/* * Copyright (c) 2019 TAOS Data, Inc. * * This program is free software: you can use, redistribute, and/or modify * it under the terms of the GNU Affero General Public License, version 3 * or later ("AGPL"), as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . */ #ifndef TBASE_TSKIPLIST_H #define TBASE_TSKIPLIST_H #ifdef __cplusplus extern "C" { #endif #define MAX_SKIP_LIST_LEVEL 20 #include #include #include #include "os.h" #include "ttypes.h" /* * key of each node * todo move to as the global structure in all search codes... */ const static size_t SKIP_LIST_STR_KEY_LENGTH_THRESHOLD = 15; typedef tVariant tSkipListKey; typedef enum tSkipListPointQueryType { INCLUDE_POINT_QUERY, EXCLUDE_POINT_QUERY, } tSkipListPointQueryType; typedef struct tSkipListNode { uint16_t nLevel; char * pData; struct tSkipListNode **pForward; struct tSkipListNode **pBackward; tSkipListKey key; } tSkipListNode; /* * @version 0.2 * @date 2017/11/12 * the simple version of SkipList. * for multi-thread safe purpose, we employ pthread_rwlock_t to guarantee to generate * deterministic result. Later, we will remove the lock in SkipList to further * enhance the performance. In this case, one should use the concurrent skip list (by * using michael-scott algorithm) instead of this simple version in a multi-thread * environment, to achieve higher performance of read/write operations. * * Note: Duplicated primary key situation. * In case of duplicated primary key, two ways can be employed to handle this situation: * 1. add as normal insertion with out special process. * 2. add an overflow pointer at each list node, all nodes with the same key will be added * in the overflow pointer. In this case, the total steps of each search will be reduced significantly. * Currently, we implement the skip list in a line with the first means, maybe refactor it soon. * * Memory consumption: the memory alignment causes many memory wasted. So, employ a memory * pool will significantly reduce the total memory consumption, as well as the calloc/malloc operation costs. * * 3. use the iterator pattern to refactor all routines to make it more clean */ // state struct, record following information: // number of links in each level. // avg search steps, for latest 1000 queries // avg search rsp time, for latest 1000 queries // total memory size typedef struct tSkipListState { // in bytes, sizeof(tSkipList)+sizeof(tSkipListNode)*tSkipList->nSize uint64_t nTotalMemSize; uint64_t nLevelNodeCnt[MAX_SKIP_LIST_LEVEL]; uint64_t queryCount; // total query count /* * only record latest 1000 queries * when the value==1000, = 0, * nTotalStepsForQueries = 0, * nTotalElapsedTimeForQueries = 0 */ uint64_t nRecQueries; uint16_t nTotalStepsForQueries; uint64_t nTotalElapsedTimeForQueries; uint16_t nInsertObjs; uint16_t nTotalStepsForInsert; uint64_t nTotalElapsedTimeForInsert; } tSkipListState; typedef struct tSkipList { tSkipListNode pHead; uint64_t nSize; uint16_t nMaxLevel; uint16_t nLevel; uint16_t keyType; uint16_t nMaxKeyLen; __compar_fn_t comparator; pthread_rwlock_t lock; // will be removed soon tSkipListState state; // skiplist state } tSkipList; /* * iterate the skiplist * this will cause the multi-thread problem, when the skiplist is destroyed, the iterate may * continue iterating the skiplist, so add the reference count for skiplist * TODO add the ref for skiplist when one iterator is created */ typedef struct SSkipListIterator { tSkipList * pSkipList; tSkipListNode *cur; int64_t num; } SSkipListIterator; /* * query condition structure to denote the range query * todo merge the point query cond with range query condition */ typedef struct tSKipListQueryCond { // when the upper bounding == lower bounding, it is a point query tSkipListKey lowerBnd; tSkipListKey upperBnd; int32_t lowerBndRelOptr; // relation operator to denote if lower bound is int32_t upperBndRelOptr; // included or not } tSKipListQueryCond; tSkipList *tSkipListCreate(int16_t nMaxLevel, int16_t keyType, int16_t nMaxKeyLen); void *tSkipListDestroy(tSkipList *pSkipList); // create skip list key tSkipListKey tSkipListCreateKey(int32_t type, char *val, size_t keyLength); // destroy skip list key void tSkipListDestroyKey(tSkipListKey *pKey); // put data into skiplist tSkipListNode *tSkipListPut(tSkipList *pSkipList, void *pData, tSkipListKey *pKey, int32_t insertIdenticalKey); /* * get only *one* node of which key is equalled to pKey, even there are more * than one nodes are of the same key */ tSkipListNode *tSkipListGetOne(tSkipList *pSkipList, tSkipListKey *pKey); /* * get all data with the same keys */ int32_t tSkipListGets(tSkipList *pSkipList, tSkipListKey *pKey, tSkipListNode ***pRes); int32_t tSkipListIterateList(tSkipList *pSkipList, tSkipListNode ***pRes, bool (*fp)(tSkipListNode *, void *), void *param); /* * remove only one node of the pKey value. * If more than one node has the same value, any one will be removed * * @Return * true: one node has been removed * false: no node has been removed */ bool tSkipListRemove(tSkipList *pSkipList, tSkipListKey *pKey); /* * remove the specified node in parameters */ void tSkipListRemoveNode(tSkipList *pSkipList, tSkipListNode *pNode); // for debug purpose only void tSkipListPrint(tSkipList *pSkipList, int16_t nlevel); /* * range query & single point query function */ int32_t tSkipListQuery(tSkipList *pSkipList, tSKipListQueryCond *pQueryCond, tSkipListNode ***pResult); /* * include/exclude point query */ int32_t tSkipListPointQuery(tSkipList *pSkipList, tSkipListKey *pKey, int32_t numOfKey, tSkipListPointQueryType type, tSkipListNode ***pResult); int32_t tSkipListIteratorReset(tSkipList *pSkipList, SSkipListIterator *iter); bool tSkipListIteratorNext(SSkipListIterator *iter); tSkipListNode *tSkipListIteratorGet(SSkipListIterator *iter); #ifdef __cplusplus } #endif #endif // TBASE_TSKIPLIST_H