Make getting parents/children a function of the mempool, not a mempool entry

diff --git a/src/rpc/mempool.cpp b/src/rpc/mempool.cpp
index 7a016335..f07f06f8 100644
--- a/src/rpc/mempool.cpp
+++ b/src/rpc/mempool.cpp
@@ -327,7 +327,7 @@ static void entryToJSON(const CTxMemPool& pool, UniValue& info, const CTxMemPool
     info.pushKV("depends", std::move(depends));
 
     UniValue spent(UniValue::VARR);
-    for (const CTxMemPoolEntry& child : e.GetMemPoolChildrenConst()) {
+    for (const CTxMemPoolEntry& child : pool.GetChildren(e)) {
         spent.push_back(child.GetTx().GetHash().ToString());
     }
 
diff --git a/src/test/fuzz/package_eval.cpp b/src/test/fuzz/package_eval.cpp
index 50f4c416..3f1eeeb3 100644
--- a/src/test/fuzz/package_eval.cpp
+++ b/src/test/fuzz/package_eval.cpp
@@ -174,7 +174,7 @@ std::optional<COutPoint> GetChildEvictingPrevout(const CTxMemPool& tx_pool)
         const auto& entry = *Assert(tx_pool.GetEntry(tx_info.tx->GetHash()));
         std::vector<uint32_t> dust_indexes{GetDust(*tx_info.tx, tx_pool.m_opts.dust_relay_feerate)};
         if (!dust_indexes.empty()) {
-            const auto& children = entry.GetMemPoolChildrenConst();
+            const auto& children = tx_pool.GetChildren(entry);
             if (!children.empty()) {
                 Assert(children.size() == 1);
                 // Find an input that doesn't spend from parent's txid
diff --git a/src/test/util/txmempool.cpp b/src/test/util/txmempool.cpp
index ffa21a41..e85c496d 100644
--- a/src/test/util/txmempool.cpp
+++ b/src/test/util/txmempool.cpp
@@ -157,7 +157,7 @@ void CheckMempoolEphemeralInvariants(const CTxMemPool& tx_pool)
         Assert(entry.GetFee() == 0 && entry.GetModifiedFee() == 0);
 
         // Transaction has single dust; make sure it's swept or will not be mined
-        const auto& children = entry.GetMemPoolChildrenConst();
+        const auto& children = tx_pool.GetChildren(entry);
 
         // Multiple children should never happen as non-dust-spending child
         // can get mined as package
@@ -199,12 +199,12 @@ void CheckMempoolTRUCInvariants(const CTxMemPool& tx_pool)
             if (anc_count > 1) {
                 Assert(entry.GetTxSize() <= TRUC_CHILD_MAX_VSIZE);
                 // All TRUC transactions must only have TRUC unconfirmed parents.
-                const auto& parents = entry.GetMemPoolParentsConst();
+                const auto& parents = tx_pool.GetParents(entry);
                 Assert(parents.begin()->get().GetSharedTx()->version == TRUC_VERSION);
             }
         } else if (anc_count > 1) {
             // All non-TRUC transactions must only have non-TRUC unconfirmed parents.
-            for (const auto& parent : entry.GetMemPoolParentsConst()) {
+            for (const auto& parent : tx_pool.GetParents(entry)) {
                 Assert(parent.get().GetSharedTx()->version != TRUC_VERSION);
             }
         }
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 8ba41e94..fb835b1f 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -54,6 +54,38 @@ bool TestLockPointValidity(CChain& active_chain, const LockPoints& lp)
     return true;
 }
 
+std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> CTxMemPool::GetChildren(const CTxMemPoolEntry& entry) const
+{
+    LOCK(cs);
+    std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> ret;
+    setEntries children;
+    auto iter = mapNextTx.lower_bound(COutPoint(entry.GetTx().GetHash(), 0));
+    for (; iter != mapNextTx.end() && iter->first->hash == entry.GetTx().GetHash(); ++iter) {
+        children.insert(iter->second);
+    }
+    for (const auto& child : children) {
+        ret.emplace_back(*child);
+    }
+    return ret;
+}
+
+std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> CTxMemPool::GetParents(const CTxMemPoolEntry& entry) const
+{
+    LOCK(cs);
+    std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> ret;
+    std::set<Txid> inputs;
+    for (const auto& txin : entry.GetTx().vin) {
+        inputs.insert(txin.prevout.hash);
+    }
+    for (const auto& hash : inputs) {
+        std::optional<txiter> piter = GetIter(hash);
+        if (piter) {
+            ret.emplace_back(**piter);
+        }
+    }
+    return ret;
+}
+
 void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<Txid>& vHashesToUpdate)
 {
     AssertLockHeld(cs);
diff --git a/src/txmempool.h b/src/txmempool.h
index 3c488215..addf3e13 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -289,6 +289,8 @@ public:
     int64_t GetDescendantCount(txiter it) const { LOCK(cs); return m_txgraph->GetDescendants(*it, TxGraph::Level::MAIN).size(); }
     int64_t GetDescendantCount(const CTxMemPoolEntry &e) const { LOCK(cs); return m_txgraph->GetDescendants(e, TxGraph::Level::MAIN).size(); }
     int64_t GetAncestorCount(const CTxMemPoolEntry &e) const { LOCK(cs); return m_txgraph->GetAncestors(e, TxGraph::Level::MAIN).size(); }
+    std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> GetChildren(const CTxMemPoolEntry &entry) const;
+    std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> GetParents(const CTxMemPoolEntry &entry) const;
 
 private:
     typedef std::map<txiter, setEntries, CompareIteratorByHash> cacheMap;