core: make the sync chunk block count overridable

src/common/command_line.cpp

@@ -30,6 +30,7 @@
 
 #include "command_line.h"
 #include "string_tools.h"
+#include "cryptonote_config.h"
 
 namespace command_line
 {
@@ -92,4 +93,9 @@ namespace command_line
   , "Show time-stats when processing blocks/txs and disk synchronization."
   , 0
   };
+  const command_line::arg_descriptor<size_t> arg_block_sync_size  = {
+    "block-sync-size"
+  , "How many blocks to sync at once during chain synchronization."
+  , BLOCKS_SYNCHRONIZING_DEFAULT_COUNT
+  };
 }

src/common/command_line.h

@@ -216,4 +216,5 @@ namespace command_line
   extern const arg_descriptor<uint64_t> arg_prep_blocks_threads;
   extern const arg_descriptor<uint64_t> arg_db_auto_remove_logs;
   extern const arg_descriptor<uint64_t> arg_show_time_stats;
+  extern const arg_descriptor<size_t> arg_block_sync_size;
 }

src/cryptonote_core/cryptonote_core.cpp

@@ -142,6 +142,7 @@ namespace cryptonote
     command_line::add_arg(desc, command_line::arg_db_sync_mode);
     command_line::add_arg(desc, command_line::arg_show_time_stats);
     command_line::add_arg(desc, command_line::arg_db_auto_remove_logs);
+    command_line::add_arg(desc, command_line::arg_block_sync_size);
   }
   //-----------------------------------------------------------------------------------------------
   bool core::handle_command_line(const boost::program_options::variables_map& vm)
@@ -403,6 +404,10 @@ namespace cryptonote
     m_blockchain_storage.set_show_time_stats(show_time_stats);
     CHECK_AND_ASSERT_MES(r, false, "Failed to initialize blockchain storage");
 
+    block_sync_size = command_line::get_arg(vm, command_line::arg_block_sync_size);
+    if (block_sync_size == 0)
+      block_sync_size = BLOCKS_SYNCHRONIZING_DEFAULT_COUNT;
+
     // load json & DNS checkpoints, and verify them
     // with respect to what blocks we already have
     CHECK_AND_ASSERT_MES(update_checkpoints(), false, "One or more checkpoints loaded from json or dns conflicted with existing checkpoints.");

src/cryptonote_core/cryptonote_core.h

@@ -611,6 +611,13 @@ namespace cryptonote
       */
      bool are_key_images_spent(const std::vector<crypto::key_image>& key_im, std::vector<bool> &spent) const;
 
+     /**
+      * @brief get the number of blocks to sync in one go
+      *
+      * @return the number of blocks to sync in one go
+      */
+     size_t get_block_sync_size() const { return block_sync_size; }
+
    private:
 
      /**
@@ -798,6 +805,8 @@ namespace cryptonote
      std::atomic_flag m_checkpoints_updating; //!< set if checkpoints are currently updating to avoid multiple threads attempting to update at once
 
      boost::interprocess::file_lock db_lock; //!< a lock object for a file lock in the db directory
+
+     size_t block_sync_size;
    };
 }
 

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -650,9 +650,9 @@ namespace cryptonote
       size_t count = 0;
       auto it = context.m_needed_objects.begin();
 
-      size_t count_limit = BLOCKS_SYNCHRONIZING_DEFAULT_COUNT;
+      const size_t count_limit = m_core.get_block_sync_size();
       _note_c("net/req-calc" , "Setting count_limit: " << count_limit);
-      while(it != context.m_needed_objects.end() && count < BLOCKS_SYNCHRONIZING_DEFAULT_COUNT)
+      while(it != context.m_needed_objects.end() && count < count_limit)
       {
         if( !(check_having_blocks && m_core.have_block(*it)))
         {