Add chaser_candidate and stub in event handling.

Makefile.am

@@ -41,6 +41,7 @@ src_libbitcoin_node_la_SOURCES = \
     src/parser.cpp \
     src/settings.cpp \
     src/chasers/chaser.cpp \
+    src/chasers/chaser_candidate.cpp \
     src/chasers/chaser_check.cpp \
     src/chasers/chaser_confirm.cpp \
     src/chasers/chaser_connect.cpp \
@@ -116,6 +117,7 @@ include_bitcoin_node_HEADERS = \
 include_bitcoin_node_chasersdir = ${includedir}/bitcoin/node/chasers
 include_bitcoin_node_chasers_HEADERS = \
     include/bitcoin/node/chasers/chaser.hpp \
+    include/bitcoin/node/chasers/chaser_candidate.hpp \
     include/bitcoin/node/chasers/chaser_check.hpp \
     include/bitcoin/node/chasers/chaser_confirm.hpp \
     include/bitcoin/node/chasers/chaser_connect.hpp \

builds/cmake/CMakeLists.txt

@@ -251,6 +251,7 @@ add_library( ${CANONICAL_LIB_NAME}
     "../../src/parser.cpp"
     "../../src/settings.cpp"
     "../../src/chasers/chaser.cpp"
+    "../../src/chasers/chaser_candidate.cpp"
     "../../src/chasers/chaser_check.cpp"
     "../../src/chasers/chaser_confirm.cpp"
     "../../src/chasers/chaser_connect.cpp"

builds/msvc/vs2022/libbitcoin-node/libbitcoin-node.vcxproj

@@ -74,6 +74,7 @@
   </ImportGroup>
   <ItemGroup>
     <ClCompile Include="..\..\..\..\src\chasers\chaser.cpp" />
+    <ClCompile Include="..\..\..\..\src\chasers\chaser_candidate.cpp" />
     <ClCompile Include="..\..\..\..\src\chasers\chaser_check.cpp" />
     <ClCompile Include="..\..\..\..\src\chasers\chaser_confirm.cpp" />
     <ClCompile Include="..\..\..\..\src\chasers\chaser_connect.cpp" />
@@ -101,6 +102,7 @@
   <ItemGroup>
     <ClInclude Include="..\..\..\..\include\bitcoin\node.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser.hpp" />
+    <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_candidate.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_check.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_confirm.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_connect.hpp" />

builds/msvc/vs2022/libbitcoin-node/libbitcoin-node.vcxproj.filters

@@ -45,6 +45,9 @@
     <ClCompile Include="..\..\..\..\src\chasers\chaser.cpp">
       <Filter>src\chasers</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\..\src\chasers\chaser_candidate.cpp">
+      <Filter>src\chasers</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\..\src\chasers\chaser_check.cpp">
       <Filter>src\chasers</Filter>
     </ClCompile>
@@ -122,6 +125,9 @@
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser.hpp">
       <Filter>include\bitcoin\node\chasers</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_candidate.hpp">
+      <Filter>include\bitcoin\node\chasers</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\..\..\include\bitcoin\node\chasers\chaser_check.hpp">
       <Filter>include\bitcoin\node\chasers</Filter>
     </ClInclude>

include/bitcoin/node.hpp

@@ -24,6 +24,7 @@
 #include <bitcoin/node/settings.hpp>
 #include <bitcoin/node/version.hpp>
 #include <bitcoin/node/chasers/chaser.hpp>
+#include <bitcoin/node/chasers/chaser_candidate.hpp>
 #include <bitcoin/node/chasers/chaser_check.hpp>
 #include <bitcoin/node/chasers/chaser_confirm.hpp>
 #include <bitcoin/node/chasers/chaser_connect.hpp>

include/bitcoin/node/chasers/chaser.hpp

@@ -28,34 +28,81 @@ namespace node {
 class full_node;
 
 /// Abstract base chaser.
-
 /// Chasers impose order on blockchain/pool construction as necessary.
-
 /// Each chaser operates on its own strand, implemented here, allowing
 /// concurrent chaser operations to the extent that threads are available.
-
 /// Events are passed between chasers using the full_node shared notifier.
 /// Notifications are bounced from sink (e.g. chaser) to its strand, and
-/// full_node::notify bounces from source (e.g. chaser) to network strand.
-
+/// notify bounces from source (e.g. chaser) to network strand.
 class BCN_API chaser
-  : public network::enable_shared_from_base<chaser>,
-    public network::reporter
+  : public network::reporter
 {
 public:
+    enum class chase
+    {
+        /// Initialize chaser state (no data).
+        start,
+
+        /// A new strong branch exists (strong header link).
+        /// Issued by 'header' and handled by 'check'.
+        header,
+
+        /// A block has been downloaded, checked and stored (header link).
+        /// Issued by 'check' and handled by 'connect'.
+        checked,
+
+        /// A branch has been connected (header link).
+        /// Issued by 'connect' and handled by 'confirm'.
+        connected,
+
+        /// A branch has been confirmed (top header link).
+        /// Issued by 'confirm' and handled by 'transaction'.
+        confirmed,
+
+        /// A new transaction has been added to the pool (tx link).
+        /// Issued by 'transaction' and handled by 'candidate'.
+        transaction,
+
+        /// A new candidate block has been created (data?).
+        /// Issued by 'candidate' and handled by miners.
+        candidate,
+
+        /// Service is stopping (accompanied by error::service_stopped).
+        stop
+    };
+
+    typedef network::subscriber<chase> event_subscriber;
+    typedef event_subscriber::handler event_handler;
     DELETE_COPY_MOVE(chaser);
 
-    /// True if the current thread is on the chaser strand.
-    virtual bool stranded() const NOEXCEPT;
+    // TODO: public method to check/store a block.
+    // TODO: not stranded, thread safe, and posts checked event.
 
 protected:
     chaser(full_node& node) NOEXCEPT;
-    virtual ~chaser() NOEXCEPT;
+    ~chaser() NOEXCEPT;
+
+    /// Close the node.
+    void close(const code& ec) NOEXCEPT;
+
+    /// True if the current thread is on the chaser strand.
+    bool stranded() const NOEXCEPT;
+
+    /// Subscribe to chaser events.
+    code subscribe(event_handler&& handler) NOEXCEPT;
+
+    /// Set chaser event (does not require network strand).
+    void notify(const code& ec, chase value) NOEXCEPT;
 
 private:
+    void do_notify(const code& ec, chase value) NOEXCEPT;
+
     // These are thread safe (mostly).
     full_node& node_;
     network::asio::strand strand_;
+
+    // This is protected by the network strand.
+    event_subscriber& subscriber_;
 };
 
 } // namespace node

include/bitcoin/node/chasers/chaser_candidate.hpp

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2011-2023 libbitcoin developers (see AUTHORS)
+ *
+ * This file is part of libbitcoin.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef LIBBITCOIN_NODE_CHASERS_CHASER_CANDIDATE_HPP
+#define LIBBITCOIN_NODE_CHASERS_CHASER_CANDIDATE_HPP
+
+#include <bitcoin/network.hpp>
+#include <bitcoin/node/define.hpp>
+#include <bitcoin/node/chasers/chaser.hpp>
+
+namespace libbitcoin {
+namespace node {
+
+class full_node;
+
+/// Construct candidate blocks upon modification of the transaction DAG.
+/// Notify subscribers with "candidate" event.
+class BCN_API chaser_candidate
+  : public chaser, protected network::tracker<chaser_candidate>
+{
+public:
+    typedef std::unique_ptr<chaser_candidate> ptr;
+
+    chaser_candidate(full_node& node) NOEXCEPT;
+};
+
+} // namespace node
+} // namespace libbitcoin
+
+#endif

include/bitcoin/node/chasers/chaser_check.hpp

@@ -34,7 +34,12 @@ class BCN_API chaser_check
   : public chaser, protected network::tracker<chaser_check>
 {
 public:
+    typedef std::unique_ptr<chaser_check> ptr;
+
     chaser_check(full_node& node) NOEXCEPT;
+
+private:
+    void handle_event(const code& ec, chase value) NOEXCEPT;
 };
 
 } // namespace node

include/bitcoin/node/chasers/chaser_confirm.hpp

@@ -34,6 +34,8 @@ class BCN_API chaser_confirm
   : public chaser, protected network::tracker<chaser_confirm>
 {
 public:
+    typedef std::unique_ptr<chaser_confirm> ptr;
+
     chaser_confirm(full_node& node) NOEXCEPT;
 };
 

include/bitcoin/node/chasers/chaser_connect.hpp

@@ -31,9 +31,11 @@ class full_node;
 /// Chase down blocks in the the candidate header chain for validation.
 /// Notify subscribers with the "block connected" event.
 class BCN_API chaser_connect
-   : public chaser, protected network::tracker<chaser_connect>
+  : public chaser, protected network::tracker<chaser_connect>
 {
 public:
+    typedef std::unique_ptr<chaser_connect> ptr;
+
     chaser_connect(full_node& node) NOEXCEPT;
 };
 

include/bitcoin/node/chasers/chaser_header.hpp

@@ -31,9 +31,11 @@ class full_node;
 /// Chase down stronger header branches for the candidate chain.
 /// Notify subscribers with "strong header" event.
 class BCN_API chaser_header
-   : public chaser, protected network::tracker<chaser_header>
+  : public chaser, protected network::tracker<chaser_header>
 {
 public:
+    typedef std::unique_ptr<chaser_header> ptr;
+
     chaser_header(full_node& node) NOEXCEPT;
 };
 

include/bitcoin/node/chasers/chaser_transaction.hpp

@@ -30,9 +30,11 @@ class full_node;
 
 /// Chase down unconfirmed transactions.
 class BCN_API chaser_transaction
-   : public chaser, protected network::tracker<chaser_transaction>
+  : public chaser, protected network::tracker<chaser_transaction>
 {
 public:
+    typedef std::unique_ptr<chaser_transaction> ptr;
+
     chaser_transaction(full_node& node) NOEXCEPT;
 };
 

include/bitcoin/node/chasers/chasers.hpp

@@ -20,6 +20,7 @@
 #define LIBBITCOIN_NODE_CHASERS_CHASERS_HPP
 
 #include <bitcoin/node/chasers/chaser.hpp>
+#include <bitcoin/node/chasers/chaser_candidate.hpp>
 #include <bitcoin/node/chasers/chaser_check.hpp>
 #include <bitcoin/node/chasers/chaser_confirm.hpp>
 #include <bitcoin/node/chasers/chaser_connect.hpp>

include/bitcoin/node/error.hpp

@@ -38,6 +38,7 @@ enum error_t : uint8_t
 {
     success,
     unknown,
+    unexpected_event,
 
     // database
     store_uninitialized,

include/bitcoin/node/full_node.hpp

@@ -22,6 +22,7 @@
 #include <memory>
 #include <bitcoin/database.hpp>
 #include <bitcoin/network.hpp>
+#include <bitcoin/node/chasers/chasers.hpp>
 #include <bitcoin/node/configuration.hpp>
 #include <bitcoin/node/define.hpp>
 
@@ -35,7 +36,6 @@ class BCN_API full_node
     typedef std::shared_ptr<full_node> ptr;
     typedef database::store<database::map> store;
     typedef database::query<store> query;
-    typedef network::subscriber<> event_subscriber;
 
     /// Constructors.
     /// -----------------------------------------------------------------------
@@ -56,11 +56,6 @@ class BCN_API full_node
     /// Close the node.
     void close() NOEXCEPT override;
 
-    /// Events.
-    /// -----------------------------------------------------------------------
-
-    // TODO: subscribe/notify.
-
     /// Properties.
     /// -----------------------------------------------------------------------
 
@@ -70,8 +65,15 @@ class BCN_API full_node
     /// Thread safe synchronous archival interface.
     query& archive() const NOEXCEPT;
 
+    /// Obtain reference to the chaser event subscriber.
+    chaser::event_subscriber& event_subscriber() NOEXCEPT;
+
 protected:
+    virtual code create_chasers() NOEXCEPT;
+    virtual void stop_chasers() NOEXCEPT;
+
     /// Session attachments.
+    /// -----------------------------------------------------------------------
     network::session_manual::ptr attach_manual_session() NOEXCEPT override;
     network::session_inbound::ptr attach_inbound_session() NOEXCEPT override;
     network::session_outbound::ptr attach_outbound_session() NOEXCEPT override;
@@ -85,8 +87,14 @@ class BCN_API full_node
     const configuration& config_;
     query& query_;
 
-    // This is protected by strand.
-    event_subscriber event_subscriber_;
+    // These are protected by strand.
+    chaser::event_subscriber event_subscriber_;
+    chaser_header::ptr chaser_header_{};
+    chaser_check::ptr chaser_check_{};
+    chaser_connect::ptr chaser_connect_{};
+    chaser_confirm::ptr chaser_confirm_{};
+    chaser_transaction::ptr chaser_transaction_{};
+    chaser_candidate::ptr chaser_candidate_{};
 };
 
 } // namespace node