From a0052d4bd35f2a0882a051a44b5b9f656317b9e3 Mon Sep 17 00:00:00 2001
From: Peter Conrad <conrad@quisquis.de>
Date: Thu, 13 Jul 2017 20:26:35 +0200
Subject: [PATCH] Enable undo + fork database for final blocks in a replay

Dont remove blocks from block db when popping blocks, handle edge case in replay wrt fork_db, adapted unit tests
---
 libraries/chain/db_block.cpp      |  1 -
 libraries/chain/db_management.cpp | 40 ++++++++++++++++++-------------
 tests/tests/block_tests.cpp       |  6 ++++-
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/libraries/chain/db_block.cpp b/libraries/chain/db_block.cpp
index 9b2c7f36..ad4ad1a0 100644
--- a/libraries/chain/db_block.cpp
+++ b/libraries/chain/db_block.cpp
@@ -506,7 +506,6 @@ void database::pop_block()
    GRAPHENE_ASSERT( head_block.valid(), pop_empty_chain, "there are no blocks to pop" );
 
    _fork_db.pop_block();
-   _block_id_to_block.remove( head_id );
    pop_undo();
 
    _popped_tx.insert( _popped_tx.begin(), head_block->transactions.begin(), head_block->transactions.end() );
diff --git a/libraries/chain/db_management.cpp b/libraries/chain/db_management.cpp
index ca4004e6..1a60520a 100644
--- a/libraries/chain/db_management.cpp
+++ b/libraries/chain/db_management.cpp
@@ -64,11 +64,16 @@ void database::reindex( fc::path data_dir )
    uint32_t undo_point = last_block_num - 50;
 
    ilog( "Replaying blocks..." );
-   // Right now, we leave undo_db enabled when replaying when the bookie plugin is
-   // enabled.  It depends on new/changed/removed object notifications, and those are 
-   // only fired when the undo_db is enabled
-   if (!_slow_replays)
-      _undo_db.disable();
+   if( head_block_num() >= undo_point )
+      _fork_db.start_block( *fetch_block_by_number( head_block_num() ) );
+   else
+   {
+       // Right now, we leave undo_db enabled when replaying when the bookie plugin is
+       // enabled.  It depends on new/changed/removed object notifications, and those are
+       // only fired when the undo_db is enabled
+        if (!_slow_replays)
+            _undo_db.disable();
+   }
    for( uint32_t i = head_block_num() + 1; i <= last_block_num; ++i )
    {
       if( i % 10000 == 0 ) std::cerr << "   " << double(i*100)/last_block_num << "%   "<<i << " of " <<last_block_num<<"   \n";
@@ -78,8 +83,6 @@ void database::reindex( fc::path data_dir )
          flush();
          ilog( "Done" );
       }
-      if( i == undo_point )
-         _undo_db.enable();
       fc::optional< signed_block > block = _block_id_to_block.fetch_by_number(i);
       if( !block.valid() )
       {
@@ -100,21 +103,26 @@ void database::reindex( fc::path data_dir )
          wlog( "Dropped ${n} blocks from after the gap", ("n", dropped_count) );
          break;
       }
-      if (_slow_replays)
-         push_block(*block, skip_fork_db |
-                            skip_witness_signature |
-                            skip_transaction_signatures |
-                            skip_transaction_dupe_check |
-                            skip_tapos_check |
-                            skip_witness_schedule_check |
-                            skip_authority_check);
-      else
+      if( i < undo_point && !_slow_replays)
+      {
          apply_block(*block, skip_witness_signature |
                              skip_transaction_signatures |
                              skip_transaction_dupe_check |
                              skip_tapos_check |
                              skip_witness_schedule_check |
                              skip_authority_check);
+      }
+      else
+      {
+          if (!_slow_replays)
+             _undo_db.enable();
+         push_block(*block, skip_witness_signature |
+                            skip_transaction_signatures |
+                            skip_transaction_dupe_check |
+                            skip_tapos_check |
+                            skip_witness_schedule_check |
+                            skip_authority_check);
+      }
    }
    if (!_slow_replays)
      _undo_db.enable();
diff --git a/tests/tests/block_tests.cpp b/tests/tests/block_tests.cpp
index 5990b12b..daa0734b 100644
--- a/tests/tests/block_tests.cpp
+++ b/tests/tests/block_tests.cpp
@@ -136,6 +136,7 @@ BOOST_AUTO_TEST_CASE( generate_empty_blocks )
       // TODO:  Don't generate this here
       auto init_account_priv_key = fc::ecc::private_key::regenerate(fc::sha256::hash(string("null_key")) );
       signed_block cutoff_block;
+      uint32_t last_block;
       {
          database db;
          db.open(data_dir.path(), make_genesis, "TEST" );
@@ -155,6 +156,7 @@ BOOST_AUTO_TEST_CASE( generate_empty_blocks )
             if( cutoff_height >= 200 )
             {
                cutoff_block = *(db.fetch_block_by_number( cutoff_height ));
+               last_block = db.head_block_num();
                break;
             }
          }
@@ -163,7 +165,9 @@ BOOST_AUTO_TEST_CASE( generate_empty_blocks )
       {
          database db;
          db.open(data_dir.path(), []{return genesis_state_type();}, "TEST");
-         BOOST_CHECK_EQUAL( db.head_block_num(), cutoff_block.block_num() );
+         BOOST_CHECK_EQUAL( db.head_block_num(), last_block );
+         while( db.head_block_num() > cutoff_block.block_num() )
+            db.pop_block();
          b = cutoff_block;
          for( uint32_t i = 0; i < 200; ++i )
          {