From 472b1d4af527fb5e86ffd9b7eb9dba818d594299 Mon Sep 17 00:00:00 2001
From: Kevin Heifner <heifnerk@objectcomputing.com>
Date: Thu, 8 Feb 2024 14:10:40 -0600
Subject: [PATCH] GH-2125 Optimize fetch_block_branch

---
 libraries/chain/controller.cpp                |  4 +--
 libraries/chain/fork_database.cpp             | 31 ++++++++++++++-----
 .../include/eosio/chain/fork_database.hpp     |  5 ++-
 programs/leap-util/actions/blocklog.cpp       |  2 +-
 4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/libraries/chain/controller.cpp b/libraries/chain/controller.cpp
index bb46a5058e..c679f8425b 100644
--- a/libraries/chain/controller.cpp
+++ b/libraries/chain/controller.cpp
@@ -1339,13 +1339,13 @@ struct controller_impl {
             forkdb.reset( *head );
          } else if( !except_ptr && !check_shutdown() && forkdb.head() ) {
             auto head_block_num = head->block_num();
-            auto branch = forkdb.fetch_branch( forkdb.head()->id() );
+            auto branch = fork_db.fetch_branch_from_head();
             int rev = 0;
             for( auto i = branch.rbegin(); i != branch.rend(); ++i ) {
                if( check_shutdown() ) break;
                if( (*i)->block_num() <= head_block_num ) continue;
                ++rev;
-               replay_push_block<BSP>( (*i)->block, controller::block_status::validated );
+               replay_push_block<BSP>( *i, controller::block_status::validated );
             }
             ilog( "${n} reversible blocks replayed", ("n",rev) );
          }
diff --git a/libraries/chain/fork_database.cpp b/libraries/chain/fork_database.cpp
index 1d6f920178..272b88957a 100644
--- a/libraries/chain/fork_database.cpp
+++ b/libraries/chain/fork_database.cpp
@@ -72,6 +72,7 @@ namespace eosio::chain {
       void             advance_root_impl( const block_id_type& id );
       void             remove_impl( const block_id_type& id );
       branch_type      fetch_branch_impl( const block_id_type& h, uint32_t trim_after_block_num ) const;
+      block_branch_t   fetch_block_branch_impl( const block_id_type& h, uint32_t trim_after_block_num ) const;
       bsp              search_on_branch_impl( const block_id_type& h, uint32_t block_num ) const;
       void             mark_valid_impl( const bsp& h );
       branch_type_pair fetch_branch_from_impl( const block_id_type& first, const block_id_type& second ) const;
@@ -420,6 +421,25 @@ namespace eosio::chain {
       return result;
    }
 
+   template <class bsp>
+   block_branch_t
+   fork_database_t<bsp>::fetch_block_branch(const block_id_type& h, uint32_t trim_after_block_num) const {
+      std::lock_guard g(my->mtx);
+      return my->fetch_block_branch_impl(h, trim_after_block_num);
+   }
+
+   template <class bsp>
+   block_branch_t
+   fork_database_impl<bsp>::fetch_block_branch_impl(const block_id_type& h, uint32_t trim_after_block_num) const {
+      block_branch_t result;
+      for (auto s = get_block_impl(h); s; s = get_block_impl(s->previous())) {
+         if (s->block_num() <= trim_after_block_num)
+            result.push_back(s->block);
+      }
+
+      return result;
+   }
+
    template<class bsp>
    bsp fork_database_t<bsp>::search_on_branch( const block_id_type& h, uint32_t block_num ) const {
       std::lock_guard g( my->mtx );
@@ -648,15 +668,10 @@ namespace eosio::chain {
       });
    }
 
-   std::vector<signed_block_ptr> fork_database::fetch_branch_from_head() {
-      std::vector<signed_block_ptr> r;
-      apply<void>([&](auto& forkdb) {
-         auto branch = forkdb.fetch_branch(forkdb.head()->id());
-         r.reserve(branch.size());
-         for (auto& b : branch)
-            r.push_back(b->block);
+   block_branch_t fork_database::fetch_branch_from_head() const {
+      return apply<block_branch_t>([&](auto& forkdb) {
+         return forkdb.fetch_block_branch(forkdb.head()->id());
       });
-      return r;
    }
 
    // do class instantiations
diff --git a/libraries/chain/include/eosio/chain/fork_database.hpp b/libraries/chain/include/eosio/chain/fork_database.hpp
index c9ad269914..56b17744f9 100644
--- a/libraries/chain/include/eosio/chain/fork_database.hpp
+++ b/libraries/chain/include/eosio/chain/fork_database.hpp
@@ -10,6 +10,8 @@ namespace eosio::chain {
    template<class bsp>
    struct fork_database_impl;
 
+   using block_branch_t = deque<signed_block_ptr>;
+
    /**
     * @class fork_database_t
     * @brief manages light-weight state for all potential unconfirmed forks
@@ -85,6 +87,7 @@ namespace eosio::chain {
        *  A block with an id of `h` must exist in the fork database otherwise this method will throw an exception.
        */
       branch_type fetch_branch( const block_id_type& h, uint32_t trim_after_block_num = std::numeric_limits<uint32_t>::max() ) const;
+      block_branch_t fetch_block_branch( const block_id_type& h, uint32_t trim_after_block_num = std::numeric_limits<uint32_t>::max() ) const;
 
 
       /**
@@ -131,7 +134,7 @@ namespace eosio::chain {
       void switch_from_legacy();
 
       // see fork_database_t::fetch_branch(forkdb->head()->id())
-      std::vector<signed_block_ptr> fetch_branch_from_head();
+      block_branch_t fetch_branch_from_head() const;
 
       template <class R, class F>
       R apply(const F& f) {
diff --git a/programs/leap-util/actions/blocklog.cpp b/programs/leap-util/actions/blocklog.cpp
index 1807081b59..869d25732f 100644
--- a/programs/leap-util/actions/blocklog.cpp
+++ b/programs/leap-util/actions/blocklog.cpp
@@ -266,7 +266,7 @@ int blocklog_actions::read_log() {
       opt->first_block = block_logger.first_block_num();
    }
 
-   std::vector<signed_block_ptr> fork_db_branch;
+   block_branch_t fork_db_branch;
 
    if(std::filesystem::exists(std::filesystem::path(opt->blocks_dir) / config::reversible_blocks_dir_name / config::forkdb_filename)) {
       ilog("opening fork_db");