |
| |
| #include "qapi/qapi-builtin-types.h" |
| |
| struct QObject { |
| QType type; |
| size_t refcnt; |
| }; |
| |
| /* Get the 'base' part of an object */ |
| #define QOBJECT(obj) (&(obj)->base) |
| |
| /* High-level interface for qobject_incref() */ |
| #define QINCREF(obj) \ |
| qobject_incref(QOBJECT(obj)) |
| |
| /* High-level interface for qobject_decref() */ |
| #define QDECREF(obj) \ |
| qobject_decref(obj ? QOBJECT(obj) : NULL) |
| |
| /* Required for qobject_to() */ |
| #define QTYPE_CAST_TO_QNull QTYPE_QNULL |
| #define QTYPE_CAST_TO_QNum QTYPE_QNUM |
| #define QTYPE_CAST_TO_QString QTYPE_QSTRING |
| #define QTYPE_CAST_TO_QDict QTYPE_QDICT |
| #define QTYPE_CAST_TO_QList QTYPE_QLIST |
| #define QTYPE_CAST_TO_QBool QTYPE_QBOOL |
| |
| QEMU_BUILD_BUG_MSG(QTYPE__MAX != 7, |
| "The QTYPE_CAST_TO_* list needs to be extended"); |
| |
| #define qobject_to(type, obj) ({ \ |
| QObject *_tmp = qobject_check_type(obj, glue(QTYPE_CAST_TO_, type)); \ |
| _tmp ? container_of(_tmp, type, base) : (type *)NULL; }) |
| |
| /* Initialize an object to default values */ |
| static inline void qobject_init(QObject *obj, QType type) |
| { |
| assert(QTYPE_NONE < type && type < QTYPE__MAX); |
| obj->refcnt = 1; |
| obj->type = type; |
| } |
| |
| /** |
| * qobject_incref(): Increment QObject's reference count |
| */ |
| static inline void qobject_incref(QObject *obj) |
| { |
| if (obj) |
| obj->refcnt++; |
| } |
| |
| /** |
| * qobject_is_equal(): Return whether the two objects are equal. |
| * |
| * Any of the pointers may be NULL; return true if both are. Always |
| * return false if only one is (therefore a QNull object is not |
| * considered equal to a NULL pointer). |
| */ |
| bool qobject_is_equal(const QObject *x, const QObject *y); |
| |
| /** |
| * qobject_destroy(): Free resources used by the object |
| */ |
| void qobject_destroy(QObject *obj); |
| |
| /** |
| * qobject_decref(): Decrement QObject's reference count, deallocate |
| * when it reaches zero |
| */ |
| static inline void qobject_decref(QObject *obj) |
| { |
| assert(!obj || obj->refcnt); |
| if (obj && --obj->refcnt == 0) { |
| qobject_destroy(obj); |
| } |
| } |
| |
| /** |
| * qobject_type(): Return the QObject's type |
| */ |
| static inline QType qobject_type(const QObject *obj) |
| { |
| assert(QTYPE_NONE < obj->type && obj->type < QTYPE__MAX); |
| return obj->type; |
| } |
| |
| /** |
| * qobject_check_type(): Helper function for the qobject_to() macro. |
| * Return @obj, but only if @obj is not NULL and @type is equal to |
| * @obj's type. Return NULL otherwise. |
| */ |
| static inline QObject *qobject_check_type(const QObject *obj, QType type) |
| { |
| if (obj && qobject_type(obj) == type) { |
| return (QObject *)obj; |
| } else { |
| return NULL; |
| } |
| } |
| |
| #endif /* QOBJECT_H */ |