From 1e24adf247da28fd11096875613dfcf771ff9e3d Mon Sep 17 00:00:00 2001
From: "Alexander A. Klimov" <alexander.klimov@icinga.com>
Date: Thu, 5 Dec 2024 11:08:37 +0100
Subject: [PATCH] Introduce AsioConditionVariable

---
 lib/base/io-engine.cpp | 24 ++++++++++++++++++++++++
 lib/base/io-engine.hpp | 18 ++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/lib/base/io-engine.cpp b/lib/base/io-engine.cpp
index aa20a1052..94397204e 100644
--- a/lib/base/io-engine.cpp
+++ b/lib/base/io-engine.cpp
@@ -143,6 +143,30 @@ void AsioDualEvent::WaitForClear(boost::asio::yield_context yc)
 	m_IsFalse.Wait(std::move(yc));
 }
 
+AsioConditionVariable::AsioConditionVariable(boost::asio::io_context& io)
+	: m_Timer(io)
+{
+	m_Timer.expires_at(boost::posix_time::pos_infin);
+}
+
+void AsioConditionVariable::Wait(boost::asio::yield_context yc)
+{
+	boost::system::error_code ec;
+	m_Timer.async_wait(yc[ec]);
+}
+
+bool AsioConditionVariable::NotifyOne()
+{
+	boost::system::error_code ec;
+	return m_Timer.cancel_one(ec);
+}
+
+size_t AsioConditionVariable::NotifyAll()
+{
+	boost::system::error_code ec;
+	return m_Timer.cancel(ec);
+}
+
 /**
  * Cancels any pending timeout callback.
  *
diff --git a/lib/base/io-engine.hpp b/lib/base/io-engine.hpp
index c215b0a30..c51aa7d2b 100644
--- a/lib/base/io-engine.hpp
+++ b/lib/base/io-engine.hpp
@@ -55,6 +55,24 @@ private:
 	bool m_Done;
 };
 
+/**
+ * Condition variable which doesn't block I/O threads
+ *
+ * @ingroup base
+ */
+class AsioConditionVariable
+{
+public:
+	AsioConditionVariable(boost::asio::io_context& io);
+
+	void Wait(boost::asio::yield_context yc);
+	bool NotifyOne();
+	size_t NotifyAll();
+
+private:
+	boost::asio::deadline_timer m_Timer;
+};
+
 /**
  * Async I/O engine
  *