Improve chainbase mapped and heap behavior

libraries/chain/controller.cpp

@@ -37,6 +37,7 @@
 
 #include <new>
 #include <shared_mutex>
+#include <utility>
 
 namespace eosio { namespace chain {
 
@@ -605,7 +606,9 @@ struct controller_impl {
          }
          ilog( "Snapshot loaded, lib: ${lib}", ("lib", head->block_num) );
 
-         init(check_shutdown);
+         init(std::move(check_shutdown));
+         if (conf.revert_to_private_mode)
+            db.revert_to_private_mode();
          ilog( "Finished initialization from snapshot" );
       } catch (boost::interprocess::bad_alloc& e) {
          elog( "Failed initialization from snapshot - db storage not configured to have enough storage for the provided snapshot, please increase and retry snapshot" );
@@ -621,7 +624,7 @@ struct controller_impl {
                   ("genesis_chain_id", genesis_chain_id)("controller_chain_id", chain_id)
       );
 
-      this->shutdown = shutdown;
+      this->shutdown = std::move(shutdown);
       if( fork_db.head() ) {
          if( read_mode == db_read_mode::IRREVERSIBLE && fork_db.head()->id != fork_db.root()->id ) {
             fork_db.rollback_head_to_root();
@@ -643,14 +646,14 @@ struct controller_impl {
       } else {
          blog.reset( genesis, head->block );
       }
-      init(check_shutdown);
+      init(std::move(check_shutdown));
    }
 
    void startup(std::function<void()> shutdown, std::function<bool()> check_shutdown) {
       EOS_ASSERT( db.revision() >= 1, database_exception, "This version of controller::startup does not work with a fresh state database." );
       EOS_ASSERT( fork_db.head(), fork_database_exception, "No existing fork database despite existing chain state. Replay required." );
 
-      this->shutdown = shutdown;
+      this->shutdown = std::move(shutdown);
       uint32_t lib_num = fork_db.root()->block_num;
       auto first_block_num = blog.first_block_num();
       if( auto blog_head = blog.head() ) {
@@ -673,7 +676,7 @@ struct controller_impl {
       }
       head = fork_db.head();
 
-      init(check_shutdown);
+      init(std::move(check_shutdown));
    }
 
 
@@ -3468,9 +3471,14 @@ void controller::validate_tapos( const transaction& trx )const { try {
 } FC_CAPTURE_AND_RETHROW() }
 
 void controller::validate_db_available_size() const {
-   const auto free = db().get_segment_manager()->get_free_memory();
+   const auto free = db().get_free_memory();
    const auto guard = my->conf.state_guard_size;
    EOS_ASSERT(free >= guard, database_guard_exception, "database free: ${f}, guard size: ${g}", ("f", free)("g",guard));
+
+   // give a change to chainbase to write some pages to disk if memory becomes scarce.
+   if (auto flushed_pages = mutable_db().check_memory_and_flush_if_needed()) {
+      ilog("CHAINBASE: flushed ${p} pages to disk to decrease memory pressure", ("p", flushed_pages));
+   }
 }
 
 bool controller::is_protocol_feature_activated( const digest_type& feature_digest )const {

libraries/chain/include/eosio/chain/controller.hpp

@@ -79,6 +79,7 @@ namespace eosio { namespace chain {
             bool                     disable_replay_opts    =  false;
             bool                     contracts_console      =  false;
             bool                     allow_ram_billing_in_notify = false;
+            bool                     revert_to_private_mode =  false;
             uint32_t                 maximum_variable_signature_length = chain::config::default_max_variable_signature_length;
             bool                     disable_all_subjective_mitigations = false; //< for developer & testing purposes, can be configured using `disable-all-subjective-mitigations` when `EOSIO_DEVELOPER` build option is provided
             uint32_t                 terminate_at_block     = 0;

plugins/chain_plugin/chain_plugin.cpp

@@ -934,6 +934,13 @@ void chain_plugin_impl::plugin_initialize(const variables_map& options) {
 
       chain_config->db_map_mode = options.at("database-map-mode").as<pinnable_mapped_file::map_mode>();
 
+      // when loading a snapshot, all the state will be modified, so temporarily use the `mapped` mode instead
+      // of `mapped_private` to lower memory requirements.
+      if (snapshot_path && chain_config->db_map_mode == pinnable_mapped_file::mapped_private) {
+        chain_config->db_map_mode = pinnable_mapped_file::mapped;
+        chain_config->revert_to_private_mode = true; // revert to `mapped_private` mode after loading snapshot.
+      }
+
 #ifdef EOSIO_EOS_VM_OC_RUNTIME_ENABLED
       if( options.count("eos-vm-oc-cache-size-mb") )
          chain_config->eosvmoc_config.cache_size = options.at( "eos-vm-oc-cache-size-mb" ).as<uint64_t>() * 1024u * 1024u;

programs/leap-util/actions/snapshot.cpp

@@ -80,6 +80,8 @@ int snapshot_actions::run_subcommand() {
    cfg.state_size = opt->db_size * 1024 * 1024;
    cfg.state_guard_size = opt->guard_size * 1024 * 1024;
    cfg.eosvmoc_tierup = wasm_interface::vm_oc_enable::oc_none; // wasm not used, no use to fire up oc
+
+   cfg.db_map_mode = pinnable_mapped_file::map_mode::mapped;
    protocol_feature_set pfs = initialize_protocol_features( std::filesystem::path("protocol_features"), false );
 
    try {