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Implemented caching of null nodes in getNode (Node, String, Relation). A singleton

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nullNode is used to cache Node objects in the application cache if they don't exist.
This commit is contained in:
hns 2001-03-09 16:05:31 +00:00
parent 3f285ac8fd
commit 405555278d
1 changed files with 26 additions and 2 deletions
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28
src/helma/objectmodel/db/NodeManager.java
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@ -38,6 +38,9 @@ public final class NodeManager {
// a wrapper that catches some Exceptions while accessing this NM
public final WrappedNodeManager safe;
// an instance of Node that's used to cache null values
private Node nullNode;
public NodeManager (Application app, String dbHome, Properties props) throws DbException {
this.app = app;
int cacheSize = Integer.parseInt (props.getProperty ("cachesize", "1000"));
@ -47,6 +50,7 @@ public final class NodeManager {
app.logEvent ("set up node cache ("+cacheSize+")");
safe = new WrappedNodeManager (this);
nullNode = new Node ("nullNode", "nullNode", null, safe);
// get the initial id generator value
String idb = props.getProperty ("idBaseValue");
@ -222,15 +226,35 @@ public final class NodeManager {
// check if node is already in cache with primary key
Node oldnode = (Node) cache.put (primKey, node);
// no need to check for oldnode != node because we fetched a new node from db
if (oldnode != null && oldnode.getState () != Node.INVALID) {
if (oldnode != null && oldnode != nullNode && oldnode.getState () != Node.INVALID) {
cache.put (primKey, oldnode);
if (!keyIsPrimary)
cache.put (key, oldnode);
node = oldnode;
} else if (!keyIsPrimary) // cache node with secondary key
} else if (!keyIsPrimary) {
// cache node with secondary key
cache.put (key, node);
}
} // synchronized
} else {
// node fetched from db is null, cache result using nullNode
synchronized (cache) {
Node oldnode = (Node) cache.put (key, nullNode);
// for the rare case that some other thread created the node in the meantime
if (oldnode != null && oldnode != nullNode && oldnode.getState () != Node.INVALID) {
Key primKey = oldnode.getKey ();
boolean keyIsPrimary = primKey.equals (key);
cache.put (oldnode.getKey (), oldnode);
if (!keyIsPrimary)
cache.put (key, oldnode);
node = oldnode;
} else {
return null;
}
}
}
} else if (node == nullNode) {
return null;
} else {
// update primary key in cache to keep it from being flushed, see above
if (!rel.usesPrimaryKey ()) {