00001 /* 00002 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. 00003 * 00004 * Licensed under the Universal Permissive License v 1.0 as shown at 00005 * http://oss.oracle.com/licenses/upl. 00006 */ 00007 #ifndef COH_EVICTION_POLICY_HPP 00008 #define COH_EVICTION_POLICY_HPP 00009 00010 #include "coherence/lang.ns" 00011 00012 #include "coherence/util/Map.hpp" 00013 00014 COH_OPEN_NAMESPACE3(coherence,net,cache) 00015 00016 using coherence::util::Map; 00017 00018 00019 /** 00020 * An eviction policy is an object that the cache provides with access 00021 * information, and when requested, the eviction policy selects and 00022 * evicts entries from the cache. If the eviction policy needs to be 00023 * aware of changes to the cache, it must implement the MapListener 00024 * interface; if it does, it will automatically be registered to receive 00025 * MapEvents. 00026 * 00027 * @author nsa 2008.06.23 00028 */ 00029 class EvictionPolicy 00030 : public interface_spec<EvictionPolicy> 00031 { 00032 // ----- constants ------------------------------------------------------ 00033 00034 public: 00035 /** 00036 * EvictionPolicyType describes the eviction policies available 00037 */ 00038 typedef enum 00039 { 00040 /** 00041 * By default, the cache prunes based on a hybrid LRU+LFU 00042 * algorithm. 00043 */ 00044 eviction_policy_hybrid = 0, 00045 /** 00046 * The cache can prune based on a pure Least Recently Used (LRU) 00047 * algorithm. 00048 */ 00049 eviction_policy_lru = 1, 00050 /** 00051 * The cache can prune based on a pure Least Frequently Used (LFU) 00052 * algorithm. 00053 */ 00054 eviction_policy_lfu = 2, 00055 /** 00056 * The cache can prune using an external eviction policy. 00057 */ 00058 eviction_policy_external = 3 00059 } EvictionPolicyType; 00060 00061 // ----- EvictionPolicy interface --------------------------------------- 00062 00063 public: 00064 /** 00065 * This method is called by the cache to indicate that an entry has 00066 * been touched. 00067 * 00068 * @param hEntry the Cache Entry that has been touched 00069 */ 00070 virtual void entryTouched(Map::Entry::Handle hEntry) = 0; // TODO NSA - Have Mark Review 00071 00072 /** 00073 * This method is called by the cache when the cache requires the 00074 * eviction policy to evict entries. 00075 * 00076 * @param cMaximum the maximum number of units that should remain 00077 * in the cache when the eviction is complete 00078 */ 00079 virtual void requestEviction(int32_t cMaximum) = 0; 00080 }; 00081 00082 COH_CLOSE_NAMESPACE3 00083 00084 #endif // #define COH_EVICTION_POLICY_HPP