lib: allow listnode memory to be managed by the app

In most cases this memory is pre-allocated along with the base element.
Similarly it is stored in the base element to allow efficient del
without lookup (main reason for using DLL vs. SLL).

So (in most cases) there should be no need to manage the element/data
and listnode memories separately.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

diff --git a/lib/linklist.c b/lib/linklist.c
index 272e153276025b80dd6d3cb95497c7fb2da02923..2936c5b502a0fa38f4474c473c810da1b431ac89 100644 (file)
--- a/lib/linklist.c
+++ b/lib/linklist.c
@@ -38,16 +38,30 @@ static void list_free_internal(struct list *l)
        XFREE(MTYPE_LINK_LIST, l);
 }
 
+
 /* Allocate new listnode.  Internal use only. */
-static struct listnode *listnode_new(void)
+static struct listnode *listnode_new(struct list *list, void *val)
 {
-       return XCALLOC(MTYPE_LINK_NODE, sizeof(struct listnode));
+       struct listnode *node;
+
+       /* if listnode memory is managed by the app then the val
+        * passed in is the listnode
+        */
+       if (list->flags & LINKLIST_FLAG_NODE_MEM_BY_APP) {
+               node = val;
+               node->prev = node->next = NULL;
+       } else {
+               node = XCALLOC(MTYPE_LINK_NODE, sizeof(struct listnode));
+               node->data = val;
+       }
+       return node;
 }
 
 /* Free listnode. */
-static void listnode_free(struct listnode *node)
+static void listnode_free(struct list *list, struct listnode *node)
 {
-       XFREE(MTYPE_LINK_NODE, node);
+       if (!(list->flags & LINKLIST_FLAG_NODE_MEM_BY_APP))
+               XFREE(MTYPE_LINK_NODE, node);
 }
 
 struct listnode *listnode_add(struct list *list, void *val)
@@ -56,10 +70,9 @@ struct listnode *listnode_add(struct list *list, void *val)
 
        assert(val != NULL);
 
-       node = listnode_new();
+       node = listnode_new(list, val);
 
        node->prev = list->tail;
-       node->data = val;
 
        if (list->head == NULL)
                list->head = node;
@@ -78,10 +91,9 @@ void listnode_add_head(struct list *list, void *val)
 
        assert(val != NULL);
 
-       node = listnode_new();
+       node = listnode_new(list, val);
 
        node->next = list->head;
-       node->data = val;
 
        if (list->head == NULL)
                list->head = node;
@@ -97,15 +109,22 @@ bool listnode_add_sort_nodup(struct list *list, void *val)
        struct listnode *n;
        struct listnode *new;
        int ret;
+       void *data;
 
        assert(val != NULL);
 
+       if (list->flags & LINKLIST_FLAG_NODE_MEM_BY_APP) {
+               n = val;
+               data = n->data;
+       } else {
+               data = val;
+       }
+
        if (list->cmp) {
                for (n = list->head; n; n = n->next) {
-                       ret = (*list->cmp)(val, n->data);
+                       ret = (*list->cmp)(data, n->data);
                        if (ret < 0) {
-                               new = listnode_new();
-                               new->data = val;
+                               new = listnode_new(list, val);
 
                                new->next = n;
                                new->prev = n->prev;
@@ -124,8 +143,7 @@ bool listnode_add_sort_nodup(struct list *list, void *val)
                }
        }
 
-       new = listnode_new();
-       new->data = val;
+       new = listnode_new(list, val);
 
        LISTNODE_ATTACH(list, new);
 
@@ -139,8 +157,8 @@ void listnode_add_sort(struct list *list, void *val)
 
        assert(val != NULL);
 
-       new = listnode_new();
-       new->data = val;
+       new = listnode_new(list, val);
+       val = new->data;
 
        if (list->cmp) {
                for (n = list->head; n; n = n->next) {
@@ -177,8 +195,7 @@ struct listnode *listnode_add_after(struct list *list, struct listnode *pp,
 
        assert(val != NULL);
 
-       nn = listnode_new();
-       nn->data = val;
+       nn = listnode_new(list, val);
 
        if (pp == NULL) {
                if (list->head)
@@ -212,8 +229,7 @@ struct listnode *listnode_add_before(struct list *list, struct listnode *pp,
 
        assert(val != NULL);
 
-       nn = listnode_new();
-       nn->data = val;
+       nn = listnode_new(list, val);
 
        if (pp == NULL) {
                if (list->tail)
@@ -276,7 +292,7 @@ void list_delete_all_node(struct list *list)
                next = node->next;
                if (*list->del)
                        (*list->del)(node->data);
-               listnode_free(node);
+               listnode_free(list, node);
        }
        list->head = list->tail = NULL;
        list->count = 0;
@@ -336,7 +352,7 @@ void list_delete_node(struct list *list, struct listnode *node)
        else
                list->tail = node->prev;
        list->count--;
-       listnode_free(node);
+       listnode_free(list, node);
 }
 
 void list_sort(struct list *list, int (*cmp)(const void **, const void **))

diff --git a/lib/linklist.h b/lib/linklist.h
index 00cb9f871460be3105b5d31700fc96f6e0cbbf59..94a1a1604a3899c36a7f6e6f3d112db1c4c7e651 100644 (file)
--- a/lib/linklist.h
+++ b/lib/linklist.h
@@ -43,6 +43,12 @@ struct list {
        /* invariant: count is the number of listnodes in the list */
        unsigned int count;
 
+       uint8_t flags;
+/* Indicates that listnode memory is managed by the application and
+ * doesn't need to be freed by this library via listnode_delete etc.
+ */
+#define LINKLIST_FLAG_NODE_MEM_BY_APP (1 << 0)
+
        /*
         * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
         * Used as definition of sorted for listnode_add_sort
@@ -60,10 +66,14 @@ struct list {
 #define listhead(X) ((X) ? ((X)->head) : NULL)
 #define listhead_unchecked(X) ((X)->head)
 #define listtail(X) ((X) ? ((X)->tail) : NULL)
+#define listtail_unchecked(X) ((X)->tail)
 #define listcount(X) ((X)->count)
 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
 /* return X->data only if X and X->data are not NULL */
 #define listgetdata(X) (assert(X), assert((X)->data != NULL), (X)->data)
+/* App is going to manage listnode memory */
+#define listset_app_node_mem(X) ((X)->flags |= LINKLIST_FLAG_NODE_MEM_BY_APP)
+#define listnode_init(X, val) ((X)->data = (val))
 
 /*
  * Create a new linked list.
@@ -95,7 +105,7 @@ extern struct listnode *listnode_add(struct list *list, void *data);
  *    list to operate on
  *
  * data
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 extern void listnode_add_head(struct list *list, void *data);
 
@@ -112,7 +122,7 @@ extern void listnode_add_head(struct list *list, void *data);
  *    list to operate on
  *
  * val
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 extern void listnode_add_sort(struct list *list, void *val);
 
@@ -128,7 +138,7 @@ extern void listnode_add_sort(struct list *list, void *val);
  *    listnode to insert after
  *
  * data
- *    data to insert
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  *
  * Returns:
  *    pointer to newly created listnode that contains the inserted data
@@ -148,7 +158,7 @@ extern struct listnode *listnode_add_after(struct list *list,
  *    listnode to insert before
  *
  * data
- *    data to insert
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  *
  * Returns:
  *    pointer to newly created listnode that contains the inserted data
@@ -313,7 +323,7 @@ extern void list_filter_out_nodes(struct list *list, bool (*cond)(void *data));
  *    list to operate on
  *
  * val
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 
 extern bool listnode_add_sort_nodup(struct list *list, void *val);