SERVER-6405: don't throw away Collection* across yield

4 files changed, 28 insertions, 24 deletions

diff --git a/src/mongo/db/structure/collection.cpp b/src/mongo/db/structure/collection.cpp
index 57f523a53e6..128d3efe160 100644
--- a/src/mongo/db/structure/collection.cpp
+++ b/src/mongo/db/structure/collection.cpp
@@ -32,10 +32,17 @@ namespace mongo {
         _ns = fullNS.toString();
         _details = details;
         _database = database;
+        _magic = 1357924;
+    }
+
+    CollectionTemp::~CollectionTemp() {
+        verify( ok() );
+        _magic = 0;
     }
 
     CollectionIterator* CollectionTemp::getIterator( const DiskLoc& start, bool tailable,
                                                      const CollectionScanParams::Direction& dir) const {
+        verify( ok() );
         if ( _details->isCapped() )
             return new CappedIterator( _ns, start, tailable, dir );
         return new FlatIterator( this, start, dir );
@@ -43,10 +50,12 @@ namespace mongo {
 
 
     ExtentManager* CollectionTemp::getExtentManager() {
+        verify( ok() );
         return &_database->getExtentManager();
     }
 
     const ExtentManager* CollectionTemp::getExtentManager() const {
+        verify( ok() );
         return &_database->getExtentManager();
     }
 
diff --git a/src/mongo/db/structure/collection.h b/src/mongo/db/structure/collection.h
index e577a8a307d..95443235cba 100644
--- a/src/mongo/db/structure/collection.h
+++ b/src/mongo/db/structure/collection.h
@@ -44,6 +44,10 @@ namespace mongo {
                         NamespaceDetails* details,
                         Database* database );
 
+        ~CollectionTemp();
+
+        bool ok() const { return _magic == 1357924; }
+
         StringData ns() const { return _ns; }
 
         CollectionIterator* getIterator( const DiskLoc& start, bool tailable,
@@ -54,6 +58,8 @@ namespace mongo {
         ExtentManager* getExtentManager();
         const ExtentManager* getExtentManager() const;
 
+        int _magic;
+
         std::string _ns; // TODO: this copy might be annoyingly slow
         NamespaceDetails* _details;
         Database* _database;
diff --git a/src/mongo/db/structure/collection_iterator.cpp b/src/mongo/db/structure/collection_iterator.cpp
index 9f8f00e8e7d..41c6f4a2d95 100644
--- a/src/mongo/db/structure/collection_iterator.cpp
+++ b/src/mongo/db/structure/collection_iterator.cpp
@@ -16,7 +16,12 @@
 
 #include "mongo/db/structure/collection_iterator.h"
 
-#include "mongo/db/pdfile.h"
+#include "mongo/db/namespace_details.h"
+#include "mongo/db/storage/extent.h"
+#include "mongo/db/storage/extent_manager.h"
+#include "mongo/db/structure/collection.h"
+
+#include "mongo/db/pdfile.h" // XXX-ERH
 
 namespace mongo {
 
@@ -27,7 +32,7 @@ namespace mongo {
     FlatIterator::FlatIterator(const CollectionTemp* collection,
                                const DiskLoc& start,
                                const CollectionScanParams::Direction& dir)
-        : _curr(start), _ns(collection->ns().toString()), _collection(collection), _direction(dir) {
+        : _curr(start), _collection(collection), _direction(dir) {
 
         if (_curr.isNull()) {
 
@@ -85,37 +90,24 @@ namespace mongo {
     }
 
     void FlatIterator::invalidate(const DiskLoc& dl) {
+        verify( _collection->ok() );
+
         // Just move past the thing being deleted.
         if (dl == _curr) {
-
-            _collection = cc().database()->getCollectionTemp( _ns );
-            if ( _collection == NULL ) {
-                return;
-            }
-
             // We don't care about the return of getNext so much as the side effect of moving _curr
             // to the 'next' thing.
             getNext();
-
-            _collection = NULL;
         }
     }
 
     void FlatIterator::prepareToYield() {
-        _collection = NULL;
     }
 
     bool FlatIterator::recoverFromYield() {
-        _collection = cc().database()->getCollectionTemp( _ns );
-
-        // If the collection we're iterating over was dropped...
-        if ( _collection == NULL ) {
-            // Go right to EOF as a preventative measure.
-            _curr = DiskLoc();
-
-            // And return "NOT OK."
-            return false;
-        }
+        // if the collection is dropped, then the cursor should be destroyed
+        // this check is just a sanity check that the Collection instance we're about to use
+        // has need been destroyed
+        verify( _collection->ok() );
 
         return true;
     }
diff --git a/src/mongo/db/structure/collection_iterator.h b/src/mongo/db/structure/collection_iterator.h
index 2a85462286f..3b71ec1f8ea 100644
--- a/src/mongo/db/structure/collection_iterator.h
+++ b/src/mongo/db/structure/collection_iterator.h
@@ -72,9 +72,6 @@ namespace mongo {
         // The result returned on the next call to getNext().
         DiskLoc _curr;
 
-        // The collection we're iterating over.
-        string _ns;
-
         const CollectionTemp* _collection;
 
         CollectionScanParams::Direction _direction;