{"id":4302,"date":"2020-05-06T20:10:21","date_gmt":"2020-05-06T12:10:21","guid":{"rendered":"https:\/\/damogame.cn\/wordpress\/?p=4302"},"modified":"2020-05-06T20:10:21","modified_gmt":"2020-05-06T12:10:21","slug":"%e6%97%a0%e9%94%81%e6%9c%89%e5%ba%8f%e9%93%be%e8%a1%a8%e7%9a%84%e5%ae%9e%e7%8e%b0","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/4302","title":{"rendered":"\u65e0\u9501\u6709\u5e8f\u94fe\u8868\u7684\u5b9e\u73b0"},"content":{"rendered":"

\u539f\u6587\u5730\u5740<\/a><\/h3>\n

 <\/p>\n

\n
\n

\u611f\u8c22\u540c\u4e8b\u3010kevinlynx<\/a>\u3011\u5728\u672c\u7ad9\u53d1\u8868\u6b64\u6587<\/p>\n

\u65e0\u9501\u6709\u5e8f\u94fe\u8868\u53ef\u4ee5\u4fdd\u8bc1\u5143\u7d20\u7684\u552f\u4e00\u6027\uff0c\u4f7f\u5176\u53ef\u7528\u4e8e\u54c8\u5e0c\u8868\u7684\u6876\uff0c\u751a\u81f3\u76f4\u63a5\u4f5c\u4e3a\u4e00\u4e2a\u6548\u7387\u4e0d\u90a3\u4e48\u9ad8\u7684map\u3002\u666e\u901a\u94fe\u8868\u7684\u65e0\u9501\u5b9e\u73b0\u76f8\u5bf9\u7b80\u5355\u70b9\uff0c\u56e0\u4e3a\u63d2\u5165\u5143\u7d20\u53ef\u4ee5\u5728\u8868\u5934\u63d2\uff0c\u800c\u6709\u5e8f\u94fe\u8868\u7684\u63d2\u5165\u5219\u662f\u4efb\u610f\u4f4d\u7f6e\u3002<\/p>\n

\u672c\u6587\u4e3b\u8981\u57fa\u4e8e\u8bba\u6587High Performance Dynamic Lock-Free Hash Tables<\/a>\u5b9e\u73b0\u3002
\n<\/span><\/p>\n

 <\/p>\n

\u4e3b\u8981\u95ee\u9898<\/h2>\n

\u94fe\u8868\u7684\u4e3b\u8981\u64cd\u4f5c\u5305\u542binsert<\/code>\u548cremove<\/code>\uff0c\u5148\u7b80\u5355\u5b9e\u73b0\u4e00\u4e2a\u7248\u672c\uff0c\u5c31\u4f1a\u770b\u5230\u95ee\u9898\u6240\u5728\uff0c\u4ee5\u4e0b\u4ee3\u7801\u53ea\u7528\u4f5c\u793a\u4f8b\uff1a<\/p>\n

\n
struct node_t {\r\n        key_t key;\r\n        value_t val;\r\n        node_t *next;\r\n    };\r\n\r\n    int l_find(node_t **pred_ptr, node_t **item_ptr, node_t *head, key_t key) {\r\n        node_t *pred = head;\r\n        node_t *item = head->next;\r\n        while (item) {\r\n            int d = KEY_CMP(item->key, key);\r\n            if (d >= 0) {\r\n                *pred_ptr = pred;\r\n                *item_ptr = item;\r\n                return d == 0 ? TRUE : FALSE;\r\n            }\r\n            pred = item;\r\n            item = item->next;\r\n        } \r\n        *pred_ptr = pred;\r\n        *item_ptr = NULL;\r\n        return FALSE;\r\n    }\r\n\r\n    int l_insert(node_t *head, key_t key, value_t val) {\r\n        node_t *pred, *item, *new_item;\r\n        while (TRUE) {\r\n            if (l_find(&pred, &item, head, key)) {\r\n                return FALSE;\r\n            }\r\n            new_item = (node_t*) malloc(sizeof(node_t));\r\n            new_item->key = key;\r\n            new_item->val = val;\r\n            new_item->next = item;\r\n            \/\/ A. \u5982\u679cpred\u672c\u8eab\u88ab\u79fb\u9664\u4e86\r\n            if (CAS(&pred->next, item, new_item)) {\r\n                return TRUE;\r\n            }\r\n            free(new_item);\r\n        }\r\n    }\r\n\r\n    int l_remove(node_t *head, key_t key) {\r\n        node_t *pred, *item;\r\n        while (TRUE) {\r\n            if (!l_find(&pred, &item, head, key)) {\r\n                return TRUE;\r\n            }\r\n            \/\/ B. \u5982\u679cpred\u88ab\u79fb\u9664\uff1b\u5982\u679citem\u4e5f\u88ab\u79fb\u9664\r\n            if (CAS(&pred->next, item, item->next)) {\r\n                haz_free(item);\r\n                return TRUE;\r\n            }\r\n        }\r\n    }<\/pre>\n<\/div>\n
l_find<\/code>\u51fd\u6570\u8fd4\u56de\u67e5\u627e\u5230\u7684\u524d\u5e8f\u5143\u7d20\u548c\u5143\u7d20\u672c\u8eab\uff0c\u4ee3\u7801A\u548cB\u867d\u7136\u62ff\u5230\u4e86pred<\/code>\u548citem<\/code>\uff0c\u4f46\u5728CAS<\/code>\u7684\u65f6\u5019\uff0c\u5176\u53ef\u80fd\u88ab\u5176\u4ed6\u7ebf\u7a0b\u79fb\u9664\u3002\u751a\u81f3\uff0c\u5728l_find<\/code>\u8fc7\u7a0b\u4e2d\uff0c\u5176\u6bcf\u4e00\u4e2a\u5143\u7d20\u90fd\u53ef\u80fd\u88ab\u79fb\u9664\u3002\u95ee\u9898\u5728\u4e8e\uff0c\u4efb\u4f55\u65f6\u5019\u62ff\u5230\u4e00\u4e2a\u5143\u7d20\u65f6\uff0c\u90fd\u4e0d\u786e\u5b9a\u5176\u662f\u5426\u8fd8\u6709\u6548<\/strong>\u3002\u5143\u7d20\u7684\u6709\u6548\u6027\u5305\u62ec\u5176\u662f\u5426\u8fd8\u5728\u94fe\u8868\u4e2d\uff0c\u5176\u6307\u5411\u7684\u5185\u5b58\u662f\u5426\u8fd8\u6709\u6548\u3002<\/p>\n
\u89e3\u51b3\u65b9\u6848<\/h2>\n
\u901a\u8fc7\u4e3a\u5143\u7d20\u6307\u9488\u589e\u52a0\u4e00\u4e2a\u6709\u6548\u6027\u6807\u5fd7\u4f4d\uff0c\u914d\u5408CAS\u64cd\u4f5c\u7684\u4e92\u65a5\u6027<\/strong>\uff0c\u5c31\u53ef\u4ee5\u89e3\u51b3\u5143\u7d20\u6709\u6548\u6027\u5224\u5b9a\u95ee\u9898\u3002<\/p>\n
\u56e0\u4e3anode_t<\/code>\u653e\u5728\u5185\u5b58\u4e2d\u662f\u4f1a\u5bf9\u9f50\u7684\uff0c\u6240\u4ee5\u6307\u5411node_t<\/code>\u7684\u6307\u9488\u503c\u4f4e\u51e0\u4f4d\u662f\u4e0d\u4f1a\u7528\u5230\u7684\uff0c\u4ece\u800c\u53ef\u4ee5\u5728\u4f4e\u51e0\u4f4d\u91cc\u8bbe\u7f6e\u6807\u5fd7\uff0c\u8fd9\u6837\u5728\u505aCAS\u7684\u65f6\u5019\uff0c\u5c31\u5b9e\u73b0\u4e86DCAS\u7684\u6548\u679c\uff0c\u76f8\u5f53\u4e8e\u5c06\u4e24\u4e2a\u903b\u8f91\u4e0a\u7684\u64cd\u4f5c\u53d8\u6210\u4e86\u4e00\u4e2a\u539f\u5b50\u64cd\u4f5c\u3002\u60f3\u8c61\u4e0b\u5f15\u7528\u8ba1\u6570\u5bf9\u8c61\u7684\u7ebf\u7a0b\u5b89\u5168\u6027\uff0c\u5176\u5185\u5305\u88c5\u7684\u6307\u9488\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u4f46\u5bf9\u8c61\u672c\u8eab\u4e0d\u662f\u3002<\/p>\n
CAS\u7684\u4e92\u65a5\u6027\uff0c\u5728\u82e5\u5e72\u4e2a\u7ebf\u7a0bCAS\u76f8\u540c\u7684\u5bf9\u8c61\u65f6\uff0c\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u4f1a\u6210\u529f\uff0c\u5931\u8d25\u7684\u7ebf\u7a0b\u5c31\u53ef\u4ee5\u4ee5\u6b64\u5224\u5b9a\u76ee\u6807\u5bf9\u8c61\u53d1\u751f\u4e86\u53d8\u66f4\u3002\u6539\u8fdb\u540e\u7684\u4ee3\u7801\uff08\u4ee3\u7801\u4ec5\u505a\u793a\u4f8b\u7528\uff0c\u4e0d\u4fdd\u8bc1\u6b63\u786e\uff09\uff1a<\/p>\n
\n
typedef size_t markable_t;\r\n    \/\/ \u6700\u4f4e\u4f4d\u7f6e1\uff0c\u8868\u793a\u5143\u7d20\u88ab\u5220\u9664\r\n    #define HAS_MARK(p) ((markable_t)p & 0x01)\r\n    #define MARK(p) ((markable_t)p | 0x01)\r\n    #define STRIP_MARK(p) ((markable_t)p & ~0x01)\r\n\r\n    int l_insert(node_t *head, key_t key, value_t val) {\r\n        node_t *pred, *item, *new_item;\r\n        while (TRUE) {\r\n            if (l_find(&pred, &item, head, key)) { \r\n                return FALSE;\r\n            }\r\n            new_item = (node_t*) malloc(sizeof(node_t));\r\n            new_item->key = key;\r\n            new_item->val = val;\r\n            new_item->next = item;\r\n            \/\/ A. \u867d\u7136find\u62ff\u5230\u4e86\u5408\u6cd5\u7684pred\uff0c\u4f46\u662f\u5728\u4ee5\u4e0b\u4ee3\u7801\u4e4b\u524dpred\u53ef\u80fd\u88ab\u5220\u9664\uff0c\u6b64\u65f6pred->next\u88ab\u6807\u8bb0\r\n            \/\/    pred->next != item\uff0c\u8be5CAS\u4f1a\u5931\u8d25\uff0c\u5931\u8d25\u540e\u91cd\u8bd5\r\n            if (CAS(&pred->next, item, new_item)) {\r\n                return TRUE;\r\n            }\r\n            free(new_item);\r\n        }\r\n        return FALSE;\r\n    }\r\n\r\n    int l_remove(node_t *head, key_t key) {\r\n        node_t *pred, *item;\r\n        while (TRUE) {\r\n            if (!l_find(&pred, &item, head, key)) {\r\n                return FALSE;\r\n            }\r\n            node_t *inext = item->next;\r\n            \/\/ B. \u5220\u9664item\u524d\u5148\u6807\u8bb0item->next\uff0c\u5982\u679cCAS\u5931\u8d25\uff0c\u90a3\u4e48\u60c5\u51b5\u540cinsert\u4e00\u6837\uff0c\u6709\u5176\u4ed6\u7ebf\u7a0b\u5728find\u4e4b\u540e\r\n            \/\/    \u5220\u9664\u4e86item\uff0c\u5931\u8d25\u540e\u91cd\u8bd5\r\n            if (!CAS(&item->next, inext, MARK(inext))) {\r\n                continue;\r\n            }\r\n            \/\/ C. \u5bf9\u540c\u4e00\u4e2a\u5143\u7d20item\u5220\u9664\u65f6\uff0c\u53ea\u4f1a\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6210\u529f\u8d70\u5230\u8fd9\u91cc\r\n            if (CAS(&pred->next, item, STRIP_MARK(item->next))) {\r\n                haz_defer_free(item);\r\n                return TRUE;\r\n            }\r\n        }\r\n        return FALSE;\r\n    }\r\n\r\n    int l_find(node_t **pred_ptr, node_t **item_ptr, node_t *head, key_t key) {\r\n        node_t *pred = head;\r\n        node_t *item = head->next;\r\n        hazard_t *hp1 = haz_get(0);\r\n        hazard_t *hp2 = haz_get(1);\r\n        while (item) {\r\n            haz_set_ptr(hp1, pred);\r\n            haz_set_ptr(hp2, item);\r\n            \/* \r\n             \u5982\u679c\u5df2\u88ab\u6807\u8bb0\uff0c\u90a3\u4e48\u7d27\u63a5\u7740item\u53ef\u80fd\u88ab\u79fb\u9664\u94fe\u8868\u751a\u81f3\u91ca\u653e\uff0c\u6240\u4ee5\u9700\u8981\u91cd\u5934\u67e5\u627e\r\n            *\/\r\n            if (HAS_MARK(item->next)) { \r\n                return l_find(pred_ptr, item_ptr, head, key);\r\n            }\r\n            int d = KEY_CMP(item->key, key);\r\n            if (d >= 0) {\r\n                *pred_ptr = pred;\r\n                *item_ptr = item;\r\n                return d == 0 ? TRUE : FALSE;\r\n            }\r\n            pred = item;\r\n            item = item->next;\r\n        } \r\n        *pred_ptr = pred;\r\n        *item_ptr = NULL;\r\n        return FALSE;\r\n    }<\/pre>\n<\/div>\n
haz_get<\/code>\u3001haz_set_ptr<\/code>\u4e4b\u7c7b\u7684\u51fd\u6570\u662f\u4e00\u4e2ahazard pointer\u5b9e\u73b0\uff0c\u7528\u4e8e\u652f\u6301\u591a\u7ebf\u7a0b\u4e0b\u5185\u5b58\u7684GC\u3002\u4e0a\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u8981\u5220\u9664\u4e00\u4e2a\u5143\u7d20item<\/code>\u65f6\uff0c\u4f1a\u6807\u8bb0item->next<\/code>\uff0c\u4ece\u800c\u4f7f\u5f97insert<\/code>\u65f6\u4e2d\u90a3\u4e2aCAS<\/code>\u4e0d\u9700\u8981\u505a\u4efb\u4f55\u8c03\u6574\u3002\u603b\u7ed3\u4e0b\u8fd9\u91cc\u7684\u7ebf\u7a0b\u7ade\u4e89\u60c5\u51b5\uff1a<\/p>\n