新增adlisr.h adlist.c部分注释

src/adlist.c

@@ -39,6 +39,7 @@
  * listSetFreeMethod.
  *
  * On error, NULL is returned. Otherwise the pointer to the new list. */
+//链表创建
 list *listCreate(void)
 {
     struct list *list;
@@ -54,6 +55,7 @@ list *listCreate(void)
 }
 
 /* Remove all the elements from the list without destroying the list itself. */
+//清空列表所有元素
 void listEmpty(list *list)
 {
     unsigned long len;
@@ -74,6 +76,7 @@ void listEmpty(list *list)
 /* Free the whole list.
  *
  * This function can't fail. */
+//释放整个列表
 void listRelease(list *list)
 {
     listEmpty(list);
@@ -86,6 +89,7 @@ void listRelease(list *list)
  * On error, NULL is returned and no operation is performed (i.e. the
  * list remains unaltered).
  * On success the 'list' pointer you pass to the function is returned. */
+//链表头添加结点
 list *listAddNodeHead(list *list, void *value)
 {
     listNode *node;
@@ -112,6 +116,7 @@ list *listAddNodeHead(list *list, void *value)
  * On error, NULL is returned and no operation is performed (i.e. the
  * list remains unaltered).
  * On success the 'list' pointer you pass to the function is returned. */
+//链表尾添加节点
 list *listAddNodeTail(list *list, void *value)
 {
     listNode *node;
@@ -123,9 +128,13 @@ list *listAddNodeTail(list *list, void *value)
         list->head = list->tail = node;
         node->prev = node->next = NULL;
     } else {
+        //当前要插入的节点的头指向链表的尾指针
         node->prev = list->tail;
+        //当前要插入节点的下一个节点置为NULL
         node->next = NULL;
+        //链表的尾节点的下一个节点指向当前要插入的节点
         list->tail->next = node;
+        //链表的尾指针指向当前要插入的节点
         list->tail = node;
     }
     list->len++;

src/adlist.h

@@ -27,51 +27,67 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
-
+/**
+ * 双向链表 被广泛运用于 redisClients、redisServer、发布订阅、慢查询、监视器等。
+ * 有点：
+ *  在插入、删除结点的时间复杂度很低
+ * 缺点
+ *  内存利用率低
+ *  由于内存不连续，容易产生内存碎片
+ */
 #ifndef __ADLIST_H__
 #define __ADLIST_H__
 
 /* Node, List, and Iterator are the only data structures used currently. */
-
+// 链表结点
 typedef struct listNode {
     struct listNode *prev;
     struct listNode *next;
+    // 可以指向任何类型的值
     void *value;
 } listNode;
-
+// 迭代器，负责所有和链表遍历有关的行为
+// 遍历 list 时，只需要调用 listIter 的遍历函数即可
 typedef struct listIter {
     listNode *next;
+    // 迭代器遍历方向
     int direction;
 } listIter;
-
+// 链表
 typedef struct list {
+    // 头指针
     listNode *head;
+    // 尾指针
     listNode *tail;
+    // 节点复制函数
     void *(*dup)(void *ptr);
+    // 节点释放函数
     void (*free)(void *ptr);
+    // 节点对比函数
     int (*match)(void *ptr, void *key);
+    // 链表的长度
     unsigned long len;
 } list;
 
 /* Functions implemented as macros */
-#define listLength(l) ((l)->len)
-#define listFirst(l) ((l)->head)
-#define listLast(l) ((l)->tail)
-#define listPrevNode(n) ((n)->prev)
-#define listNextNode(n) ((n)->next)
-#define listNodeValue(n) ((n)->value)
+#define listLength(l) ((l)->len) //链表长度
+#define listFirst(l) ((l)->head) //链表头
+#define listLast(l) ((l)->tail) //链表尾
+#define listPrevNode(n) ((n)->prev) //上一个节点
+#define listNextNode(n) ((n)->next) // 下一个几点
+#define listNodeValue(n) ((n)->value) //节点值
 
-#define listSetDupMethod(l,m) ((l)->dup = (m))
-#define listSetFreeMethod(l,m) ((l)->free = (m))
-#define listSetMatchMethod(l,m) ((l)->match = (m))
+#define listSetDupMethod(l,m) ((l)->dup = (m))  // 节点复制
+#define listSetFreeMethod(l,m) ((l)->free = (m)) // 节点释放
+#define listSetMatchMethod(l,m) ((l)->match = (m)) //节点对比
 
-#define listGetDupMethod(l) ((l)->dup)
-#define listGetFreeMethod(l) ((l)->free)
-#define listGetMatchMethod(l) ((l)->match)
+#define listGetDupMethod(l) ((l)->dup) // 链表复制
+#define listGetFreeMethod(l) ((l)->free) //链表释放
+#define listGetMatchMethod(l) ((l)->match) //链表对比
 
 /* Prototypes */
-list *listCreate(void);
-void listRelease(list *list);
+list *listCreate(void); //链表创建
+void listRelease(list *list); //释放整个列表
 void listEmpty(list *list);
 list *listAddNodeHead(list *list, void *value);
 list *listAddNodeTail(list *list, void *value);
@@ -90,7 +106,9 @@ void listRotateHeadToTail(list *list);
 void listJoin(list *l, list *o);
 
 /* Directions for iterators */
+// 从头遍历
 #define AL_START_HEAD 0
+// 从尾遍历
 #define AL_START_TAIL 1
 
 #endif /* __ADLIST_H__ */