Add is_coalesced() and prune(...) methods.

include/bitcoin/database/impl/query/query.ipp

@@ -98,6 +98,12 @@ bool CLASS::is_full() const NOEXCEPT
     return to_bool(get_space()) && !is_fault();
 }
 
+TEMPLATE
+bool CLASS::is_coalesced() const NOEXCEPT
+{
+    return get_fork() == get_top_candidate();
+}
+
 TEMPLATE
 size_t CLASS::get_space() const NOEXCEPT
 {
@@ -110,6 +116,12 @@ code CLASS::reload(const typename Store::event_handler& handler) const NOEXCEPT
     return store_.reload(handler);
 }
 
+TEMPLATE
+code CLASS::prune(const typename Store::event_handler& handler) const NOEXCEPT
+{
+    return store_.prune(handler);
+}
+
 TEMPLATE
 code CLASS::snapshot(const typename Store::event_handler& handler) const NOEXCEPT
 {

include/bitcoin/database/impl/store.ipp

@@ -456,8 +456,7 @@ code CLASS::prune(const event_handler& handler) NOEXCEPT
     };
 
     // Prevouts resettable if all candidates confirmed (fork is candidate top).
-    const query<CLASS> query_{ *this };
-    if (query_.get_fork() == query_.get_top_candidate())
+    if (query<CLASS>{ *this }.is_coalesced())
     {
         // zeroize table head, set body logical size to zero.
         prune(ec, prevout, table_t::prevout_table);

include/bitcoin/database/query.hpp

@@ -98,12 +98,18 @@ class query
     /// True if there is a disk full condition.
     bool is_full() const NOEXCEPT;
 
+    /// True if candidate top is fork point header.
+    bool is_coalesced() const NOEXCEPT;
+
     /// Get the space required to clear the disk full condition.
     size_t get_space() const NOEXCEPT;
 
     /// Resume from disk full condition.
     code reload(const typename Store::event_handler& handler) const NOEXCEPT;
 
+    /// Prune the store while running.
+    code prune(const typename Store::event_handler& handler) const NOEXCEPT;
+
     /// Snapshot the store while running.
     code snapshot(const typename Store::event_handler& handler) const NOEXCEPT;