[mempool] check ancestor/descendant limits for packages

When calculating ancestor/descendant counts for transactions in the
package, as a heuristic, count every transaction in the package as an
ancestor and descendant of every other transaction in the package.

This may overestimate, but will not underestimate, the
ancestor/descendant counts. This shortcut still produces an accurate
count for packages of 1 parent + 1 child.

1 files changed, 23 insertions, 0 deletions

diff --git a/src/txmempool.h b/src/txmempool.h
index 71345ffb5d..0a84a6e6b1 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -18,6 +18,7 @@
 #include <coins.h>
 #include <indirectmap.h>
 #include <policy/feerate.h>
+#include <policy/packages.h>
 #include <primitives/transaction.h>
 #include <random.h>
 #include <sync.h>
@@ -700,6 +701,28 @@ public:
      */
     bool CalculateMemPoolAncestors(const CTxMemPoolEntry& entry, setEntries& setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string& errString, bool fSearchForParents = true) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
+    /** Calculate all in-mempool ancestors of a set of transactions not already in the mempool and
+     * check ancestor and descendant limits. Heuristics are used to estimate the ancestor and
+     * descendant count of all entries if the package were to be added to the mempool.  The limits
+     * are applied to the union of all package transactions. For example, if the package has 3
+     * transactions and limitAncestorCount = 25, the union of all 3 sets of ancestors (including the
+     * transactions themselves) must be <= 22.
+     * @param[in]       package                 Transaction package being evaluated for acceptance
+     *                                          to mempool. The transactions need not be direct
+     *                                          ancestors/descendants of each other.
+     * @param[in]       limitAncestorCount      Max number of txns including ancestors.
+     * @param[in]       limitAncestorSize       Max virtual size including ancestors.
+     * @param[in]       limitDescendantCount    Max number of txns including descendants.
+     * @param[in]       limitDescendantSize     Max virtual size including descendants.
+     * @param[out]      errString               Populated with error reason if a limit is hit.
+     */
+    bool CheckPackageLimits(const Package& package,
+                            uint64_t limitAncestorCount,
+                            uint64_t limitAncestorSize,
+                            uint64_t limitDescendantCount,
+                            uint64_t limitDescendantSize,
+                            std::string &errString) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+
     /** Populate setDescendants with all in-mempool descendants of hash.
      *  Assumes that setDescendants includes all in-mempool descendants of anything
      *  already in it.  */