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-rw-r--r--lib/qobj.h154
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diff --git a/lib/qobj.h b/lib/qobj.h
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+/*
+ * Copyright (c) 2015-16 David Lamparter, for NetDEF, Inc.
+ *
+ * Permission to use, copy, modify, and 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 THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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.
+ */
+
+#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 */