1 files changed, 103 insertions, 0 deletions
diff --git a/src/mongo/db/s/recover_transaction_decision_from_local_participant.cpp b/src/mongo/db/s/recover_transaction_decision_from_local_participant.cpp
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index 00000000000..35f90c58c51
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+++ b/src/mongo/db/s/recover_transaction_decision_from_local_participant.cpp
@@ -0,0 +1,103 @@
+
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/s/recover_transaction_decision_from_local_participant.h"
+
+#include "mongo/db/repl/repl_client_info.h"
+#include "mongo/db/session_catalog_mongod.h"
+#include "mongo/db/transaction_participant.h"
+
+namespace mongo {
+
+void recoverDecisionFromLocalParticipantOrAbortLocalParticipant(OperationContext* opCtx) {
+    ON_BLOCK_EXIT([opCtx] {
+        // Ensure waiting for the user-supplied writeConcern of the decision.
+        repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
+    });
+
+    MongoDOperationContextSession checkOutSession(opCtx);
+
+    auto txnParticipant = TransactionParticipant::get(opCtx);
+
+    try {
+        if (txnParticipant->getActiveTxnNumber() < *opCtx->getTxnNumber()) {
+            // TODO (SERVER-38133): Remove the if-block and just execute the else-block.
+            // Until SERVER-38133, calling beginOrContinue with startTransaction=boost::none with a
+            // higher txnNumber than the local participant's txnNumber will return NoSuchTransaction
+            // *without* marking the transaction at the higher txnNumber as aborted. As a stop-gap,
+            // if the request's txnNumber is higher than the local participant's txnNumber,
+            // explicitly start a transaction at the higher txnNumber here by calling
+            // beginOrContinue with startTransaction=true; the higher transaction will be aborted
+            // below.
+            // After SERVER-38133, the new transaction will be started *and* aborted by calling
+            // beginOrContinue with startTransaction=boost::none.
+            txnParticipant->beginOrContinue(
+                *opCtx->getTxnNumber(), false /* autocommit */, true /* startTransaction */);
+        } else {
+            // If the local participant's transaction number is *equal* to this request's and
+            // corresponds to a *retryable write*, throws NoSuchTransaction, else is a no-op.
+            // If the local participant's transaction number is *higher* than this request's, throws
+            // TransactionTooOld.
+            txnParticipant->beginOrContinue(
+                *opCtx->getTxnNumber(), false /* autocommit */, boost::none /* startTransaction */);
+        }
+
+        // The local participant's txnNumber matched the request's txnNumber, and the txnNumber
+        // corresponds to a transaction (not a retryable write).
+
+        if (txnParticipant->transactionIsCommitted()) {
+            return;
+        }
+
+        txnParticipant->unstashTransactionResources(opCtx, "coordinateCommitTransaction");
+    } catch (const DBException& e) {
+        // Convert a PreparedTransactionInProgress error to an anonymous error code.
+        uassert(51021,
+                "coordinateCommitTransaction command found local participant is prepared but no "
+                "active coordinator exists",
+                e.code() != ErrorCodes::PreparedTransactionInProgress);
+        throw;
+    }
+
+    // Abort the transaction. Since there was no active coordinator for this transaction on this
+    // node, either the coordinator has already timed out waiting for the participant list and
+    // the local participant's transaction will time out and abort anyway, or another node in
+    // this replica set has stepped up and received all the transaction statements and may
+    // commit. It's safe to abort the transaction even if the latter is the case, because this
+    // command will fail waiting for majority writeConcern.
+    txnParticipant->abortActiveTransaction(opCtx);
+    uassert(ErrorCodes::NoSuchTransaction,
+            "Transaction was aborted",
+            txnParticipant->transactionIsCommitted());
+}
+
+}  // namespace mongo