blockchain: ensure all blocks get their longhash precalculated

If the number of blocks to check was not a multiple of the
number of preparation threads, the last few blocks would
not be included in the threaded long hash calculation.
Those would still get calculated when the block gets added
to the chain, however, so this was only a tiny performance
hit, rather than a security bug.

2 files changed, 4 insertions, 2 deletions

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 742e1ac3d..1313f9141 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -3743,9 +3743,11 @@ bool Blockchain::prepare_handle_incoming_blocks(const std::list<block_complete_e
     if (!blocks_exist)
     {
       m_blocks_longhash_table.clear();
+      uint64_t thread_height = height;
       for (uint64_t i = 0; i < threads; i++)
       {
-        thread_list.push_back(new boost::thread(attrs, boost::bind(&Blockchain::block_longhash_worker, this, height + (i * batches), std::cref(blocks[i]), std::ref(maps[i]))));
+        thread_list.push_back(new boost::thread(attrs, boost::bind(&Blockchain::block_longhash_worker, this, thread_height, std::cref(blocks[i]), std::ref(maps[i]))));
+        thread_height += blocks[i].size();
       }
 
       for (size_t j = 0; j < thread_list.size(); j++)
diff --git a/src/cryptonote_core/blockchain.h b/src/cryptonote_core/blockchain.h
index 4f2e4f0d3..564b53af3 100644
--- a/src/cryptonote_core/blockchain.h
+++ b/src/cryptonote_core/blockchain.h
@@ -846,7 +846,7 @@ namespace cryptonote
      * @param blocks the blocks to be hashed
      * @param map return-by-reference the hashes for each block
      */
-    void block_longhash_worker(const uint64_t height, const std::vector<block> &blocks,
+    void block_longhash_worker(uint64_t height, const std::vector<block> &blocks,
         std::unordered_map<crypto::hash, crypto::hash> &map) const;
 
     /**