Add organizer prioritize for equal work branch preference.

include/bitcoin/node/chasers/chaser_organize.hpp

@@ -44,6 +44,10 @@ class chaser_organize
     virtual void organize(const typename Block::cptr& block,
         organize_handler&& handler) NOEXCEPT;
 
+    /// Reorganize to the branch of an archived block of at least equal work.
+    virtual void prioritize(const system::hash_digest& hash,
+        organize_handler&& handler) NOEXCEPT;
+
 protected:
     using header_link = database::header_link;
     using chain_state = system::chain::chain_state;
@@ -89,13 +93,17 @@ class chaser_organize
     virtual bool handle_chase(const code&, chase event_,
         event_value value) NOEXCEPT;
 
-    /// Organize a discovered Block.
-    virtual void do_organize(typename Block::cptr block,
+    /// Organize a discovered Block, prioritized accepts a tied branch.
+    virtual void do_organize(typename Block::cptr block, bool prioritized,
         const organize_handler& handler) NOEXCEPT;
 
     /// Reorganize following Block unconfirmability.
     virtual void do_disorganize(header_t header) NOEXCEPT;
 
+    /// Reorganize to the branch of the given block.
+    virtual void do_prioritize(const system::hash_digest& hash,
+        const organize_handler& handler) NOEXCEPT;
+
     /// Properties
     /// -----------------------------------------------------------------------
 

include/bitcoin/node/full_node.hpp

@@ -69,6 +69,10 @@ class BCN_API full_node
     virtual void organize(const system::chain::block::cptr& block,
         organize_handler&& handler) NOEXCEPT;
 
+    /// Reorganize to the branch of an archived block of at least equal work.
+    virtual void prioritize(const system::hash_digest& hash,
+        organize_handler&& handler) NOEXCEPT;
+
     /// Manage download queue.
     virtual void get_hashes(map_handler&& handler) NOEXCEPT;
     virtual void put_hashes(const map_ptr& map,

include/bitcoin/node/impl/chasers/chaser_organize.ipp

@@ -1,4 +1,4 @@
-/**
+/**
  * Copyright (c) 2011-2026 libbitcoin developers
  *
  * This file is part of libbitcoin.
@@ -73,7 +73,17 @@ void CLASS::organize(const typename Block::cptr& block,
     if (closed())
         return;
 
-    POST(do_organize, block, std::move(handler));
+    POST(do_organize, block, false, std::move(handler));
+}
+
+TEMPLATE
+void CLASS::prioritize(const system::hash_digest& hash,
+    organize_handler&& handler) NOEXCEPT
+{
+    if (closed())
+        return;
+
+    POST(do_prioritize, hash, std::move(handler));
 }
 
 // Methods
@@ -113,7 +123,7 @@ bool CLASS::handle_chase(const code&, chase event_, event_value value) NOEXCEPT
 }
 
 TEMPLATE
-void CLASS::do_organize(typename Block::cptr block,
+void CLASS::do_organize(typename Block::cptr block, bool prioritized,
     const organize_handler& handler) NOEXCEPT
 {
     BC_ASSERT(stranded());
@@ -217,7 +227,7 @@ void CLASS::do_organize(typename Block::cptr block,
     bool strong{};
     const auto branch_size = tree_branch.size() + store_branch.size();
     const auto branch_point = height - add1(branch_size);
-    if (!query.get_strong_branch(strong, work, branch_point))
+    if (!query.get_strong_branch(strong, work, branch_point, prioritized))
     {
         handler(fault(error::organize3), height);
         return;
@@ -333,6 +343,38 @@ void CLASS::do_organize(typename Block::cptr block,
     handler(error::success, height);
 }
 
+// bitcoind's preciousblock, a manual tie break between equal work branches.
+// The preference is not retained, as the reorganized branch then wins ties.
+TEMPLATE
+void CLASS::do_prioritize(const system::hash_digest& hash,
+    const organize_handler& handler) NOEXCEPT
+{
+    BC_ASSERT(stranded());
+
+    if (closed())
+        return;
+
+    // Only the top of a cached branch can tie the candidate top.
+    if (std::any_of(tree_.begin(), tree_.end(), [&](const auto& item) NOEXCEPT
+        {
+            return get_header(*item.second).previous_block_hash() == hash;
+        }))
+    {
+        handler(error::success, {});
+        return;
+    }
+
+    // A tied branch is cached, extract it for reevaluation as prioritized.
+    auto handle = tree_.extract(hash);
+    if (!handle)
+    {
+        handler(database::error::not_found, {});
+        return;
+    }
+
+    do_organize(handle.mapped(), true, handler);
+}
+
 TEMPLATE
 void CLASS::do_disorganize(header_t link) NOEXCEPT
 {

include/bitcoin/node/protocols/protocol.hpp

@@ -113,6 +113,10 @@ class BCN_API protocol
     virtual void organize(const system::chain::block::cptr& block,
         organize_handler&& handler) NOEXCEPT;
 
+    /// Reorganize to the branch of an archived block of at least equal work.
+    virtual void prioritize(const system::hash_digest& hash,
+        organize_handler&& handler) NOEXCEPT;
+
     /// Events subscription.
     /// -----------------------------------------------------------------------
 

include/bitcoin/node/sessions/session.hpp

@@ -47,6 +47,10 @@ class BCN_API session
     virtual void organize(const system::chain::block::cptr& block,
         organize_handler&& handler) NOEXCEPT;
 
+    /// Reorganize to the branch of an archived block of at least equal work.
+    virtual void prioritize(const system::hash_digest& hash,
+        organize_handler&& handler) NOEXCEPT;
+
     /// Manage download queue.
     virtual void get_hashes(map_handler&& handler) NOEXCEPT;
     virtual void put_hashes(const map_ptr& map,

src/chasers/chaser_confirm.cpp

@@ -164,8 +164,9 @@ void chaser_confirm::do_bumped(height_t) NOEXCEPT
         }
 
         // Compares candidate branch work to confirmed (above fork point).
+        // A tie is accepted because only prioritization creates one.
         bool strong{};
-        if (!query.get_strong_fork(strong, work, fork_point))
+        if (!query.get_strong_fork(strong, work, fork_point, true))
         {
             fault(error::confirm3);
             return;

src/full_node.cpp

@@ -175,6 +175,15 @@ void full_node::organize(const system::chain::block::cptr& block,
     chaser_block_.organize(block, std::move(handler));
 }
 
+void full_node::prioritize(const system::hash_digest& hash,
+    organize_handler&& handler) NOEXCEPT
+{
+    if (config_.node.headers_first)
+        chaser_header_.prioritize(hash, std::move(handler));
+    else
+        chaser_block_.prioritize(hash, std::move(handler));
+}
+
 void full_node::get_hashes(map_handler&& handler) NOEXCEPT
 {
     chaser_check_.get_hashes(std::move(handler));

src/protocols/protocol.cpp

@@ -139,6 +139,12 @@ void protocol::organize(const system::chain::block::cptr& block,
     session_->organize(block, std::move(handler));
 }
 
+void protocol::prioritize(const system::hash_digest& hash,
+    organize_handler&& handler) NOEXCEPT
+{
+    session_->prioritize(hash, std::move(handler));
+}
+
 void protocol::subscribe_chase(event_notifier&& handler) NOEXCEPT
 {
     // This is a shared instance multiply-derived from network::protocol.

src/sessions/session.cpp

@@ -52,6 +52,12 @@ void session::organize(const block::cptr& block,
     node_.organize(block, std::move(handler));
 }
 
+void session::prioritize(const hash_digest& hash,
+    organize_handler&& handler) NOEXCEPT
+{
+    node_.prioritize(hash, std::move(handler));
+}
+
 void session::get_hashes(map_handler&& handler) NOEXCEPT
 {
     node_.get_hashes(std::move(handler));