Merge bitcoin/bitcoin#23173: Add ChainstateManager::ProcessTransaction

0fdb619aaf [validation] Always call mempool.check() after processing a new transaction (John Newbery)
2c64270bbe [refactor] Don't call AcceptToMemoryPool() from outside validation.cpp (John Newbery)
92a3aeecf6 [validation] Add CChainState::ProcessTransaction() (John Newbery)
36167faea9 [logging/documentation] Remove reference to AcceptToMemoryPool from error string (John Newbery)
4c24142b1e [validation] Remove comment about AcceptToMemoryPool() (John Newbery)
5759fd12b8 [test] Don't set bypass_limits to true in txvalidation_tests.cpp (John Newbery)
497c9e2964 [test] Don't set bypass_limits to true in txvalidationcache_tests.cpp (John Newbery)

Pull request description:

  Similarly to how #18698 added `ProcessNewBlock()` and `ProcessNewBlockHeaders()` methods to the `ChainstateManager` class, this PR adds a new `ProcessTransaction()` method. Code outside validation no longer calls `AcceptToMemoryPool()` directly, but calls through the higher-level `ProcessTransaction()` method. Advantages:

  - The interface is simplified. Calling code no longer needs to know about the active chainstate or mempool object, since `AcceptToMemoryPool()` can only ever be called for the active chainstate, and that chainstate knows which mempool it's using. We can also remove the `bypass_limits` argument, since that can only be used internally in validation.
  - responsibility for calling `CTxMemPool::check()` is removed from the callers, and run automatically by `ChainstateManager` every time `ProcessTransaction()` is called.

ACKs for top commit:
  lsilva01:
    tACK 0fdb619 on Ubuntu 20.04
  theStack:
    Code-review ACK 0fdb619aaf
  ryanofsky:
    Code review ACK 0fdb619aaf. Only changes since last review: splitting & joining commits, adding more explanations to commit messages, tweaking MEMPOOL_ERROR string, fixing up argument name comments.

Tree-SHA512: 0b395c2e3ef242f0d41d47174b1646b0a73aeece38f1fe29349837e6fb832f4bf8d57e1a1eaed82a97c635cfd59015a7e07f824e0d7c00b2bee4144e80608172

src/validation.h

@@ -208,9 +208,16 @@ struct PackageMempoolAcceptResult
 };
 
 /**
- * (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.
+ * Try to add a transaction to the mempool. This is an internal function and is
+ * exposed only for testing. Client code should use ChainstateManager::ProcessTransaction()
+ *
+ * @param[in]  active_chainstate  Reference to the active chainstate.
+ * @param[in]  pool               Reference to the node's mempool.
+ * @param[in]  tx                 The transaction to submit for mempool acceptance.
+ * @param[in]  bypass_limits      When true, don't enforce mempool fee and capacity limits.
+ * @param[in]  test_accept        When true, run validation checks but don't submit to mempool.
+ *
+ * @returns a MempoolAcceptResult indicating whether the transaction was accepted/rejected with reason.
  */
 MempoolAcceptResult AcceptToMemoryPool(CChainState& active_chainstate, CTxMemPool& pool, const CTransactionRef& tx,
                                        bool bypass_limits, bool test_accept=false) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
@@ -996,6 +1003,15 @@ public:
      */
     bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, BlockValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex = nullptr) LOCKS_EXCLUDED(cs_main);
 
+    /**
+     * Try to add a transaction to the memory pool.
+     *
+     * @param[in]  tx              The transaction to submit for mempool acceptance.
+     * @param[in]  test_accept     When true, run validation checks but don't submit to mempool.
+     */
+    [[nodiscard]] MempoolAcceptResult ProcessTransaction(const CTransactionRef& tx, bool test_accept=false)
+        EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
     //! Load the block tree and coins database from disk, initializing state if we're running with -reindex
     bool LoadBlockIndex() EXCLUSIVE_LOCKS_REQUIRED(cs_main);