IndexTree.rb in perobs-2.4.2

- old
+ new

@@ -33,15 +33,10 @@
 
   # The IndexTree maps the object ID to the address in the FlatFile. The
   # search in the tree is much faster than the linear search in the FlatFile.
   class IndexTree
 
-    # Determines how many levels of the IndexTree will be kept in memory to
-    # accerlerate the access. A number of 7 will keep up to 21845 entries in
-    # the cache but will accelerate the access to the FlatFile address.
-    MAX_CACHED_LEVEL = 7
-
     attr_reader :nodes, :ids
 
     def initialize(db_dir)
       # Directory path used to store the files.
       @db_dir = db_dir
@@ -53,14 +48,10 @@
       # The node sequence usually only reveals a partial match with the
       # requested ID. So, the leaves of the tree point to the object_id_index
       # file which contains the full object ID and the address of the
       # corresponding object in the FlatFile.
       @ids = FixedSizeBlobFile.new(db_dir, 'object_id_index', 2 * 8)
-
-      # The first MAX_CACHED_LEVEL levels of nodes will be cached in memory to
-      # improve access times.
-      @node_cache = {}
     end
 
     # Open the tree files.
     def open
       @nodes.open
@@ -70,10 +61,11 @@
 
     # Close the tree files.
     def close
       @ids.close
       @nodes.close
+      @root = nil
     end
 
     # Flush out all unwritten data
     def sync
       @ids.sync
@@ -82,11 +74,10 @@
 
     # Delete all data from the tree.
     def clear
       @nodes.clear
       @ids.clear
-      @node_cache = {}
       @root = IndexTreeNode.new(self, 0, 0)
     end
 
     # Return an IndexTreeNode object that corresponds to the given address.
     # @param nibble [Fixnum] Index of the nibble the node should correspond to
@@ -94,54 +85,34 @@
     def get_node(nibble, address = nil)
       if nibble >= 16
         # We only support 64 bit keys, so nibble cannot be larger than 15.
         PEROBS.log.fatal "Nibble must be within 0 - 15 but is #{nibble}"
       end
-      # Generate a mask for the least significant bits up to and including the
-      # nibble.
-      mask = (2 ** ((1 + nibble) * 4)) - 1
-      #if address && (node = @node_cache[address & mask])
-      #  # We have an address and have found the node in the node cache.
-      #  return node
-      #else
-      begin
-        # We don't have a IndexTreeNode object yet for this node. Create it
-        # with the data from the 'database_index' file.
-        node = IndexTreeNode.new(self, nibble, address)
-        # Add the node to the node cache if it's up to MAX_CACHED_LEVEL levels
-        # down from the root.
-        #@node_cache[address & mask] = node if nibble <= MAX_CACHED_LEVEL
-        return node
-      end
+      # We don't have a IndexTreeNode object yet for this node. Create it
+      # with the data from the 'database_index' file.
+      node = IndexTreeNode.new(self, nibble, address)
+      return node
     end
 
     # Delete a node from the tree that corresponds to the address.
     # @param nibble [Fixnum] The corresponding nibble for the node
     # @param address [Integer] The address of the node in @nodes
     def delete_node(nibble, address)
       if nibble >= 16
         # We only support 64 bit keys, so nibble cannot be larger than 15.
         PEROBS.log.fatal "Nibble must be within 0 - 15 but is #{nibble}"
       end
-      # First delete the node from the node cache.
-      mask = (2 ** ((1 + nibble) * 4)) - 1
-      #@node_cache.delete(address & mask)
-      # Then delete it from the 'database_index' file.
+
+      # Delete it from the 'database_index' file.
       @nodes.delete_blob(address)
     end
 
     # Store a ID/value touple into the tree. The value can later be retrieved
     # by the ID again. IDs are always unique in the tree. If the ID already
     # exists in the tree, the value will be overwritten.
     # @param id [Integer] ID or key
     # @param value [Integer] value to store
     def put_value(id, value)
-      #MAX_CACHED_LEVEL.downto(0) do |i|
-      #  mask = (2 ** ((1 + i) * 4)) - 1
-      #  if (node = @node_cache[value & mask])
-      #    return node.put_value(id, value)
-      #  end
-      #end
       @root.put_value(id, value)
     end
 
     # Retrieve the value that was stored with the given ID.
     # @param id [Integer] ID of the value to retrieve