Rev 4209: Use a simple dict cache for btree internal_node lookups. in http://bzr.arbash-meinel.com/branches/bzr/jam-integration

[John Arbash Meinel]

At http://bzr.arbash-meinel.com/branches/bzr/jam-integration

------------------------------------------------------------
revno: 4209
revision-id: john at arbash-meinel.com-20090326205221-ddrlzj00y65k5t0w
parent: pqm at pqm.ubuntu.com-20090326131816-4nzmlssnd4huc5cu
committer: John Arbash Meinel <john at arbash-meinel.com>
branch nick: jam-integration
timestamp: Thu 2009-03-26 15:52:21 -0500
message:
  Use a simple dict cache for btree internal_node lookups.
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=== modified file 'bzrlib/btree_index.py'
--- a/bzrlib/btree_index.py	2009-03-24 01:53:42 +0000
+++ b/bzrlib/btree_index.py	2009-03-26 20:52:21 +0000
@@ -641,7 +641,11 @@
         # Default max size is 100,000 leave values
         self._leaf_value_cache = None # lru_cache.LRUCache(100*1000)
         self._leaf_node_cache = lru_cache.LRUCache(_NODE_CACHE_SIZE)
-        self._internal_node_cache = lru_cache.LRUCache()
+        # We could limit this, but even a 300k record btree has only 3k leaf
+        # nodes, and only 20 internal nodes. So the default of 100 nodes in an
+        # LRU would mean we always cache everything anyway, no need to pay the
+        # overhead of LRU
+        self._internal_node_cache = {}
         self._key_count = None
         self._row_lengths = None
         self._row_offsets = None # Start of each row, [-1] is the end