core: do not commit half constructed batch db txn

src/blockchain_db/blockchain_db.h

@@ -753,6 +753,21 @@ public:
    */
   virtual void batch_stop() = 0;
 
+  /**
+   * @brief aborts a batch transaction
+   *
+   * If the subclass implements batching, this function should abort the
+   * batch it is currently on.
+   *
+   * If no batch is in-progress, this function should throw a DB_ERROR.
+   * This exception may change in the future if it is deemed necessary to
+   * have a more granular exception type for this scenario.
+   *
+   * If any of this cannot be done, the subclass should throw the corresponding
+   * subclass of DB_EXCEPTION
+   */
+  virtual void batch_abort() = 0;
+
   /**
    * @brief sets whether or not to batch transactions
    *

src/blockchain_db/testdb.h

@@ -54,6 +54,7 @@ public:
   virtual void unlock() override { }
   virtual bool batch_start(uint64_t batch_num_blocks=0, uint64_t batch_bytes=0) override { return true; }
   virtual void batch_stop() override {}
+  virtual void batch_abort() override {}
   virtual void set_batch_transactions(bool) override {}
   virtual void block_wtxn_start() override {}
   virtual void block_wtxn_stop() override {}

src/cryptonote_core/blockchain.cpp

@@ -137,7 +137,8 @@ Blockchain::Blockchain(tx_memory_pool& tx_pool) :
   m_long_term_block_weights_cache_rolling_median(CRYPTONOTE_LONG_TERM_BLOCK_WEIGHT_WINDOW_SIZE),
   m_difficulty_for_next_block_top_hash(crypto::null_hash),
   m_difficulty_for_next_block(1),
-  m_btc_valid(false)
+  m_btc_valid(false),
+  m_batch_success(true)
 {
   LOG_PRINT_L3("Blockchain::" << __func__);
 }
@@ -574,14 +575,7 @@ void Blockchain::pop_blocks(uint64_t nblocks)
   CRITICAL_REGION_LOCAL(m_tx_pool);
   CRITICAL_REGION_LOCAL1(m_blockchain_lock);
 
-  while (!m_db->batch_start())
-  {
-    m_blockchain_lock.unlock();
-    m_tx_pool.unlock();
-    epee::misc_utils::sleep_no_w(1000);
-    m_tx_pool.lock();
-    m_blockchain_lock.lock();
-  }
+  bool stop_batch = m_db->batch_start();
 
   try
   {
@@ -592,10 +586,14 @@ void Blockchain::pop_blocks(uint64_t nblocks)
   }
   catch (const std::exception& e)
   {
-    LOG_ERROR("Error when popping blocks, only " << i << " blocks are popped: " << e.what());
+    LOG_ERROR("Error when popping blocks after processing " << i << " blocks: " << e.what());
+    if (stop_batch)
+      m_db->batch_abort();
+    return;
   }
 
-  m_db->batch_stop();
+  if (stop_batch)
+    m_db->batch_stop();
 }
 //------------------------------------------------------------------
 // This function tells BlockchainDB to remove the top block from the
@@ -3862,6 +3860,7 @@ leave:
     catch (const KEY_IMAGE_EXISTS& e)
     {
       LOG_ERROR("Error adding block with hash: " << id << " to blockchain, what = " << e.what());
+      m_batch_success = false;
       bvc.m_verifivation_failed = true;
       return_tx_to_pool(txs);
       return false;
@@ -3870,6 +3869,7 @@ leave:
     {
       //TODO: figure out the best way to deal with this failure
       LOG_ERROR("Error adding block with hash: " << id << " to blockchain, what = " << e.what());
+      m_batch_success = false;
       bvc.m_verifivation_failed = true;
       return_tx_to_pool(txs);
       return false;
@@ -4179,7 +4179,10 @@ bool Blockchain::cleanup_handle_incoming_blocks(bool force_sync)
 
   try
   {
-    m_db->batch_stop();
+    if (m_batch_success)
+      m_db->batch_stop();
+    else
+      m_db->batch_abort();
     success = true;
   }
   catch (const std::exception &e)
@@ -4403,6 +4406,7 @@ bool Blockchain::prepare_handle_incoming_blocks(const std::vector<block_complete
     m_tx_pool.lock();
     m_blockchain_lock.lock();
   }
+  m_batch_success = true;
 
   const uint64_t height = m_db->height();
   if ((height + blocks_entry.size()) < m_blocks_hash_check.size())

src/cryptonote_core/blockchain.h

@@ -1102,6 +1102,9 @@ namespace cryptonote
     uint64_t m_btc_expected_reward;
     bool m_btc_valid;
 
+
+    bool m_batch_success;
+
     std::shared_ptr<tools::Notify> m_block_notify;
     std::shared_ptr<tools::Notify> m_reorg_notify;
 

src/cryptonote_core/tx_pool.cpp

@@ -95,13 +95,17 @@ namespace cryptonote
     // the whole prepare/handle/cleanup incoming block sequence.
     class LockedTXN {
     public:
-      LockedTXN(Blockchain &b): m_blockchain(b), m_batch(false) {
+      LockedTXN(Blockchain &b): m_blockchain(b), m_batch(false), m_active(false) {
         m_batch = m_blockchain.get_db().batch_start();
+        m_active = true;
       }
-      ~LockedTXN() { try { if (m_batch) { m_blockchain.get_db().batch_stop(); } } catch (const std::exception &e) { MWARNING("LockedTXN dtor filtering exception: " << e.what()); } }
+      void commit() { try { if (m_batch && m_active) { m_blockchain.get_db().batch_stop(); m_active = false; } } catch (const std::exception &e) { MWARNING("LockedTXN::commit filtering exception: " << e.what()); } }
+      void abort() { try { if (m_batch && m_active) { m_blockchain.get_db().batch_abort(); m_active = false; } } catch (const std::exception &e) { MWARNING("LockedTXN::abort filtering exception: " << e.what()); } }
+      ~LockedTXN() { abort(); }
     private:
       Blockchain &m_blockchain;
       bool m_batch;
+      bool m_active;
     };
   }
   //---------------------------------------------------------------------------------
@@ -255,6 +259,7 @@ namespace cryptonote
           if (!insert_key_images(tx, id, kept_by_block))
             return false;
           m_txs_by_fee_and_receive_time.emplace(std::pair<double, std::time_t>(fee / (double)tx_weight, receive_time), id);
+          lock.commit();
         }
         catch (const std::exception &e)
         {
@@ -299,6 +304,7 @@ namespace cryptonote
         if (!insert_key_images(tx, id, kept_by_block))
           return false;
         m_txs_by_fee_and_receive_time.emplace(std::pair<double, std::time_t>(fee / (double)tx_weight, receive_time), id);
+        lock.commit();
       }
       catch (const std::exception &e)
       {
@@ -398,6 +404,7 @@ namespace cryptonote
         return;
       }
     }
+    lock.commit();
     if (changed)
       ++m_cookie;
     if (m_txpool_weight > bytes)
@@ -494,6 +501,7 @@ namespace cryptonote
       m_blockchain.remove_txpool_tx(id);
       m_txpool_weight -= tx_weight;
       remove_transaction_keyimages(tx, id);
+      lock.commit();
     }
     catch (const std::exception &e)
     {
@@ -578,6 +586,7 @@ namespace cryptonote
           // ignore error
         }
       }
+      lock.commit();
       ++m_cookie;
     }
     return true;
@@ -641,6 +650,7 @@ namespace cryptonote
         // continue
       }
     }
+    lock.commit();
   }
   //---------------------------------------------------------------------------------
   size_t tx_memory_pool::get_transactions_count(bool include_unrelayed_txes) const
@@ -1119,6 +1129,7 @@ namespace cryptonote
         }
       }
     }
+    lock.commit();
     if (changed)
       ++m_cookie;
   }
@@ -1271,6 +1282,7 @@ namespace cryptonote
       append_key_images(k_images, tx);
       LOG_PRINT_L2("  added, new block weight " << total_weight << "/" << max_total_weight << ", coinbase " << print_money(best_coinbase));
     }
+    lock.commit();
 
     expected_reward = best_coinbase;
     LOG_PRINT_L2("Block template filled with " << bl.tx_hashes.size() << " txes, weight "
@@ -1336,6 +1348,7 @@ namespace cryptonote
           // continue
         }
       }
+      lock.commit();
     }
     if (n_removed > 0)
       ++m_cookie;
@@ -1395,6 +1408,7 @@ namespace cryptonote
           // ignore error
         }
       }
+      lock.commit();
     }
 
     m_cookie = 0;