Use new MetaView functionality in RippleCalc (RIPD-954):

RippleCalc is changed to stack views when calculating results
instead of making a copy of the MetaView, improving efficiency.

src/ripple/app/ledger/MetaView.h

@@ -94,6 +94,7 @@ private:
     using list_type = std::map<uint256, Item>;
 
     BasicView* parent_;
+    MetaView* mParent_ = NULL;
     list_type items_;
     boost::optional<DeferredCredits> mDeferredCredits;
     TransactionMetaSet mSet;
@@ -115,13 +116,9 @@ public:
     MetaView (Ledger::ref ledger,
         TransactionEngineParams tep);
 
-    /** Construct a copy.
+    /** Construct a nested view.
-        Effects:
-            The copy is identical except that
-            the sequence number is one higher.
     */
-    // DEPRECATED
+    MetaView (MetaView&);
-    MetaView (MetaView const&);
 
     //--------------------------------------------------------------------------
     //

src/ripple/app/ledger/impl/MetaView.cpp

@@ -69,16 +69,18 @@ MetaView::MetaView (Ledger::ref ledger,
 {
 }
 
-MetaView::MetaView (MetaView const& other)
+MetaView::MetaView (MetaView& other)
-    : parent_(other.parent_)
+    : parent_(&other)
+    , mParent_(&other)
     , items_(other.items_)
-    , mDeferredCredits(other.mDeferredCredits)
     , mSet(other.mSet)
     // VFALCO NOTE This is a change in behavior,
     //        previous version set tapNONE
     , mParams(other.mParams)
     , mSeq(other.mSeq + 1)
 {
+    if (other.mDeferredCredits)
+        mDeferredCredits.emplace();
 }
 
 //------------------------------------------------------------------------------
@@ -279,8 +281,23 @@ MetaView::deprecatedBalance(
         STAmount const& amount) const
 {
     if (mDeferredCredits)
+    {
+        if (mParent_)
+        {
+            assert (mParent_->mDeferredCredits);
+            return mDeferredCredits->adjustedBalance(
+                account, issuer, mParent_->deprecatedBalance(account, issuer, amount));
+        }
+
         return mDeferredCredits->adjustedBalance(
             account, issuer, amount);
+    }
+    else if (mParent_ && mParent_->mDeferredCredits)
+    {
+        return mParent_->mDeferredCredits->adjustedBalance(
+            account, issuer, amount);
+    }
+
     return amount;
 }
 
@@ -422,6 +439,7 @@ MetaView::deprecatedCreditHint(
 
 void MetaView::apply()
 {
+
     // Write back the account states
     for (auto& item : items_)
     {
@@ -433,7 +451,7 @@ void MetaView::apply()
         {
         case taaCACHED:
             assert(parent_->exists(
-                keylet::child(item.first)));
+                Keylet(sle->getType(), item.first)));
             break;
 
         case taaCREATE:
@@ -458,6 +476,20 @@ void MetaView::apply()
             break;
         }
     }
+
+    if (mDeferredCredits)
+    {
+        assert (mParent_ != NULL);
+        if (mParent_->areCreditsDeferred())
+        {
+            for (auto& credit : *mDeferredCredits)
+            {
+                // This will go away soon
+                mParent_->mDeferredCredits->merge (credit);
+            }
+        }
+    }
+
     // Safety precaution since we moved the
     // entries out, apply() cannot be called twice.
     items_.clear();

src/ripple/app/paths/PathState.cpp

@@ -268,7 +268,7 @@ TER PathState::pushNode (
             auto const& backNode = nodes_.back ();
             if (backNode.isAccount())
             {
-                auto sleRippleState = metaView_->peek(
+                auto sleRippleState = metaView_.peek(
                     keylet::line(backNode.account_, node.account_, backNode.issue_.currency));
 
                 // A "RippleState" means a balance betweeen two accounts for a
@@ -291,7 +291,7 @@ TER PathState::pushNode (
                             << backNode.account_ << " and " << node.account_
                             << " for " << node.issue_.currency << "." ;
 
-                    auto sleBck  = metaView_->peek (
+                    auto sleBck  = metaView_.peek (
                         keylet::account(backNode.account_));
                     // Is the source account the highest numbered account ID?
                     bool bHigh = backNode.account_ > node.account_;
@@ -318,13 +318,13 @@ TER PathState::pushNode (
 
                     if (resultCode == tesSUCCESS)
                     {
-                        STAmount saOwed = creditBalance (*metaView_,
+                        STAmount saOwed = creditBalance (metaView_,
                             node.account_, backNode.account_,
                             node.issue_.currency);
                         STAmount saLimit;
 
                         if (saOwed <= zero) {
-                            saLimit = creditLimit (*metaView_,
+                            saLimit = creditLimit (metaView_,
                                 node.account_,
                                 backNode.account_,
                                 node.issue_.currency);
@@ -413,7 +413,6 @@ TER PathState::pushNode (
 // terStatus = tesSUCCESS, temBAD_PATH, terNO_LINE, terNO_ACCOUNT, terNO_AUTH,
 // or temBAD_PATH_LOOP
 TER PathState::expandPath (
-    MetaView const& viewSource,
     STPath const& spSourcePath,
     AccountID const& uReceiverID,
     AccountID const& uSenderID)
@@ -432,8 +431,6 @@ TER PathState::expandPath (
     WriteLog (lsTRACE, RippleCalc)
         << "expandPath> " << spSourcePath.getJson (0);
 
-    metaView_.emplace(viewSource);
-
     terStatus = tesSUCCESS;
 
     // XRP with issuer is malformed.
@@ -627,7 +624,7 @@ void PathState::checkFreeze()
         // Check each order book for a global freeze
         if (nodes_[i].uFlags & STPathElement::typeIssuer)
         {
-            sle = metaView_->peek (keylet::account(nodes_[i].issue_.account));
+            sle = metaView_.peek (keylet::account(nodes_[i].issue_.account));
 
             if (sle && sle->isFlag (lsfGlobalFreeze))
             {
@@ -645,7 +642,7 @@ void PathState::checkFreeze()
 
             if (inAccount != outAccount)
             {
-                sle = metaView_->peek (keylet::account(outAccount));
+                sle = metaView_.peek (keylet::account(outAccount));
 
                 if (sle && sle->isFlag (lsfGlobalFreeze))
                 {
@@ -653,7 +650,7 @@ void PathState::checkFreeze()
                     return;
                 }
 
-                sle = metaView_->peek (keylet::line(inAccount,
+                sle = metaView_.peek (keylet::line(inAccount,
                         outAccount, currencyID));
 
                 if (sle && sle->isFlag (
@@ -680,9 +677,9 @@ TER PathState::checkNoRipple (
     Currency const& currency)
 {
     // fetch the ripple lines into and out of this node
-    SLE::pointer sleIn = metaView_->peek (
+    SLE::pointer sleIn = metaView_.peek (
         keylet::line(firstAccount, secondAccount, currency));
-    SLE::pointer sleOut = metaView_->peek (
+    SLE::pointer sleOut = metaView_.peek (
         keylet::line(secondAccount, thirdAccount, currency));
 
     if (!sleIn || !sleOut)

src/ripple/app/paths/PathState.h

@@ -35,20 +35,18 @@ class PathState : public CountedObject <PathState>
     using Ptr = std::shared_ptr<PathState>;
     using List = std::vector<Ptr>;
 
-    PathState (STAmount const& saSend, STAmount const& saSendMax)
+    PathState (MetaView& view, STAmount const& saSend, STAmount const& saSendMax)
-        : mIndex (0)
+        : metaView_ (view)
+        , mIndex (0)
         , uQuality (0)
         , saInReq (saSendMax)
         , saOutReq (saSend)
     {
     }
 
-    explicit PathState (const PathState& psSrc) = default;
-
     void reset(STAmount const& in, STAmount const& out);
 
     TER expandPath (
-        MetaView const&  viewSource,
         STPath const&    spSourcePath,
         AccountID const& uReceiverID,
         AccountID const& uSenderID
@@ -105,7 +103,12 @@ class PathState : public CountedObject <PathState>
 
     MetaView& metaView()
     {
-        return *metaView_;
+        return metaView_;
+    }
+
+    void resetView (MetaView& view)
+    {
+        reconstruct (metaView_, view);
     }
 
     bool isDry() const
@@ -149,7 +152,7 @@ private:
     // Source may only be used there if not mentioned by an account.
     AccountIssueToNodeIndex umReverse;
 
-    boost::optional<MetaView> metaView_;
+    MetaView                    metaView_;
 
     int                         mIndex;    // Index/rank amoung siblings.
     std::uint64_t               uQuality;  // 0 = no quality/liquity left.

src/ripple/app/paths/RippleCalc.cpp

@@ -94,7 +94,7 @@ RippleCalc::Output RippleCalc::rippleCalculate (
 bool RippleCalc::addPathState(STPath const& path, TER& resultCode)
 {
     auto pathState = std::make_shared<PathState> (
-        saDstAmountReq_, saMaxAmountReq_);
+        metaView, saDstAmountReq_, saMaxAmountReq_);
 
     if (!pathState)
     {
@@ -103,7 +103,6 @@ bool RippleCalc::addPathState(STPath const& path, TER& resultCode)
     }
 
     pathState->expandPath (
-        metaView,
         path,
         uDstAccountID_,
         uSrcAccountID_);
@@ -208,7 +207,6 @@ TER RippleCalc::rippleCalculate ()
     while (resultCode == temUNCERTAIN)
     {
         int iBest = -1;
-        MetaView lesCheckpoint = metaView;
         int iDry = 0;
 
         // True, if ever computed multi-quality.
@@ -228,7 +226,7 @@ TER RippleCalc::rippleCalculate ()
 
                 // Error if done, output met.
                 PathCursor pc(*this, *pathState, multiQuality);
-                pc.nextIncrement (lesCheckpoint);
+                pc.nextIncrement ();
 
                 // Compute increment.
                 WriteLog (lsDEBUG, RippleCalc)
@@ -287,13 +285,6 @@ TER RippleCalc::rippleCalculate ()
                             << " inPass()=" << pathState->inPass()
                             << " saOutPass=" << pathState->outPass();
 
-                        assert (metaView.isValid ());
-                        metaView.swapWith (pathState->metaView());
-                        // For the path, save ledger state.
-
-                        // VFALCO Can this be done without the function call?
-                        metaView.deprecatedInvalidate();
-
                         iBest   = pathState->index ();
                     }
                 }
@@ -339,14 +330,9 @@ TER RippleCalc::rippleCalculate ()
                 pathState->unfundedOffers().begin (),
                 pathState->unfundedOffers().end ());
 
-            // Record best pass' MetaView to build off of and potentially
+            // Apply best pass' MetaView
-            // return.
             assert (pathState->metaView().isValid ());
-            metaView.swapWith (pathState->metaView());
+            pathState->metaView().apply();
-            
-            // VFALCO Why is this needed? Can it be done
-            //        without the function call?
-            pathState->metaView().deprecatedInvalidate();
 
             actualAmountIn_ += pathState->inPass();
             actualAmountOut_ += pathState->outPass();
@@ -421,10 +407,7 @@ TER RippleCalc::rippleCalculate ()
         }
         else
         {
-            // We must restore the activeLedger from lesCheckpoint in the case
+            // Don't apply any payment increments
-            // when iBest is -1 and just before the result is set to tesSUCCESS.
-
-            metaView.swapWith (lesCheckpoint);
             resultCode   = tesSUCCESS;
         }
     }

src/ripple/app/paths/RippleCalc.h

@@ -98,11 +98,10 @@ public:
         STPathSet const& spsPaths,
         Input const* const pInputs = nullptr);
 
-    /** The active ledger. */
+    // The view we are currently working on
-    // VFALCO TODO Fix this comment its not the ledger
-    // VFALCO TODO Rename this to view
     MetaView& metaView;
 
+
     // If the transaction fails to meet some constraint, still need to delete
     // unfunded offers.
     //

src/ripple/app/paths/cursor/Liquidity.cpp

@@ -25,13 +25,12 @@
 namespace ripple {
 namespace path {
 
-TER PathCursor::liquidity (MetaView const& lesCheckpoint) const
+TER PathCursor::liquidity () const
 {
     TER resultCode = tecPATH_DRY;
     PathCursor pc = *this;
 
-    // duplicate
+    pathState_.resetView (rippleCalc_.metaView);
-    reconstruct(rippleCalc_.metaView, lesCheckpoint);
 
     for (pc.nodeIndex_ = pc.nodeSize(); pc.nodeIndex_--; )
     {
@@ -60,9 +59,7 @@ TER PathCursor::liquidity (MetaView const& lesCheckpoint) const
     if (resultCode != tesSUCCESS)
         return resultCode;
 
-    // Do forward.
+    pathState_.resetView (rippleCalc_.metaView);
-    // duplicate
-    reconstruct(rippleCalc_.metaView, lesCheckpoint);
 
     for (pc.nodeIndex_ = 0; pc.nodeIndex_ < pc.nodeSize(); ++pc.nodeIndex_)
     {

src/ripple/app/paths/cursor/NextIncrement.cpp

@@ -34,7 +34,7 @@ namespace path {
 // This is the wrapper that restores a checkpointed version of the ledger so we
 // can write all over it without consequence.
 
-void PathCursor::nextIncrement (MetaView const& lesCheckpoint) const
+void PathCursor::nextIncrement () const
 {
     // The next state is what is available in preference order.
     // This is calculated when referenced accounts changed.
@@ -42,7 +42,7 @@ void PathCursor::nextIncrement (MetaView const& lesCheckpoint) const
     // WriteLog (lsTRACE, RippleCalc)
     //     << "nextIncrement: Path In: " << pathState_.getJson ();
 
-    auto status = liquidity(lesCheckpoint);
+    auto status = liquidity();
 
     if (status == tesSUCCESS)
     {

src/ripple/app/paths/cursor/PathCursor.h

@@ -50,7 +50,7 @@ public:
     {
     }
 
-    void nextIncrement(MetaView const& checkpoint) const;
+    void nextIncrement() const;
 
 private:
     PathCursor(PathCursor const&) = default;
@@ -60,7 +60,7 @@ private:
         return {rippleCalc_, pathState_, multiQuality_, nodeIndex_ + delta};
     }
 
-    TER liquidity(MetaView const& lesCheckpoint) const;
+    TER liquidity() const;
     TER reverseLiquidity () const;
     TER forwardLiquidity () const;
 
@@ -95,7 +95,8 @@ private:
     MetaView& ledger() const
     {
         // VFALCO Rename metaView to view
-        return rippleCalc_.metaView;
+        //return rippleCalc_.metaView;
+        return pathState_.metaView();
     }
 
     NodeIndex nodeSize() const

src/ripple/ledger/DeferredCredits.h

@@ -59,6 +59,10 @@ public:
                  STAmount const& amount);
 
     void clear ();
+
+    std::map<Key, Value>::iterator begin() { return map_.begin(); }
+    std::map<Key, Value>::iterator end() { return map_.end(); }
+    void merge (std::pair <Key, Value> const& p);
 };
 
 } // ripple

src/ripple/ledger/impl/DeferredCredits.cpp

@@ -147,5 +147,16 @@ void DeferredCredits::clear ()
     map_.clear ();
 }
 
+void DeferredCredits::merge (std::pair <Key, Value> const& p)
+{
+    using std::get;
+    auto r = map_.emplace(p);
+    if (!r.second)
+    {
+        get<0>(r.first->second) += get<0>(p.second);
+        get<1>(r.first->second) += get<1>(p.second);
+    }
+}
+
 } // ripple