feat: the first round lru cache for last/last_row

include/util/tlrucache.h

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _TD_UTIL_LRUCACHE_H_
+#define _TD_UTIL_LRUCACHE_H_
+
+#include "thash.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct SLRUCache SLRUCache;
+
+typedef void (*_taos_lru_deleter_t)(const void *key, size_t keyLen, void *value);
+
+typedef struct LRUHandle {
+} LRUHandle;
+
+typedef enum {
+  TAOS_LRU_PRIORITY_HIGH,
+  TAOS_LRU_PRIORITY_LOW
+} LRUPriority;
+  
+typedef enum {
+  TAOS_LRU_STATUS_OK,
+  TAOS_LRU_STATUS_FAIL,
+  TAOS_LRU_STATUS_INCOMPLETE,
+  TAOS_LRU_STATUS_OK_OVERWRITTEN
+} LRUStatus;
+  
+SLRUCache *taosLRUCacheInit(size_t capacity, int numShardBits, double highPriPoolRatio);  
+void taosLRUCacheCleanup(SLRUCache *cache);
+
+LRUStatus taosLRUCacheInsert(SLRUCache *cache, const void *key, size_t keyLen, void *value, size_t charge,
+                             _taos_lru_deleter_t deleter, LRUHandle **handle, LRUPriority priority);
+LRUHandle *taosLRUCacheLookup(SLRUCache * cache, const void *key, size_t keyLen);
+void taosLRUCacheErase(SLRUCache * cache, const void *key, size_t keyLen);
+
+void taosLRUCacheEraseUnrefEntries(SLRUCache *cache);
+
+bool taosLRUCacheRef(SLRUCache *cache, LRUHandle *handle);
+bool taosLRUCacheRelease(SLRUCache *cache, LRUHandle *handle, bool eraseIfLastRef);
+
+void* taosLRUCacheValue(SLRUCache *cache, LRUHandle *handle);
+
+size_t taosLRUCacheGetUsage(SLRUCache *cache);
+size_t taosLRUCacheGetPinnedUsage(SLRUCache *cache);
+
+void taosLRUCacheSetCapacity(SLRUCache *cache, size_t capacity);
+size_t taosLRUCacheGetCapacity(SLRUCache *cache);
+
+void taosLRUCacheSetStrictCapacity(SLRUCache *cache, bool strict);
+bool taosLRUCacheIsStrictCapacity(SLRUCache *cache);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // _TD_UTIL_LRUCACHE_H_