PerfData: Server Timeouts for InfluxDB Writer

Exposes the TCP socket used to communicate with the InfluxDB server.  When we are
expecing a response we can now call poll() on the socket to wait for data to become
available.  If it doesn't in a user configurable timeout period we abort the request.

fixes #4927
fixes #4941

Signed-off-by: Michael Friedrich <michael.friedrich@icinga.com>

doc/9-object-types.md

@@ -933,6 +933,7 @@ Configuration Attributes:
   enable_send_metadata   | **Optional.** Whether to send check metadata e.g. states, execution time, latency etc.
   flush_interval         | **Optional.** How long to buffer data points before transfering to InfluxDB. Defaults to `10s`.
   flush_threshold        | **Optional.** How many data points to buffer before forcing a transfer to InfluxDB.  Defaults to `1024`.
+  socket_timeout         | **Optional.** How long to wait for InfluxDB to respond.  Defaults to `5s`.
 
 ### <a id="objecttype-influxdbwriter-instance-tags"></a> Instance Tagging
 

lib/perfdata/influxdbwriter.cpp

@@ -78,9 +78,9 @@ void InfluxdbWriter::Start(bool runtimeCreated)
 	Service::OnNewCheckResult.connect(boost::bind(&InfluxdbWriter::CheckResultHandler, this, _1, _2));
 }
 
-Stream::Ptr InfluxdbWriter::Connect(void)
+Stream::Ptr InfluxdbWriter::Connect(TcpSocket::Ptr& socket)
 {
-	TcpSocket::Ptr socket = new TcpSocket();
+	socket = new TcpSocket();
 
 	Log(LogNotice, "InfluxdbWriter")
 	    << "Reconnecting to InfluxDB on host '" << GetHost() << "' port '" << GetPort() << "'.";
@@ -345,7 +345,8 @@ void InfluxdbWriter::FlushTimeout(void)
 
 void InfluxdbWriter::Flush(void)
 {
-	Stream::Ptr stream = Connect();
+	TcpSocket::Ptr socket;
+	Stream::Ptr stream = Connect(socket);
 
 	// Unable to connect, play it safe and lose the data points
 	// to avoid a memory leak
@@ -391,6 +392,13 @@ void InfluxdbWriter::Flush(void)
 	HttpResponse resp(stream, req);
 	StreamReadContext context;
 
+	struct timeval timeout = { GetSocketTimeout(), 0 };
+	if (!socket->Poll(true, false, &timeout)) {
+		Log(LogWarning, "InfluxdbWriter")
+		    << "Response timeout of TCP socket from host '" << GetHost() << "' port '" << GetPort() << "'.";
+		return;
+	}
+
 	try {
 		resp.Parse(context, true);
 	} catch (const std::exception&) {

lib/perfdata/influxdbwriter.hpp

@@ -65,7 +65,7 @@ private:
 	static String EscapeKey(const String& str);
 	static String EscapeField(const String& str);
 
-	Stream::Ptr Connect(void);
+	Stream::Ptr Connect(TcpSocket::Ptr& socket);
 };
 
 }

lib/perfdata/influxdbwriter.ti

@@ -90,6 +90,9 @@ class InfluxdbWriter : ConfigObject
 	[config] int flush_threshold {
 		default {{{ return 1024; }}}
 	};
+	[config] int socket_timeout {
+		default {{{ return 5; }}}
+	};
 };
 
 validator InfluxdbWriter {