Improve exception handling:

* Self-document the code by renaming Throw to Rethrow.
* Write a message to the debug log when we throw or
  rethrow an exception.

src/ripple/app/ledger/Ledger.cpp

@@ -603,7 +603,7 @@ Ledger::setup (Config const& config)
     }
     catch (std::exception const&)
     {
-        Throw();
+        Rethrow();
     }
 
     try
@@ -616,7 +616,7 @@ Ledger::setup (Config const& config)
     }
     catch (std::exception const&)
     {
-        Throw();
+        Rethrow();
     }
 
     return ret;
@@ -639,7 +639,6 @@ Ledger::peek (Keylet const& k) const
 }
 
 //------------------------------------------------------------------------------
-
 bool Ledger::walkLedger (beast::Journal j) const
 {
     std::vector <SHAMapMissingNode> missingNodes1;

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

@@ -487,7 +487,7 @@ void LedgerConsensusImp::mapComplete (
         leaveConsensus();
         JLOG (j_.error()) <<
             "Missing node processing complete map " << mn;
-        Throw();
+        Rethrow();
     }
 }
 
@@ -693,7 +693,7 @@ void LedgerConsensusImp::timerEntry ()
         leaveConsensus ();
         JLOG (j_.error()) <<
            "Missing node during consensus process " << mn;
-        Throw();
+        Rethrow();
     }
 }
 

src/ripple/app/paths/RippleCalc.cpp

@@ -143,7 +143,7 @@ RippleCalc::Output RippleCalc::rippleCalculate (
         {
             JLOG (j.trace()) << "Exception from flow" << e.what ();
             if (!useFlowV1Output)
-                Throw();
+                Rethrow();
         }
 
         if (j.debug())
@@ -151,12 +151,12 @@ RippleCalc::Output RippleCalc::rippleCalculate (
             auto logResult = [&] (std::string const& algoName, Output const& result)
             {
                 j.debug() << "RippleCalc Result> " <<
-                " actualIn: " << result.actualAmountIn <<
-                ", actualOut: " << result.actualAmountOut <<
-                ", result: " << result.result () <<
-                ", dstAmtReq: " << saDstAmountReq <<
-                ", sendMax: " << saMaxAmountReq <<
-                ", algo: " << algoName;
+                    " actualIn: " << result.actualAmountIn <<
+                    ", actualOut: " << result.actualAmountOut <<
+                    ", result: " << result.result () <<
+                    ", dstAmtReq: " << saDstAmountReq <<
+                    ", sendMax: " << saMaxAmountReq <<
+                    ", algo: " << algoName;
             };
             if (callFlowV1)
             {

src/ripple/basics/contract.h

@@ -33,11 +33,22 @@ namespace ripple {
     preconditions, postconditions, and invariants.
 */
 
+/** Generates and logs a call stack */
+void
+LogThrow (std::string const& title);
+
+/** Rethrow the exception currently being handled.
+
+    When called from within a catch block, it will pass
+    control to the next matching exception handler, if any.
+    Otherwise, std::terminate will be called.
+*/
 [[noreturn]]
 inline
 void
-Throw ()
+Rethrow ()
 {
+    LogThrow ("Re-throwing exception");
     throw;
 }
 
@@ -49,7 +60,10 @@ Throw (Args&&... args)
 {
     static_assert (std::is_convertible<E*, std::exception*>::value,
         "Exception must derive from std::exception.");
-    throw E(std::forward<Args>(args)...);
+
+    E e(std::forward<Args>(args)...);
+    LogThrow (std::string("Throwing exception: ") + e.what());
+    throw e;
 }
 
 /** Called when faulty logic causes a broken invariant. */

src/ripple/basics/impl/contract.cpp

@@ -19,6 +19,7 @@
 
 #include <BeastConfig.h>
 #include <ripple/basics/contract.h>
+#include <ripple/basics/Log.h>
 #include <cstdlib>
 #include <exception>
 #include <iostream>
@@ -39,10 +40,17 @@ accessViolation() noexcept
 
 } // detail
 
+void
+LogThrow (std::string const& title)
+{
+    JLOG(debugLog()) << title;
+}
+
 [[noreturn]]
 void
 LogicError (std::string const& s) noexcept
 {
+    JLOG(debugLog()) << s;
     std::cerr << "Logic error: " << s << std::endl;
     detail::accessViolation();
 }

src/ripple/basics/tests/contract.test.cpp

@@ -39,7 +39,7 @@ public:
 
             try
             {
-                Throw();
+                Rethrow();
             }
             catch (std::runtime_error const& e)
             {

src/ripple/nodestore/tests/Timing.test.cpp

@@ -317,7 +317,7 @@ public:
         #if NODESTORE_TIMING_DO_VERIFY
             backend->verify();
         #endif
-            Throw();
+            Rethrow();
         }
         backend->close();
     }
@@ -378,7 +378,7 @@ public:
         #if NODESTORE_TIMING_DO_VERIFY
             backend->verify();
         #endif
-            Throw();
+            Rethrow();
         }
         backend->close();
     }
@@ -441,7 +441,7 @@ public:
         #if NODESTORE_TIMING_DO_VERIFY
             backend->verify();
         #endif
-            Throw();
+            Rethrow();
         }
         backend->close();
     }
@@ -519,7 +519,7 @@ public:
         #if NODESTORE_TIMING_DO_VERIFY
             backend->verify();
         #endif
-            Throw();
+            Rethrow();
         }
         backend->close();
     }
@@ -631,7 +631,7 @@ public:
         #if NODESTORE_TIMING_DO_VERIFY
             backend->verify();
         #endif
-            Throw();
+            Rethrow();
         }
         backend->close();
     }

src/ripple/server/impl/Port.cpp

@@ -154,7 +154,7 @@ parse_Port (ParsedPort& port, Section const& section, std::ostream& log)
             {
                 log << "Invalid value '" << result.first <<
                     "' for key 'ip' in [" << section.name() << "]\n";
-                Throw();
+                Rethrow();
             }
         }
     }
@@ -177,7 +177,7 @@ parse_Port (ParsedPort& port, Section const& section, std::ostream& log)
                 log <<
                     "Invalid value '" << result.first << "' for key " <<
                     "'port' in [" << section.name() << "]\n";
-                Throw();
+                Rethrow();
             }
         }
     }
@@ -207,7 +207,7 @@ parse_Port (ParsedPort& port, Section const& section, std::ostream& log)
                 log <<
                     "Invalid value '" << lim << "' for key " <<
                     "'limit' in [" << section.name() << "]\n";
-                Throw();
+                Rethrow();
             }
         }
     }

src/ripple/test/jtx/impl/Env.cpp

@@ -450,7 +450,7 @@ Env::autofill (JTx& jt)
         test.log <<
             "parse failed:\n" <<
             pretty(jv);
-        Throw();
+        Rethrow();
     }
 }
 
@@ -469,7 +469,7 @@ Env::st (JTx const& jt)
         test.log <<
             "Exception: parse_error\n" <<
             pretty(jt.jv);
-        Throw();
+        Rethrow();
     }
 
     try

src/ripple/test/jtx/impl/multisign.cpp

@@ -89,7 +89,7 @@ msig::operator()(Env& env, JTx& jt) const
         catch(parse_error const&)
         {
             env.test.log << pretty(jt.jv);
-            Throw();
+            Rethrow();
         }
         auto& js = jt[sfSigners.getJsonName()];
         js.resize(mySigners.size());