Added the mechanism of maintaining shadow nodes alive.

I refactored the node cache in such a way that it now only
maintains references to nodes (the reason is that only
directory nodes and shadow nodes are created, therefore the
existing node cache is very well suited for this purpose).
It must be remarked that the node cache, borrowed from
unionfs, has never actually been a *cache*, therefore this
small change does not alter things badly.

I also removed the command line option --ncache-size.

1 files changed, 21 insertions, 14 deletions

diff --git a/ncache.c b/ncache.c
index 5d39c0d38..f54331554 100644
--- a/ncache.c
+++ b/ncache.c
@@ -36,7 +36,11 @@
 ncache_t ncache;
 /*----------------------------------------------------------------------------*/
 /*Cache size (may be overwritten by the user)*/
-int ncache_size = NCACHE_SIZE;
+/*int ncache_size = NCACHE_SIZE;*/
+/*Our cache is not really a cache now (actually, it has never been one). Its
+	main task now will be to maintain additional references to shadow nodes,
+	which are still in use by some clients and which could possibly go away if
+	nobody maintained references to them explicitly.*/
 /*----------------------------------------------------------------------------*/
 
 /*----------------------------------------------------------------------------*/
@@ -45,14 +49,15 @@ int ncache_size = NCACHE_SIZE;
 void
 ncache_init
 	(
-	int size_max
+	/*int size_max*/
+	void
 	)
 	{
 	/*Reset the LRU and MRU ends of the list*/
 	ncache.mru = ncache.lru = NULL;
 	
 	/*Set the maximal size according to the parameter*/
-	ncache.size_max = size_max;
+	/*ncache.size_max = size_max;*/
 	
 	/*The cache is empty so far; remark that*/
 	ncache.size_current = 0;
@@ -101,8 +106,9 @@ ncache_node_lookup
 	return err;
 	}/*ncache_node_lookup*/
 /*----------------------------------------------------------------------------*/
-/*Removes the given node from the cache*/
-static
+/*Removes the given node from the cache. Does not release the reference held
+	by the cache (for some further finalization actions on the node)*/
+/*Nodes will NOT be removed from the cache automatically*/
 void
 ncache_node_remove
 	(
@@ -139,16 +145,17 @@ ncache_node_remove
 	}/*ncache_node_remove*/
 /*----------------------------------------------------------------------------*/
 /*Resets the node cache*/
+/*No references to nodes are released*/
 void
 ncache_reset(void)
 	{
-	/*The node being currently deleted*/
+	/*The node being currently removed from the cache*/
 	node_t * node;
 	
 	/*Acquire a lock on the cache*/
 	mutex_lock(&ncache.lock);
 	
-	/*Remove the whole cache chain*/
+	/*Release the whole cache chain*/
 	for(node = ncache.mru; node != NULL; ncache_node_remove(node), node = ncache.mru);
 
 	/*Release the lock*/
@@ -165,8 +172,8 @@ ncache_node_add
 	/*Acquire a lock on the cache*/
 	mutex_lock(&ncache.lock);
 	
-	/*If there already are some nodes in the cache and it is enabled*/
-	if((ncache.size_max > 0) || (ncache.size_current > 0))
+	/*If there already are some nodes in the cache already*/
+	if(ncache.size_current > 0)
 		{
 		/*If the node to be added is not at the MRU end already*/
 		if(ncache.mru != node)
@@ -200,20 +207,20 @@ ncache_node_add
 		}
 		
 	/*While the size of the cache is exceeding the maximal size*/
-	node_t * old_lru;
+/*	node_t * old_lru;
 	for
 		(
 		old_lru = ncache.lru;
 		ncache.size_current > ncache.size_max;
 		old_lru = ncache.lru
 		)
-		{
+		{*/
 		/*remove the current LRU end of the list from the cache*/
-		ncache_node_remove(old_lru);
+		/*ncache_node_remove(old_lru);*/
 		
 		/*release the reference to the node owned by this thread*/
-		netfs_nrele(old_lru);
-		}
+		/*netfs_nrele(old_lru);
+		}*/
 		
 	/*Release the lock on the cache*/
 	mutex_unlock(&ncache.lock);