bool leveldb_chain_keeper::end_slice(size_t slice_begin_index,
    block_detail_list& sliced_blocks)
{
    leveldb_transaction_batch batch;
    leveldb_iterator it(db_.block->NewIterator(leveldb::ReadOptions()));
    data_chunk raw_depth = uncast_type(slice_begin_index);
    for (it->Seek(slice(raw_depth)); it->Valid(); it->Next())
    {
        block_detail_ptr sliced_block =
            reconstruct_block(common_, it->value().ToString());
        if (!sliced_block)
            return false;
        // Add to list of sliced blocks
        sliced_blocks.push_back(sliced_block);
        // Make sure to delete hash secondary index too.
        const hash_digest& block_hash = sliced_block->hash();
        // Delete block header...
        batch.block.Delete(it->key());
        // And it's secondary index.
        batch.block_hash.Delete(slice_block_hash(block_hash));
        // Remove txs + spends + addresses too
        const auto& transactions = sliced_block->actual().transactions;
        for (const transaction_type& block_tx: transactions)
            if (!clear_transaction_data(batch, block_tx))
                return false;
    }
    leveldb::WriteOptions options;
    // Execute batches.
    db_.write(batch);
    return true;
}
bool simple_chain_impl::release(size_t begin_index,
    block_detail_list& released_blocks)
{
    const auto last_height = interface_.blocks.last_height();
    BITCOIN_ASSERT(last_height != block_database::null_height);
    BITCOIN_ASSERT_MSG(begin_index > 0, "This loop will underflow.");
    for (size_t height = last_height; height >= begin_index; --height)
    {
        const auto block = std::make_shared<block_detail>(interface_.pop());
        released_blocks.push_back(block);
    }

    return true;
}
bool leveldb_chain_keeper::end_slice(size_t slice_begin_index,
    block_detail_list& sliced_blocks)
{
    leveldb::WriteBatch blk_batch, blk_hash_batch;
    leveldb_transaction_batch tx_batch;
    leveldb_iterator it(db_blocks_->NewIterator(leveldb::ReadOptions()));
    data_chunk raw_depth = uncast_type(slice_begin_index);
    for (it->Seek(slice(raw_depth)); it->Valid(); it->Next())
    {
        std::stringstream ss;
        ss.str(it->value().ToString());
        protobuf::Block proto_block;
        proto_block.ParseFromIstream(&ss);
        // Convert protobuf block header into actual block
        block_type sliced_block;
        if (!reconstruct_block(common_, proto_block, sliced_block))
            return false;
        // Add to list of sliced blocks
        block_detail_ptr sliced_detail =
            std::make_shared<block_detail>(sliced_block);
        sliced_blocks.push_back(sliced_detail);
        // Make sure to delete hash secondary index too.
        hash_digest block_hash = hash_block_header(sliced_block);
        // Delete block header...
        blk_batch.Delete(it->key());
        // And it's secondary index.
        blk_hash_batch.Delete(slice_block_hash(block_hash));
        // Remove txs + spends + addresses too
        for (const transaction_type& block_tx: sliced_block.transactions)
            if (!clear_transaction_data(tx_batch, block_tx))
                return false;
    }
    leveldb::WriteOptions options;
    // Execute batches.
    db_blocks_->Write(options, &blk_batch);
    db_blocks_hash_->Write(options, &blk_hash_batch);
    db_txs_->Write(options, &tx_batch.tx_batch);
    db_spends_->Write(options, &tx_batch.spends_batch);
    db_address_->Write(options, &tx_batch.address_batch);
    return true;
}