Return refund from TransactionFrame

src/transactions/FeeBumpTransactionFrame.cpp

@@ -159,11 +159,9 @@ FeeBumpTransactionFrame::processPostApply(Application& app,
                                           AbstractLedgerTxn& ltx,
                                           TransactionMetaFrame& meta)
 {
-    int64_t preRefundFeeCharged = mInnerTx->getResult().feeCharged;
-
     // We must forward the Fee-bump source so the refund is applied to the
     // correct account
-    mInnerTx->processPostApply(app, ltx, meta, getFeeSourceID());
+    int64_t refund = mInnerTx->processRefund(app, ltx, meta, getFeeSourceID());
 
 #ifdef ENABLE_NEXT_PROTOCOL_VERSION_UNSAFE_FOR_PRODUCTION
     // The result codes and a feeCharged without the refund are set in
@@ -179,10 +177,7 @@ FeeBumpTransactionFrame::processPostApply(Application& app,
         auto& innerRes = irp.result;
         innerRes.feeCharged = mInnerTx->getResult().feeCharged;
 
-        // Now set update feeCharged on the fee bump. We don't have access to
-        // the refund value here, but we can calculate it using the pre and post
-        // feeCharged of mInnerTx.
-        int64_t refund = preRefundFeeCharged - mInnerTx->getResult().feeCharged;
+        // Now set the updated feeCharged on the fee bump.
         mResult.feeCharged -= refund;
     }
 #endif

src/transactions/TransactionFrame.cpp

@@ -794,7 +794,7 @@ TransactionFrame::validateSorobanResources(SorobanNetworkConfig const& config,
     return true;
 }
 
-void
+int64_t
 TransactionFrame::refundSorobanFee(AbstractLedgerTxn& ltxOuter,
                                    AccountID const& feeSource)
 {
@@ -803,7 +803,7 @@ TransactionFrame::refundSorobanFee(AbstractLedgerTxn& ltxOuter,
     auto const feeRefund = mSorobanExtension->mFeeRefund;
     if (feeRefund == 0)
     {
-        return;
+        return 0;
     }
 
     LedgerTxn ltx(ltxOuter);
@@ -814,19 +814,21 @@ TransactionFrame::refundSorobanFee(AbstractLedgerTxn& ltxOuter,
     if (!feeSourceAccount)
     {
         // Account was merged (shouldn't be possible)
-        return;
+        return 0;
     }
 
     if (!addBalance(header, feeSourceAccount, feeRefund))
     {
         // Liabilities in the way of the refund, just skip.
-        return;
+        return 0;
     }
 
     getResult().feeCharged -= feeRefund;
 
     header.current().feePool -= feeRefund;
     ltx.commit();
+
+    return feeRefund;
 }
 
 void
@@ -1943,29 +1945,30 @@ TransactionFrame::processPostApply(Application& app,
                                    AbstractLedgerTxn& ltxOuter,
                                    TransactionMetaFrame& meta)
 {
-    processPostApply(app, ltxOuter, meta, getSourceID());
+    processRefund(app, ltxOuter, meta, getSourceID());
 }
 
 // This is a TransactionFrame specific function that should only be used by
 // FeeBumpTransactionFrame to forward a different account for the refund.
-void
-TransactionFrame::processPostApply(Application& app,
-                                   AbstractLedgerTxn& ltxOuter,
-                                   TransactionMetaFrame& meta,
-                                   AccountID const& feeSource)
+int64_t
+TransactionFrame::processRefund(Application& app, AbstractLedgerTxn& ltxOuter,
+                                TransactionMetaFrame& meta,
+                                AccountID const& feeSource)
 {
     ZoneScoped;
 
     if (!isSoroban())
     {
-        return;
+        return 0;
     }
     // Process Soroban resource fee refund (this is independent of the
     // transaction success).
     LedgerTxn ltx(ltxOuter);
-    refundSorobanFee(ltx, feeSource);
+    int64_t refund = refundSorobanFee(ltx, feeSource);
     meta.pushTxChangesAfter(ltx.getChanges());
     ltx.commit();
+
+    return refund;
 }
 
 StellarMessage

src/transactions/TransactionFrame.h

@@ -145,7 +145,8 @@ class TransactionFrame : public TransactionFrameBase
     bool validateSorobanResources(SorobanNetworkConfig const& config,
                                   Config const& appConfig,
                                   uint32_t protocolVersion);
-    void refundSorobanFee(AbstractLedgerTxn& ltx, AccountID const& feeSource);
+    int64_t refundSorobanFee(AbstractLedgerTxn& ltx,
+                             AccountID const& feeSource);
     void updateSorobanMetrics(Application& app);
 #ifdef BUILD_TESTS
   public:
@@ -282,8 +283,9 @@ class TransactionFrame : public TransactionFrameBase
                           TransactionMetaFrame& meta) override;
 
     // TransactionFrame specific function that allows fee bumps to forward a
-    // different account for the refund.
-    void processPostApply(Application& app, AbstractLedgerTxn& ltx,
+    // different account for the refund. It also returns the refund so
+    // FeeBumpTransactionFrame can adjust feeCharged.
+    int64_t processRefund(Application& app, AbstractLedgerTxn& ltx,
                           TransactionMetaFrame& meta,
                           AccountID const& feeSource);