Avoid copying and improve optimization opportunities

src/ripple/app/consensus/LedgerConsensus.cpp

@@ -44,6 +44,7 @@
 #include <ripple/protocol/UintTypes.h>
 #include <beast/module/core/text/LexicalCast.h>
 #include <beast/utility/make_lock.h>
+#include <type_traits>
 
 namespace ripple {
 
@@ -1306,10 +1307,10 @@ private:
 
         s.set_ledgerseq (ledger.getLedgerSeq ());
         s.set_networktime (getApp().getOPs ().getNetworkTimeNC ());
-        uint256 hash = ledger.getParentHash ();
-        s.set_ledgerhashprevious (hash.begin (), hash.size ());
-        hash = ledger.getHash ();
-        s.set_ledgerhash (hash.begin (), hash.size ());
+        s.set_ledgerhashprevious(ledger.getParentHash ().begin (),
+            std::decay_t<decltype(ledger.getParentHash ())>::bytes);
+        s.set_ledgerhash (ledger.getHash ().begin (),
+            std::decay_t<decltype(ledger.getHash ())>::bytes);
 
         std::uint32_t uMin, uMax;
         if (!getApp().getOPs ().getFullValidatedRange (uMin, uMax))

src/ripple/app/ledger/Ledger.cpp

@@ -616,7 +616,8 @@ bool Ledger::getMetaHex (uint256 const& transID, std::string& hex) const
     return true;
 }
 
-uint256 Ledger::getHash ()
+uint256 const&
+Ledger::getHash ()
 {
     if (!mValidHash)
         updateHash ();

src/ripple/app/ledger/Ledger.h

@@ -187,7 +187,7 @@ public:
     void addRaw (Serializer & s) const;
     void setRaw (Serializer & s, bool hasPrefix);
 
-    uint256 getHash ();
+    uint256 const& getHash ();
     uint256 const& getParentHash () const
     {
         return mParentHash;

src/ripple/basics/impl/strHex.cpp

@@ -19,22 +19,9 @@
 
 #include <BeastConfig.h>
 #include <algorithm>
-    
+
 namespace ripple {
 
-char charHex (int iDigit)
-{
-    if (iDigit >= 0)
-    {
-        if(iDigit < 10)
-            return '0' + iDigit;
-        if(iDigit < 16)
-            return 'A' - 10 + iDigit;
-    }
-
-    return 0;
-}
-
 int charUnHex (unsigned char c)
 {
     struct HexTab

src/ripple/basics/strHex.h

@@ -26,14 +26,24 @@
 #define RIPPLE_BASICS_STRHEX_H_INCLUDED
 
 #include <string>
-    
+
 namespace ripple {
 
 /** Converts an integer to the corresponding hex digit
     @param iDigit 0-15 inclusive
-    @return a character from '0'-'9' or 'A'-'F' on success; 0 on failure.
+    @return a character from '0'-'9' or 'A'-'F'.
 */
-char charHex (int iDigit);
+inline
+char
+charHex (unsigned int digit)
+{
+    static
+    char const xtab[] = "0123456789ABCDEF";
+
+    assert (digit < 16);
+
+    return xtab[digit];
+}
 
 /** @{ */
 /** Converts a hex digit to the corresponding integer