SERVER-12899 append "waited" field to all fsync GLE calls for 2.4 compatibility

3 files changed, 21 insertions, 3 deletions

diff --git a/src/mongo/db/commands/get_last_error.cpp b/src/mongo/db/commands/get_last_error.cpp
index 868af360f64..460029b6ab4 100644
--- a/src/mongo/db/commands/get_last_error.cpp
+++ b/src/mongo/db/commands/get_last_error.cpp
@@ -238,7 +238,7 @@ namespace mongo {
 
             WriteConcernResult wcResult;
             status = waitForWriteConcern( writeConcern, lastOpTime, &wcResult );
-            wcResult.appendTo( &result );
+            wcResult.appendTo( writeConcern, &result );
 
             // For backward compatibility with 2.4, wtimeout returns ok : 1.0
             if ( wcResult.wTimedOut ) {
diff --git a/src/mongo/db/write_concern.cpp b/src/mongo/db/write_concern.cpp
index c52cfb545e3..18bea25ce65 100644
--- a/src/mongo/db/write_concern.cpp
+++ b/src/mongo/db/write_concern.cpp
@@ -78,7 +78,9 @@ namespace mongo {
         return Status::OK();
     }
 
-    void WriteConcernResult::appendTo( BSONObjBuilder* result ) const {
+    void WriteConcernResult::appendTo( const WriteConcernOptions& writeConcern,
+                                       BSONObjBuilder* result ) const {
+
         if ( syncMillis >= 0 )
             result->appendNumber( "syncMillis", syncMillis );
 
@@ -104,6 +106,22 @@ namespace mongo {
             result->appendNull( "err" );
         else
             result->append( "err", err );
+
+        // *** 2.4 SyncClusterConnection compatibility ***
+        // 2.4 expects either fsync'd files, or a "waited" field exist after running an fsync : true
+        // GLE, but with journaling we don't actually need to run the fsync (fsync command is
+        // preferred in 2.6).  So we add a "waited" field if one doesn't exist.
+
+        if ( writeConcern.syncMode == WriteConcernOptions::FSYNC ) {
+
+            if ( fsyncFiles < 0 && ( wTime < 0 || !wTimedOut ) ) {
+                dassert( result->asTempObj()["waited"].eoo() );
+                result->appendNumber( "waited", syncMillis );
+            }
+
+            dassert( result->asTempObj()["fsyncFiles"].numberInt() > 0 ||
+                     !result->asTempObj()["waited"].eoo() );
+        }
     }
 
     Status waitForWriteConcern( const WriteConcernOptions& writeConcern,
diff --git a/src/mongo/db/write_concern.h b/src/mongo/db/write_concern.h
index 69c438d3ba3..c88404c1055 100644
--- a/src/mongo/db/write_concern.h
+++ b/src/mongo/db/write_concern.h
@@ -50,7 +50,7 @@ namespace mongo {
             err = "";
         }
 
-        void appendTo( BSONObjBuilder* result ) const;
+        void appendTo( const WriteConcernOptions& writeConcern, BSONObjBuilder* result ) const;
 
         int syncMillis;
         int fsyncFiles;