Fixed bug #8390 : Deadlock might happens when database is shutting down with internal worker attachments exists.

Author: hvlad

src/jrd/WorkerAttachment.cpp

@@ -49,8 +49,10 @@ const unsigned WORKER_IDLE_TIMEOUT = 60;	// 1 minute
 
 /// class WorkerStableAttachment
 
-WorkerStableAttachment::WorkerStableAttachment(FbStatusVector* status, Jrd::Attachment* attachment) :
-	SysStableAttachment(attachment)
+WorkerStableAttachment::WorkerStableAttachment(FbStatusVector* status, Jrd::Attachment* attachment,
+											   WorkerAttachment* workers) :
+	SysStableAttachment(attachment),
+	m_workers(workers)
 {
 	UserId user;
 	user.setUserName("<Worker>");
@@ -69,14 +71,16 @@ WorkerStableAttachment::WorkerStableAttachment(FbStatusVector* status, Jrd::Atta
 	Monitoring::publishAttachment(tdbb);
 
 	initDone();
+	m_workers->incWorkers();
 }
 
 WorkerStableAttachment::~WorkerStableAttachment()
 {
 	fini();
 }
 
-WorkerStableAttachment* WorkerStableAttachment::create(FbStatusVector* status, Database* dbb, JProvider* provider)
+WorkerStableAttachment* WorkerStableAttachment::create(FbStatusVector* status, Database* dbb,
+	JProvider* provider, WorkerAttachment* workers)
 {
 	Attachment* attachment = NULL;
 	try
@@ -85,7 +89,7 @@ WorkerStableAttachment* WorkerStableAttachment::create(FbStatusVector* status, D
 		attachment->att_filename = dbb->dbb_filename;
 		attachment->att_flags |= ATT_worker;
 
-		WorkerStableAttachment* sAtt = FB_NEW WorkerStableAttachment(status, attachment);
+		WorkerStableAttachment* sAtt = FB_NEW WorkerStableAttachment(status, attachment, workers);
 		return sAtt;
 	}
 	catch (const Exception& ex)
@@ -129,6 +133,8 @@ void WorkerStableAttachment::fini()
 	}
 
 	destroy(attachment);
+
+	m_workers->decWorkers();
 }
 
 /// class WorkerAttachment
@@ -139,8 +145,7 @@ bool WorkerAttachment::m_shutdown = false;
 
 WorkerAttachment::WorkerAttachment() :
 	m_idleAtts(*getDefaultMemoryPool()),
-	m_activeAtts(*getDefaultMemoryPool()),
-	m_cntUserAtts(0)
+	m_activeAtts(*getDefaultMemoryPool())
 {
 }
 
@@ -177,6 +182,30 @@ void WorkerAttachment::decUserAtts(const PathName& dbname)
 	}
 }
 
+void WorkerAttachment::incWorkers()
+{
+	fb_assert(Config::getServerMode() == MODE_SUPER);
+
+	MutexLockGuard guard(m_mutex, FB_FUNCTION);
+	++m_cntWorkers;
+}
+
+void WorkerAttachment::decWorkers()
+{
+	fb_assert(Config::getServerMode() == MODE_SUPER);
+
+	MutexLockGuard guard(m_mutex, FB_FUNCTION);
+	if (--m_cntWorkers == 0)
+		m_noWorkers.notifyAll();
+}
+
+void WorkerAttachment::waitForWorkers()
+{
+	MutexLockGuard guard(m_mutex, FB_FUNCTION);
+	while (m_cntWorkers != 0)
+		m_noWorkers.wait(m_mutex);
+}
+
 WorkerAttachment* WorkerAttachment::getByName(const PathName& dbname)
 {
 	if (m_shutdown)
@@ -230,13 +259,17 @@ void WorkerAttachment::shutdownDbb(Database* dbb)
 	if (Config::getServerMode() != MODE_SUPER)
 		return;
 
-	MutexLockGuard guard(m_mapMutex, FB_FUNCTION);
-
 	WorkerAttachment* item = NULL;
-	if (!m_map->get(dbb->dbb_filename, item))
-		return;
+
+	{
+		MutexLockGuard guard(m_mapMutex, FB_FUNCTION);
+
+		if (!m_map->get(dbb->dbb_filename, item))
+			return;
+	}
 
 	item->clear(false);
+	item->waitForWorkers();
 }
 
 StableAttachmentPart* WorkerAttachment::getAttachment(FbStatusVector* status, Database* dbb)
@@ -301,7 +334,7 @@ StableAttachmentPart* WorkerAttachment::getAttachment(FbStatusVector* status, Da
 
 		MutexUnlockGuard unlock(item->m_mutex, FB_FUNCTION);
 		status->init();
-		sAtt = doAttach(status, dbb);
+		sAtt = item->doAttach(status, dbb);
 		if (!sAtt)
 		{
 			// log error ?
@@ -439,7 +472,7 @@ StableAttachmentPart* WorkerAttachment::doAttach(FbStatusVector* status, Databas
 	//jInstance->setDbCryptCallback(&status, tdbb->getAttachment()->att_crypt_callback);
 
 	if (Config::getServerMode() == MODE_SUPER)
-		sAtt = WorkerStableAttachment::create(status, dbb, jInstance);
+		sAtt = WorkerStableAttachment::create(status, dbb, jInstance, this);
 	else
 	{
 		ClumpletWriter dpb(ClumpletReader::Tagged, MAX_DPB_SIZE, isc_dpb_version1);

src/jrd/WorkerAttachment.h

@@ -31,6 +31,7 @@
 #include "firebird.h"
 #include "../common/classes/alloc.h"
 #include "../common/classes/array.h"
+#include "../common/classes/condition.h"
 #include "../common/classes/fb_string.h"
 #include "../common/classes/GenericMap.h"
 #include "../common/classes/init.h"
@@ -43,19 +44,24 @@
 namespace Jrd
 {
 
+class WorkerAttachment;
+
 class WorkerStableAttachment : public SysStableAttachment
 {
 public:
-	static WorkerStableAttachment* create(FbStatusVector* status, Database* dbb, JProvider* provider);
+	static WorkerStableAttachment* create(FbStatusVector* status, Database* dbb, JProvider* provider,
+		WorkerAttachment* workers);
 
 	void fini();
 
 protected:
 	virtual void doOnIdleTimer(Firebird::TimerImpl* timer);
 
 private:
-	explicit WorkerStableAttachment(FbStatusVector* status, Jrd::Attachment* att);
+	explicit WorkerStableAttachment(FbStatusVector* status, Jrd::Attachment* att, WorkerAttachment* workers);
 	virtual ~WorkerStableAttachment();
+
+	WorkerAttachment* m_workers;
 };
 
 
@@ -77,6 +83,8 @@ class WorkerContextHolder : public Jrd::DatabaseContextHolder, public Jrd::Attac
 
 class WorkerAttachment
 {
+	friend class WorkerStableAttachment;
+
 public:
 	explicit WorkerAttachment();
 
@@ -93,10 +101,14 @@ class WorkerAttachment
 
 private:
 	static WorkerAttachment* getByName(const Firebird::PathName& dbname);
-	static Jrd::StableAttachmentPart* doAttach(FbStatusVector* status, Jrd::Database* dbb);
+	Jrd::StableAttachmentPart* doAttach(FbStatusVector* status, Jrd::Database* dbb);
 	static void doDetach(FbStatusVector* status, Jrd::StableAttachmentPart* sAtt);
 	void clear(bool checkRefs);
 
+	void incWorkers();
+	void decWorkers();
+	void waitForWorkers();
+
 
 	typedef Firebird::GenericMap<Firebird::Pair<Firebird::Left<Firebird::PathName, WorkerAttachment*> > >
 		MapDbIdToWorkAtts;
@@ -109,7 +121,15 @@ class WorkerAttachment
 	Firebird::HalfStaticArray<Jrd::StableAttachmentPart*, 8> m_idleAtts;
 	Firebird::SortedArray<Jrd::StableAttachmentPart*,
 		Firebird::InlineStorage<Jrd::StableAttachmentPart*, 8> > m_activeAtts;
-	int m_cntUserAtts;
+
+	// count of regular user attachments, used with non-shared Database
+	int m_cntUserAtts = 0;
+
+	// count of internal worker attachments, used with shared Database
+	int m_cntWorkers = 0;
+
+	// used to wait for "no internal workers" condition
+	Firebird::Condition m_noWorkers;
 };
 
 } // namespace Jrd