move the rct commitments to the output_amounts database

Since these are needed at the same time as the output pubkeys,
this is a whole lot faster, and takes less space. Only outputs
of 0 amount store the commitment. When reading other outputs,
a fake commitment is regenerated on the fly. This avoids having
to rewrite the database to add space for fake commitments for
existing outputs.

This code relies on two things:

- LMDB must support fixed size records per key, rather than
per database (ie, all records on key 0 are the same size, all
records for non 0 keys are same size, but records from key 0
and non 0 keys do have different sizes).

- the commitment must be directly after the rest of the data
in outkey and output_data_t.

1 files changed, 2 insertions, 23 deletions

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 82bc6c0d4..f46de9ca8 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -207,21 +207,8 @@ bool Blockchain::scan_outputkeys_for_indexes(size_t tx_version, const txin_to_ke
         else
           output_index = m_db->get_output_key(tx_in_to_key.amount, i);
 
-        rct::key commitment;
-        if (tx_version > 1)
-        {
-          if (tx_in_to_key.amount == 0)
-            commitment = m_db->get_rct_commitment(i);
-          else
-            commitment = rct::zeroCommit(tx_in_to_key.amount);
-        }
-        else
-        {
-          rct::identity(commitment);
-        }
-
         // call to the passed boost visitor to grab the public key for the output
-        if (!vis.handle_output(output_index.unlock_time, output_index.pubkey, commitment))
+        if (!vis.handle_output(output_index.unlock_time, output_index.pubkey, output_index.commitment))
         {
           LOG_PRINT_L0("Failed to handle_output for output no = " << count << ", with absolute offset " << i);
           return false;
@@ -1633,15 +1620,7 @@ void Blockchain::add_out_to_get_rct_random_outs(std::list<COMMAND_RPC_GET_RANDOM
   oen.global_amount_index = i;
   output_data_t data = m_db->get_output_key(amount, i);
   oen.out_key = data.pubkey;
-  if (amount == 0)
-  {
-    oen.commitment = m_db->get_rct_commitment(i);
-  }
-  else
-  {
-    // not a rct output, make a fake commitment with zero key
-    oen.commitment = rct::zeroCommit(amount);
-  }
+  oen.commitment = data.commitment;
 }
 //------------------------------------------------------------------
 // This function takes an RPC request for mixins and creates an RPC response