blockchain_db: faster fetching of consecutive txes

Useful for wallet refresh or node sync

src/blockchain_db/blockchain_db.h

@@ -1290,6 +1290,25 @@ public:
    */
   virtual bool get_pruned_tx_blobs_from(const crypto::hash& h, size_t count, std::vector<cryptonote::blobdata> &bd) const = 0;
 
+  /**
+   * @brief fetches a variable number of blocks and transactions from the given height, in canonical blockchain order
+   *
+   * The subclass should return the blocks and transactions stored from the one with the given
+   * height. The number of blocks returned is variable, based on the max_size passed.
+   *
+   * @param start_height the height of the first block
+   * @param min_count the minimum number of blocks to return, if they exist
+   * @param max_count the maximum number of blocks to return
+   * @param max_size the maximum size of block/transaction data to return (will be exceeded by one blocks's worth at most, if min_count is met)
+   * @param blocks the returned block/transaction data
+   * @param pruned whether to return full or pruned tx data
+   * @param skip_coinbase whether to return or skip coinbase transactions (they're in blocks regardless)
+   * @param get_miner_tx_hash whether to calculate and return the miner (coinbase) tx hash
+   *
+   * @return true iff the blocks and transactions were found
+   */
+  virtual bool get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const = 0;
+
   /**
    * @brief fetches the prunable transaction blob with the given hash
    *

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -3107,6 +3107,104 @@ bool BlockchainLMDB::get_pruned_tx_blobs_from(const crypto::hash& h, size_t coun
   return true;
 }
 
+bool BlockchainLMDB::get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  TXN_PREFIX_RDONLY();
+  RCURSOR(blocks);
+  RCURSOR(tx_indices);
+  RCURSOR(txs_pruned);
+  if (!pruned)
+  {
+    RCURSOR(txs_prunable);
+  }
+
+  blocks.reserve(std::min<size_t>(max_count, 10000)); // guard against very large max count if only checking bytes
+  const uint64_t blockchain_height = height();
+  uint64_t size = 0;
+  MDB_val_copy<uint64_t> key(start_height);
+  MDB_val k, v, val_tx_id;
+  uint64_t tx_id = ~0;
+  MDB_cursor_op op = MDB_SET;
+  for (uint64_t h = start_height; h < blockchain_height && blocks.size() < max_count && (size < max_size || blocks.size() < min_count); ++h)
+  {
+    MDB_cursor_op op = h == start_height ? MDB_SET : MDB_NEXT;
+    int result = mdb_cursor_get(m_cur_blocks, &key, &v, op);
+    if (result == MDB_NOTFOUND)
+      throw0(BLOCK_DNE(std::string("Attempt to get block from height ").append(boost::lexical_cast<std::string>(h)).append(" failed -- block not in db").c_str()));
+    else if (result)
+      throw0(DB_ERROR(lmdb_error("Error attempting to retrieve a block from the db", result).c_str()));
+
+    blocks.resize(blocks.size() + 1);
+    auto &current_block = blocks.back();
+
+    current_block.first.first.assign(reinterpret_cast<char*>(v.mv_data), v.mv_size);
+    size += v.mv_size;
+
+    cryptonote::block b;
+    if (!parse_and_validate_block_from_blob(current_block.first.first, b))
+      throw0(DB_ERROR("Invalid block"));
+    current_block.first.second = get_miner_tx_hash ? cryptonote::get_transaction_hash(b.miner_tx) : crypto::null_hash;
+
+    // get the tx_id for the first tx (the first block's coinbase tx)
+    if (h == start_height)
+    {
+      crypto::hash hash = cryptonote::get_transaction_hash(b.miner_tx);
+      MDB_val_set(v, hash);
+      result = mdb_cursor_get(m_cur_tx_indices, (MDB_val *)&zerokval, &v, MDB_GET_BOTH);
+      if (result)
+        throw0(DB_ERROR(lmdb_error("Error attempting to retrieve block coinbase transaction from the db: ", result).c_str()));
+
+      const txindex *tip = (const txindex *)v.mv_data;
+      tx_id = tip->data.tx_id;
+      val_tx_id.mv_data = &tx_id;
+      val_tx_id.mv_size = sizeof(tx_id);
+    }
+
+    if (skip_coinbase)
+    {
+      result = mdb_cursor_get(m_cur_txs_pruned, &val_tx_id, &v, op);
+      if (result)
+        throw0(DB_ERROR(lmdb_error("Error attempting to retrieve transaction data from the db: ", result).c_str()));
+      if (!pruned)
+      {
+        result = mdb_cursor_get(m_cur_txs_prunable, &val_tx_id, &v, op);
+        if (result)
+          throw0(DB_ERROR(lmdb_error("Error attempting to retrieve transaction data from the db: ", result).c_str()));
+      }
+    }
+
+    op = MDB_NEXT;
+
+    current_block.second.reserve(b.tx_hashes.size());
+    for (const auto &tx_hash: b.tx_hashes)
+    {
+      // get pruned data
+      cryptonote::blobdata tx_blob;
+      result = mdb_cursor_get(m_cur_txs_pruned, &val_tx_id, &v, op);
+      if (result)
+        throw0(DB_ERROR(lmdb_error("Error attempting to retrieve transaction data from the db: ", result).c_str()));
+      tx_blob.assign((const char*)v.mv_data, v.mv_size);
+
+      if (!pruned)
+      {
+        result = mdb_cursor_get(m_cur_txs_prunable, &val_tx_id, &v, op);
+        if (result)
+          throw0(DB_ERROR(lmdb_error("Error attempting to retrieve transaction data from the db: ", result).c_str()));
+        tx_blob.append(reinterpret_cast<const char*>(v.mv_data), v.mv_size);
+      }
+      current_block.second.push_back(std::make_pair(tx_hash, std::move(tx_blob)));
+      size += current_block.second.back().second.size();
+    }
+  }
+
+  TXN_POSTFIX_RDONLY();
+
+  return true;
+}
+
 bool BlockchainLMDB::get_prunable_tx_blob(const crypto::hash& h, cryptonote::blobdata &bd) const
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);

src/blockchain_db/lmdb/db_lmdb.h

@@ -255,6 +255,7 @@ public:
   virtual bool get_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const;
   virtual bool get_pruned_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const;
   virtual bool get_pruned_tx_blobs_from(const crypto::hash& h, size_t count, std::vector<cryptonote::blobdata> &bd) const;
+  virtual bool get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const;
   virtual bool get_prunable_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const;
   virtual bool get_prunable_tx_hash(const crypto::hash& tx_hash, crypto::hash &prunable_hash) const;
 

src/blockchain_db/testdb.h

@@ -70,6 +70,7 @@ public:
   virtual bool get_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
   virtual bool get_pruned_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
   virtual bool get_pruned_tx_blobs_from(const crypto::hash& h, size_t count, std::vector<cryptonote::blobdata> &bd) const { return false; }
+  virtual bool get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const { return false; }
   virtual bool get_prunable_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
   virtual bool get_prunable_tx_hash(const crypto::hash& tx_hash, crypto::hash &prunable_hash) const override { return false; }
   virtual uint64_t get_block_height(const crypto::hash& h) const override { return 0; }

src/cryptonote_core/blockchain.cpp

@@ -2488,38 +2488,10 @@ bool Blockchain::find_blockchain_supplement(const uint64_t req_start_block, cons
   }
 
   db_rtxn_guard rtxn_guard(m_db);
-  total_height = get_current_blockchain_height();
-  size_t count = 0, size = 0;
   blocks.reserve(std::min(std::min(max_count, (size_t)10000), (size_t)(total_height - start_height)));
-  for(uint64_t i = start_height; i < total_height && count < max_count && (size < FIND_BLOCKCHAIN_SUPPLEMENT_MAX_SIZE || count < 3); i++, count++)
-  {
-    blocks.resize(blocks.size()+1);
-    blocks.back().first.first = m_db->get_block_blob_from_height(i);
-    block b;
-    CHECK_AND_ASSERT_MES(parse_and_validate_block_from_blob(blocks.back().first.first, b), false, "internal error, invalid block");
-    blocks.back().first.second = get_miner_tx_hash ? cryptonote::get_transaction_hash(b.miner_tx) : crypto::null_hash;
-    std::vector<cryptonote::blobdata> txs;
-    if (pruned)
-    {
-      CHECK_AND_ASSERT_MES(m_db->get_pruned_tx_blobs_from(b.tx_hashes.front(), b.tx_hashes.size(), txs), false, "Failed to retrieve all transactions needed");
-    }
-    else
-    {
-      std::vector<crypto::hash> mis;
-      get_transactions_blobs(b.tx_hashes, txs, mis, pruned);
-      CHECK_AND_ASSERT_MES(!mis.size(), false, "internal error, transaction from block not found");
-    }
-    size += blocks.back().first.first.size();
-    for (const auto &t: txs)
-      size += t.size();
+  CHECK_AND_ASSERT_MES(m_db->get_blocks_from(start_height, 3, max_count, FIND_BLOCKCHAIN_SUPPLEMENT_MAX_SIZE, blocks, pruned, true, get_miner_tx_hash),
+      false, "Error getting blocks");
 
-    CHECK_AND_ASSERT_MES(txs.size() == b.tx_hashes.size(), false, "mismatched sizes of b.tx_hashes and txs");
-    blocks.back().second.reserve(txs.size());
-    for (size_t i = 0; i < txs.size(); ++i)
-    {
-      blocks.back().second.push_back(std::make_pair(b.tx_hashes[i], std::move(txs[i])));
-    }
-  }
   return true;
 }
 //------------------------------------------------------------------