diff options
Diffstat (limited to 'lib/qobj.h')
| -rw-r--r-- | lib/qobj.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/lib/qobj.h b/lib/qobj.h new file mode 100644 index 0000000..a3883fd --- /dev/null +++ b/lib/qobj.h @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: ISC +/* + * Copyright (c) 2015-16 David Lamparter, for NetDEF, Inc. + */ + +#ifndef _QOBJ_H +#define _QOBJ_H + +#include <stdint.h> +#include <stdlib.h> +#include <stddef.h> + +#include "typesafe.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* reserve a specific amount of bytes for a struct, which can grow up to + * that size (or be dummy'd out if not needed) + * + * note the padding's array size will be an error if it gets negative or zero; + * this is intentional to prevent the struct from growing beyond the allocated + * space. + */ +#ifndef __cplusplus +#define RESERVED_SPACE_STRUCT(name, fieldname, size) \ + struct { \ + struct name fieldname; \ + char padding##fieldname[size - sizeof(struct name)]; \ + }; +#else +#define RESERVED_SPACE_STRUCT(name, fieldname, size) \ + struct name fieldname; \ + char padding##fieldname[size - sizeof(struct name)]; +#endif + +/* don't need struct definitions for these here. code actually using + * these needs to define the struct *before* including this header. + * HAVE_QOBJ_xxx should be defined to +1 in that case, like this: + * + * #if defined(HAVE_QOBJ_NODETYPE_CLI) && HAVE_QOBJ_NODETYPE_CLI < 0 + * #error include files are in wrong order + * #else + * #define HAVE_QOBJ_NODETYPE_CLI 1 + * struct qobj_nodetype_cli { ... } + * #endif + */ +#ifndef HAVE_QOBJ_NODETYPE_CLI +#define HAVE_QOBJ_NODETYPE_CLI -1 +struct qobj_nodetype_cli { + int dummy; +}; +#endif + +#ifndef HAVE_QOBJ_NODETYPE_CAPNP +#define HAVE_QOBJ_NODETYPE_CAPNP -1 +struct qobj_nodetype_capnp { + int dummy; +}; +#endif + +#include "typesafe.h" + +/* each different kind of object will have a global variable of this type, + * which can be used by various other pieces to store type-related bits. + * type equality can be tested as pointer equality. (cf. QOBJ_GET_TYPESAFE) + */ +struct qobj_nodetype { + ptrdiff_t node_member_offset; + RESERVED_SPACE_STRUCT(qobj_nodetype_cli, cli, 256) + RESERVED_SPACE_STRUCT(qobj_nodetype_capnp, capnp, 256) +}; + +PREDECL_HASH(qobj_nodes); + +/* anchor to be embedded somewhere in the object's struct */ +struct qobj_node { + uint64_t nid; + struct qobj_nodes_item nodehash; + const struct qobj_nodetype *type; +}; + +#define QOBJ_FIELDS struct qobj_node qobj_node + +/* call these at the end of any _create function (QOBJ_REG) + * and beginning of any _destroy function (QOBJ_UNREG) */ +#define QOBJ_REG(n, structname) qobj_reg(&n->qobj_node, &qobj_t_##structname) +#define QOBJ_UNREG(n) qobj_unreg(&n->qobj_node) + +/* internals - should not be directly used without a good reason + * + * note: qobj_get is essentially never safe to use in MT context because + * the object could be deleted by another thread -- and worse, it could be + * of the "wrong" type and deleted. + * + * with qobj_get_typed, the type check is done under lock, which means that + * it can be used as long as another lock prevents the deletion of objects + * of the expected type. + * + * in the long this may need another touch, e.g. built-in per-object locking. + */ +void qobj_reg(struct qobj_node *node, const struct qobj_nodetype *type); +void qobj_unreg(struct qobj_node *node); +struct qobj_node *qobj_get(uint64_t id); +void *qobj_get_typed(uint64_t id, const struct qobj_nodetype *type); + +/* type declarations */ +#define DECLARE_QOBJ_TYPE(structname) \ + extern const struct qobj_nodetype qobj_t_##structname \ + /* end */ +#define DEFINE_QOBJ_TYPE(structname) \ + const struct qobj_nodetype qobj_t_##structname = { \ + .node_member_offset = \ + (ptrdiff_t)offsetof(struct structname, qobj_node)} \ + /* end */ +#define DEFINE_QOBJ_TYPE_INIT(structname, ...) \ + const struct qobj_nodetype qobj_t_##structname = { \ + .node_member_offset = \ + (ptrdiff_t)offsetof(struct structname, qobj_node), \ + __VA_ARGS__} \ + /* end */ + +/* ID dereference with typecheck. + * will return NULL if id not found or wrong type. */ +#define QOBJ_GET_TYPESAFE(id, structname) \ + ((struct structname *)qobj_get_typed((id), &qobj_t_##structname)) + +#define QOBJ_ID(ptr) ((ptr)->qobj_node.nid) +#define QOBJ_ID_0SAFE(ptr) \ + ({ \ + typeof(ptr) _ptr = (ptr); \ + _ptr ? _ptr->qobj_node.nid : 0ULL; \ + }) + +void qobj_init(void); +void qobj_finish(void); + +#ifdef __cplusplus +} +#endif + +#endif /* _QOBJ_H */ |