commit af24bc3ae505391add182bfc95449d7f9f1ed6ff
Author: A. Jesse Jiryu Davis <jesse@mongodb.com>
Date:   Sat Feb 16 17:24:58 2019 -0500

    fix side transaction

diff --git a/src/mongo/db/transaction_participant.cpp b/src/mongo/db/transaction_participant.cpp
index b484d0fc07..8421a68362 100644
--- a/src/mongo/db/transaction_participant.cpp
+++ b/src/mongo/db/transaction_participant.cpp
@@ -685,6 +685,11 @@ TransactionParticipant::SideTransactionBlock::SideTransactionBlock(OperationCont
         _txnResources = TransactionParticipant::TxnResources(
             _opCtx, TxnResources::StashStyle::kSideTransaction);
     }
+
+    auto txnParticipant = TransactionParticipant::get(opCtx);
+    if (txnParticipant) {
+        txnParticipant->pushSideTransactionBlock();
+    }
 }
 
 TransactionParticipant::SideTransactionBlock::~SideTransactionBlock() {
@@ -692,7 +697,13 @@ TransactionParticipant::SideTransactionBlock::~SideTransactionBlock() {
         // Restore the transaction state onto '_opCtx'.
         _txnResources->release(_opCtx);
     }
+
+    auto txnParticipant = TransactionParticipant::get(_opCtx);
+    if (txnParticipant) {
+        txnParticipant->popSideTransactionBlock();
+    }
 }
+
 void TransactionParticipant::_stashActiveTransaction(WithLock, OperationContext* opCtx) {
     if (_inShutdown) {
         return;
@@ -990,6 +1001,11 @@ void TransactionParticipant::addTransactionOperation(OperationContext* opCtx,
                                                      const repl::ReplOperation& operation) {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
 
+    if (_sideTransactionBlocks) {
+        // This operation is in a side transaction.
+        return;
+    }
+
     // Always check _getSession()'s txnNumber and '_txnState', since they can be modified by session
     // kill and migration, which do not check out the session.
     _checkIsActiveTransaction(lk, *opCtx->getTxnNumber(), true);
diff --git a/src/mongo/db/transaction_participant.h b/src/mongo/db/transaction_participant.h
index 650e1296f6..ae571e065f 100644
--- a/src/mongo/db/transaction_participant.h
+++ b/src/mongo/db/transaction_participant.h
@@ -501,6 +501,22 @@ public:
      */
     void reportUnstashedState(OperationContext* opCtx, BSONObjBuilder* builder) const;
 
+    /**
+     * Called by SideTransactionBlock to inform the transaction participant that a block began.
+     * Not thread-safe.
+     */
+    void pushSideTransactionBlock() {
+        ++_sideTransactionBlocks;
+    }
+
+    /**
+     * Called by SideTransactionBlock to inform the transaction participant that a block ended.
+     * Not thread-safe.
+     */
+    void popSideTransactionBlock() {
+        --_sideTransactionBlocks;
+    }
+
     //
     // Methods used for unit-testing only
     //
@@ -891,6 +907,8 @@ private:
     // opTime. Used for fast retryability check and retrieving the previous write's data without
     // having to scan through the oplog.
     CommittedStatementTimestampMap _activeTxnCommittedStatements;
+
+    int _sideTransactionBlocks = 0;
 };
 
 }  // namespace mongo