RedisConnection#Connect(): get rid of spin lock

Instead of IoEngine::YieldCurrentCoroutine(yc) until m_Queues.FutureResponseActions.empty(), async-wait a CV which is updated along with m_Queues.FutureResponseActions.
Icinga · Dec 6, 2024 · c0dd426 · c0dd426
1 parent 4b884ea
commit c0dd426
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Showing 2 changed files with 10 additions and 11 deletions.
diff --git a/lib/icingadb/redisconnection.cpp b/lib/icingadb/redisconnection.cpp
@@ -45,7 +45,7 @@ RedisConnection::RedisConnection(boost::asio::io_context& io, String host, int p
 	  m_DbIndex(db), m_CertPath(std::move(certPath)), m_KeyPath(std::move(keyPath)), m_Insecure(insecure),
 	  m_CaPath(std::move(caPath)), m_CrlPath(std::move(crlPath)), m_TlsProtocolmin(std::move(tlsProtocolmin)),
 	  m_CipherList(std::move(cipherList)), m_ConnectTimeout(connectTimeout), m_DebugInfo(std::move(di)), m_Connecting(false), m_Connected(false),
-	  m_Started(false), m_Strand(io), m_QueuedWrites(io), m_QueuedReads(io), m_LogStatsTimer(io), m_Parent(parent)
+	  m_Started(false), m_Strand(io), m_QueuedWrites(io), m_QueuedReads(io), m_NoQueuedReads(io, true), m_LogStatsTimer(io), m_Parent(parent)
 {
 	if (useTls && m_Path.IsEmpty()) {
 		UpdateTLSContext();
@@ -302,12 +302,6 @@ void RedisConnection::Connect(asio::yield_context& yc)
 
 	boost::asio::deadline_timer timer (m_Strand.context());
 
-	auto waitForReadLoop ([this, &yc]() {
-		while (!m_Queues.FutureResponseActions.empty()) {
-			IoEngine::YieldCurrentCoroutine(yc);
-		}
-	});
-
 	for (;;) {
 		try {
 			if (m_Path.IsEmpty()) {
@@ -340,7 +334,7 @@ void RedisConnection::Connect(asio::yield_context& yc)
 					}
 
 					Handshake(conn, yc);
-					waitForReadLoop();
+					m_NoQueuedReads.Wait(yc);
 					m_TlsConn = std::move(conn);
 				} else {
 					Log(m_Parent ? LogNotice : LogInformation, "IcingaDB")
@@ -352,7 +346,7 @@ void RedisConnection::Connect(asio::yield_context& yc)
 
 					icinga::Connect(conn->next_layer(), m_Host, Convert::ToString(m_Port), yc);
 					Handshake(conn, yc);
-					waitForReadLoop();
+					m_NoQueuedReads.Wait(yc);
 					m_TcpConn = std::move(conn);
 				}
 			} else {
@@ -365,7 +359,7 @@ void RedisConnection::Connect(asio::yield_context& yc)
 
 				conn->next_layer().async_connect(Unix::endpoint(m_Path.CStr()), yc);
 				Handshake(conn, yc);
-				waitForReadLoop();
+				m_NoQueuedReads.Wait(yc);
 				m_UnixConn = std::move(conn);
 			}
 
@@ -477,6 +471,7 @@ void RedisConnection::ReadLoop(asio::yield_context& yc)
 		}
 
 		m_QueuedReads.Clear();
+		m_NoQueuedReads.Set();
 	}
 }
 
@@ -577,6 +572,7 @@ void RedisConnection::WriteItem(boost::asio::yield_context& yc, RedisConnection:
 		}
 
 		m_QueuedReads.Set();
+		m_NoQueuedReads.Clear();
 	}
 
 	if (next.FireAndForgetQueries) {
@@ -613,6 +609,7 @@ void RedisConnection::WriteItem(boost::asio::yield_context& yc, RedisConnection:
 		}
 
 		m_QueuedReads.Set();
+		m_NoQueuedReads.Clear();
 	}
 
 	if (next.GetResultOfQuery) {
@@ -638,6 +635,7 @@ void RedisConnection::WriteItem(boost::asio::yield_context& yc, RedisConnection:
 		}
 
 		m_QueuedReads.Set();
+		m_NoQueuedReads.Clear();
 	}
 
 	if (next.GetResultsOfQueries) {
@@ -660,6 +658,7 @@ void RedisConnection::WriteItem(boost::asio::yield_context& yc, RedisConnection:
 		m_Queues.FutureResponseActions.emplace(FutureResponseAction{item.first.size(), ResponseAction::DeliverBulk});
 
 		m_QueuedReads.Set();
+		m_NoQueuedReads.Clear();
 	}
 
 	if (next.Callback) {

diff --git a/lib/icingadb/redisconnection.hpp b/lib/icingadb/redisconnection.hpp
@@ -262,7 +262,7 @@ namespace icinga
 		std::set<QueryPriority> m_SuppressedQueryKinds;
 
 		// Indicate that there's something to send/receive
-		AsioConditionVariable m_QueuedWrites, m_QueuedReads;
+		AsioConditionVariable m_QueuedWrites, m_QueuedReads, m_NoQueuedReads;
 
 		std::function<void(boost::asio::yield_context& yc)> m_ConnectedCallback;