Calculate deep offer quality

src/ripple/app/book/BookTip.h

@@ -44,6 +44,7 @@ private:
     uint256 m_dir;
     uint256 m_index;
     SLE::pointer m_entry;
+    Quality m_quality;
 
     LedgerView&
     view() const noexcept
@@ -67,10 +68,10 @@ public:
         return m_index;
     }
 
-    Quality const
+    Quality const&
     quality() const noexcept
     {
-        return Quality (getQuality (m_dir));
+        return m_quality;
     }
 
     SLE::pointer const&

src/ripple/app/book/impl/BookTip.cpp

@@ -45,32 +45,36 @@ BookTip::step ()
 
     for(;;)
     {
-        // See if there's an entry at or worse than current quality.
-        auto const page (
-            view().getNextLedgerIndex (m_book, m_end));
+        // See if there's an entry at or worse than current quality. Notice
+        // that the quality is encoded only in the index of the first page
+        // of a directory.
+        auto const first_page (view().getNextLedgerIndex (m_book, m_end));
 
-        if (page.isZero())
+        if (first_page.isZero())
             return false;
 
         unsigned int di (0);
         SLE::pointer dir;
-        if (view().dirFirst (page, dir, di, m_index))
+
+        if (view().dirFirst (first_page, dir, di, m_index))
         {
             m_dir = dir->getIndex();
             m_entry = view().entryCache (ltOFFER, m_index);
+            m_quality = Quality (getQuality (first_page));
             m_valid = true;
 
             // Next query should start before this directory
-            m_book = page;
+            m_book = first_page;
 
             // The quality immediately before the next quality
             --m_book;
 
             break;
         }
+
         // There should never be an empty directory but just in case,
         // we handle that case by advancing to the next directory.
-        m_book = page;
+        m_book = first_page;
     }
 
     return true;