[validation] package validation for test accepts

Only allow test accepts for now. Use the CoinsViewTemporary to keep
track of coins created by each transaction so that subsequent
transactions can spend them. Uncache all coins since we only
ever do test accepts (Note this is different from ATMP which doesn't
uncache for valid test_accepts) to minimize impact on the coins cache.

Require that the input txns have no conflicts and be ordered
topologically. This commit isn't able to detect unsorted packages.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/validation.h b/src/validation.h
index 231f55d827..3f09e59dab 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -18,6 +18,7 @@
 #include <fs.h>
 #include <node/utxo_snapshot.h>
 #include <policy/feerate.h>
+#include <policy/packages.h>
 #include <protocol.h> // For CMessageHeader::MessageStartChars
 #include <script/script_error.h>
 #include <sync.h>
@@ -205,6 +206,28 @@ private:
 };
 
 /**
+* Validation result for package mempool acceptance.
+*/
+struct PackageMempoolAcceptResult
+{
+    const PackageValidationState m_state;
+    /**
+    * Map from wtxid to finished MempoolAcceptResults. The client is responsible
+    * for keeping track of the transaction objects themselves. If a result is not
+    * present, it means validation was unfinished for that transaction.
+    */
+    std::map<const uint256, const MempoolAcceptResult> m_tx_results;
+
+    explicit PackageMempoolAcceptResult(PackageValidationState state,
+                                        std::map<const uint256, const MempoolAcceptResult>&& results)
+        : m_state{state}, m_tx_results(std::move(results)) {}
+
+    /** Constructor to create a PackageMempoolAcceptResult from a single MempoolAcceptResult */
+    explicit PackageMempoolAcceptResult(const uint256& wtxid, const MempoolAcceptResult& result)
+        : m_tx_results{ {wtxid, result} } {}
+};
+
+/**
  * (Try to) add a transaction to the memory pool.
  * @param[in]  bypass_limits   When true, don't enforce mempool fee limits.
  * @param[in]  test_accept     When true, run validation checks but don't submit to mempool.
@@ -212,6 +235,18 @@ private:
 MempoolAcceptResult AcceptToMemoryPool(CChainState& active_chainstate, CTxMemPool& pool, const CTransactionRef& tx,
                                        bool bypass_limits, bool test_accept=false) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
+/**
+* Atomically test acceptance of a package. If the package only contains one tx, package rules still apply.
+* @param[in]    txns                Group of transactions which may be independent or contain
+*                                   parent-child dependencies. The transactions must not conflict, i.e.
+*                                   must not spend the same inputs, even if it would be a valid BIP125
+*                                   replace-by-fee. Parents must appear before children.
+* @returns a PackageMempoolAcceptResult which includes a MempoolAcceptResult for each transaction.
+* If a transaction fails, validation will exit early and some results may be missing.
+*/
+PackageMempoolAcceptResult ProcessNewPackage(CChainState& active_chainstate, CTxMemPool& pool,
+                                                   const Package& txns, bool test_accept)
+                                                   EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** Apply the effects of this transaction on the UTXO set represented by view */
 void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight);