From 9b15ab48ad086abb0ce0424d5e369b14fad0a9ac Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Wed, 7 Apr 2021 11:14:18 +0300
Subject: [PATCH] core: restore MPT collapsing logic

Fix #1867, revert part of bf20db09e05fae4d7e3ef142b823bab8df32ce7e.
---
 pkg/core/blockchain.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 41c2758e2..f6cd03577 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -754,6 +754,13 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 			writeBuf.Reset()
 		}
 	}
+	// Every persist cycle we also compact our in-memory MPT. It's flushed
+	// already in AddMPTBatch, so collapsing it is safe.
+	persistedHeight := atomic.LoadUint32(&bc.persistedHeight)
+	if persistedHeight == block.Index-1 {
+		// 10 is good and roughly estimated to fit remaining trie into 1M of memory.
+		mpt.Collapse(10)
+	}
 
 	bc.lock.Lock()
 	_, err = cache.Persist()