3 files changed, 32 insertions, 3 deletions
diff --git a/src/blockchain_utilities/blockchain_import.cpp b/src/blockchain_utilities/blockchain_import.cpp
index 635a70b10..3841911fe 100644
--- a/src/blockchain_utilities/blockchain_import.cpp
+++ b/src/blockchain_utilities/blockchain_import.cpp
@@ -169,6 +169,26 @@ int check_flush(cryptonote::core &core, std::list<block_complete_entry> &blocks,
   if (!force && blocks.size() < db_batch_size)
     return 0;
 
+  // wait till we can verify a full HOH without extra, for speed
+  uint64_t new_height = core.get_blockchain_storage().get_db().height() + blocks.size();
+  if (!force && new_height % HASH_OF_HASHES_STEP)
+    return 0;
+
+  std::list<crypto::hash> hashes;
+  for (const auto &b: blocks)
+  {
+    cryptonote::block block;
+    if (!parse_and_validate_block_from_blob(b.block, block))
+    {
+      MERROR("Failed to parse block: "
+          << epee::string_tools::pod_to_hex(get_blob_hash(b.block)));
+      core.cleanup_handle_incoming_blocks();
+      return 1;
+    }
+    hashes.push_back(cryptonote::get_block_hash(block));
+  }
+  core.prevalidate_block_hashes(core.get_blockchain_storage().get_db().height(), hashes);
+
   core.prepare_handle_incoming_blocks(blocks);
 
   for(const block_complete_entry& block_entry: blocks)
diff --git a/src/blockchain_utilities/blocksdat_file.cpp b/src/blockchain_utilities/blocksdat_file.cpp
index 63224225f..32e93345e 100644
--- a/src/blockchain_utilities/blocksdat_file.cpp
+++ b/src/blockchain_utilities/blocksdat_file.cpp
@@ -82,7 +82,7 @@ bool BlocksdatFile::open_writer(const boost::filesystem::path& file_path, uint64
 
 bool BlocksdatFile::initialize_file(uint64_t block_stop)
 {
-  const uint32_t nblocks = block_stop + 1;
+  const uint32_t nblocks = (block_stop + 1) / HASH_OF_HASHES_STEP;
   unsigned char nblocksc[4];
 
   nblocksc[0] = nblocks & 0xff;
@@ -101,8 +101,16 @@ bool BlocksdatFile::initialize_file(uint64_t block_stop)
 
 void BlocksdatFile::write_block(const crypto::hash& block_hash)
 {
-  const std::string data(block_hash.data, sizeof(block_hash));
-  *m_raw_data_file << data;
+  m_hashes.push_back(block_hash);
+  while (m_hashes.size() >= HASH_OF_HASHES_STEP)
+  {
+    crypto::hash hash;
+    crypto::cn_fast_hash(m_hashes.data(), HASH_OF_HASHES_STEP * sizeof(crypto::hash), hash);
+    memmove(m_hashes.data(), m_hashes.data() + HASH_OF_HASHES_STEP * sizeof(crypto::hash), (m_hashes.size() - HASH_OF_HASHES_STEP) * sizeof(crypto::hash));
+    m_hashes.resize(m_hashes.size() - HASH_OF_HASHES_STEP);
+    const std::string data(hash.data, sizeof(hash));
+    *m_raw_data_file << data;
+  }
 }
 
 bool BlocksdatFile::close()
diff --git a/src/blockchain_utilities/blocksdat_file.h b/src/blockchain_utilities/blocksdat_file.h
index 0a5913058..d43811772 100644
--- a/src/blockchain_utilities/blocksdat_file.h
+++ b/src/blockchain_utilities/blocksdat_file.h
@@ -76,4 +76,5 @@ protected:
 private:
 
   uint64_t m_cur_height; // tracks current height during export
+  std::vector<crypto::hash> m_hashes;
 };