SERVER-50984 Add CollectionPtr to replace usage of const Collection*

It implements a yieldable interface that is used to re-load the
Collection pointer from the catalog after a yield that released locks.
With lock-free reads and copy-on-write on Collection instances releasing
locks without notifying an AutoGetCollection at a higher level may cause
its pointers to dangle if a MODE_X writer installs a new Collection
instance in the catalog.

CollectionPtr should be passed by const reference so a yield can notify
all the way up.

1 files changed, 8 insertions, 8 deletions

diff --git a/src/mongo/db/exec/geo_near.h b/src/mongo/db/exec/geo_near.h
index 08001ecc77c..d29d7536bea 100644
--- a/src/mongo/db/exec/geo_near.h
+++ b/src/mongo/db/exec/geo_near.h
@@ -71,13 +71,13 @@ public:
     GeoNear2DStage(const GeoNearParams& nearParams,
                    ExpressionContext* expCtx,
                    WorkingSet* workingSet,
-                   const Collection* collection,
+                   const CollectionPtr& collection,
                    const IndexDescriptor* twoDIndex);
 
 protected:
     std::unique_ptr<CoveredInterval> nextInterval(OperationContext* opCtx,
                                                   WorkingSet* workingSet,
-                                                  const Collection* collection) final;
+                                                  const CollectionPtr& collection) final;
 
     double computeDistance(WorkingSetMember* member) final;
 
@@ -88,7 +88,7 @@ protected:
 private:
     class DensityEstimator {
     public:
-        DensityEstimator(const Collection* collection,
+        DensityEstimator(const CollectionPtr& collection,
                          PlanStage::Children* children,
                          BSONObj infoObj,
                          const GeoNearParams* nearParams,
@@ -105,7 +105,7 @@ private:
                             WorkingSet* workingSet,
                             const IndexDescriptor* twoDIndex);
 
-        const Collection* _collection;
+        const CollectionPtr& _collection;
         PlanStage::Children* _children;    // Points to PlanStage::_children in the NearStage.
         const GeoNearParams* _nearParams;  // Not owned here.
         const R2Annulus& _fullBounds;
@@ -140,13 +140,13 @@ public:
     GeoNear2DSphereStage(const GeoNearParams& nearParams,
                          ExpressionContext* expCtx,
                          WorkingSet* workingSet,
-                         const Collection* collection,
+                         const CollectionPtr& collection,
                          const IndexDescriptor* s2Index);
 
 protected:
     std::unique_ptr<CoveredInterval> nextInterval(OperationContext* opCtx,
                                                   WorkingSet* workingSet,
-                                                  const Collection* collection) final;
+                                                  const CollectionPtr& collection) final;
 
     double computeDistance(WorkingSetMember* member) final;
 
@@ -158,7 +158,7 @@ private:
     // Estimate the density of data by search the nearest cells level by level around center.
     class DensityEstimator {
     public:
-        DensityEstimator(const Collection* collection,
+        DensityEstimator(const CollectionPtr& collection,
                          PlanStage::Children* children,
                          const GeoNearParams* nearParams,
                          const S2IndexingParams& indexParams,
@@ -177,7 +177,7 @@ private:
                             WorkingSet* workingSet,
                             const IndexDescriptor* s2Index);
 
-        const Collection* _collection;
+        const CollectionPtr& _collection;
         PlanStage::Children* _children;    // Points to PlanStage::_children in the NearStage.
         const GeoNearParams* _nearParams;  // Not owned here.
         const S2IndexingParams _indexParams;