trie: cache collapsed tries node, not rlp blobs (#16876)

The current trie memory database/cache that we do pruning on stores
trie nodes as binary rlp encoded blobs, and also stores the node
relationships/references for GC purposes. However, most of the trie
nodes (everything apart from a value node) is in essence just a
collection of references.

This PR switches out the RLP encoded trie blobs with the
collapsed-but-not-serialized trie nodes. This permits most of the
references to be recovered from within the node data structure,
avoiding the need to track them a second time (expensive memory wise).

1 files changed, 2 insertions, 2 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index 34832252a..0b50e3f37 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -672,7 +672,7 @@ func (bc *BlockChain) Stop() {
 			}
 		}
 		for !bc.triegc.Empty() {
-			triedb.Dereference(bc.triegc.PopItem().(common.Hash), common.Hash{})
+			triedb.Dereference(bc.triegc.PopItem().(common.Hash))
 		}
 		if size, _ := triedb.Size(); size != 0 {
 			log.Error("Dangling trie nodes after full cleanup")
@@ -947,7 +947,7 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 					bc.triegc.Push(root, number)
 					break
 				}
-				triedb.Dereference(root.(common.Hash), common.Hash{})
+				triedb.Dereference(root.(common.Hash))
 			}
 		}
 	}