From 47c6ab0ced4563fe473c9396cbaea874619c2921 Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Wed, 25 Mar 2015 13:03:10 -0700
Subject: [PATCH] Reduce SHAMapTreeNode copying during SHAMap unsharing:

In some code paths, we bump the SHAMap sequence number
before we unshare. This forces SHAMapTreeNode to be
copied. By making the ledger immutable we cause the
unsharing to occur earlier, eliminating the copies.
---
 src/ripple/app/ledger/LedgerMaster.cpp | 5 +++--
 src/ripple/app/main/Application.cpp    | 1 +
 src/ripple/shamap/SHAMap.h             | 1 +
 src/ripple/shamap/impl/SHAMap.cpp      | 2 +-
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/ripple/app/ledger/LedgerMaster.cpp b/src/ripple/app/ledger/LedgerMaster.cpp
index ee7b95dee..4a8b07fea 100644
--- a/src/ripple/app/ledger/LedgerMaster.cpp
+++ b/src/ripple/app/ledger/LedgerMaster.cpp
@@ -394,8 +394,9 @@ public:
         }
         if (didApply)
         {
-           mCurrentLedger.set (ledger);
-           getApp().getOPs ().pubProposedTransaction (ledger, txn, result);
+            ledger->setImmutable (); // So the next line doesn't have to copy
+            mCurrentLedger.set (ledger);
+            getApp().getOPs ().pubProposedTransaction (ledger, txn, result);
         }
         return result;
     }
diff --git a/src/ripple/app/main/Application.cpp b/src/ripple/app/main/Application.cpp
index 3e70418eb..6cff83eac 100644
--- a/src/ripple/app/main/Application.cpp
+++ b/src/ripple/app/main/Application.cpp
@@ -1084,6 +1084,7 @@ void ApplicationImp::startNewLedger ()
         firstLedger->updateHash ();
         firstLedger->setClosed ();
         firstLedger->setAccepted ();
+        firstLedger->setImmutable();
         m_ledgerMaster->pushLedger (firstLedger);
 
         Ledger::pointer secondLedger = std::make_shared<Ledger> (true, std::ref (*firstLedger));
diff --git a/src/ripple/shamap/SHAMap.h b/src/ripple/shamap/SHAMap.h
index c97cb18fe..2fac043b8 100644
--- a/src/ripple/shamap/SHAMap.h
+++ b/src/ripple/shamap/SHAMap.h
@@ -274,6 +274,7 @@ void
 SHAMap::setImmutable ()
 {
     assert (state_ != SHAMapState::Invalid);
+    unshare ();
     state_ = SHAMapState::Immutable;
 }
 
diff --git a/src/ripple/shamap/impl/SHAMap.cpp b/src/ripple/shamap/impl/SHAMap.cpp
index e043e5662..962ae1207 100644
--- a/src/ripple/shamap/impl/SHAMap.cpp
+++ b/src/ripple/shamap/impl/SHAMap.cpp
@@ -75,7 +75,7 @@ SHAMap::snapShot (bool isMutable) const
     newMap.seq_ = seq_ + 1;
     newMap.root_ = root_;
 
-    if ((state_ != SHAMapState::Immutable) || !isMutable)
+    if ((state_ != SHAMapState::Immutable) || isMutable)
     {
         // If either map may change, they cannot share nodes
         newMap.unshare ();