From a9c6161def024fc89e3a59a2bd01386f9ad2c209 Mon Sep 17 00:00:00 2001
From: "Alexander A. Klimov" <alexander.klimov@icinga.com>
Date: Tue, 1 Mar 2022 15:28:03 +0100
Subject: [PATCH] IcingaDB#Stop(): don't block shutdown, timeout instead

---
 lib/icingadb/icingadb.cpp | 10 ++++++++--
 lib/icingadb/icingadb.hpp |  4 ++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/icingadb/icingadb.cpp b/lib/icingadb/icingadb.cpp
index bf3f06594..1adcaee84 100644
--- a/lib/icingadb/icingadb.cpp
+++ b/lib/icingadb/icingadb.cpp
@@ -172,7 +172,9 @@ void IcingaDB::Start(bool runtimeCreated)
 	m_Rcon->SuppressQueryKind(Prio::CheckResult);
 	m_Rcon->SuppressQueryKind(Prio::RuntimeStateSync);
 
-	m_HistoryThread = std::thread([this]() { ForwardHistoryEntries(); });
+	Ptr keepAlive (this);
+
+	m_HistoryThread = std::async(std::launch::async, [this, keepAlive]() { ForwardHistoryEntries(); });
 }
 
 void IcingaDB::ExceptionHandler(boost::exception_ptr exp)
@@ -234,7 +236,11 @@ void IcingaDB::Stop(bool runtimeRemoved)
 	Log(LogInformation, "IcingaDB")
 		<< "Flushing history data buffer to Redis.";
 
-	m_HistoryThread.join();
+	if (m_HistoryThread.wait_for(std::chrono::minutes(1)) == std::future_status::timeout) {
+		Log(LogCritical, "IcingaDB")
+			<< "Flushing takes more than one minute (while we're about to shut down). Giving up and discarding "
+			<< m_HistoryBulker.Size() << " queued history queries.";
+	}
 
 	Log(LogInformation, "IcingaDB")
 		<< "'" << GetName() << "' stopped.";
diff --git a/lib/icingadb/icingadb.hpp b/lib/icingadb/icingadb.hpp
index 665b29694..3d3dc04cd 100644
--- a/lib/icingadb/icingadb.hpp
+++ b/lib/icingadb/icingadb.hpp
@@ -15,10 +15,10 @@
 #include "remote/messageorigin.hpp"
 #include <atomic>
 #include <chrono>
+#include <future>
 #include <memory>
 #include <mutex>
 #include <set>
-#include <thread>
 #include <unordered_map>
 #include <utility>
 
@@ -181,7 +181,7 @@ private:
 	Timer::Ptr m_StatsTimer;
 	WorkQueue m_WorkQueue{0, 1, LogNotice};
 
-	std::thread m_HistoryThread;
+	std::future<void> m_HistoryThread;
 	Bulker<RedisConnection::Query> m_HistoryBulker {4096, std::chrono::milliseconds(250)};
 
 	String m_PrefixConfigObject;