SERVER-21678 setting fromMigrate flag for deletes in oplog

(cherry picked from commit c28bf48e5d3cbe6c1aceed89adcdf8ed7cba5f42)

9 files changed, 44 insertions, 11 deletions

diff --git a/src/mongo/db/catalog/collection.cpp b/src/mongo/db/catalog/collection.cpp
index daa74399995..9e41d643452 100644
--- a/src/mongo/db/catalog/collection.cpp
+++ b/src/mongo/db/catalog/collection.cpp
@@ -476,10 +476,8 @@ Status Collection::aboutToDeleteCapped(OperationContext* txn,
     return Status::OK();
 }
 
-void Collection::deleteDocument(OperationContext* txn,
-                                const RecordId& loc,
-                                bool cappedOK,
-                                bool noWarn) {
+void Collection::deleteDocument(
+    OperationContext* txn, const RecordId& loc, bool fromMigrate, bool cappedOK, bool noWarn) {
     if (isCapped() && !cappedOK) {
         log() << "failing remove on a capped ns " << _ns << endl;
         uasserted(10089, "cannot remove from a capped collection");
@@ -498,7 +496,7 @@ void Collection::deleteDocument(OperationContext* txn,
 
     _recordStore->deleteRecord(txn, loc);
 
-    opObserver->onDelete(txn, ns(), std::move(deleteState));
+    opObserver->onDelete(txn, ns(), std::move(deleteState), fromMigrate);
 }
 
 Counter64 moveCounter;
diff --git a/src/mongo/db/catalog/collection.h b/src/mongo/db/catalog/collection.h
index 5db3fe09984..261ac42bf97 100644
--- a/src/mongo/db/catalog/collection.h
+++ b/src/mongo/db/catalog/collection.h
@@ -243,8 +243,20 @@ public:
      */
     std::vector<std::unique_ptr<RecordCursor>> getManyCursors(OperationContext* txn) const;
 
+    /**
+     * Deletes the document with the given RecordId from the collection.
+     *
+     * 'fromMigrate' indicates whether the delete was induced by a chunk migration, and
+     * so should be ignored by the user as an internal maintenance operation and not a
+     * real delete.
+     * 'loc' key to uniquely identify a record in a collection.
+     * 'cappedOK' if true, allows deletes on capped collections (Cloner::copyDB uses this).
+     * 'noWarn' if unindexing the record causes an error, if noWarn is true the error
+     * will not be logged.
+     */
     void deleteDocument(OperationContext* txn,
                         const RecordId& loc,
+                        bool fromMigrate = false,
                         bool cappedOK = false,
                         bool noWarn = false);
 
diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index a5cf8451558..8fda1b0b17f 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -639,7 +639,7 @@ Status Cloner::copyDb(OperationContext* txn,
                 // dupsAllowed in IndexCatalog::_unindexRecord and SERVER-17487.
                 for (set<RecordId>::const_iterator it = dups.begin(); it != dups.end(); ++it) {
                     WriteUnitOfWork wunit(txn);
-                    c->deleteDocument(txn, *it, true, true);
+                    c->deleteDocument(txn, *it, false, true, true);
                     wunit.commit();
                 }
 
diff --git a/src/mongo/db/dbhelpers.cpp b/src/mongo/db/dbhelpers.cpp
index e42979d6649..6ea104b6faa 100644
--- a/src/mongo/db/dbhelpers.cpp
+++ b/src/mongo/db/dbhelpers.cpp
@@ -429,7 +429,7 @@ long long Helpers::removeRange(OperationContext* txn,
             if (callback)
                 callback->goingToDelete(obj);
 
-            collection->deleteDocument(txn, rloc);
+            collection->deleteDocument(txn, rloc, fromMigrate);
             wuow.commit();
             numDeleted++;
         }
diff --git a/src/mongo/db/exec/delete.cpp b/src/mongo/db/exec/delete.cpp
index c0708617b5a..9db64a9ea20 100644
--- a/src/mongo/db/exec/delete.cpp
+++ b/src/mongo/db/exec/delete.cpp
@@ -210,7 +210,7 @@ PlanStage::StageState DeleteStage::work(WorkingSetID* out) {
         // Do the write, unless this is an explain.
         if (!_params.isExplain) {
             WriteUnitOfWork wunit(getOpCtx());
-            _collection->deleteDocument(getOpCtx(), rloc);
+            _collection->deleteDocument(getOpCtx(), rloc, _params.fromMigrate);
             wunit.commit();
         }
 
diff --git a/src/mongo/db/op_observer.h b/src/mongo/db/op_observer.h
index e9c18f4bbe7..406402b093d 100644
--- a/src/mongo/db/op_observer.h
+++ b/src/mongo/db/op_observer.h
@@ -68,10 +68,19 @@ public:
                    bool fromMigrate = false);
     void onUpdate(OperationContext* txn, oplogUpdateEntryArgs args);
     DeleteState aboutToDelete(OperationContext* txn, const NamespaceString& ns, const BSONObj& doc);
+    /**
+     * Handles logging before document is deleted.
+     *
+     * "ns" name of the collection from which deleteState.idDoc will be deleted.
+     * "deleteState" holds information about the deleted document.
+     * "fromMigrate" indicates whether the delete was induced by a chunk migration, and
+     * so should be ignored by the user as an internal maintenance operation and not a
+     * real delete.
+     */
     void onDelete(OperationContext* txn,
                   const NamespaceString& ns,
                   DeleteState deleteState,
-                  bool fromMigrate = false);
+                  bool fromMigrate);
     void onOpMessage(OperationContext* txn, const BSONObj& msgObj);
     void onCreateCollection(OperationContext* txn,
                             const NamespaceString& collectionName,
diff --git a/src/mongo/db/s/migration_source_manager.cpp b/src/mongo/db/s/migration_source_manager.cpp
index 59eb96222fb..09680bae2a3 100644
--- a/src/mongo/db/s/migration_source_manager.cpp
+++ b/src/mongo/db/s/migration_source_manager.cpp
@@ -234,8 +234,8 @@ void MigrationSourceManager::logOp(OperationContext* txn,
         // won't be transferred to the recipient shard. Also ignore ops from
         // _migrateClone and _transferMods since it is impossible to move a chunk
         // to self.
-        // Also ignore out of range deletes when migrating (notInActiveChunk is set in
-        // OpObserver::onDelete)
+        // Also ignore out of range deletes when migrating a chunk (is set
+        // in OpObserver::onDelete)
         return;
     }
 
diff --git a/src/mongo/db/s/migration_source_manager.h b/src/mongo/db/s/migration_source_manager.h
index 8c6251fe49b..076c14fa9f0 100644
--- a/src/mongo/db/s/migration_source_manager.h
+++ b/src/mongo/db/s/migration_source_manager.h
@@ -71,6 +71,10 @@ public:
                BSONObj* patt,
                bool notInActiveChunk);
 
+    /**
+     * Determines whether the given document 'doc' in namespace 'ns' is within the range
+     * of a currently migrating chunk.
+     */
     bool isInMigratingChunk(const NamespaceString& ns, const BSONObj& doc);
 
     /**
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 6a7abe7f723..9983ccd58df 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -430,6 +430,16 @@ public:
 
 }  // namespace
 
+/**
+ * If sharding is enabled, logs the operation for an active migration in the transfer mods log.
+ *
+ * 'ns' name of the collection in which the operation will occur.
+ * 'notInActiveChunk' a true value indicates that either:
+ *      1) the delete is coming from a donor shard in a current chunk migration,
+ *         and so does not need to be entered in this shard's outgoing transfer log.
+ *      2) the document is not within this shard's outgoing chunk migration range,
+ *         and so does not need to be forwarded to the migration recipient via the transfer log.
+ */
 void logOpForSharding(OperationContext* txn,
                       const char* opstr,
                       const char* ns,