bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/variable/NodeCache.java

   1 package org.simantics.db.layer0.variable;
   2
   3 import java.util.HashMap;
   4 import java.util.Map;
   5 import java.util.TreeMap;
   6
   7 import gnu.trove.map.hash.TObjectLongHashMap;
   8
   9 /**
  10  * @author Antti Villberg
  11  *
  12  * @param <Node>
  13  * @param <Value>
  14  *
  15  * @since 1.23
  16  */
  17 public class NodeCache<Node,Value> {
  18
  19         // Expiration time for items in this cache
  20         private long defaultExpirationTimeInNs;
  21
  22         // Here we hold all nodes with finite expiration times
  23         private TreeMap<Long,Node> expirationTimes = new TreeMap<Long,Node>();
  24         // Finite expiration times for nodes
  25         private TObjectLongHashMap<Node> exp = new TObjectLongHashMap<Node>(10, 0.5f, -1L);
  26
  27         // All node values
  28         private Map<Node,Value> map = new HashMap<Node,Value>();
  29
  30         private boolean disposed;
  31
  32         public NodeCache() {
  33                 this(1_000_000_000L);
  34         }
  35
  36         public NodeCache(long defaultExpirationTimeInNs) {
  37                 this.defaultExpirationTimeInNs = defaultExpirationTimeInNs;
  38         }
  39
  40         public synchronized Value get(Node node) {
  41                 return map.get(node);
  42         }
  43
  44         public synchronized void clearExpired() {
  45
  46                 long now = System.nanoTime();
  47                 while(!expirationTimes.isEmpty()) {
  48                         Long first = expirationTimes.firstKey();
  49                         if(first < now) {
  50                                 Node node = expirationTimes.remove(first);
  51                                 exp.remove(node);
  52                                 map.remove(node);
  53                         } else {
  54                                 return;
  55                         }
  56                 }
  57
  58         }
  59
  60         private long scheduleExpiration(Node node, long expiration) {
  61                 while(expirationTimes.containsKey(expiration)) expiration++;
  62                 expirationTimes.put(expiration, node);
  63                 exp.put(node, expiration);
  64                 return expiration;
  65         }
  66
  67         private void refreshExpiration(Node node, long newExpiration, boolean existing) {
  68
  69                 long current = exp.get(node);
  70                 if(current == -1) {
  71                         if(existing) {
  72                                 // We have infinite expiration => do nothing
  73                         } else {
  74                                 // This is a new value
  75                                 if(newExpiration == 0) {
  76                                         // We require infinite expiration => do nothing
  77                                 } else {
  78                                         scheduleExpiration(node, newExpiration);
  79                                 }
  80                         }
  81                         return;
  82                 }
  83
  84                 // This node is already under expiration tracking
  85                 if(newExpiration == 0) {
  86                         // We now want infinite expiration => remove expiration time info
  87                         expirationTimes.remove(current);
  88                         exp.remove(node);
  89                 } else {
  90                         if(newExpiration > current) {
  91                                 // Update expiration time
  92                                 expirationTimes.remove(current);
  93                                 scheduleExpiration(node, newExpiration);
  94                         }
  95                 }
  96
  97         }
  98
  99         public synchronized void put(Node node, Value value) {
 100                 if (disposed)
 101                         return;
 102                 Value existing = map.put(node, value);
 103                 refreshExpiration(node, 0, existing != null);
 104         }
 105
 106         public synchronized void put(Node node, Value value, long expiration) {
 107                 if (disposed)
 108                         return;
 109                 Value existing = map.put(node, value);
 110                 refreshExpiration(node, System.nanoTime() + expiration, existing != null);
 111         }
 112
 113         public synchronized void removeListening(Node node) {
 114                 if (disposed)
 115                         return;
 116                 scheduleExpiration(node, System.nanoTime() + defaultExpirationTimeInNs);
 117         }
 118
 119         public synchronized void dispose() {
 120                 disposed = true;
 121                 expirationTimes.clear();
 122                 exp.clear();
 123                 map.clear();
 124         }
 125
 126 }