Fixed issues with shutdown thread, reported by Ilya Eremin privately

(cherry picked from commit dd1593b67d)

src/jrd/Attachment.h

@@ -936,6 +936,11 @@ public:
 		iter.remove();
 	}
 
+	bool hasData() const
+	{
+		return m_attachments.hasData();
+	}
+
 private:
 	AttachmentsRefHolder(const AttachmentsRefHolder&);
 

src/jrd/ThreadCollect.h

@@ -118,13 +118,13 @@ namespace Jrd {
 			while (thr.hasData())
 			{
 				FB_SIZE_T n = thr.getCount() - 1;
-				Thrd& t = thr[n];
+				Thrd t = thr[n];
+				thr.remove(n);
 				{
 					Firebird::MutexUnlockGuard u(threadsMutex, FB_FUNCTION);
 					Thread::waitForCompletion(t.hndl);
 					fb_assert(t.ending);
 				}
-				thr.remove(n);
 			}
 		}
 

src/jrd/jrd.cpp

@@ -482,7 +482,7 @@ namespace
 
 	struct AttShutParams
 	{
-		Semaphore thdStartedSem;
+		Semaphore thdStartedSem, startCallCompleteSem;
 		Thread::Handle thrHandle;
 		AttachmentsRefHolder* attachments;
 	};
@@ -8699,6 +8699,17 @@ namespace
 
 		AttShutParams* params = static_cast<AttShutParams*>(arg);
 		AttachmentsRefHolder* attachments = params->attachments;
+
+		try
+		{
+			params->startCallCompleteSem.enter();
+		}
+		catch (const Exception& ex)
+		{
+			iscLogException("attachmentShutdownThread", ex);
+			return 0;
+		}
+
 		Thread::Handle th = params->thrHandle;
 		fb_assert(th);
 
@@ -9550,6 +9561,8 @@ void JRD_shutdown_attachment(Attachment* attachment)
 		AttShutParams params;
 		params.attachments = queue;
 		Thread::start(attachmentShutdownThread, &params, THREAD_high, &params.thrHandle);
+		params.startCallCompleteSem.release();
+
 		queue.release();
 		shutThreadCollect->houseKeeping();
 		params.thdStartedSem.enter();
@@ -9600,11 +9613,13 @@ void JRD_shutdown_attachments(Database* dbb)
 			}
 		}
 
-		if (queue.hasData())
+		if (queue->hasData())
 		{
 			AttShutParams params;
 			params.attachments = queue;
 			Thread::start(attachmentShutdownThread, &params, THREAD_high, &params.thrHandle);
+			params.startCallCompleteSem.release();
+
 			queue.release();
 			shutThreadCollect->houseKeeping();
 			params.thdStartedSem.enter();