RPC and ZeroMQ APIs to support p2pool

Adds the following:

- "get_miner_data" to RPC API
- "json-miner-data" to ZeroMQ subscriber contexts

Both provide the necessary data to create a custom block template. They are used by p2pool.

Data provided:

- major fork version
- current height
- previous block id
- RandomX seed hash
- network difficulty
- median block weight
- coins mined by the network so far
- mineable mempool transactions

7 files changed, 174 insertions, 9 deletions

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 06e7cd87b..18d5e5dac 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -1234,6 +1234,12 @@ bool Blockchain::switch_to_alternative_blockchain(std::list<block_extended_info>
     reorg_notify->notify("%s", std::to_string(split_height).c_str(), "%h", std::to_string(m_db->height()).c_str(),
         "%n", std::to_string(m_db->height() - split_height).c_str(), "%d", std::to_string(discarded_blocks).c_str(), NULL);
 
+  crypto::hash prev_id;
+  if (!get_block_hash(alt_chain.back().bl, prev_id))
+    MERROR("Failed to get block hash of an alternative chain's tip");
+  else
+    send_miner_notifications(prev_id, alt_chain.back().already_generated_coins);
+
   for (const auto& notifier : m_block_notifiers)
   {
     std::size_t notify_height = split_height;
@@ -1780,6 +1786,30 @@ bool Blockchain::create_block_template(block& b, const account_public_address& m
   return create_block_template(b, NULL, miner_address, diffic, height, expected_reward, ex_nonce, seed_height, seed_hash);
 }
 //------------------------------------------------------------------
+bool Blockchain::get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog)
+{
+  prev_id = m_db->top_block_hash(&height);
+  ++height;
+
+  major_version = m_hardfork->get_ideal_version(height);
+
+  seed_hash = crypto::null_hash;
+  if (m_hardfork->get_current_version() >= RX_BLOCK_VERSION)
+  {
+    uint64_t seed_height, next_height;
+    crypto::rx_seedheights(height, &seed_height, &next_height);
+    seed_hash = get_block_id_by_height(seed_height);
+  }
+
+  difficulty = get_difficulty_for_next_block();
+  median_weight = m_current_block_cumul_weight_median;
+  already_generated_coins = m_db->get_block_already_generated_coins(height - 1);
+
+  m_tx_pool.get_block_template_backlog(tx_backlog);
+
+  return true;
+}
+//------------------------------------------------------------------
 // for an alternate chain, get the timestamps from the main chain to complete
 // the needed number of timestamps for the BLOCKCHAIN_TIMESTAMP_CHECK_WINDOW.
 bool Blockchain::complete_timestamps_vector(uint64_t start_top_height, std::vector<uint64_t>& timestamps) const
@@ -4378,6 +4408,7 @@ leave:
   get_difficulty_for_next_block(); // just to cache it
   invalidate_block_template_cache();
 
+  send_miner_notifications(id, already_generated_coins);
 
   for (const auto& notifier: m_block_notifiers)
     notifier(new_height - 1, {std::addressof(bl), 1});
@@ -5286,7 +5317,7 @@ void Blockchain::set_user_options(uint64_t maxthreads, bool sync_on_blocks, uint
   m_max_prepare_blocks_threads = maxthreads;
 }
 
-void Blockchain::add_block_notify(boost::function<void(std::uint64_t, epee::span<const block>)>&& notify)
+void Blockchain::add_block_notify(BlockNotifyCallback&& notify)
 {
   if (notify)
   {
@@ -5295,6 +5326,15 @@ void Blockchain::add_block_notify(boost::function<void(std::uint64_t, epee::span
   }
 }
 
+void Blockchain::add_miner_notify(MinerNotifyCallback&& notify)
+{
+  if (notify)
+  {
+    CRITICAL_REGION_LOCAL(m_blockchain_lock);
+    m_miner_notifiers.push_back(std::move(notify));
+  }
+}
+
 void Blockchain::safesyncmode(const bool onoff)
 {
   /* all of this is no-op'd if the user set a specific
@@ -5547,6 +5587,33 @@ void Blockchain::cache_block_template(const block &b, const cryptonote::account_
   m_btc_valid = true;
 }
 
+void Blockchain::send_miner_notifications(const crypto::hash &prev_id, uint64_t already_generated_coins)
+{
+  if (m_miner_notifiers.empty())
+    return;
+
+  const uint64_t height = m_db->height();
+  const uint8_t major_version = m_hardfork->get_ideal_version(height);
+  const difficulty_type diff = get_difficulty_for_next_block();
+  const uint64_t median_weight = m_current_block_cumul_weight_median;
+
+  crypto::hash seed_hash = crypto::null_hash;
+  if (m_hardfork->get_current_version() >= RX_BLOCK_VERSION)
+  {
+    uint64_t seed_height, next_height;
+    crypto::rx_seedheights(height, &seed_height, &next_height);
+    seed_hash = get_block_id_by_height(seed_height);
+  }
+
+  std::vector<tx_block_template_backlog_entry> tx_backlog;
+  m_tx_pool.get_block_template_backlog(tx_backlog);
+
+  for (const auto& notifier : m_miner_notifiers)
+  {
+    notifier(major_version, height, prev_id, seed_hash, diff, median_weight, already_generated_coins, tx_backlog);
+  }
+}
+
 namespace cryptonote {
 template bool Blockchain::get_transactions(const std::vector<crypto::hash>&, std::vector<transaction>&, std::vector<crypto::hash>&) const;
 template bool Blockchain::get_split_transactions_blobs(const std::vector<crypto::hash>&, std::vector<std::tuple<crypto::hash, cryptonote::blobdata, crypto::hash, cryptonote::blobdata>>&, std::vector<crypto::hash>&) const;
diff --git a/src/cryptonote_core/blockchain.h b/src/cryptonote_core/blockchain.h
index 3529255e1..acbc361ef 100644
--- a/src/cryptonote_core/blockchain.h
+++ b/src/cryptonote_core/blockchain.h
@@ -89,6 +89,9 @@ namespace cryptonote
    */
   typedef std::function<const epee::span<const unsigned char>(cryptonote::network_type network)> GetCheckpointsCallback;
 
+  typedef boost::function<void(uint64_t /* height */, epee::span<const block> /* blocks */)> BlockNotifyCallback;
+  typedef boost::function<void(uint8_t /* major_version */, uint64_t /* height */, const crypto::hash& /* prev_id */, const crypto::hash& /* seed_hash */, difficulty_type /* diff */, uint64_t /* median_weight */, uint64_t /* already_generated_coins */, const std::vector<tx_block_template_backlog_entry>& /* tx_backlog */)> MinerNotifyCallback;
+
   /************************************************************************/
   /*                                                                      */
   /************************************************************************/
@@ -370,6 +373,22 @@ namespace cryptonote
     bool create_block_template(block& b, const crypto::hash *from_block, const account_public_address& miner_address, difficulty_type& di, uint64_t& height, uint64_t& expected_reward, const blobdata& ex_nonce, uint64_t &seed_height, crypto::hash &seed_hash);
 
     /**
+     * @brief gets data required to create a block template and start mining on it
+     *
+     * @param major_version current hardfork version
+     * @param height current blockchain height
+     * @param prev_id hash of the top block
+     * @param seed_hash seed hash used for RandomX initialization
+     * @param difficulty current mining difficulty
+     * @param median_weight current median block weight
+     * @param already_generated_coins current emission
+     * @param tx_backlog transactions in mempool ready to be mined
+     *
+     * @return true if block template filled in successfully, else false
+     */
+    bool get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog);
+
+    /**
      * @brief checks if a block is known about with a given hash
      *
      * This function checks the main chain, alternate chains, and invalid blocks
@@ -771,7 +790,14 @@ namespace cryptonote
      *
      * @param notify the notify object to call at every new block
      */
-    void add_block_notify(boost::function<void(std::uint64_t, epee::span<const block>)> &&notify);
+    void add_block_notify(BlockNotifyCallback&& notify);
+
+    /**
+     * @brief sets a miner notify object to call for every new block
+     *
+     * @param notify the notify object to call at every new block
+     */
+    void add_miner_notify(MinerNotifyCallback&& notify);
 
     /**
      * @brief sets a reorg notify object to call for every reorg
@@ -1153,7 +1179,8 @@ namespace cryptonote
        the callable object has a single `std::shared_ptr` or `std::weap_ptr`
        internally. Whereas, the libstdc++ `std::function` will allocate. */
 
-    std::vector<boost::function<void(std::uint64_t, epee::span<const block>)>> m_block_notifiers;
+    std::vector<BlockNotifyCallback> m_block_notifiers;
+    std::vector<MinerNotifyCallback> m_miner_notifiers;
     std::shared_ptr<tools::Notify> m_reorg_notify;
 
     // for prepare_handle_incoming_blocks
@@ -1533,5 +1560,13 @@ namespace cryptonote
      * At some point, may be used to push an update to miners
      */
     void cache_block_template(const block &b, const cryptonote::account_public_address &address, const blobdata &nonce, const difficulty_type &diff, uint64_t height, uint64_t expected_reward, uint64_t seed_height, const crypto::hash &seed_hash, uint64_t pool_cookie);
+
+    /**
+     * @brief sends new block notifications to ZMQ `miner_data` subscribers
+     *
+     * @param prev_id hash of new blockchain tip
+     * @param already_generated_coins total coins mined by the network so far
+     */
+    void send_miner_notifications(const crypto::hash &prev_id, uint64_t already_generated_coins);
   };
 }  // namespace cryptonote
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index 12125fb9d..17dca7dba 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -1061,8 +1061,9 @@ namespace cryptonote
       if (already_have[i])
         continue;
 
-      const uint64_t weight = results[i].tx.pruned ? get_pruned_transaction_weight(results[i].tx) : get_transaction_weight(results[i].tx, it->blob.size());
-      ok &= add_new_tx(results[i].tx, results[i].hash, tx_blobs[i].blob, weight, tvc[i], tx_relay, relayed);
+      results[i].blob_size = it->blob.size();
+      results[i].weight = results[i].tx.pruned ? get_pruned_transaction_weight(results[i].tx) : get_transaction_weight(results[i].tx, it->blob.size());
+      ok &= add_new_tx(results[i].tx, results[i].hash, tx_blobs[i].blob, results[i].weight, tvc[i], tx_relay, relayed);
 
       if(tvc[i].m_verifivation_failed)
       {MERROR_VER("Transaction verification failed: " << results[i].hash);}
@@ -1401,6 +1402,11 @@ namespace cryptonote
     return m_blockchain_storage.create_block_template(b, prev_block, adr, diffic, height, expected_reward, ex_nonce, seed_height, seed_hash);
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog)
+  {
+    return m_blockchain_storage.get_miner_data(major_version, height, prev_id, seed_hash, difficulty, median_weight, already_generated_coins, tx_backlog);
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::find_blockchain_supplement(const std::list<crypto::hash>& qblock_ids, bool clip_pruned, NOTIFY_RESPONSE_CHAIN_ENTRY::request& resp) const
   {
     return m_blockchain_storage.find_blockchain_supplement(qblock_ids, clip_pruned, resp);
diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h
index a6cce8617..82abfe918 100644
--- a/src/cryptonote_core/cryptonote_core.h
+++ b/src/cryptonote_core/cryptonote_core.h
@@ -237,6 +237,13 @@ namespace cryptonote
      virtual bool get_block_template(block& b, const crypto::hash *prev_block, const account_public_address& adr, difficulty_type& diffic, uint64_t& height, uint64_t& expected_reward, const blobdata& ex_nonce, uint64_t &seed_height, crypto::hash &seed_hash);
 
      /**
+      * @copydoc Blockchain::get_miner_data
+      *
+      * @note see Blockchain::get_miner_data
+      */
+     bool get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog);
+
+     /**
       * @brief called when a transaction is relayed.
       * @note Should only be invoked from `levin_notify`.
       */
diff --git a/src/cryptonote_core/cryptonote_tx_utils.h b/src/cryptonote_core/cryptonote_tx_utils.h
index 73cdd31cd..06412d6bf 100644
--- a/src/cryptonote_core/cryptonote_tx_utils.h
+++ b/src/cryptonote_core/cryptonote_tx_utils.h
@@ -108,6 +108,15 @@ namespace cryptonote
   };
 
   //---------------------------------------------------------------
+
+  struct tx_block_template_backlog_entry
+  {
+    crypto::hash id;
+    uint64_t weight;
+    uint64_t fee;
+  };
+
+  //---------------------------------------------------------------
   crypto::public_key get_destination_view_key_pub(const std::vector<tx_destination_entry> &destinations, const boost::optional<cryptonote::account_public_address>& change_addr);
   bool construct_tx(const account_keys& sender_account_keys, std::vector<tx_source_entry> &sources, const std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time);
   bool construct_tx_with_tx_key(const account_keys& sender_account_keys, const std::unordered_map<crypto::public_key, subaddress_index>& subaddresses, std::vector<tx_source_entry>& sources, std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time, const crypto::secret_key &tx_key, const std::vector<crypto::secret_key> &additional_tx_keys, bool rct = false, const rct::RCTConfig &rct_config = { rct::RangeProofBorromean, 0 }, rct::multisig_out *msout = NULL, bool shuffle_outs = true);
diff --git a/src/cryptonote_core/tx_pool.cpp b/src/cryptonote_core/tx_pool.cpp
index d059ab78f..42d0b9cf6 100644
--- a/src/cryptonote_core/tx_pool.cpp
+++ b/src/cryptonote_core/tx_pool.cpp
@@ -914,6 +914,32 @@ namespace cryptonote
     }, false, category);
   }
   //------------------------------------------------------------------
+  void tx_memory_pool::get_block_template_backlog(std::vector<tx_block_template_backlog_entry>& backlog, bool include_sensitive) const
+  {
+    CRITICAL_REGION_LOCAL(m_transactions_lock);
+    CRITICAL_REGION_LOCAL1(m_blockchain);
+    const relay_category category = include_sensitive ? relay_category::all : relay_category::broadcasted;
+    backlog.reserve(m_blockchain.get_txpool_tx_count(include_sensitive));
+    txpool_tx_meta_t tmp_meta;
+    m_blockchain.for_all_txpool_txes([this, &backlog, &tmp_meta](const crypto::hash &txid, const txpool_tx_meta_t &meta, const cryptonote::blobdata_ref *bd){
+      transaction tx;
+      if (!(meta.pruned ? parse_and_validate_tx_base_from_blob(*bd, tx) : parse_and_validate_tx_from_blob(*bd, tx)))
+      {
+        MERROR("Failed to parse tx from txpool");
+        // continue
+        return true;
+      }
+      tx.set_hash(txid);
+
+      tmp_meta = meta;
+
+      if (is_transaction_ready_to_go(tmp_meta, txid, *bd, tx))
+        backlog.push_back({txid, meta.weight, meta.fee});
+
+      return true;
+    }, true, category);
+  }
+  //------------------------------------------------------------------
   void tx_memory_pool::get_transaction_stats(struct txpool_stats& stats, bool include_sensitive) const
   {
     CRITICAL_REGION_LOCAL(m_transactions_lock);
@@ -1224,11 +1250,11 @@ namespace cryptonote
     return ret;
   }
   //---------------------------------------------------------------------------------
-  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata &txblob, transaction &tx) const
+  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata_ref& txblob, transaction &tx) const
   {
-    struct transction_parser
+    struct transaction_parser
     {
-      transction_parser(const cryptonote::blobdata &txblob, const crypto::hash &txid, transaction &tx): txblob(txblob), txid(txid), tx(tx), parsed(false) {}
+      transaction_parser(const cryptonote::blobdata_ref &txblob, const crypto::hash &txid, transaction &tx): txblob(txblob), txid(txid), tx(tx), parsed(false) {}
       cryptonote::transaction &operator()()
       {
         if (!parsed)
@@ -1240,7 +1266,7 @@ namespace cryptonote
         }
         return tx;
       }
-      const cryptonote::blobdata &txblob;
+      const cryptonote::blobdata_ref &txblob;
       const crypto::hash &txid;
       transaction &tx;
       bool parsed;
@@ -1291,6 +1317,11 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------------------------
+  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata& txblob, transaction &tx) const
+  {
+    return is_transaction_ready_to_go(txd, txid, cryptonote::blobdata_ref{txblob.data(), txblob.size()}, tx);
+  }
+  //---------------------------------------------------------------------------------
   bool tx_memory_pool::have_key_images(const std::unordered_set<crypto::key_image>& k_images, const transaction_prefix& tx)
   {
     for(size_t i = 0; i!= tx.vin.size(); i++)
diff --git a/src/cryptonote_core/tx_pool.h b/src/cryptonote_core/tx_pool.h
index ab2a57ea2..80b38c51d 100644
--- a/src/cryptonote_core/tx_pool.h
+++ b/src/cryptonote_core/tx_pool.h
@@ -266,6 +266,15 @@ namespace cryptonote
     void get_transaction_backlog(std::vector<tx_backlog_entry>& backlog, bool include_sensitive = false) const;
 
     /**
+     * @brief get (hash, weight, fee) for all transactions in the pool - the minimum required information to create a block template
+     *
+     * @param backlog return-by-reference that data
+     * @param include_sensitive return stempool, anonymity-pool, and unrelayed txes
+     *
+     */
+    void get_block_template_backlog(std::vector<tx_block_template_backlog_entry>& backlog, bool include_sensitive = false) const;
+
+    /**
      * @brief get a summary statistics of all transaction hashes in the pool
      *
      * @param stats return-by-reference the pool statistics
@@ -540,6 +549,7 @@ namespace cryptonote
      *
      * @return true if the transaction is good to go, otherwise false
      */
+    bool is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata_ref &txblob, transaction&tx) const;
     bool is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata &txblob, transaction&tx) const;
 
     /**