refactor: Pathfinding 2.0 using Dijkstra's Algorithm

.cspell.config.yaml

@@ -36,7 +36,9 @@ overrides:
       - /'[^']*'/g # single-quoted strings
       - /`[^`]*`/g # backtick strings
 suggestWords:
-  - unsynched->unsynced
+  - xprl->xrpl
+  - xprld->xrpld # cspell: disable-line not sure what this problem is....
+  - unsynched->unsynced # cspell: disable-line not sure what this problem is....
   - synched->synced
   - synch->sync
 words:
@@ -58,7 +60,6 @@ words:
   - autobridging
   - bimap
   - bindir
-  - blindings
   - bookdir
   - Bougalis
   - Britto
@@ -85,7 +86,6 @@ words:
   - coro
   - coros
   - cowid
-  - cpack
   - cryptocondition
   - cryptoconditional
   - cryptoconditions
@@ -96,6 +96,7 @@ words:
   - daria
   - dcmake
   - dearmor
+  - dedupe
   - decryptor
   - dedented
   - deleteme
@@ -108,11 +109,9 @@ words:
   - distro
   - doxyfile
   - dxrpl
-  - elgamal
   - enabled
   - enablerepo
   - endmacro
-  - envrc
   - exceptioned
   - EXPECT_STREQ
   - Falco
@@ -122,7 +121,6 @@ words:
   - fmtdur
   - fsanitize
   - funclets
-  - Gamal
   - gcov
   - gcovr
   - ghead
@@ -161,18 +159,23 @@ words:
   - libpb
   - libxrpl
   - llection
+  - localised
   - LOCALGOOD
   - logwstream
   - lseq
   - lsmf
   - ltype
+  - materialisations
+  - materialises
+  - materialised
   - mathbunnyru
   - mcmodel
   - MEMORYSTATUSEX
   - MPTAMM
   - MPTDEX
   - Merkle
   - Metafuncton
+  - minimisation
   - misprediction
   - missingok
   - mptbalance
@@ -192,6 +195,7 @@ words:
   - multisign
   - multisigned
   - Nakamoto
+  - neighbours
   - nftid
   - nftoffer
   - nftoken
@@ -220,7 +224,6 @@ words:
   - partitioner
   - paychan
   - paychans
-  - Pedersen
   - permdex
   - perminute
   - permissioned
@@ -239,15 +242,9 @@ words:
   - pyenv
   - pyparsing
   - qalloc
-  - qbsprofile
   - queuable
   - Raphson
-  - rcflags
   - replayer
-  - rerandomize
-  - rerandomization
-  - rerandomized
-  - rerandomizes
   - rerere
   - retriable
   - RIPD
@@ -267,10 +264,10 @@ words:
   - sahyadri
   - Satoshi
   - scons
-  - Schnorr
   - secp
   - sendq
   - seqit
+  - Serialises
   - sf
   - SFIELD
   - sfields
@@ -300,9 +297,10 @@ words:
   - stvar
   - stvector
   - stxchainattestations
-  - summands
   - superpeer
   - superpeers
+  - specialisation
+  - summands
   - takergets
   - takerpays
   - ters
@@ -319,7 +317,6 @@ words:
   - txs
   - ubsan
   - UBSAN
-  - ufdio
   - umant
   - unacquired
   - unambiguity
@@ -331,6 +328,7 @@ words:
   - unflatten
   - unfund
   - unimpair
+  - unranked
   - unroutable
   - unscalable
   - unserviced

cfg/xrpld-example.cfg

@@ -773,33 +773,10 @@
 #
 #
 # [path_search]
-#   When searching for paths, the default search aggressiveness. This can take
-#   exponentially more resources as the size is increased.
+#   Set to 1 to enable path finding, or 0 to disable it.
+#   Path finding is disabled by default; set to 1 to enable it.
 #
-#   The recommended value to support advanced pathfinding is: 7
-#
-#   The default is: 2
-#
-# [path_search_fast]
-# [path_search_max]
-#   When searching for paths, the minimum and maximum search aggressiveness.
-#
-#   If you do not need pathfinding, you can set path_search_max to zero to
-#   disable it and avoid some expensive bookkeeping.
-#
-#   To support advanced pathfinding the recommended value for
-#   'path_search_fast' is 2, and for 'path_search_max' is 10.
-#
-#   The default for 'path_search_fast' is 2. The default for 'path_search_max' is 3.
-#
-# [path_search_old]
-#
-#   For clients that use the legacy path finding interfaces, the search
-#   aggressiveness to use.
-#
-#   The recommended value to support advanced pathfinding is: 7.
-#
-#   The default is: 2
+#   The default is: 0
 #
 #
 #

include/xrpl/ledger/OrderBookDB.h

@@ -83,6 +83,18 @@ class OrderBookDB
      */
     virtual bool
     isBookToXRP(Asset const& asset, std::optional<Domain> const& domain = std::nullopt) = 0;
+
+    /** Get all assets that appear as takerPays in any known order book.
+
+        Used by pathfinding to seed vertex discovery so that
+        non-XRP-rooted assets are always included even when they have no
+        direct XRP book.
+
+        @param domain Optional domain restriction
+        @return Vector of all known takerPays assets
+    */
+    virtual std::vector<Asset>
+    getAllTakerPaysAssets(std::optional<Domain> const& domain = std::nullopt) = 0;
 };
 
 /**

include/xrpl/tx/paths/detail/Steps.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <xrpl/basics/UnorderedContainers.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/beast/utility/Zero.h>
@@ -19,6 +20,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
+#include <mutex>
 #include <optional>
 #include <ostream>
 #include <stdexcept>
@@ -32,6 +34,51 @@ class ReadView;
 class ApplyView;
 class AMMContext;
 
+// Process-wide: AMMs that threw FlowException (broken pool invariant) during
+// flow.  One exception excludes only that AMM; CLOB offers on the same book
+// remain usable.  Cleared when the ledger sequence advances.
+struct FailedAMMBlacklist
+{
+    std::mutex mutex;
+    std::uint32_t ledgerSeq{0};
+    hash_set<Book> amms;
+};
+
+inline FailedAMMBlacklist&
+failedAMMBlacklist()
+{
+    static FailedAMMBlacklist store;
+    return store;
+}
+
+inline void
+noteFailedAMM(Book const& ammBook, std::uint32_t ledgerSeq)
+{
+    auto& store = failedAMMBlacklist();
+    std::lock_guard const lock(store.mutex);
+    if (store.ledgerSeq != ledgerSeq)
+    {
+        store.amms.clear();
+        store.ledgerSeq = ledgerSeq;
+    }
+    store.amms.insert(ammBook);
+    store.amms.insert(reversed(ammBook));
+}
+
+[[nodiscard]] inline bool
+isFailedAMM(Book const& ammBook, std::uint32_t ledgerSeq)
+{
+    auto& store = failedAMMBlacklist();
+    std::lock_guard const lock(store.mutex);
+    if (store.ledgerSeq != ledgerSeq)
+    {
+        store.amms.clear();
+        store.ledgerSeq = ledgerSeq;
+        return false;
+    }
+    return store.amms.contains(ammBook) || store.amms.contains(reversed(ammBook));
+}
+
 enum class DebtDirection { Issues, Redeems };
 enum class QualityDirection { In, Out };
 enum class StrandDirection { Forward, Reverse };
@@ -504,11 +551,19 @@ class FlowException : public std::runtime_error
 {
 public:
     TER ter;
+    // When set, the AMM pool (book pair) that failed. One exception excludes
+    // only that AMM via noteFailedAMM / isFailedAMM.
+    std::optional<Book> ammBook;
 
     FlowException(TER t, std::string const& msg) : std::runtime_error(msg), ter(t)
     {
     }
 
+    FlowException(TER t, std::string const& msg, Book const& amm)
+        : std::runtime_error(msg), ter(t), ammBook(amm)
+    {
+    }
+
     explicit FlowException(TER t) : std::runtime_error(transHuman(t)), ter(t)
     {
     }

src/libxrpl/tx/paths/BookStep.cpp

@@ -869,7 +869,11 @@ BookStep<TIn, TOut, TDerived>::consumeOffer(
         // when the amendment isn't active.
         if (sb.rules().enabled(fixAMMOverflowOffer))
         {
-            Throw<FlowException>(tecINVARIANT_FAILED, "AMM pool product invariant failed.");
+            // One exception excludes only this AMM (not the CLOB on this book).
+            // StrandFlow swallows FlowException, so pathfinding cannot catch it;
+            // note here so later getAMMOffer() skips this pool.
+            noteFailedAMM(book_, sb.seq());
+            Throw<FlowException>(tecINVARIANT_FAILED, "AMM pool product invariant failed.", book_);
         }
     }
 
@@ -911,7 +915,9 @@ BookStep<TIn, TOut, TDerived>::getAMMOffer(
     // AMM for domain books).
     if (book_.domain && view.rules().enabled(fixCleanup3_3_0))
         return std::nullopt;
-    if (ammLiquidity_)
+    // Skip AMMs that already failed an invariant this ledger.  CLOB offers
+    // on the same book are unaffected.
+    if (ammLiquidity_ && !isFailedAMM(book_, view.seq()))
         return ammLiquidity_->getOffer(view, clobQuality);
     return std::nullopt;
 }

src/libxrpl/tx/transactors/payment/Payment.cpp

@@ -439,17 +439,38 @@ Payment::preclaim(PreclaimContext const& ctx)
     {
         STPathSet const& paths = ctx.tx.getFieldPathSet(sfPaths);
 
-        if (paths.size() > kMaxPathSize || std::ranges::any_of(paths, [](STPath const& path) {
-                return path.size() > kMaxPathLength;
-            }))
+        // Validate path count and length with detailed logging
+        if (paths.size() > kMaxPathSize)
         {
+            JLOG(ctx.j.error()) << "Payment rejected: Too many paths (" << paths.size() << " > "
+                                << kMaxPathSize << ")";
             // Open view: the soft tel (unchanged). Inner batch txns are claimed
             // on a closed view, where a tel is invalid, so use the tef.
             if (ctx.view.open())
                 return telBAD_PATH_COUNT;
             if (ctx.parentBatchId && ctx.view.rules().enabled(featureBatchV1_1))
                 return tefBAD_PATH_COUNT;
         }
+
+        // Check each path for length violations and log details
+        for (std::size_t i = 0; i < paths.size(); ++i)
+        {
+            if (paths[i].size() > kMaxPathLength)
+            {
+                JLOG(ctx.j.error()) << "Payment rejected: Path " << i << " exceeds maximum length ("
+                                    << paths[i].size() << " > " << kMaxPathLength << ")";
+                // Log the path elements for debugging
+                JLOG(ctx.j.debug()) << "Path " << i << " has " << paths[i].size()
+                                    << " elements (max allowed: " << kMaxPathLength << ")";
+
+                // Open view: the soft tel (unchanged). Inner batch txns are claimed
+                // on a closed view, where a tel is invalid, so use the tef.
+                if (ctx.view.open())
+                    return telBAD_PATH_COUNT;
+                if (ctx.parentBatchId && ctx.view.rules().enabled(featureBatchV1_1))
+                    return tefBAD_PATH_COUNT;
+            }
+        }
     }
 
     if (auto const err = credentials::valid(ctx.tx, ctx.view, ctx.tx[sfAccount], ctx.j);

src/test/app/Offer_test.cpp

@@ -6,6 +6,7 @@
 #include <test/jtx/acctdelete.h>
 #include <test/jtx/amount.h>
 #include <test/jtx/balance.h>
+#include <test/jtx/envconfig.h>
 #include <test/jtx/fee.h>
 #include <test/jtx/flags.h>
 #include <test/jtx/jtx_json.h>
@@ -4330,7 +4331,13 @@ class OfferBaseUtil_test : public beast::unit_test::Suite
         testcase("RippleConnect Smoketest payment flow");
         using namespace jtx;
 
-        Env env{*this, features};
+        Env env(
+            *this,
+            envconfig([](std::unique_ptr<Config> cfg) {
+                cfg->pathSearch = true;
+                return cfg;
+            }),
+            features);
 
         // This test mimics a payment flow. The players:
         //   A USD gateway with hot and cold wallets

src/test/app/PathMPT_test.cpp

@@ -87,9 +87,7 @@ class PathMPT_test : public beast::unit_test::Suite
         // with the search parameters that the tests were written for.
         using namespace jtx;
         return Env(*this, envconfig([](std::unique_ptr<Config> cfg) {
-            cfg->pathSearchOld = 7;
-            cfg->pathSearch = 7;
-            cfg->pathSearchMax = 10;
+            cfg->pathSearch = true;
             return cfg;
         }));
     }