LMDB should now dynamically resize the mapsize

Some filesystems (*cough* NTFS *cough*) aren't good with sparse files,
so this makes LMDB dynamically resize its mapsize as needed.  Note: the
check interval is currently every 10 blocks (for testing) and will
probably need to change to 1000 or something.  Default mapsize set to
1GiB.

Blockchain conversion tools using batching will probably segfault, I'll
fix that in the next commit.

1 files changed, 34 insertions, 1 deletions

diff --git a/src/blockchain_db/lmdb/db_lmdb.h b/src/blockchain_db/lmdb/db_lmdb.h
index 6c05de06e..ec552a0f6 100644
--- a/src/blockchain_db/lmdb/db_lmdb.h
+++ b/src/blockchain_db/lmdb/db_lmdb.h
@@ -26,6 +26,8 @@
 // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #pragma once
 
+#include <atomic>
+
 #include "blockchain_db/blockchain_db.h"
 #include "cryptonote_protocol/blobdatatype.h" // for type blobdata
 
@@ -57,11 +59,34 @@ struct mdb_txn_safe
     return &m_txn;
   }
 
+  uint64_t num_active_tx();
+
+  static void prevent_new_txns();
+  static void wait_no_active_txns();
+  static void allow_new_txns();
+
   MDB_txn* m_txn;
   bool m_batch_txn = false;
+  static std::atomic<uint64_t> num_active_txns;
+
+  // could use a mutex here, but this should be sufficient.
+  static std::atomic_flag creation_gate;
 };
 
 
+// If m_batch_active is set, a batch transaction exists beyond this class, such
+// as a batch import with verification enabled, or possibly (later) a batch
+// network sync.
+//
+// For some of the lookup methods, such as get_block_timestamp(), tx_exists(),
+// and get_tx(), when m_batch_active is set, the lookup uses the batch
+// transaction. This isn't only because the transaction is available, but it's
+// necessary so that lookups include the database updates only present in the
+// current batch write.
+//
+// A regular network sync without batch writes is expected to open a new read
+// transaction, as those lookups are part of the validation done prior to the
+// write for block and tx data, so no write transaction is open at the time.
 class BlockchainLMDB : public BlockchainDB
 {
 public:
@@ -174,6 +199,10 @@ public:
   virtual void pop_block(block& blk, std::vector<transaction>& txs);
 
 private:
+  void do_resize();
+
+  bool need_resize();
+
   virtual void add_block( const block& blk
                 , const size_t& block_size
                 , const difficulty_type& cumulative_difficulty
@@ -258,10 +287,14 @@ private:
   uint64_t m_num_outputs;
   std::string m_folder;
   mdb_txn_safe* m_write_txn; // may point to either a short-lived txn or a batch txn
-  mdb_txn_safe m_write_batch_txn; // persist batch txn outside of BlockchainLMDB
+  mdb_txn_safe* m_write_batch_txn; // persist batch txn outside of BlockchainLMDB
 
   bool m_batch_transactions; // support for batch transactions
   bool m_batch_active; // whether batch transaction is in progress
+
+  constexpr static uint64_t DEFAULT_MAPSIZE = 1 << 30;
+  constexpr static float RESIZE_PERCENT = 0.8f;
+  constexpr static float RESIZE_FACTOR = 1.5f;
 };
 
 }  // namespace cryptonote