From d25b0b6ebdc05f4b05f531478bc52f9219aee333 Mon Sep 17 00:00:00 2001
From: moneromooo-monero <moneromooo-monero@users.noreply.github.com>
Date: Sat, 5 Dec 2020 23:51:09 +0000
Subject: [PATCH] blockchain: only update pruning when the chain changed

Most of the addition calls will end up adding nothing, since we
expect to receive every block from all peers, and only the first
time we get it leads to actual addition.
---
 src/cryptonote_core/blockchain.cpp | 12 +++++++++---
 src/cryptonote_core/blockchain.h   |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index ad27f1358..284fc8f34 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -88,7 +88,7 @@ DISABLE_VS_WARNINGS(4267)
 //------------------------------------------------------------------
 Blockchain::Blockchain(tx_memory_pool& tx_pool) :
   m_db(), m_tx_pool(tx_pool), m_hardfork(NULL), m_timestamps_and_difficulties_height(0), m_reset_timestamps_and_difficulties_height(true), m_current_block_cumul_weight_limit(0), m_current_block_cumul_weight_median(0),
-  m_enforce_dns_checkpoints(false), m_max_prepare_blocks_threads(4), m_db_sync_on_blocks(true), m_db_sync_threshold(1), m_db_sync_mode(db_async), m_db_default_sync(false), m_fast_sync(true), m_show_time_stats(false), m_sync_counter(0), m_bytes_to_sync(0), m_cancel(false),
+  m_enforce_dns_checkpoints(false), m_max_prepare_blocks_threads(4), m_db_sync_on_blocks(true), m_db_sync_threshold(1), m_db_sync_mode(db_async), m_db_default_sync(false), m_fast_sync(true), m_show_time_stats(false), m_sync_counter(0), m_update_pruning(false), m_bytes_to_sync(0), m_cancel(false),
   m_long_term_block_weights_window(CRYPTONOTE_LONG_TERM_BLOCK_WEIGHT_WINDOW_SIZE),
   m_long_term_effective_median_block_weight(0),
   m_long_term_block_weights_cache_tip_hash(crypto::null_hash),
@@ -647,6 +647,7 @@ block Blockchain::pop_block_from_blockchain()
   crypto::hash top_block_hash = get_tail_id(top_block_height);
   m_tx_pool.on_blockchain_dec(top_block_height, top_block_hash);
   invalidate_block_template_cache();
+  m_update_pruning = true;
 
   return popped_block;
 }
@@ -4339,6 +4340,7 @@ leave:
 
   bvc.m_added_to_main_chain = true;
   ++m_sync_counter;
+  m_update_pruning = true;
 
   // appears to be a NOP *and* is called elsewhere.  wat?
   m_tx_pool.on_blockchain_inc(new_height, id);
@@ -4617,7 +4619,7 @@ void Blockchain::block_longhash_worker(uint64_t height, const epee::span<const b
 //------------------------------------------------------------------
 bool Blockchain::cleanup_handle_incoming_blocks(bool force_sync)
 {
-  bool success = false;
+  bool success = false, update_pruning = false;
 
   MTRACE("Blockchain::" << __func__);
   CRITICAL_REGION_BEGIN(m_blockchain_lock);
@@ -4684,10 +4686,14 @@ bool Blockchain::cleanup_handle_incoming_blocks(bool force_sync)
     m_blocks_hash_check.shrink_to_fit();
   }
 
+  update_pruning = m_update_pruning;
+  m_update_pruning = false;
+
   CRITICAL_REGION_END();
   m_tx_pool.unlock();
 
-  update_blockchain_pruning();
+  if (update_pruning)
+    update_blockchain_pruning();
 
   return success;
 }
diff --git a/src/cryptonote_core/blockchain.h b/src/cryptonote_core/blockchain.h
index a8e251c71..f9cbf6d08 100644
--- a/src/cryptonote_core/blockchain.h
+++ b/src/cryptonote_core/blockchain.h
@@ -1149,6 +1149,7 @@ namespace cryptonote
 
 
     bool m_batch_success;
+    bool m_update_pruning;
 
     /* `boost::function` is used because the implementation never allocates if
        the callable object has a single `std::shared_ptr` or `std::weap_ptr`