SERVER-19364 move query stage OperationContext pointer management into the base class

68 files changed, 232 insertions, 307 deletions

diff --git a/src/mongo/db/exec/and_hash.cpp b/src/mongo/db/exec/and_hash.cpp
index 1c21b4adf83..3e153316931 100644
--- a/src/mongo/db/exec/and_hash.cpp
+++ b/src/mongo/db/exec/and_hash.cpp
@@ -54,8 +54,8 @@ const size_t AndHashStage::kLookAheadWorks = 10;
 // static
 const char* AndHashStage::kStageType = "AND_HASH";
 
-AndHashStage::AndHashStage(WorkingSet* ws, const Collection* collection)
-    : PlanStage(kStageType),
+AndHashStage::AndHashStage(OperationContext* opCtx, WorkingSet* ws, const Collection* collection)
+    : PlanStage(kStageType, opCtx),
       _collection(collection),
       _ws(ws),
       _hashingChildren(true),
@@ -63,8 +63,11 @@ AndHashStage::AndHashStage(WorkingSet* ws, const Collection* collection)
       _memUsage(0),
       _maxMemUsage(kDefaultMaxMemUsageBytes) {}
 
-AndHashStage::AndHashStage(WorkingSet* ws, const Collection* collection, size_t maxMemUsage)
-    : PlanStage(kStageType),
+AndHashStage::AndHashStage(OperationContext* opCtx,
+                           WorkingSet* ws,
+                           const Collection* collection,
+                           size_t maxMemUsage)
+    : PlanStage(kStageType, opCtx),
       _collection(collection),
       _ws(ws),
       _hashingChildren(true),
diff --git a/src/mongo/db/exec/and_hash.h b/src/mongo/db/exec/and_hash.h
index 9f42f93d5e1..8f888fb17ab 100644
--- a/src/mongo/db/exec/and_hash.h
+++ b/src/mongo/db/exec/and_hash.h
@@ -51,12 +51,15 @@ namespace mongo {
  */
 class AndHashStage final : public PlanStage {
 public:
-    AndHashStage(WorkingSet* ws, const Collection* collection);
+    AndHashStage(OperationContext* opCtx, WorkingSet* ws, const Collection* collection);
 
     /**
      * For testing only. Allows tests to set memory usage threshold.
      */
-    AndHashStage(WorkingSet* ws, const Collection* collection, size_t maxMemUsage);
+    AndHashStage(OperationContext* opCtx,
+                 WorkingSet* ws,
+                 const Collection* collection,
+                 size_t maxMemUsage);
 
     void addChild(PlanStage* child);
 
diff --git a/src/mongo/db/exec/and_sorted.cpp b/src/mongo/db/exec/and_sorted.cpp
index 873e545a2dd..5844078c762 100644
--- a/src/mongo/db/exec/and_sorted.cpp
+++ b/src/mongo/db/exec/and_sorted.cpp
@@ -44,8 +44,10 @@ using stdx::make_unique;
 // static
 const char* AndSortedStage::kStageType = "AND_SORTED";
 
-AndSortedStage::AndSortedStage(WorkingSet* ws, const Collection* collection)
-    : PlanStage(kStageType),
+AndSortedStage::AndSortedStage(OperationContext* opCtx,
+                               WorkingSet* ws,
+                               const Collection* collection)
+    : PlanStage(kStageType, opCtx),
       _collection(collection),
       _ws(ws),
       _targetNode(numeric_limits<size_t>::max()),
diff --git a/src/mongo/db/exec/and_sorted.h b/src/mongo/db/exec/and_sorted.h
index ca6ea3e7410..3ea040b0428 100644
--- a/src/mongo/db/exec/and_sorted.h
+++ b/src/mongo/db/exec/and_sorted.h
@@ -53,7 +53,7 @@ namespace mongo {
  */
 class AndSortedStage final : public PlanStage {
 public:
-    AndSortedStage(WorkingSet* ws, const Collection* collection);
+    AndSortedStage(OperationContext* opCtx, WorkingSet* ws, const Collection* collection);
 
     void addChild(PlanStage* child);
 
diff --git a/src/mongo/db/exec/cached_plan.cpp b/src/mongo/db/exec/cached_plan.cpp
index dd0b751c326..7dead20013d 100644
--- a/src/mongo/db/exec/cached_plan.cpp
+++ b/src/mongo/db/exec/cached_plan.cpp
@@ -60,8 +60,7 @@ CachedPlanStage::CachedPlanStage(OperationContext* txn,
                                  const QueryPlannerParams& params,
                                  size_t decisionWorks,
                                  PlanStage* root)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _ws(ws),
       _canonicalQuery(cq),
@@ -228,7 +227,7 @@ Status CachedPlanStage::replan(PlanYieldPolicy* yieldPolicy, bool shouldCache) {
 
         PlanStage* newRoot;
         // Only one possible plan. Build the stages from the solution.
-        verify(StageBuilder::build(_txn, _collection, *solutions[0], _ws, &newRoot));
+        verify(StageBuilder::build(getOpCtx(), _collection, *solutions[0], _ws, &newRoot));
         _children.emplace_back(newRoot);
         _replannedQs.reset(solutions.popAndReleaseBack());
         return Status::OK();
@@ -236,7 +235,8 @@ Status CachedPlanStage::replan(PlanYieldPolicy* yieldPolicy, bool shouldCache) {
 
     // Many solutions. Create a MultiPlanStage to pick the best, update the cache,
     // and so on. The working set will be shared by all candidate plans.
-    _children.emplace_back(new MultiPlanStage(_txn, _collection, _canonicalQuery, shouldCache));
+    _children.emplace_back(
+        new MultiPlanStage(getOpCtx(), _collection, _canonicalQuery, shouldCache));
     MultiPlanStage* multiPlanStage = static_cast<MultiPlanStage*>(child().get());
 
     for (size_t ix = 0; ix < solutions.size(); ++ix) {
@@ -245,7 +245,7 @@ Status CachedPlanStage::replan(PlanYieldPolicy* yieldPolicy, bool shouldCache) {
         }
 
         PlanStage* nextPlanRoot;
-        verify(StageBuilder::build(_txn, _collection, *solutions[ix], _ws, &nextPlanRoot));
+        verify(StageBuilder::build(getOpCtx(), _collection, *solutions[ix], _ws, &nextPlanRoot));
 
         // Takes ownership of 'solutions[ix]' and 'nextPlanRoot'.
         multiPlanStage->addPlan(solutions.releaseAt(ix), nextPlanRoot, _ws);
@@ -291,11 +291,6 @@ PlanStage::StageState CachedPlanStage::work(WorkingSetID* out) {
     return childStatus;
 }
 
-
-void CachedPlanStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 void CachedPlanStage::doInvalidate(OperationContext* txn,
                                    const RecordId& dl,
                                    InvalidationType type) {
diff --git a/src/mongo/db/exec/cached_plan.h b/src/mongo/db/exec/cached_plan.h
index 5216e33eac0..d9f54716acb 100644
--- a/src/mongo/db/exec/cached_plan.h
+++ b/src/mongo/db/exec/cached_plan.h
@@ -65,7 +65,6 @@ public:
 
     StageState work(WorkingSetID* out) final;
 
-    void doReattachToOperationContext(OperationContext* opCtx) final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -115,9 +114,6 @@ private:
      */
     Status tryYield(PlanYieldPolicy* yieldPolicy);
 
-    // Not owned.
-    OperationContext* _txn;
-
     // Not owned. Must be non-null.
     Collection* _collection;
 
diff --git a/src/mongo/db/exec/collection_scan.cpp b/src/mongo/db/exec/collection_scan.cpp
index ef5fb5f9fee..28ed97662c4 100644
--- a/src/mongo/db/exec/collection_scan.cpp
+++ b/src/mongo/db/exec/collection_scan.cpp
@@ -58,8 +58,7 @@ CollectionScan::CollectionScan(OperationContext* txn,
                                const CollectionScanParams& params,
                                WorkingSet* workingSet,
                                const MatchExpression* filter)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _workingSet(workingSet),
       _filter(filter),
       _params(params),
@@ -98,7 +97,7 @@ PlanStage::StageState CollectionScan::work(WorkingSetID* out) {
     try {
         if (needToMakeCursor) {
             const bool forward = _params.direction == CollectionScanParams::FORWARD;
-            _cursor = _params.collection->getCursor(_txn, forward);
+            _cursor = _params.collection->getCursor(getOpCtx(), forward);
 
             if (!_lastSeenId.isNull()) {
                 invariant(_params.tailable);
@@ -165,7 +164,7 @@ PlanStage::StageState CollectionScan::work(WorkingSetID* out) {
     WorkingSetID id = _workingSet->allocate();
     WorkingSetMember* member = _workingSet->get(id);
     member->loc = record->id;
-    member->obj = {_txn->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
+    member->obj = {getOpCtx()->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
     _workingSet->transitionToLocAndObj(id);
 
     return returnIfMatches(member, id, out);
@@ -223,23 +222,21 @@ void CollectionScan::doSaveState() {
 void CollectionScan::doRestoreState() {
     if (_cursor) {
         if (!_cursor->restore()) {
-            warning() << "Could not restore RecordCursor for CollectionScan: " << _txn->getNS();
+            warning() << "Could not restore RecordCursor for CollectionScan: "
+                      << getOpCtx()->getNS();
             _isDead = true;
         }
     }
 }
 
 void CollectionScan::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_cursor)
         _cursor->detachFromOperationContext();
 }
 
-void CollectionScan::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void CollectionScan::doReattachToOperationContext() {
     if (_cursor)
-        _cursor->reattachToOperationContext(opCtx);
+        _cursor->reattachToOperationContext(getOpCtx());
 }
 
 unique_ptr<PlanStageStats> CollectionScan::getStats() {
diff --git a/src/mongo/db/exec/collection_scan.h b/src/mongo/db/exec/collection_scan.h
index 2cfac584456..c886a6435d6 100644
--- a/src/mongo/db/exec/collection_scan.h
+++ b/src/mongo/db/exec/collection_scan.h
@@ -61,7 +61,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
 
     StageType stageType() const final {
         return STAGE_COLLSCAN;
@@ -80,9 +80,6 @@ private:
      */
     StageState returnIfMatches(WorkingSetMember* member, WorkingSetID memberID, WorkingSetID* out);
 
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // WorkingSet is not owned by us.
     WorkingSet* _workingSet;
 
diff --git a/src/mongo/db/exec/count.cpp b/src/mongo/db/exec/count.cpp
index 40bc4e36c5c..83f7f952fae 100644
--- a/src/mongo/db/exec/count.cpp
+++ b/src/mongo/db/exec/count.cpp
@@ -49,8 +49,7 @@ CountStage::CountStage(OperationContext* txn,
                        const CountRequest& request,
                        WorkingSet* ws,
                        PlanStage* child)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _request(request),
       _leftToSkip(request.getSkip()),
@@ -73,7 +72,7 @@ bool CountStage::isEOF() {
 
 void CountStage::trivialCount() {
     invariant(_collection);
-    long long nCounted = _collection->numRecords(_txn);
+    long long nCounted = _collection->numRecords(getOpCtx());
 
     if (0 != _request.getSkip()) {
         nCounted -= _request.getSkip();
@@ -163,10 +162,6 @@ PlanStage::StageState CountStage::work(WorkingSetID* out) {
     return PlanStage::NEED_TIME;
 }
 
-void CountStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 unique_ptr<PlanStageStats> CountStage::getStats() {
     _commonStats.isEOF = isEOF();
     unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_COUNT);
diff --git a/src/mongo/db/exec/count.h b/src/mongo/db/exec/count.h
index b84f0bbe498..63c37face02 100644
--- a/src/mongo/db/exec/count.h
+++ b/src/mongo/db/exec/count.h
@@ -56,8 +56,6 @@ public:
     bool isEOF() final;
     StageState work(WorkingSetID* out) final;
 
-    void doReattachToOperationContext(OperationContext* opCtx) final;
-
     StageType stageType() const final {
         return STAGE_COUNT;
     }
@@ -75,9 +73,6 @@ private:
      */
     void trivialCount();
 
-    // Transactional context for read locks. Not owned by us.
-    OperationContext* _txn;
-
     // The collection over which we are counting.
     Collection* _collection;
 
diff --git a/src/mongo/db/exec/count_scan.cpp b/src/mongo/db/exec/count_scan.cpp
index 6ba9d710f5d..56b7cf34eee 100644
--- a/src/mongo/db/exec/count_scan.cpp
+++ b/src/mongo/db/exec/count_scan.cpp
@@ -43,8 +43,7 @@ using stdx::make_unique;
 const char* CountScan::kStageType = "COUNT_SCAN";
 
 CountScan::CountScan(OperationContext* txn, const CountScanParams& params, WorkingSet* workingSet)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _workingSet(workingSet),
       _descriptor(params.descriptor),
       _iam(params.descriptor->getIndexCatalog()->getIndex(params.descriptor)),
@@ -81,7 +80,7 @@ PlanStage::StageState CountScan::work(WorkingSetID* out) {
 
         if (needInit) {
             // First call to work().  Perform cursor init.
-            _cursor = _iam->newCursor(_txn);
+            _cursor = _iam->newCursor(getOpCtx());
             _cursor->setEndPosition(_params.endKey, _params.endKeyInclusive);
 
             entry = _cursor->seek(_params.startKey, _params.startKeyInclusive, kWantLoc);
@@ -131,20 +130,17 @@ void CountScan::doRestoreState() {
 
     // This can change during yielding.
     // TODO this isn't sufficient. See SERVER-17678.
-    _shouldDedup = _descriptor->isMultikey(_txn);
+    _shouldDedup = _descriptor->isMultikey(getOpCtx());
 }
 
 void CountScan::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_cursor)
         _cursor->detachFromOperationContext();
 }
 
-void CountScan::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void CountScan::doReattachToOperationContext() {
     if (_cursor)
-        _cursor->reattachToOperationContext(opCtx);
+        _cursor->reattachToOperationContext(getOpCtx());
 }
 
 void CountScan::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
diff --git a/src/mongo/db/exec/count_scan.h b/src/mongo/db/exec/count_scan.h
index f7f65700134..7bc593d0695 100644
--- a/src/mongo/db/exec/count_scan.h
+++ b/src/mongo/db/exec/count_scan.h
@@ -73,7 +73,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -87,9 +87,6 @@ public:
     static const char* kStageType;
 
 private:
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // The WorkingSet we annotate with results.  Not owned by us.
     WorkingSet* _workingSet;
 
diff --git a/src/mongo/db/exec/delete.cpp b/src/mongo/db/exec/delete.cpp
index 4a9f6638c2d..90b87cce6bc 100644
--- a/src/mongo/db/exec/delete.cpp
+++ b/src/mongo/db/exec/delete.cpp
@@ -58,8 +58,7 @@ DeleteStage::DeleteStage(OperationContext* txn,
                          WorkingSet* ws,
                          Collection* collection,
                          PlanStage* child)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _params(params),
       _ws(ws),
       _collection(collection),
@@ -138,9 +137,9 @@ PlanStage::StageState DeleteStage::work(WorkingSetID* out) {
             // If the snapshot changed, then we have to make sure we have the latest copy of the
             // doc and that it still matches.
             std::unique_ptr<RecordCursor> cursor;
-            if (_txn->recoveryUnit()->getSnapshotId() != member->obj.snapshotId()) {
-                cursor = _collection->getCursor(_txn);
-                if (!WorkingSetCommon::fetch(_txn, _ws, id, cursor)) {
+            if (getOpCtx()->recoveryUnit()->getSnapshotId() != member->obj.snapshotId()) {
+                cursor = _collection->getCursor(getOpCtx());
+                if (!WorkingSetCommon::fetch(getOpCtx(), _ws, id, cursor)) {
                     // Doc is already deleted. Nothing more to do.
                     ++_commonStats.needTime;
                     return PlanStage::NEED_TIME;
@@ -179,13 +178,13 @@ PlanStage::StageState DeleteStage::work(WorkingSetID* out) {
 
             // Do the write, unless this is an explain.
             if (!_params.isExplain) {
-                WriteUnitOfWork wunit(_txn);
+                WriteUnitOfWork wunit(getOpCtx());
 
                 const bool deleteCappedOK = false;
                 const bool deleteNoWarn = false;
                 BSONObj deletedId;
 
-                _collection->deleteDocument(_txn,
+                _collection->deleteDocument(getOpCtx(),
                                             rloc,
                                             deleteCappedOK,
                                             deleteNoWarn,
@@ -265,10 +264,6 @@ void DeleteStage::doRestoreState() {
                 repl::getGlobalReplicationCoordinator()->canAcceptWritesFor(ns));
 }
 
-void DeleteStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 unique_ptr<PlanStageStats> DeleteStage::getStats() {
     _commonStats.isEOF = isEOF();
     unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_DELETE);
diff --git a/src/mongo/db/exec/delete.h b/src/mongo/db/exec/delete.h
index 528bad31088..5387e4e8ddf 100644
--- a/src/mongo/db/exec/delete.h
+++ b/src/mongo/db/exec/delete.h
@@ -90,7 +90,6 @@ public:
     StageState work(WorkingSetID* out) final;
 
     void doRestoreState() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
 
     StageType stageType() const final {
         return STAGE_DELETE;
@@ -110,9 +109,6 @@ public:
     static long long getNumDeleted(const PlanExecutor& exec);
 
 private:
-    // Transactional context.  Not owned by us.
-    OperationContext* _txn;
-
     DeleteStageParams _params;
 
     // Not owned by us.
diff --git a/src/mongo/db/exec/distinct_scan.cpp b/src/mongo/db/exec/distinct_scan.cpp
index f663bf99cee..0f00c2669d7 100644
--- a/src/mongo/db/exec/distinct_scan.cpp
+++ b/src/mongo/db/exec/distinct_scan.cpp
@@ -48,8 +48,7 @@ const char* DistinctScan::kStageType = "DISTINCT_SCAN";
 DistinctScan::DistinctScan(OperationContext* txn,
                            const DistinctParams& params,
                            WorkingSet* workingSet)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _workingSet(workingSet),
       _descriptor(params.descriptor),
       _iam(params.descriptor->getIndexCatalog()->getIndex(params.descriptor)),
@@ -74,7 +73,7 @@ PlanStage::StageState DistinctScan::work(WorkingSetID* out) {
     boost::optional<IndexKeyEntry> kv;
     try {
         if (!_cursor)
-            _cursor = _iam->newCursor(_txn, _params.direction == 1);
+            _cursor = _iam->newCursor(getOpCtx(), _params.direction == 1);
         kv = _cursor->seek(_seekPoint);
     } catch (const WriteConflictException& wce) {
         *out = WorkingSet::INVALID_ID;
@@ -140,16 +139,13 @@ void DistinctScan::doRestoreState() {
 }
 
 void DistinctScan::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_cursor)
         _cursor->detachFromOperationContext();
 }
 
-void DistinctScan::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void DistinctScan::doReattachToOperationContext() {
     if (_cursor)
-        _cursor->reattachToOperationContext(opCtx);
+        _cursor->reattachToOperationContext(getOpCtx());
 }
 
 unique_ptr<PlanStageStats> DistinctScan::getStats() {
diff --git a/src/mongo/db/exec/distinct_scan.h b/src/mongo/db/exec/distinct_scan.h
index 6caafeae2ff..d915af433cc 100644
--- a/src/mongo/db/exec/distinct_scan.h
+++ b/src/mongo/db/exec/distinct_scan.h
@@ -81,7 +81,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
 
     StageType stageType() const final {
         return STAGE_DISTINCT_SCAN;
@@ -94,9 +94,6 @@ public:
     static const char* kStageType;
 
 private:
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // The WorkingSet we annotate with results.  Not owned by us.
     WorkingSet* _workingSet;
 
diff --git a/src/mongo/db/exec/eof.cpp b/src/mongo/db/exec/eof.cpp
index aebb31b0277..f5f127f016a 100644
--- a/src/mongo/db/exec/eof.cpp
+++ b/src/mongo/db/exec/eof.cpp
@@ -42,7 +42,7 @@ using stdx::make_unique;
 // static
 const char* EOFStage::kStageType = "EOF";
 
-EOFStage::EOFStage() : PlanStage(kStageType) {}
+EOFStage::EOFStage(OperationContext* opCtx) : PlanStage(kStageType, opCtx) {}
 
 EOFStage::~EOFStage() {}
 
diff --git a/src/mongo/db/exec/eof.h b/src/mongo/db/exec/eof.h
index 33462ca3aa9..6796e4994e7 100644
--- a/src/mongo/db/exec/eof.h
+++ b/src/mongo/db/exec/eof.h
@@ -38,7 +38,7 @@ namespace mongo {
  */
 class EOFStage final : public PlanStage {
 public:
-    EOFStage();
+    EOFStage(OperationContext* opCtx);
 
     ~EOFStage();
 
diff --git a/src/mongo/db/exec/fetch.cpp b/src/mongo/db/exec/fetch.cpp
index 85c404c17e6..fb76a5f9f81 100644
--- a/src/mongo/db/exec/fetch.cpp
+++ b/src/mongo/db/exec/fetch.cpp
@@ -54,8 +54,7 @@ FetchStage::FetchStage(OperationContext* txn,
                        PlanStage* child,
                        const MatchExpression* filter,
                        const Collection* collection)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _ws(ws),
       _filter(filter),
@@ -109,7 +108,7 @@ PlanStage::StageState FetchStage::work(WorkingSetID* out) {
 
             try {
                 if (!_cursor)
-                    _cursor = _collection->getCursor(_txn);
+                    _cursor = _collection->getCursor(getOpCtx());
 
                 if (auto fetcher = _cursor->fetcherForId(member->loc)) {
                     // There's something to fetch. Hand the fetcher off to the WSM, and pass up
@@ -123,7 +122,7 @@ PlanStage::StageState FetchStage::work(WorkingSetID* out) {
 
                 // The doc is already in memory, so go ahead and grab it. Now we have a RecordId
                 // as well as an unowned object
-                if (!WorkingSetCommon::fetch(_txn, _ws, id, _cursor)) {
+                if (!WorkingSetCommon::fetch(getOpCtx(), _ws, id, _cursor)) {
                     _ws->free(id);
                     _commonStats.needTime++;
                     return NEED_TIME;
@@ -170,16 +169,13 @@ void FetchStage::doRestoreState() {
 }
 
 void FetchStage::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_cursor)
         _cursor->detachFromOperationContext();
 }
 
-void FetchStage::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void FetchStage::doReattachToOperationContext() {
     if (_cursor)
-        _cursor->reattachToOperationContext(opCtx);
+        _cursor->reattachToOperationContext(getOpCtx());
 }
 
 void FetchStage::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
diff --git a/src/mongo/db/exec/fetch.h b/src/mongo/db/exec/fetch.h
index 4cb2c37bca4..19aa5ac4cf2 100644
--- a/src/mongo/db/exec/fetch.h
+++ b/src/mongo/db/exec/fetch.h
@@ -63,7 +63,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -83,8 +83,6 @@ private:
      */
     StageState returnIfMatches(WorkingSetMember* member, WorkingSetID memberID, WorkingSetID* out);
 
-    OperationContext* _txn;
-
     // Collection which is used by this stage. Used to resolve record ids retrieved by child
     // stages. The lifetime of the collection must supersede that of the stage.
     const Collection* _collection;
diff --git a/src/mongo/db/exec/group.cpp b/src/mongo/db/exec/group.cpp
index 891fc232796..2c0ea523a2f 100644
--- a/src/mongo/db/exec/group.cpp
+++ b/src/mongo/db/exec/group.cpp
@@ -77,8 +77,7 @@ GroupStage::GroupStage(OperationContext* txn,
                        const GroupRequest& request,
                        WorkingSet* workingSet,
                        PlanStage* child)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _request(request),
       _ws(workingSet),
       _specificStats(),
@@ -94,7 +93,8 @@ void GroupStage::initGroupScripting() {
         AuthorizationSession::get(ClientBasic::getCurrent())->getAuthenticatedUserNamesToken();
 
     const NamespaceString nss(_request.ns);
-    _scope = globalScriptEngine->getPooledScope(_txn, nss.db().toString(), "group" + userToken);
+    _scope =
+        globalScriptEngine->getPooledScope(getOpCtx(), nss.db().toString(), "group" + userToken);
     if (!_request.reduceScope.isEmpty()) {
         _scope->init(&_request.reduceScope);
     }
@@ -257,10 +257,6 @@ bool GroupStage::isEOF() {
     return _groupState == GroupState_Done;
 }
 
-void GroupStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 unique_ptr<PlanStageStats> GroupStage::getStats() {
     _commonStats.isEOF = isEOF();
     unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_GROUP);
diff --git a/src/mongo/db/exec/group.h b/src/mongo/db/exec/group.h
index ce969c9335f..97a1a3d587b 100644
--- a/src/mongo/db/exec/group.h
+++ b/src/mongo/db/exec/group.h
@@ -89,7 +89,6 @@ public:
 
     StageState work(WorkingSetID* out) final;
     bool isEOF() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
 
     StageType stageType() const final {
         return STAGE_GROUP;
@@ -128,9 +127,6 @@ private:
     // array.
     BSONObj finalizeResults();
 
-    // Transactional context for read locks.  Not owned by us.
-    OperationContext* _txn;
-
     GroupRequest _request;
 
     // The WorkingSet we annotate with results.  Not owned by us.
diff --git a/src/mongo/db/exec/idhack.cpp b/src/mongo/db/exec/idhack.cpp
index a66ad20edda..570f80a19d9 100644
--- a/src/mongo/db/exec/idhack.cpp
+++ b/src/mongo/db/exec/idhack.cpp
@@ -54,8 +54,7 @@ IDHackStage::IDHackStage(OperationContext* txn,
                          const Collection* collection,
                          CanonicalQuery* query,
                          WorkingSet* ws)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _workingSet(ws),
       _key(query->getQueryObj()["_id"].wrap()),
@@ -72,8 +71,7 @@ IDHackStage::IDHackStage(OperationContext* txn,
                          Collection* collection,
                          const BSONObj& key,
                          WorkingSet* ws)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _workingSet(ws),
       _key(key),
@@ -108,7 +106,7 @@ PlanStage::StageState IDHackStage::work(WorkingSetID* out) {
         WorkingSetID id = _idBeingPagedIn;
         _idBeingPagedIn = WorkingSet::INVALID_ID;
 
-        invariant(WorkingSetCommon::fetchIfUnfetched(_txn, _workingSet, id, _recordCursor));
+        invariant(WorkingSetCommon::fetchIfUnfetched(getOpCtx(), _workingSet, id, _recordCursor));
 
         WorkingSetMember* member = _workingSet->get(id);
         return advance(id, member, out);
@@ -120,14 +118,14 @@ PlanStage::StageState IDHackStage::work(WorkingSetID* out) {
         const IndexCatalog* catalog = _collection->getIndexCatalog();
 
         // Find the index we use.
-        IndexDescriptor* idDesc = catalog->findIdIndex(_txn);
+        IndexDescriptor* idDesc = catalog->findIdIndex(getOpCtx());
         if (NULL == idDesc) {
             _done = true;
             return PlanStage::IS_EOF;
         }
 
         // Look up the key by going directly to the index.
-        RecordId loc = catalog->getIndex(idDesc)->findSingle(_txn, _key);
+        RecordId loc = catalog->getIndex(idDesc)->findSingle(getOpCtx(), _key);
 
         // Key not found.
         if (loc.isNull()) {
@@ -145,7 +143,7 @@ PlanStage::StageState IDHackStage::work(WorkingSetID* out) {
         _workingSet->transitionToLocAndIdx(id);
 
         if (!_recordCursor)
-            _recordCursor = _collection->getCursor(_txn);
+            _recordCursor = _collection->getCursor(getOpCtx());
 
         // We may need to request a yield while we fetch the document.
         if (auto fetcher = _recordCursor->fetcherForId(loc)) {
@@ -159,7 +157,7 @@ PlanStage::StageState IDHackStage::work(WorkingSetID* out) {
         }
 
         // The doc was already in memory, so we go ahead and return it.
-        if (!WorkingSetCommon::fetch(_txn, _workingSet, id, _recordCursor)) {
+        if (!WorkingSetCommon::fetch(getOpCtx(), _workingSet, id, _recordCursor)) {
             // _id is immutable so the index would return the only record that could
             // possibly match the query.
             _workingSet->free(id);
@@ -210,16 +208,13 @@ void IDHackStage::doRestoreState() {
 }
 
 void IDHackStage::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_recordCursor)
         _recordCursor->detachFromOperationContext();
 }
 
-void IDHackStage::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void IDHackStage::doReattachToOperationContext() {
     if (_recordCursor)
-        _recordCursor->reattachToOperationContext(opCtx);
+        _recordCursor->reattachToOperationContext(getOpCtx());
 }
 
 void IDHackStage::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
diff --git a/src/mongo/db/exec/idhack.h b/src/mongo/db/exec/idhack.h
index 08a65f084c4..ef3df6f10a2 100644
--- a/src/mongo/db/exec/idhack.h
+++ b/src/mongo/db/exec/idhack.h
@@ -61,7 +61,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     /**
@@ -87,9 +87,6 @@ private:
      */
     StageState advance(WorkingSetID id, WorkingSetMember* member, WorkingSetID* out);
 
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // Not owned here.
     const Collection* _collection;
 
diff --git a/src/mongo/db/exec/index_scan.cpp b/src/mongo/db/exec/index_scan.cpp
index 32dfb4c8121..fdf3b037416 100644
--- a/src/mongo/db/exec/index_scan.cpp
+++ b/src/mongo/db/exec/index_scan.cpp
@@ -62,8 +62,7 @@ IndexScan::IndexScan(OperationContext* txn,
                      const IndexScanParams& params,
                      WorkingSet* workingSet,
                      const MatchExpression* filter)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _workingSet(workingSet),
       _iam(params.descriptor->getIndexCatalog()->getIndex(params.descriptor)),
       _keyPattern(params.descriptor->keyPattern().getOwned()),
@@ -77,7 +76,7 @@ IndexScan::IndexScan(OperationContext* txn,
     // any info we need for stats reporting out here.
     _specificStats.keyPattern = _keyPattern;
     _specificStats.indexName = _params.descriptor->indexName();
-    _specificStats.isMultiKey = _params.descriptor->isMultikey(_txn);
+    _specificStats.isMultiKey = _params.descriptor->isMultikey(getOpCtx());
     _specificStats.isUnique = _params.descriptor->unique();
     _specificStats.isSparse = _params.descriptor->isSparse();
     _specificStats.isPartial = _params.descriptor->isPartial();
@@ -89,11 +88,11 @@ boost::optional<IndexKeyEntry> IndexScan::initIndexScan() {
         _shouldDedup = false;
     } else {
         // TODO it is incorrect to rely on this not changing. SERVER-17678
-        _shouldDedup = _params.descriptor->isMultikey(_txn);
+        _shouldDedup = _params.descriptor->isMultikey(getOpCtx());
     }
 
     // Perform the possibly heavy-duty initialization of the underlying index cursor.
-    _indexCursor = _iam->newCursor(_txn, _forward);
+    _indexCursor = _iam->newCursor(getOpCtx(), _forward);
 
     if (_params.bounds.isSimpleRange) {
         // Start at one key, end at another.
@@ -251,16 +250,13 @@ void IndexScan::doRestoreState() {
 }
 
 void IndexScan::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_indexCursor)
         _indexCursor->detachFromOperationContext();
 }
 
-void IndexScan::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void IndexScan::doReattachToOperationContext() {
     if (_indexCursor)
-        _indexCursor->reattachToOperationContext(opCtx);
+        _indexCursor->reattachToOperationContext(getOpCtx());
 }
 
 void IndexScan::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
diff --git a/src/mongo/db/exec/index_scan.h b/src/mongo/db/exec/index_scan.h
index aae3d54ec4c..e3e80fc7071 100644
--- a/src/mongo/db/exec/index_scan.h
+++ b/src/mongo/db/exec/index_scan.h
@@ -100,7 +100,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -119,9 +119,6 @@ private:
      */
     boost::optional<IndexKeyEntry> initIndexScan();
 
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // The WorkingSet we fill with results.  Not owned by us.
     WorkingSet* const _workingSet;
 
diff --git a/src/mongo/db/exec/keep_mutations.cpp b/src/mongo/db/exec/keep_mutations.cpp
index 2770c2b25d3..d43cbb560f8 100644
--- a/src/mongo/db/exec/keep_mutations.cpp
+++ b/src/mongo/db/exec/keep_mutations.cpp
@@ -41,10 +41,11 @@ using stdx::make_unique;
 // static
 const char* KeepMutationsStage::kStageType = "KEEP_MUTATIONS";
 
-KeepMutationsStage::KeepMutationsStage(const MatchExpression* filter,
+KeepMutationsStage::KeepMutationsStage(OperationContext* opCtx,
+                                       const MatchExpression* filter,
                                        WorkingSet* ws,
                                        PlanStage* child)
-    : PlanStage(kStageType),
+    : PlanStage(kStageType, opCtx),
       _workingSet(ws),
       _filter(filter),
       _doneReadingChild(false),
diff --git a/src/mongo/db/exec/keep_mutations.h b/src/mongo/db/exec/keep_mutations.h
index 67ff15afca1..878de151549 100644
--- a/src/mongo/db/exec/keep_mutations.h
+++ b/src/mongo/db/exec/keep_mutations.h
@@ -46,7 +46,10 @@ namespace mongo {
  */
 class KeepMutationsStage final : public PlanStage {
 public:
-    KeepMutationsStage(const MatchExpression* filter, WorkingSet* ws, PlanStage* child);
+    KeepMutationsStage(OperationContext* opCtx,
+                       const MatchExpression* filter,
+                       WorkingSet* ws,
+                       PlanStage* child);
     ~KeepMutationsStage();
 
     bool isEOF() final;
diff --git a/src/mongo/db/exec/limit.cpp b/src/mongo/db/exec/limit.cpp
index a2c1d73b399..c4ea7485c3a 100644
--- a/src/mongo/db/exec/limit.cpp
+++ b/src/mongo/db/exec/limit.cpp
@@ -42,8 +42,8 @@ using stdx::make_unique;
 // static
 const char* LimitStage::kStageType = "LIMIT";
 
-LimitStage::LimitStage(long long limit, WorkingSet* ws, PlanStage* child)
-    : PlanStage(kStageType), _ws(ws), _numToReturn(limit) {
+LimitStage::LimitStage(OperationContext* opCtx, long long limit, WorkingSet* ws, PlanStage* child)
+    : PlanStage(kStageType, opCtx), _ws(ws), _numToReturn(limit) {
     _specificStats.limit = _numToReturn;
     _children.emplace_back(child);
 }
diff --git a/src/mongo/db/exec/limit.h b/src/mongo/db/exec/limit.h
index de8d1ae2598..f51061d6049 100644
--- a/src/mongo/db/exec/limit.h
+++ b/src/mongo/db/exec/limit.h
@@ -44,7 +44,7 @@ namespace mongo {
  */
 class LimitStage final : public PlanStage {
 public:
-    LimitStage(long long limit, WorkingSet* ws, PlanStage* child);
+    LimitStage(OperationContext* opCtx, long long limit, WorkingSet* ws, PlanStage* child);
     ~LimitStage();
 
     bool isEOF() final;
diff --git a/src/mongo/db/exec/merge_sort.cpp b/src/mongo/db/exec/merge_sort.cpp
index 5bf7db4b9ea..8faf6cfdeb3 100644
--- a/src/mongo/db/exec/merge_sort.cpp
+++ b/src/mongo/db/exec/merge_sort.cpp
@@ -45,10 +45,11 @@ using stdx::make_unique;
 // static
 const char* MergeSortStage::kStageType = "SORT_MERGE";
 
-MergeSortStage::MergeSortStage(const MergeSortStageParams& params,
+MergeSortStage::MergeSortStage(OperationContext* opCtx,
+                               const MergeSortStageParams& params,
                                WorkingSet* ws,
                                const Collection* collection)
-    : PlanStage(kStageType),
+    : PlanStage(kStageType, opCtx),
       _collection(collection),
       _ws(ws),
       _pattern(params.pattern),
diff --git a/src/mongo/db/exec/merge_sort.h b/src/mongo/db/exec/merge_sort.h
index ed9fd2f2a11..f95eb8f9a71 100644
--- a/src/mongo/db/exec/merge_sort.h
+++ b/src/mongo/db/exec/merge_sort.h
@@ -55,7 +55,8 @@ class MergeSortStageParams;
  */
 class MergeSortStage final : public PlanStage {
 public:
-    MergeSortStage(const MergeSortStageParams& params,
+    MergeSortStage(OperationContext* opCtx,
+                   const MergeSortStageParams& params,
                    WorkingSet* ws,
                    const Collection* collection);
 
diff --git a/src/mongo/db/exec/multi_iterator.cpp b/src/mongo/db/exec/multi_iterator.cpp
index f08052e06f3..508c58e86dd 100644
--- a/src/mongo/db/exec/multi_iterator.cpp
+++ b/src/mongo/db/exec/multi_iterator.cpp
@@ -46,8 +46,7 @@ const char* MultiIteratorStage::kStageType = "MULTI_ITERATOR";
 MultiIteratorStage::MultiIteratorStage(OperationContext* txn,
                                        WorkingSet* ws,
                                        Collection* collection)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _ws(ws),
       _wsidForFetch(_ws->allocate()) {}
@@ -92,7 +91,7 @@ PlanStage::StageState MultiIteratorStage::work(WorkingSetID* out) {
     *out = _ws->allocate();
     WorkingSetMember* member = _ws->get(*out);
     member->loc = record->id;
-    member->obj = {_txn->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
+    member->obj = {getOpCtx()->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
     _ws->transitionToLocAndObj(*out);
     return PlanStage::ADVANCED;
 }
@@ -121,17 +120,14 @@ void MultiIteratorStage::doRestoreState() {
 }
 
 void MultiIteratorStage::doDetachFromOperationContext() {
-    _txn = NULL;
     for (auto&& iterator : _iterators) {
         iterator->detachFromOperationContext();
     }
 }
 
-void MultiIteratorStage::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void MultiIteratorStage::doReattachToOperationContext() {
     for (auto&& iterator : _iterators) {
-        iterator->reattachToOperationContext(opCtx);
+        iterator->reattachToOperationContext(getOpCtx());
     }
 }
 
diff --git a/src/mongo/db/exec/multi_iterator.h b/src/mongo/db/exec/multi_iterator.h
index 9d67d29abaa..8c260e2042b 100644
--- a/src/mongo/db/exec/multi_iterator.h
+++ b/src/mongo/db/exec/multi_iterator.h
@@ -60,7 +60,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     // Returns empty PlanStageStats object
diff --git a/src/mongo/db/exec/multi_plan.cpp b/src/mongo/db/exec/multi_plan.cpp
index 18188ab6b68..1f50464039a 100644
--- a/src/mongo/db/exec/multi_plan.cpp
+++ b/src/mongo/db/exec/multi_plan.cpp
@@ -65,8 +65,7 @@ MultiPlanStage::MultiPlanStage(OperationContext* txn,
                                const Collection* collection,
                                CanonicalQuery* cq,
                                bool shouldCache)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _shouldCache(shouldCache),
       _query(cq),
@@ -219,7 +218,7 @@ Status MultiPlanStage::pickBestPlan(PlanYieldPolicy* yieldPolicy) {
     // make sense.
     ScopedTimer timer(&_commonStats.executionTimeMillis);
 
-    size_t numWorks = getTrialPeriodWorks(_txn, _collection);
+    size_t numWorks = getTrialPeriodWorks(getOpCtx(), _collection);
     size_t numResults = getTrialPeriodNumToReturn(*_query);
 
     // Work the plans, stopping when a plan hits EOF or returns some
@@ -388,10 +387,6 @@ bool MultiPlanStage::workAllPlans(size_t numResults, PlanYieldPolicy* yieldPolic
     return !doneWorking;
 }
 
-void MultiPlanStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 namespace {
 
 void invalidateHelper(OperationContext* txn,
diff --git a/src/mongo/db/exec/multi_plan.h b/src/mongo/db/exec/multi_plan.h
index 85cc3191d13..f0c13916a7d 100644
--- a/src/mongo/db/exec/multi_plan.h
+++ b/src/mongo/db/exec/multi_plan.h
@@ -66,8 +66,6 @@ public:
 
     StageState work(WorkingSetID* out) final;
 
-    void doReattachToOperationContext(OperationContext* opCtx) final;
-
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -167,9 +165,6 @@ private:
 
     static const int kNoSuchPlan = -1;
 
-    // Not owned here.
-    OperationContext* _txn;
-
     // Not owned here. Must be non-null.
     const Collection* _collection;
 
diff --git a/src/mongo/db/exec/near.cpp b/src/mongo/db/exec/near.cpp
index 5cf3018c8a7..1568339cbfe 100644
--- a/src/mongo/db/exec/near.cpp
+++ b/src/mongo/db/exec/near.cpp
@@ -46,8 +46,7 @@ NearStage::NearStage(OperationContext* txn,
                      StageType type,
                      WorkingSet* workingSet,
                      Collection* collection)
-    : PlanStage(typeName),
-      _txn(txn),
+    : PlanStage(typeName, txn),
       _workingSet(workingSet),
       _collection(collection),
       _searchState(SearchState_Initializing),
@@ -70,7 +69,7 @@ NearStage::CoveredInterval::CoveredInterval(PlanStage* covering,
 
 
 PlanStage::StageState NearStage::initNext(WorkingSetID* out) {
-    PlanStage::StageState state = initialize(_txn, _workingSet, _collection, out);
+    PlanStage::StageState state = initialize(getOpCtx(), _workingSet, _collection, out);
     if (state == PlanStage::IS_EOF) {
         _searchState = SearchState_Buffering;
         return PlanStage::NEED_TIME;
@@ -150,7 +149,8 @@ PlanStage::StageState NearStage::bufferNext(WorkingSetID* toReturn, Status* erro
     //
 
     if (!_nextInterval) {
-        StatusWith<CoveredInterval*> intervalStatus = nextInterval(_txn, _workingSet, _collection);
+        StatusWith<CoveredInterval*> intervalStatus =
+            nextInterval(getOpCtx(), _workingSet, _collection);
         if (!intervalStatus.isOK()) {
             _searchState = SearchState_Finished;
             *error = intervalStatus.getStatus();
@@ -302,10 +302,6 @@ bool NearStage::isEOF() {
     return SearchState_Finished == _searchState;
 }
 
-void NearStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 void NearStage::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
     // If a result is in _resultBuffer and has a RecordId it will be in _seenDocuments as
     // well. It's safe to return the result w/o the RecordId, so just fetch the result.
diff --git a/src/mongo/db/exec/near.h b/src/mongo/db/exec/near.h
index 1a10d9143da..aee013cadc6 100644
--- a/src/mongo/db/exec/near.h
+++ b/src/mongo/db/exec/near.h
@@ -92,7 +92,6 @@ public:
     bool isEOF() final;
     StageState work(WorkingSetID* out) final;
 
-    void doReattachToOperationContext(OperationContext* opCtx) final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final;
@@ -161,8 +160,6 @@ private:
     //
 
     // Not owned here
-    OperationContext* _txn;
-    // Not owned here
     WorkingSet* const _workingSet;
     // Not owned here, used for fetching buffered results before invalidation
     Collection* const _collection;
diff --git a/src/mongo/db/exec/oplogstart.cpp b/src/mongo/db/exec/oplogstart.cpp
index f43272caf47..523889df14a 100644
--- a/src/mongo/db/exec/oplogstart.cpp
+++ b/src/mongo/db/exec/oplogstart.cpp
@@ -47,8 +47,7 @@ OplogStart::OplogStart(OperationContext* txn,
                        const Collection* collection,
                        MatchExpression* filter,
                        WorkingSet* ws)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _needInit(true),
       _backwardsScanning(false),
       _extentHopping(false),
@@ -63,7 +62,7 @@ PlanStage::StageState OplogStart::work(WorkingSetID* out) {
         CollectionScanParams params;
         params.collection = _collection;
         params.direction = CollectionScanParams::BACKWARD;
-        _children.emplace_back(new CollectionScan(_txn, params, _workingSet, NULL));
+        _children.emplace_back(new CollectionScan(getOpCtx(), params, _workingSet, NULL));
 
         _needInit = false;
         _backwardsScanning = true;
@@ -108,7 +107,7 @@ PlanStage::StageState OplogStart::workExtentHopping(WorkingSetID* out) {
                 WorkingSetID id = _workingSet->allocate();
                 WorkingSetMember* member = _workingSet->get(id);
                 member->loc = record->id;
-                member->obj = {_txn->recoveryUnit()->getSnapshotId(), std::move(obj)};
+                member->obj = {getOpCtx()->recoveryUnit()->getSnapshotId(), std::move(obj)};
                 _workingSet->transitionToLocAndObj(id);
                 *out = id;
                 return PlanStage::ADVANCED;
@@ -125,7 +124,7 @@ PlanStage::StageState OplogStart::workExtentHopping(WorkingSetID* out) {
 
 void OplogStart::switchToExtentHopping() {
     // Set up our extent hopping state.
-    _subIterators = _collection->getManyCursors(_txn);
+    _subIterators = _collection->getManyCursors(getOpCtx());
 
     // Transition from backwards scanning to extent hopping.
     _backwardsScanning = false;
@@ -197,17 +196,14 @@ void OplogStart::doRestoreState() {
 }
 
 void OplogStart::doDetachFromOperationContext() {
-    _txn = NULL;
     for (auto&& iterator : _subIterators) {
         iterator->detachFromOperationContext();
     }
 }
 
-void OplogStart::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void OplogStart::doReattachToOperationContext() {
     for (auto&& iterator : _subIterators) {
-        iterator->reattachToOperationContext(opCtx);
+        iterator->reattachToOperationContext(getOpCtx());
     }
 }
 
diff --git a/src/mongo/db/exec/oplogstart.h b/src/mongo/db/exec/oplogstart.h
index 033f51a8c9d..7d9c10e5df8 100644
--- a/src/mongo/db/exec/oplogstart.h
+++ b/src/mongo/db/exec/oplogstart.h
@@ -73,7 +73,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
 
     // Returns empty PlanStageStats object
     std::unique_ptr<PlanStageStats> getStats() final;
@@ -110,9 +110,6 @@ private:
 
     StageState workExtentHopping(WorkingSetID* out);
 
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // This is only used for the extent hopping scan.
     std::vector<std::unique_ptr<RecordCursor>> _subIterators;
 
diff --git a/src/mongo/db/exec/or.cpp b/src/mongo/db/exec/or.cpp
index f1ce36bdc5b..0bc195ca236 100644
--- a/src/mongo/db/exec/or.cpp
+++ b/src/mongo/db/exec/or.cpp
@@ -43,8 +43,8 @@ using stdx::make_unique;
 // static
 const char* OrStage::kStageType = "OR";
 
-OrStage::OrStage(WorkingSet* ws, bool dedup, const MatchExpression* filter)
-    : PlanStage(kStageType), _ws(ws), _filter(filter), _currentChild(0), _dedup(dedup) {}
+OrStage::OrStage(OperationContext* opCtx, WorkingSet* ws, bool dedup, const MatchExpression* filter)
+    : PlanStage(kStageType, opCtx), _ws(ws), _filter(filter), _currentChild(0), _dedup(dedup) {}
 
 void OrStage::addChild(PlanStage* child) {
     _children.emplace_back(child);
diff --git a/src/mongo/db/exec/or.h b/src/mongo/db/exec/or.h
index d0fd1a33209..ebe9d7bc10c 100644
--- a/src/mongo/db/exec/or.h
+++ b/src/mongo/db/exec/or.h
@@ -45,7 +45,7 @@ namespace mongo {
  */
 class OrStage final : public PlanStage {
 public:
-    OrStage(WorkingSet* ws, bool dedup, const MatchExpression* filter);
+    OrStage(OperationContext* opCtx, WorkingSet* ws, bool dedup, const MatchExpression* filter);
 
     void addChild(PlanStage* child);
 
diff --git a/src/mongo/db/exec/pipeline_proxy.cpp b/src/mongo/db/exec/pipeline_proxy.cpp
index 36e2eff10b6..e45318bf3ce 100644
--- a/src/mongo/db/exec/pipeline_proxy.cpp
+++ b/src/mongo/db/exec/pipeline_proxy.cpp
@@ -45,10 +45,11 @@ using stdx::make_unique;
 
 const char* PipelineProxyStage::kStageType = "PIPELINE_PROXY";
 
-PipelineProxyStage::PipelineProxyStage(intrusive_ptr<Pipeline> pipeline,
+PipelineProxyStage::PipelineProxyStage(OperationContext* opCtx,
+                                       intrusive_ptr<Pipeline> pipeline,
                                        const std::shared_ptr<PlanExecutor>& child,
                                        WorkingSet* ws)
-    : PlanStage(kStageType),
+    : PlanStage(kStageType, opCtx),
       _pipeline(pipeline),
       _includeMetaData(_pipeline->getContext()->inShard),  // send metadata to merger
       _childExec(child),
@@ -107,11 +108,11 @@ void PipelineProxyStage::doDetachFromOperationContext() {
     }
 }
 
-void PipelineProxyStage::doReattachToOperationContext(OperationContext* opCtx) {
+void PipelineProxyStage::doReattachToOperationContext() {
     invariant(_pipeline->getContext()->opCtx == NULL);
-    _pipeline->getContext()->opCtx = opCtx;
+    _pipeline->getContext()->opCtx = getOpCtx();
     if (auto child = getChildExecutor()) {
-        child->reattachToOperationContext(opCtx);
+        child->reattachToOperationContext(getOpCtx());
     }
 }
 
diff --git a/src/mongo/db/exec/pipeline_proxy.h b/src/mongo/db/exec/pipeline_proxy.h
index a67d993d4a3..6c85f117470 100644
--- a/src/mongo/db/exec/pipeline_proxy.h
+++ b/src/mongo/db/exec/pipeline_proxy.h
@@ -44,7 +44,8 @@ namespace mongo {
  */
 class PipelineProxyStage final : public PlanStage {
 public:
-    PipelineProxyStage(boost::intrusive_ptr<Pipeline> pipeline,
+    PipelineProxyStage(OperationContext* opCtx,
+                       boost::intrusive_ptr<Pipeline> pipeline,
                        const std::shared_ptr<PlanExecutor>& child,
                        WorkingSet* ws);
 
@@ -58,7 +59,7 @@ public:
     // Manage our OperationContext.
     //
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
 
     /**
      * Make obj the next object returned by getNext().
diff --git a/src/mongo/db/exec/plan_stage.cpp b/src/mongo/db/exec/plan_stage.cpp
index 13303e94acd..95fe9b0ed95 100644
--- a/src/mongo/db/exec/plan_stage.cpp
+++ b/src/mongo/db/exec/plan_stage.cpp
@@ -62,6 +62,9 @@ void PlanStage::invalidate(OperationContext* txn, const RecordId& dl, Invalidati
 }
 
 void PlanStage::detachFromOperationContext() {
+    invariant(_opCtx);
+    _opCtx = nullptr;
+
     for (auto&& child : _children) {
         child->detachFromOperationContext();
     }
@@ -70,11 +73,14 @@ void PlanStage::detachFromOperationContext() {
 }
 
 void PlanStage::reattachToOperationContext(OperationContext* opCtx) {
+    invariant(_opCtx == nullptr);
+    _opCtx = opCtx;
+
     for (auto&& child : _children) {
         child->reattachToOperationContext(opCtx);
     }
 
-    doReattachToOperationContext(opCtx);
+    doReattachToOperationContext();
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/exec/plan_stage.h b/src/mongo/db/exec/plan_stage.h
index cd552144def..6cef4247683 100644
--- a/src/mongo/db/exec/plan_stage.h
+++ b/src/mongo/db/exec/plan_stage.h
@@ -104,7 +104,8 @@ class OperationContext;
  */
 class PlanStage {
 public:
-    PlanStage(const char* typeName) : _commonStats(typeName) {}
+    PlanStage(const char* typeName, OperationContext* opCtx)
+        : _commonStats(typeName), _opCtx(opCtx) {}
 
     virtual ~PlanStage() {}
 
@@ -323,17 +324,18 @@ protected:
 
     /**
      * Does stage-specific detaching.
+     *
+     * Implementations of this method cannot use the pointer returned from getOpCtx().
      */
     virtual void doDetachFromOperationContext() {}
 
     /**
      * Does stage-specific attaching.
      *
-     * If the stage needs an OperationContext during its execution, it may keep a handle to the
-     * provided OperationContext (which is valid until the next call to
-     * doDetachFromOperationContext()).
+     * If an OperationContext* is needed, use getOpCtx(), which will return a valid
+     * OperationContext* (the one to which the stage is reattaching).
      */
-    virtual void doReattachToOperationContext(OperationContext* opCtx) {}
+    virtual void doReattachToOperationContext() {}
 
     /**
      * Does the stage-specific invalidation work.
@@ -350,8 +352,15 @@ protected:
         return _children.front();
     }
 
+    OperationContext* getOpCtx() const {
+        return _opCtx;
+    }
+
     Children _children;
     CommonStats _commonStats;
+
+private:
+    OperationContext* _opCtx;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/exec/projection.cpp b/src/mongo/db/exec/projection.cpp
index a5698a266ab..b03fd8f3175 100644
--- a/src/mongo/db/exec/projection.cpp
+++ b/src/mongo/db/exec/projection.cpp
@@ -52,10 +52,11 @@ static const char* kIdField = "_id";
 // static
 const char* ProjectionStage::kStageType = "PROJECTION";
 
-ProjectionStage::ProjectionStage(const ProjectionStageParams& params,
+ProjectionStage::ProjectionStage(OperationContext* opCtx,
+                                 const ProjectionStageParams& params,
                                  WorkingSet* ws,
                                  PlanStage* child)
-    : PlanStage(kStageType), _ws(ws), _projImpl(params.projImpl) {
+    : PlanStage(kStageType, opCtx), _ws(ws), _projImpl(params.projImpl) {
     _children.emplace_back(child);
     _projObj = params.projObj;
 
diff --git a/src/mongo/db/exec/projection.h b/src/mongo/db/exec/projection.h
index 58588b3c1dc..710a2374822 100644
--- a/src/mongo/db/exec/projection.h
+++ b/src/mongo/db/exec/projection.h
@@ -75,7 +75,10 @@ struct ProjectionStageParams {
  */
 class ProjectionStage final : public PlanStage {
 public:
-    ProjectionStage(const ProjectionStageParams& params, WorkingSet* ws, PlanStage* child);
+    ProjectionStage(OperationContext* opCtx,
+                    const ProjectionStageParams& params,
+                    WorkingSet* ws,
+                    PlanStage* child);
 
     bool isEOF() final;
     StageState work(WorkingSetID* out) final;
diff --git a/src/mongo/db/exec/queued_data_stage.cpp b/src/mongo/db/exec/queued_data_stage.cpp
index 36edcab1893..9ea015f9c62 100644
--- a/src/mongo/db/exec/queued_data_stage.cpp
+++ b/src/mongo/db/exec/queued_data_stage.cpp
@@ -40,7 +40,8 @@ using stdx::make_unique;
 
 const char* QueuedDataStage::kStageType = "QUEUED_DATA";
 
-QueuedDataStage::QueuedDataStage(WorkingSet* ws) : PlanStage(kStageType), _ws(ws) {}
+QueuedDataStage::QueuedDataStage(OperationContext* opCtx, WorkingSet* ws)
+    : PlanStage(kStageType, opCtx), _ws(ws) {}
 
 PlanStage::StageState QueuedDataStage::work(WorkingSetID* out) {
     ++_commonStats.works;
diff --git a/src/mongo/db/exec/queued_data_stage.h b/src/mongo/db/exec/queued_data_stage.h
index a3e57f6101f..7e44bc7f3d5 100644
--- a/src/mongo/db/exec/queued_data_stage.h
+++ b/src/mongo/db/exec/queued_data_stage.h
@@ -47,7 +47,7 @@ class RecordId;
  */
 class QueuedDataStage final : public PlanStage {
 public:
-    QueuedDataStage(WorkingSet* ws);
+    QueuedDataStage(OperationContext* opCtx, WorkingSet* ws);
 
     StageState work(WorkingSetID* out) final;
 
diff --git a/src/mongo/db/exec/queued_data_stage_test.cpp b/src/mongo/db/exec/queued_data_stage_test.cpp
index c3aa0e88d63..e26d303a833 100644
--- a/src/mongo/db/exec/queued_data_stage_test.cpp
+++ b/src/mongo/db/exec/queued_data_stage_test.cpp
@@ -32,6 +32,7 @@
 
 #include "mongo/db/exec/queued_data_stage.h"
 #include "mongo/db/exec/working_set.h"
+#include "mongo/stdx/memory.h"
 #include "mongo/unittest/unittest.h"
 
 using namespace mongo;
@@ -39,13 +40,14 @@ using namespace mongo;
 namespace {
 
 using std::unique_ptr;
+using stdx::make_unique;
 
 //
 // Basic test that we get out valid stats objects.
 //
 TEST(QueuedDataStageTest, getValidStats) {
     WorkingSet ws;
-    unique_ptr<QueuedDataStage> mock(new QueuedDataStage(&ws));
+    auto mock = make_unique<QueuedDataStage>(nullptr, &ws);
     const CommonStats* commonStats = mock->getCommonStats();
     ASSERT_EQUALS(commonStats->works, static_cast<size_t>(0));
     const SpecificStats* specificStats = mock->getSpecificStats();
@@ -60,7 +62,7 @@ TEST(QueuedDataStageTest, getValidStats) {
 TEST(QueuedDataStageTest, validateStats) {
     WorkingSet ws;
     WorkingSetID wsID;
-    unique_ptr<QueuedDataStage> mock(new QueuedDataStage(&ws));
+    auto mock = make_unique<QueuedDataStage>(nullptr, &ws);
 
     // make sure that we're at all zero
     const CommonStats* stats = mock->getCommonStats();
diff --git a/src/mongo/db/exec/shard_filter.cpp b/src/mongo/db/exec/shard_filter.cpp
index 1339e13bd3e..e62b1bc8549 100644
--- a/src/mongo/db/exec/shard_filter.cpp
+++ b/src/mongo/db/exec/shard_filter.cpp
@@ -50,10 +50,11 @@ using stdx::make_unique;
 // static
 const char* ShardFilterStage::kStageType = "SHARDING_FILTER";
 
-ShardFilterStage::ShardFilterStage(const shared_ptr<CollectionMetadata>& metadata,
+ShardFilterStage::ShardFilterStage(OperationContext* opCtx,
+                                   const shared_ptr<CollectionMetadata>& metadata,
                                    WorkingSet* ws,
                                    PlanStage* child)
-    : PlanStage(kStageType), _ws(ws), _metadata(metadata) {
+    : PlanStage(kStageType, opCtx), _ws(ws), _metadata(metadata) {
     _children.emplace_back(child);
 }
 
diff --git a/src/mongo/db/exec/shard_filter.h b/src/mongo/db/exec/shard_filter.h
index 393cdbe8975..88a86c3577a 100644
--- a/src/mongo/db/exec/shard_filter.h
+++ b/src/mongo/db/exec/shard_filter.h
@@ -71,7 +71,8 @@ class CollectionMetadata;
  */
 class ShardFilterStage final : public PlanStage {
 public:
-    ShardFilterStage(const std::shared_ptr<CollectionMetadata>& metadata,
+    ShardFilterStage(OperationContext* opCtx,
+                     const std::shared_ptr<CollectionMetadata>& metadata,
                      WorkingSet* ws,
                      PlanStage* child);
     ~ShardFilterStage();
diff --git a/src/mongo/db/exec/skip.cpp b/src/mongo/db/exec/skip.cpp
index 140c4a1bdb9..15f829ed8bd 100644
--- a/src/mongo/db/exec/skip.cpp
+++ b/src/mongo/db/exec/skip.cpp
@@ -41,8 +41,8 @@ using stdx::make_unique;
 // static
 const char* SkipStage::kStageType = "SKIP";
 
-SkipStage::SkipStage(long long toSkip, WorkingSet* ws, PlanStage* child)
-    : PlanStage(kStageType), _ws(ws), _toSkip(toSkip) {
+SkipStage::SkipStage(OperationContext* opCtx, long long toSkip, WorkingSet* ws, PlanStage* child)
+    : PlanStage(kStageType, opCtx), _ws(ws), _toSkip(toSkip) {
     _children.emplace_back(child);
 }
 
diff --git a/src/mongo/db/exec/skip.h b/src/mongo/db/exec/skip.h
index 45e01bbd120..e97a75b9b64 100644
--- a/src/mongo/db/exec/skip.h
+++ b/src/mongo/db/exec/skip.h
@@ -43,7 +43,7 @@ namespace mongo {
  */
 class SkipStage final : public PlanStage {
 public:
-    SkipStage(long long toSkip, WorkingSet* ws, PlanStage* child);
+    SkipStage(OperationContext* opCtx, long long toSkip, WorkingSet* ws, PlanStage* child);
     ~SkipStage();
 
     bool isEOF() final;
diff --git a/src/mongo/db/exec/sort.cpp b/src/mongo/db/exec/sort.cpp
index 18bb6b2faa0..b61fa7e7982 100644
--- a/src/mongo/db/exec/sort.cpp
+++ b/src/mongo/db/exec/sort.cpp
@@ -278,8 +278,11 @@ bool SortStage::WorkingSetComparator::operator()(const SortableDataItem& lhs,
     return lhs.loc < rhs.loc;
 }
 
-SortStage::SortStage(const SortStageParams& params, WorkingSet* ws, PlanStage* child)
-    : PlanStage(kStageType),
+SortStage::SortStage(OperationContext* opCtx,
+                     const SortStageParams& params,
+                     WorkingSet* ws,
+                     PlanStage* child)
+    : PlanStage(kStageType, opCtx),
       _collection(params.collection),
       _ws(ws),
       _pattern(params.pattern),
diff --git a/src/mongo/db/exec/sort.h b/src/mongo/db/exec/sort.h
index f0a29b84efc..2d9f4e6c331 100644
--- a/src/mongo/db/exec/sort.h
+++ b/src/mongo/db/exec/sort.h
@@ -141,7 +141,10 @@ private:
  */
 class SortStage final : public PlanStage {
 public:
-    SortStage(const SortStageParams& params, WorkingSet* ws, PlanStage* child);
+    SortStage(OperationContext* opCtx,
+              const SortStageParams& params,
+              WorkingSet* ws,
+              PlanStage* child);
     ~SortStage();
 
     bool isEOF() final;
diff --git a/src/mongo/db/exec/sort_test.cpp b/src/mongo/db/exec/sort_test.cpp
index a60146ef1f9..a998304028d 100644
--- a/src/mongo/db/exec/sort_test.cpp
+++ b/src/mongo/db/exec/sort_test.cpp
@@ -45,9 +45,9 @@ TEST(SortStageTest, SortEmptyWorkingSet) {
     WorkingSet ws;
 
     // QueuedDataStage will be owned by SortStage.
-    QueuedDataStage* ms = new QueuedDataStage(&ws);
+    QueuedDataStage* ms = new QueuedDataStage(nullptr, &ws);
     SortStageParams params;
-    SortStage sort(params, &ws, ms);
+    SortStage sort(nullptr, params, &ws, ms);
 
     // Check initial EOF state.
     ASSERT_TRUE(ms->isEOF());
@@ -87,7 +87,7 @@ void testWork(const char* patternStr,
     WorkingSet ws;
 
     // QueuedDataStage will be owned by SortStage.
-    QueuedDataStage* ms = new QueuedDataStage(&ws);
+    QueuedDataStage* ms = new QueuedDataStage(nullptr, &ws);
     BSONObj inputObj = fromjson(inputStr);
     BSONElement inputElt = inputObj.getField("input");
     ASSERT(inputElt.isABSONObj());
@@ -112,7 +112,7 @@ void testWork(const char* patternStr,
     params.query = fromjson(queryStr);
     params.limit = limit;
 
-    SortStage sort(params, &ws, ms);
+    SortStage sort(nullptr, params, &ws, ms);
 
     WorkingSetID id = WorkingSet::INVALID_ID;
     PlanStage::StageState state = PlanStage::NEED_TIME;
diff --git a/src/mongo/db/exec/stagedebug_cmd.cpp b/src/mongo/db/exec/stagedebug_cmd.cpp
index 38bffc6dcb0..765b851d89b 100644
--- a/src/mongo/db/exec/stagedebug_cmd.cpp
+++ b/src/mongo/db/exec/stagedebug_cmd.cpp
@@ -273,7 +273,7 @@ public:
             uassert(
                 16921, "Nodes argument must be provided to AND", nodeArgs["nodes"].isABSONObj());
 
-            unique_ptr<AndHashStage> andStage(new AndHashStage(workingSet, collection));
+            auto andStage = make_unique<AndHashStage>(txn, workingSet, collection);
 
             int nodesAdded = 0;
             BSONObjIterator it(nodeArgs["nodes"].Obj());
@@ -296,7 +296,7 @@ public:
             uassert(
                 16924, "Nodes argument must be provided to AND", nodeArgs["nodes"].isABSONObj());
 
-            unique_ptr<AndSortedStage> andStage(new AndSortedStage(workingSet, collection));
+            auto andStage = make_unique<AndSortedStage>(txn, workingSet, collection);
 
             int nodesAdded = 0;
             BSONObjIterator it(nodeArgs["nodes"].Obj());
@@ -320,7 +320,7 @@ public:
                 16934, "Nodes argument must be provided to AND", nodeArgs["nodes"].isABSONObj());
             uassert(16935, "Dedup argument must be provided to OR", !nodeArgs["dedup"].eoo());
             BSONObjIterator it(nodeArgs["nodes"].Obj());
-            unique_ptr<OrStage> orStage(new OrStage(workingSet, nodeArgs["dedup"].Bool(), matcher));
+            auto orStage = make_unique<OrStage>(txn, workingSet, nodeArgs["dedup"].Bool(), matcher);
             while (it.more()) {
                 BSONElement e = it.next();
                 if (!e.isABSONObj()) {
@@ -354,7 +354,7 @@ public:
             uassert(28732,
                     "Can't parse sub-node of LIMIT: " + nodeArgs["node"].Obj().toString(),
                     NULL != subNode);
-            return new LimitStage(nodeArgs["num"].numberInt(), workingSet, subNode);
+            return new LimitStage(txn, nodeArgs["num"].numberInt(), workingSet, subNode);
         } else if ("skip" == nodeName) {
             uassert(
                 16938, "Skip stage doesn't have a filter (put it on the child)", NULL == matcher);
@@ -365,7 +365,7 @@ public:
             uassert(28733,
                     "Can't parse sub-node of SKIP: " + nodeArgs["node"].Obj().toString(),
                     NULL != subNode);
-            return new SkipStage(nodeArgs["num"].numberInt(), workingSet, subNode);
+            return new SkipStage(txn, nodeArgs["num"].numberInt(), workingSet, subNode);
         } else if ("cscan" == nodeName) {
             CollectionScanParams params;
             params.collection = collection;
@@ -406,8 +406,7 @@ public:
             params.pattern = nodeArgs["pattern"].Obj();
             // Dedup is true by default.
 
-            unique_ptr<MergeSortStage> mergeStage(
-                new MergeSortStage(params, workingSet, collection));
+            auto mergeStage = make_unique<MergeSortStage>(txn, params, workingSet, collection);
 
             BSONObjIterator it(nodeArgs["nodes"].Obj());
             while (it.more()) {
diff --git a/src/mongo/db/exec/subplan.cpp b/src/mongo/db/exec/subplan.cpp
index 7c6e5584d13..ccdc040bc38 100644
--- a/src/mongo/db/exec/subplan.cpp
+++ b/src/mongo/db/exec/subplan.cpp
@@ -59,8 +59,7 @@ SubplanStage::SubplanStage(OperationContext* txn,
                            WorkingSet* ws,
                            const QueryPlannerParams& params,
                            CanonicalQuery* cq)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _collection(collection),
       _ws(ws),
       _plannerParams(params),
@@ -186,7 +185,7 @@ Status SubplanStage::planSubqueries() {
         LOG(5) << "Subplanner: index " << i << " is " << ie.toString();
     }
 
-    const WhereCallbackReal whereCallback(_txn, _collection->ns().db());
+    const WhereCallbackReal whereCallback(getOpCtx(), _collection->ns().db());
 
     for (size_t i = 0; i < _orExpression->numChildren(); ++i) {
         // We need a place to shove the results from planning this branch.
@@ -323,13 +322,14 @@ Status SubplanStage::choosePlanForSubqueries(PlanYieldPolicy* yieldPolicy) {
 
             _ws->clear();
 
-            MultiPlanStage multiPlanStage(_txn, _collection, branchResult->canonicalQuery.get());
+            MultiPlanStage multiPlanStage(
+                getOpCtx(), _collection, branchResult->canonicalQuery.get());
 
             // Dump all the solutions into the MPS.
             for (size_t ix = 0; ix < branchResult->solutions.size(); ++ix) {
                 PlanStage* nextPlanRoot;
                 invariant(StageBuilder::build(
-                    _txn, _collection, *branchResult->solutions[ix], _ws, &nextPlanRoot));
+                    getOpCtx(), _collection, *branchResult->solutions[ix], _ws, &nextPlanRoot));
 
                 // Takes ownership of solution with index 'ix' and 'nextPlanRoot'.
                 multiPlanStage.addPlan(branchResult->solutions.releaseAt(ix), nextPlanRoot, _ws);
@@ -408,7 +408,7 @@ Status SubplanStage::choosePlanForSubqueries(PlanYieldPolicy* yieldPolicy) {
     // and set that solution as our child stage.
     _ws->clear();
     PlanStage* root;
-    invariant(StageBuilder::build(_txn, _collection, *_compositeSolution.get(), _ws, &root));
+    invariant(StageBuilder::build(getOpCtx(), _collection, *_compositeSolution.get(), _ws, &root));
     invariant(_children.empty());
     _children.emplace_back(root);
 
@@ -441,7 +441,7 @@ Status SubplanStage::choosePlanWholeQuery(PlanYieldPolicy* yieldPolicy) {
     if (1 == solutions.size()) {
         PlanStage* root;
         // Only one possible plan.  Run it.  Build the stages from the solution.
-        verify(StageBuilder::build(_txn, _collection, *solutions[0], _ws, &root));
+        verify(StageBuilder::build(getOpCtx(), _collection, *solutions[0], _ws, &root));
         invariant(_children.empty());
         _children.emplace_back(root);
 
@@ -453,7 +453,7 @@ Status SubplanStage::choosePlanWholeQuery(PlanYieldPolicy* yieldPolicy) {
         // Many solutions. Create a MultiPlanStage to pick the best, update the cache,
         // and so on. The working set will be shared by all candidate plans.
         invariant(_children.empty());
-        _children.emplace_back(new MultiPlanStage(_txn, _collection, _query));
+        _children.emplace_back(new MultiPlanStage(getOpCtx(), _collection, _query));
         MultiPlanStage* multiPlanStage = static_cast<MultiPlanStage*>(child().get());
 
         for (size_t ix = 0; ix < solutions.size(); ++ix) {
@@ -463,7 +463,8 @@ Status SubplanStage::choosePlanWholeQuery(PlanYieldPolicy* yieldPolicy) {
 
             // version of StageBuild::build when WorkingSet is shared
             PlanStage* nextPlanRoot;
-            verify(StageBuilder::build(_txn, _collection, *solutions[ix], _ws, &nextPlanRoot));
+            verify(
+                StageBuilder::build(getOpCtx(), _collection, *solutions[ix], _ws, &nextPlanRoot));
 
             // Takes ownership of 'solutions[ix]' and 'nextPlanRoot'.
             multiPlanStage->addPlan(solutions.releaseAt(ix), nextPlanRoot, _ws);
@@ -530,10 +531,6 @@ PlanStage::StageState SubplanStage::work(WorkingSetID* out) {
     return state;
 }
 
-void SubplanStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 unique_ptr<PlanStageStats> SubplanStage::getStats() {
     _commonStats.isEOF = isEOF();
     unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_SUBPLAN);
diff --git a/src/mongo/db/exec/subplan.h b/src/mongo/db/exec/subplan.h
index 47b54eea46f..bbb401d337a 100644
--- a/src/mongo/db/exec/subplan.h
+++ b/src/mongo/db/exec/subplan.h
@@ -77,8 +77,6 @@ public:
     bool isEOF() final;
     StageState work(WorkingSetID* out) final;
 
-    void doReattachToOperationContext(OperationContext* opCtx) final;
-
     StageType stageType() const final {
         return STAGE_SUBPLAN;
     }
@@ -174,9 +172,6 @@ private:
      */
     Status choosePlanWholeQuery(PlanYieldPolicy* yieldPolicy);
 
-    // transactional context for read locks. Not owned by us
-    OperationContext* _txn;
-
     // Not owned here. Must be non-null.
     Collection* _collection;
 
diff --git a/src/mongo/db/exec/text.cpp b/src/mongo/db/exec/text.cpp
index b7cc0789286..2988fa1a305 100644
--- a/src/mongo/db/exec/text.cpp
+++ b/src/mongo/db/exec/text.cpp
@@ -60,7 +60,7 @@ TextStage::TextStage(OperationContext* txn,
                      const TextStageParams& params,
                      WorkingSet* ws,
                      const MatchExpression* filter)
-    : PlanStage(kStageType), _params(params) {
+    : PlanStage(kStageType, txn), _params(params) {
     _children.emplace_back(buildTextTree(txn, ws, filter));
     _specificStats.indexPrefix = _params.indexPrefix;
     _specificStats.indexName = _params.index->indexName();
@@ -138,7 +138,8 @@ unique_ptr<PlanStage> TextStage::buildTextTree(OperationContext* txn,
     auto fetcher = make_unique<FetchStage>(
         txn, ws, textScorer.release(), nullptr, _params.index->getCollection());
 
-    auto matcher = make_unique<TextMatchStage>(std::move(fetcher), _params.query, _params.spec, ws);
+    auto matcher =
+        make_unique<TextMatchStage>(txn, std::move(fetcher), _params.query, _params.spec, ws);
 
     unique_ptr<PlanStage> treeRoot = std::move(matcher);
     return treeRoot;
diff --git a/src/mongo/db/exec/text_match.cpp b/src/mongo/db/exec/text_match.cpp
index bf92b38a57b..6e5ffe951e6 100644
--- a/src/mongo/db/exec/text_match.cpp
+++ b/src/mongo/db/exec/text_match.cpp
@@ -45,11 +45,12 @@ using stdx::make_unique;
 
 const char* TextMatchStage::kStageType = "TEXT_MATCH";
 
-TextMatchStage::TextMatchStage(unique_ptr<PlanStage> child,
+TextMatchStage::TextMatchStage(OperationContext* opCtx,
+                               unique_ptr<PlanStage> child,
                                const FTSQuery& query,
                                const FTSSpec& spec,
                                WorkingSet* ws)
-    : PlanStage(kStageType), _ftsMatcher(query, spec), _ws(ws) {
+    : PlanStage(kStageType, opCtx), _ftsMatcher(query, spec), _ws(ws) {
     _children.emplace_back(std::move(child));
 }
 
diff --git a/src/mongo/db/exec/text_match.h b/src/mongo/db/exec/text_match.h
index df3e3b9ae68..7b707efda5b 100644
--- a/src/mongo/db/exec/text_match.h
+++ b/src/mongo/db/exec/text_match.h
@@ -57,7 +57,8 @@ class RecordID;
  */
 class TextMatchStage final : public PlanStage {
 public:
-    TextMatchStage(unique_ptr<PlanStage> child,
+    TextMatchStage(OperationContext* opCtx,
+                   unique_ptr<PlanStage> child,
                    const FTSQuery& query,
                    const FTSSpec& spec,
                    WorkingSet* ws);
diff --git a/src/mongo/db/exec/text_or.cpp b/src/mongo/db/exec/text_or.cpp
index bbdbabdd4d0..bf45ba45ec6 100644
--- a/src/mongo/db/exec/text_or.cpp
+++ b/src/mongo/db/exec/text_or.cpp
@@ -59,12 +59,11 @@ TextOrStage::TextOrStage(OperationContext* txn,
                          WorkingSet* ws,
                          const MatchExpression* filter,
                          IndexDescriptor* index)
-    : PlanStage(kStageType),
+    : PlanStage(kStageType, txn),
       _ftsSpec(ftsSpec),
       _ws(ws),
       _scoreIterator(_scores.end()),
       _filter(filter),
-      _txn(txn),
       _idRetrying(WorkingSet::INVALID_ID),
       _index(index) {}
 
@@ -91,16 +90,13 @@ void TextOrStage::doRestoreState() {
 }
 
 void TextOrStage::doDetachFromOperationContext() {
-    _txn = NULL;
     if (_recordCursor)
         _recordCursor->detachFromOperationContext();
 }
 
-void TextOrStage::doReattachToOperationContext(OperationContext* opCtx) {
-    invariant(_txn == NULL);
-    _txn = opCtx;
+void TextOrStage::doReattachToOperationContext() {
     if (_recordCursor)
-        _recordCursor->reattachToOperationContext(opCtx);
+        _recordCursor->reattachToOperationContext(getOpCtx());
 }
 
 void TextOrStage::doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
@@ -186,7 +182,7 @@ PlanStage::StageState TextOrStage::work(WorkingSetID* out) {
 PlanStage::StageState TextOrStage::initStage(WorkingSetID* out) {
     *out = WorkingSet::INVALID_ID;
     try {
-        _recordCursor = _index->getCollection()->getCursor(_txn);
+        _recordCursor = _index->getCollection()->getCursor(getOpCtx());
         _internalState = State::kReadingTerms;
         return PlanStage::NEED_TIME;
     } catch (const WriteConflictException& wce) {
@@ -369,8 +365,12 @@ PlanStage::StageState TextOrStage::addTerm(WorkingSetID wsid, WorkingSetID* out)
             bool shouldKeep;
             bool wasDeleted = false;
             try {
-                TextMatchableDocument tdoc(
-                    _txn, newKeyData.indexKeyPattern, newKeyData.keyData, _ws, wsid, _recordCursor);
+                TextMatchableDocument tdoc(getOpCtx(),
+                                           newKeyData.indexKeyPattern,
+                                           newKeyData.keyData,
+                                           _ws,
+                                           wsid,
+                                           _recordCursor);
                 shouldKeep = _filter->matches(&tdoc);
             } catch (const WriteConflictException& wce) {
                 _idRetrying = wsid;
diff --git a/src/mongo/db/exec/text_or.h b/src/mongo/db/exec/text_or.h
index 5d9df26f439..0b86ad145b1 100644
--- a/src/mongo/db/exec/text_or.h
+++ b/src/mongo/db/exec/text_or.h
@@ -89,7 +89,7 @@ public:
     void doSaveState() final;
     void doRestoreState() final;
     void doDetachFromOperationContext() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
+    void doReattachToOperationContext() final;
     void doInvalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) final;
 
     StageType stageType() const final {
@@ -157,7 +157,6 @@ private:
 
     // Members needed only for using the TextMatchableDocument.
     const MatchExpression* _filter;
-    OperationContext* _txn;
     WorkingSetID _idRetrying;
     std::unique_ptr<RecordCursor> _recordCursor;
     IndexDescriptor* _index;
diff --git a/src/mongo/db/exec/update.cpp b/src/mongo/db/exec/update.cpp
index a5147ed6e3b..05c44190b5e 100644
--- a/src/mongo/db/exec/update.cpp
+++ b/src/mongo/db/exec/update.cpp
@@ -415,8 +415,7 @@ UpdateStage::UpdateStage(OperationContext* txn,
                          WorkingSet* ws,
                          Collection* collection,
                          PlanStage* child)
-    : PlanStage(kStageType),
-      _txn(txn),
+    : PlanStage(kStageType, txn),
       _params(params),
       _ws(ws),
       _collection(collection),
@@ -506,7 +505,7 @@ BSONObj UpdateStage::transformAndUpdate(const Snapshotted<BSONObj>& oldObj, Reco
     if (docWasModified) {
         // Verify that no immutable fields were changed and data is valid for storage.
 
-        if (!(!_txn->writesAreReplicated() || request->isFromMigration())) {
+        if (!(!getOpCtx()->writesAreReplicated() || request->isFromMigration())) {
             const std::vector<FieldRef*>* immutableFields = NULL;
             if (lifecycle)
                 immutableFields = lifecycle->getImmutableFields();
@@ -516,7 +515,7 @@ BSONObj UpdateStage::transformAndUpdate(const Snapshotted<BSONObj>& oldObj, Reco
         }
 
         // Prepare to write back the modified document
-        WriteUnitOfWork wunit(_txn);
+        WriteUnitOfWork wunit(getOpCtx());
 
         RecordId newLoc;
 
@@ -532,7 +531,7 @@ BSONObj UpdateStage::transformAndUpdate(const Snapshotted<BSONObj>& oldObj, Reco
                 args.criteria = idQuery;
                 args.fromMigrate = request->isFromMigration();
                 _collection->updateDocumentWithDamages(
-                    _txn,
+                    getOpCtx(),
                     loc,
                     Snapshotted<RecordData>(oldObj.snapshotId(), oldRec),
                     source,
@@ -559,7 +558,7 @@ BSONObj UpdateStage::transformAndUpdate(const Snapshotted<BSONObj>& oldObj, Reco
                 args.update = logObj;
                 args.criteria = idQuery;
                 args.fromMigrate = request->isFromMigration();
-                StatusWith<RecordId> res = _collection->updateDocument(_txn,
+                StatusWith<RecordId> res = _collection->updateDocument(getOpCtx(),
                                                                        loc,
                                                                        oldObj,
                                                                        newObj,
@@ -572,7 +571,7 @@ BSONObj UpdateStage::transformAndUpdate(const Snapshotted<BSONObj>& oldObj, Reco
             }
         }
 
-        invariant(oldObj.snapshotId() == _txn->recoveryUnit()->getSnapshotId());
+        invariant(oldObj.snapshotId() == getOpCtx()->recoveryUnit()->getSnapshotId());
         wunit.commit();
 
         // If the document moved, we might see it again in a collection scan (maybe it's
@@ -676,7 +675,7 @@ void UpdateStage::doInsert() {
     _specificStats.inserted = true;
 
     const UpdateRequest* request = _params.request;
-    bool isInternalRequest = !_txn->writesAreReplicated() || request->isFromMigration();
+    bool isInternalRequest = !getOpCtx()->writesAreReplicated() || request->isFromMigration();
 
     // Reset the document we will be writing to.
     _doc.reset();
@@ -698,17 +697,17 @@ void UpdateStage::doInsert() {
         return;
     }
     MONGO_WRITE_CONFLICT_RETRY_LOOP_BEGIN {
-        WriteUnitOfWork wunit(_txn);
+        WriteUnitOfWork wunit(getOpCtx());
         invariant(_collection);
         const bool enforceQuota = !request->isGod();
-        uassertStatusOK(
-            _collection->insertDocument(_txn, newObj, enforceQuota, request->isFromMigration()));
+        uassertStatusOK(_collection->insertDocument(
+            getOpCtx(), newObj, enforceQuota, request->isFromMigration()));
 
         // Technically, we should save/restore state here, but since we are going to return
         // immediately after, it would just be wasted work.
         wunit.commit();
     }
-    MONGO_WRITE_CONFLICT_RETRY_LOOP_END(_txn, "upsert", _collection->ns().ns());
+    MONGO_WRITE_CONFLICT_RETRY_LOOP_END(getOpCtx(), "upsert", _collection->ns().ns());
 }
 
 bool UpdateStage::doneUpdating() {
@@ -757,8 +756,8 @@ PlanStage::StageState UpdateStage::work(WorkingSetID* out) {
                 BSONObj newObj = _specificStats.objInserted;
                 *out = _ws->allocate();
                 WorkingSetMember* member = _ws->get(*out);
-                member->obj =
-                    Snapshotted<BSONObj>(_txn->recoveryUnit()->getSnapshotId(), newObj.getOwned());
+                member->obj = Snapshotted<BSONObj>(getOpCtx()->recoveryUnit()->getSnapshotId(),
+                                                   newObj.getOwned());
                 member->transitionToOwnedObj();
                 ++_commonStats.advanced;
                 return PlanStage::ADVANCED;
@@ -835,10 +834,10 @@ PlanStage::StageState UpdateStage::work(WorkingSetID* out) {
 
         try {
             std::unique_ptr<RecordCursor> cursor;
-            if (_txn->recoveryUnit()->getSnapshotId() != member->obj.snapshotId()) {
-                cursor = _collection->getCursor(_txn);
+            if (getOpCtx()->recoveryUnit()->getSnapshotId() != member->obj.snapshotId()) {
+                cursor = _collection->getCursor(getOpCtx());
                 // our snapshot has changed, refetch
-                if (!WorkingSetCommon::fetch(_txn, _ws, id, cursor)) {
+                if (!WorkingSetCommon::fetch(getOpCtx(), _ws, id, cursor)) {
                     // document was deleted, we're done here
                     ++_commonStats.needTime;
                     return PlanStage::NEED_TIME;
@@ -877,7 +876,7 @@ PlanStage::StageState UpdateStage::work(WorkingSetID* out) {
             // Set member's obj to be the doc we want to return.
             if (_params.request->shouldReturnAnyDocs()) {
                 if (_params.request->shouldReturnNewDocs()) {
-                    member->obj = Snapshotted<BSONObj>(_txn->recoveryUnit()->getSnapshotId(),
+                    member->obj = Snapshotted<BSONObj>(getOpCtx()->recoveryUnit()->getSnapshotId(),
                                                        newObj.getOwned());
                 } else {
                     invariant(_params.request->shouldReturnOldDocs());
@@ -963,7 +962,7 @@ Status UpdateStage::restoreUpdateState() {
     const NamespaceString& nsString(request.getNamespaceString());
 
     // We may have stepped down during the yield.
-    bool userInitiatedWritesAndNotPrimary = _txn->writesAreReplicated() &&
+    bool userInitiatedWritesAndNotPrimary = getOpCtx()->writesAreReplicated() &&
         !repl::getGlobalReplicationCoordinator()->canAcceptWritesFor(nsString);
 
     if (userInitiatedWritesAndNotPrimary) {
@@ -982,7 +981,7 @@ Status UpdateStage::restoreUpdateState() {
                           17270);
         }
 
-        _params.driver->refreshIndexKeys(lifecycle->getIndexKeys(_txn));
+        _params.driver->refreshIndexKeys(lifecycle->getIndexKeys(getOpCtx()));
     }
 
     return Status::OK();
@@ -992,10 +991,6 @@ void UpdateStage::doRestoreState() {
     uassertStatusOK(restoreUpdateState());
 }
 
-void UpdateStage::doReattachToOperationContext(OperationContext* opCtx) {
-    _txn = opCtx;
-}
-
 unique_ptr<PlanStageStats> UpdateStage::getStats() {
     _commonStats.isEOF = isEOF();
     unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_UPDATE);
diff --git a/src/mongo/db/exec/update.h b/src/mongo/db/exec/update.h
index 87859c9ff5f..a6427ee7f20 100644
--- a/src/mongo/db/exec/update.h
+++ b/src/mongo/db/exec/update.h
@@ -85,7 +85,6 @@ public:
     StageState work(WorkingSetID* out) final;
 
     void doRestoreState() final;
-    void doReattachToOperationContext(OperationContext* opCtx) final;
 
     StageType stageType() const final {
         return STAGE_UPDATE;
@@ -166,9 +165,6 @@ private:
      */
     Status restoreUpdateState();
 
-    // Transactional context.  Not owned by us.
-    OperationContext* _txn;
-
     UpdateStageParams _params;
 
     // Not owned by us.