add spin_yield to undo DB

libraries/db/include/graphene/db/undo_database.hpp

@@ -25,6 +25,9 @@
 #include <graphene/db/object.hpp>
 #include <deque>
 #include <fc/exception/exception.hpp>
+#include <fc/thread/spin_yield_lock.hpp>
+#include <fc/fwd.hpp>
+#include <fc/thread/unique_lock.hpp>
 
 namespace graphene { namespace db {
 
@@ -132,6 +135,8 @@ namespace graphene { namespace db {
          std::deque<undo_state>  _stack;
          object_database&        _db;
          size_t                  _max_size = 256;
+
+	 mutable fc::spin_yield_lock     _spin_yield;
    };
 
 } } // graphene::db

libraries/db/undo_database.cpp

@@ -25,6 +25,8 @@
 #include <graphene/db/undo_database.hpp>
 #include <fc/reflect/variant.hpp>
 
+#include <fc/thread/spin_yield_lock.hpp>
+
 namespace graphene { namespace db {
 
 void undo_database::enable()  { _disabled = false; }
@@ -44,6 +46,8 @@ undo_database::session::~session() {
 
 undo_database::session undo_database::start_undo_session( bool force_enable )
 {
+   synchronized(_spin_yield)
+
    if( _disabled && !force_enable ) return session(*this);
    bool disable_on_exit = _disabled  && force_enable;
    if( force_enable ) 
@@ -58,6 +62,8 @@ undo_database::session undo_database::start_undo_session( bool force_enable )
 }
 void undo_database::on_create( const object& obj )
 {
+   synchronized(_spin_yield)
+
    if( _disabled ) return;
 
    if( _stack.empty() )
@@ -73,6 +79,8 @@ void undo_database::on_modify( const object& obj )
 {
    if( _disabled ) return;
 
+   synchronized(_spin_yield)
+
    if( _stack.empty() )
       _stack.emplace_back();
    auto& state = _stack.back();
@@ -86,6 +94,8 @@ void undo_database::on_remove( const object& obj )
 {
    if( _disabled ) return;
 
+   synchronized(_spin_yield)
+
    if( _stack.empty() )
       _stack.emplace_back();
    undo_state& state = _stack.back();
@@ -105,7 +115,9 @@ void undo_database::on_remove( const object& obj )
 }
 
 void undo_database::undo()
-{ try {
+{ 
+  synchronized(_spin_yield)
+  try {
    FC_ASSERT( !_disabled );
    FC_ASSERT( _active_sessions > 0 );
    disable();
@@ -136,6 +148,8 @@ void undo_database::undo()
 
 void undo_database::merge()
 {
+   synchronized(_spin_yield)
+
    FC_ASSERT( _active_sessions > 0 );
    if( _active_sessions == 1 && _stack.size() == 1 )
    {
@@ -256,12 +270,16 @@ void undo_database::merge()
 }
 void undo_database::commit()
 {
+   synchronized(_spin_yield)
+
    FC_ASSERT( _active_sessions > 0 );
    --_active_sessions;
 }
 
 void undo_database::pop_commit()
 {
+   synchronized(_spin_yield)
+
    FC_ASSERT( _active_sessions == 0 );
    FC_ASSERT( !_stack.empty() );
 
@@ -299,6 +317,8 @@ void undo_database::pop_commit()
 }
 const undo_state& undo_database::head()const
 {
+   synchronized(_spin_yield)
+
    FC_ASSERT( !_stack.empty() );
    return _stack.back();
 }