Merge pull request #8364 from Icinga/bugfix/configsyncstagelock-unlock-owner-213

Make ApiListener::m_ConfigSyncStageLock a SpinLock

lib/base/CMakeLists.txt

@@ -64,6 +64,7 @@ set(base_SOURCES
   shared-object.hpp
   singleton.hpp
   socket.cpp socket.hpp
+  spinlock.cpp spinlock.hpp
   stacktrace.cpp stacktrace.hpp
   statsfunction.hpp
   stdiostream.cpp stdiostream.hpp

lib/base/spinlock.cpp

@@ -0,0 +1,22 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/spinlock.hpp"
+#include <atomic>
+
+using namespace icinga;
+
+void SpinLock::lock()
+{
+	while (m_Locked.test_and_set(std::memory_order_acquire)) {
+	}
+}
+
+bool SpinLock::try_lock()
+{
+	return !m_Locked.test_and_set(std::memory_order_acquire);
+}
+
+void SpinLock::unlock()
+{
+	m_Locked.clear(std::memory_order_release);
+}

lib/base/spinlock.hpp

@@ -0,0 +1,35 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef SPINLOCK_H
+#define SPINLOCK_H
+
+#include <atomic>
+
+namespace icinga
+{
+
+/**
+ * A spin lock.
+ *
+ * @ingroup base
+ */
+class SpinLock
+{
+public:
+	SpinLock() = default;
+	SpinLock(const SpinLock&) = delete;
+	SpinLock& operator=(const SpinLock&) = delete;
+	SpinLock(SpinLock&&) = delete;
+	SpinLock& operator=(SpinLock&&) = delete;
+
+	void lock();
+	bool try_lock();
+	void unlock();
+
+private:
+	std::atomic_flag m_Locked = ATOMIC_FLAG_INIT;
+};
+
+}
+
+#endif /* SPINLOCK_H */

lib/remote/apilistener-filesync.cpp

@@ -20,7 +20,7 @@ using namespace icinga;
 
 REGISTER_APIFUNCTION(Update, config, &ApiListener::ConfigUpdateHandler);
 
-boost::mutex ApiListener::m_ConfigSyncStageLock;
+SpinLock ApiListener::m_ConfigSyncStageLock;
 
 /**
  * Entrypoint for updating all authoritative configs from /etc/zones.d, packages, etc.
@@ -330,7 +330,7 @@ void ApiListener::HandleConfigUpdate(const MessageOrigin::Ptr& origin, const Dic
 	/* Only one transaction is allowed, concurrent message handlers need to wait.
 	 * This affects two parent endpoints sending the config in the same moment.
 	 */
-	auto lock (Shared<boost::mutex::scoped_lock>::Make(m_ConfigSyncStageLock));
+	auto lock (Shared<std::unique_lock<SpinLock>>::Make(m_ConfigSyncStageLock));
 
 	String apiZonesStageDir = GetApiZonesStageDir();
 	String fromEndpointName = origin->FromClient->GetEndpoint()->GetName();
@@ -627,7 +627,7 @@ void ApiListener::TryActivateZonesStageCallback(const ProcessResult& pr,
  *
  * @param relativePaths Required for later file operations in the callback. Provides the zone name plus path in a list.
  */
-void ApiListener::AsyncTryActivateZonesStage(const std::vector<String>& relativePaths, const Shared<boost::mutex::scoped_lock>::Ptr& lock)
+void ApiListener::AsyncTryActivateZonesStage(const std::vector<String>& relativePaths, const Shared<std::unique_lock<SpinLock>>::Ptr& lock)
 {
 	VERIFY(Application::GetArgC() >= 1);
 

lib/remote/apilistener.hpp

@@ -11,6 +11,7 @@
 #include "base/configobject.hpp"
 #include "base/process.hpp"
 #include "base/shared.hpp"
+#include "base/spinlock.hpp"
 #include "base/timer.hpp"
 #include "base/workqueue.hpp"
 #include "base/tcpsocket.hpp"
@@ -21,6 +22,7 @@
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/spawn.hpp>
 #include <boost/asio/ssl/context.hpp>
+#include <mutex>
 #include <set>
 
 namespace icinga
@@ -186,7 +188,7 @@ private:
 	void RemoveStatusFile();
 
 	/* filesync */
-	static boost::mutex m_ConfigSyncStageLock;
+	static SpinLock m_ConfigSyncStageLock;
 
 	void SyncLocalZoneDirs() const;
 	void SyncLocalZoneDir(const Zone::Ptr& zone) const;
@@ -200,7 +202,7 @@ private:
 
 	static void TryActivateZonesStageCallback(const ProcessResult& pr,
 		const std::vector<String>& relativePaths);
-	static void AsyncTryActivateZonesStage(const std::vector<String>& relativePaths, const Shared<boost::mutex::scoped_lock>::Ptr& lock);
+	static void AsyncTryActivateZonesStage(const std::vector<String>& relativePaths, const Shared<std::unique_lock<SpinLock>>::Ptr& lock);
 
 	static String GetChecksum(const String& content);
 	static bool CheckConfigChange(const ConfigDirInformation& oldConfig, const ConfigDirInformation& newConfig);