SERVER-15087 check for dropped collection in MR

(cherry picked from commit aa5c0a136c9ab37023d89908c8b02d6d687ed070)

2 files changed, 15 insertions, 12 deletions

diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 493997d84dc..c409bdda3ca 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -623,11 +623,7 @@ namespace mongo {
 
             Client::WriteContext ctx( ns );
             uassert(10004, "no longer master", isMasterNs(ns.c_str()));
-            Collection* coll = ctx.ctx().db()->getCollection( ns );
-            if ( !coll )
-                uasserted(13630, str::stream() << "attempted to insert into nonexistent" <<
-                                                  " collection during a mr operation." <<
-                                                  " collection expected: " << ns );
+            Collection* coll = getCollectionOrUassert(ctx.ctx().db(), ns);
 
             class BSONObjBuilder b;
             if ( !o.hasField( "_id" ) ) {
@@ -649,12 +645,7 @@ namespace mongo {
             verify( _onDisk );
 
             Client::WriteContext ctx( _config.incLong );
-            Collection* coll = ctx.ctx().db()->getCollection( _config.incLong );
-            if ( !coll )
-                uasserted(13631, str::stream() << "attempted to insert into nonexistent"
-                                                  " collection during a mr operation." <<
-                                                  " collection expected: " << _config.incLong );
-
+            Collection* coll = getCollectionOrUassert(ctx.ctx().db(), _config.incLong);
             coll->insertDocument( o, true );
             getDur().commitIfNeeded();
         }
@@ -850,6 +841,13 @@ namespace mongo {
             _config.reducer->numReduces = _scope->getNumberInt("_redCt");
         }
 
+        Collection* State::getCollectionOrUassert(Database* db, const StringData& ns) {
+            Collection* out = db ? db->getCollection(ns) : NULL;
+            uassert(18697, "Collection unexpectedly disappeared: " + ns.toString(),
+                    out);
+            return out;
+        }
+
         /**
          * Applies last reduce and finalize on a list of tuples (key, val)
          * Inserts single result {_id: key, value: val} into temp collection
@@ -924,7 +922,7 @@ namespace mongo {
 
             {
                 Client::WriteContext incCtx( _config.incLong );
-                Collection* incColl = incCtx.ctx().db()->getCollection( _config.incLong );
+                Collection* incColl = getCollectionOrUassert(incCtx.ctx().db(), _config.incLong );
 
                 bool foundIndex = false;
                 IndexCatalog::IndexIterator ii =
diff --git a/src/mongo/db/commands/mr.h b/src/mongo/db/commands/mr.h
index f32924c4bf5..5c3a550cbfe 100644
--- a/src/mongo/db/commands/mr.h
+++ b/src/mongo/db/commands/mr.h
@@ -42,6 +42,9 @@
 
 namespace mongo {
 
+    class Collection;
+    class Database;
+
     namespace mr {
 
         typedef vector<BSONObj> BSONList;
@@ -324,6 +327,8 @@ namespace mongo {
             void switchMode(bool jsMode);
             void bailFromJS();
 
+            Collection* getCollectionOrUassert(Database* db, const StringData& ns);
+
             const Config& _config;
             DBDirectClient _db;
             bool _useIncremental;   // use an incremental collection