SERVER-6793 - parallel writer batch lock needs to be involved in yield/tempRelease

Author: erh

src/mongo/db/d_concurrency.cpp

@@ -278,11 +278,24 @@ namespace mongo {
     void Lock::ParallelBatchWriterMode::iAmABatchParticipant() {
         lockState()._batchWriter = true;
     }
-    Lock::ParallelBatchWriterSupport::ParallelBatchWriterSupport() :
-        _lk( lockState()._batchWriter ? 0 : new RWLockRecursive::Shared(ParallelBatchWriterMode::_batchLock) )
-    {
+
+    Lock::ParallelBatchWriterSupport::ParallelBatchWriterSupport() {
+        relock();
     }
 
+    void Lock::ParallelBatchWriterSupport::tempRelease() {
+        _lk.reset( 0 );
+    }
+
+    void Lock::ParallelBatchWriterSupport::relock() {
+        LockState& ls = lockState();
+        if ( ! ls._batchWriter ) {
+            AcquiringParallelWriter a(ls);
+            _lk.reset( new RWLockRecursive::Shared(ParallelBatchWriterMode::_batchLock) );
+        }
+    }
+
+
     Lock::ScopedLock::ScopedLock( char type ) 
         : _type(type), _stat(0) {
         LockState& ls = lockState();
@@ -306,6 +319,7 @@ namespace mongo {
     void Lock::ScopedLock::tempRelease() {
         long long micros = _timer.micros();
         _tempRelease();
+        _pbws_lk.tempRelease();
         _recordTime( micros ); // might as well do after we unlock
     }
 
@@ -324,6 +338,7 @@ namespace mongo {
     }
 
     void Lock::ScopedLock::relock() {
+        _pbws_lk.relock();
         _relock();
         resetTime();
     }

src/mongo/db/d_concurrency.h

@@ -78,9 +78,15 @@ namespace mongo {
 
     private:
         class ParallelBatchWriterSupport : boost::noncopyable {
-            scoped_ptr<RWLockRecursive::Shared> _lk;
         public:
             ParallelBatchWriterSupport();
+
+        private:
+            void tempRelease();
+            void relock();
+
+            scoped_ptr<RWLockRecursive::Shared> _lk;
+            friend class ScopedLock;
         };
 
     public:

src/mongo/db/lockstate.cpp

@@ -35,7 +35,8 @@ namespace mongo {
           _otherCount(0), 
           _otherLock(NULL),
           _scopedLk(NULL),
-          _lockPending(false)
+          _lockPending(false),
+          _lockPendingParallelWriter(false)
     {
     }
 
@@ -241,4 +242,13 @@ namespace mongo {
             stat->recordAcquireTimeMicros( _ls.threadState(), _lock->acquireFinished( stat ) );
     }
 
+    AcquiringParallelWriter::AcquiringParallelWriter( LockState& ls )
+        : _ls( ls ) {
+        _ls._lockPendingParallelWriter = true;
+    }
+    
+    AcquiringParallelWriter::~AcquiringParallelWriter() {
+        _ls._lockPendingParallelWriter = false;
+    }
+
 }

src/mongo/db/lockstate.h

@@ -50,7 +50,7 @@ namespace mongo {
         bool isLocked( const StringData& ns ); // rwRW
 
         /** pending means we are currently trying to get a lock */
-        bool hasLockPending() const { return _lockPending; }
+        bool hasLockPending() const { return _lockPending || _lockPendingParallelWriter; }
 
         // ----
 
@@ -105,8 +105,10 @@ namespace mongo {
         Lock::ScopedLock* _scopedLk;   
 
         bool _lockPending;
+        bool _lockPendingParallelWriter;
 
         friend class Acquiring;
+        friend class AcquiringParallelWriter;
     };
 
     class WrapperForRWLock : boost::noncopyable { 
@@ -132,7 +134,14 @@ namespace mongo {
         LockState& _ls;
     };
 
+    class AcquiringParallelWriter {
+    public:
+        AcquiringParallelWriter( LockState& ls );
+        ~AcquiringParallelWriter();
 
+    private:
+        LockState& _ls;
+    };
 
 
 }