Remove initialization code from RequestMonitor

stagemonitor-requestmonitor/src/main/java/org/stagemonitor/requestmonitor/MonitoredMethodRequest.java

@@ -30,11 +30,6 @@ public MonitoredMethodRequest(Configuration configuration, String methodSignatur
 		this.safeParameters = getSafeParameterMap(parameters);
 	}
 
-	@Override
-	public String getInstanceName() {
-		return null;
-	}
-
 	private Map<String, String> getSafeParameterMap(Map<String, Object> parameters) {
 		if (parameters == null) {
 			return null;

stagemonitor-requestmonitor/src/main/java/org/stagemonitor/requestmonitor/MonitoredRequest.java

@@ -2,19 +2,8 @@
 
 import io.opentracing.Span;
 
-@Deprecated
 public abstract class MonitoredRequest {
 
-	/**
-	 * Optionally, the instance name can be derived from a request.
-	 * For instance in a HTTP context you could return the domain name.
-	 *
-	 * @return the instance name
-	 */
-	public String getInstanceName() {
-		return null;
-	}
-
 	/**
 	 * Creates a instance of {@link Span} that represents the current request, e.g. a HTTP request.
 	 * <p/>

stagemonitor-requestmonitor/src/main/java/org/stagemonitor/requestmonitor/RequestMonitor.java

@@ -1,21 +1,14 @@
 package org.stagemonitor.requestmonitor;
 
 import org.stagemonitor.core.CorePlugin;
-import org.stagemonitor.core.MeasurementSession;
-import org.stagemonitor.core.Stagemonitor;
 import org.stagemonitor.core.configuration.Configuration;
 import org.stagemonitor.core.metrics.metrics2.Metric2Registry;
 import org.stagemonitor.core.metrics.metrics2.MetricName;
-import org.stagemonitor.requestmonitor.tracing.wrapper.SpanEventListener;
 import org.stagemonitor.requestmonitor.utils.SpanUtils;
 
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 import static org.stagemonitor.core.metrics.metrics2.MetricName.name;
 
-/**
- * @deprecated we should try to do everything with {@link SpanEventListener}s
- */
-@Deprecated
 public class RequestMonitor {
 
 	private final MetricName internalOverheadMetricName = name("internal_overhead_request_monitor").build();
@@ -36,44 +29,20 @@ private RequestMonitor(Configuration configuration, Metric2Registry registry, Re
 
 	public void monitorStart(MonitoredRequest monitoredRequest) {
 		final long start = System.nanoTime();
-		try {
-			if (!corePlugin.isStagemonitorActive()) {
-				return;
-			}
-
-			if (Stagemonitor.getMeasurementSession().isNull()) {
-				createMeasurementSession();
-			}
-
-			if (Stagemonitor.getMeasurementSession().getInstanceName() == null) {
-				getInstanceNameFromExecution(monitoredRequest);
-			}
-
-			if (!Stagemonitor.isStarted()) {
-				Stagemonitor.startMonitoring();
-			}
-			if (Stagemonitor.isStarted()) {
-				monitoredRequest.createSpan();
-			}
-		} finally {
-			final SpanContextInformation info = SpanContextInformation.getCurrent();
-			if (info != null) {
-				info.setOverhead1(System.nanoTime() - start);
-			}
+		monitoredRequest.createSpan();
+		final SpanContextInformation info = SpanContextInformation.getCurrent();
+		if (info != null) {
+			info.setOverhead1(System.nanoTime() - start);
 		}
 	}
 
 	public void monitorStop() {
 		final SpanContextInformation info = SpanContextInformation.getCurrent();
-		if (info == null || !corePlugin.isStagemonitorActive()) {
-			return;
-		}
-		long overhead2 = System.nanoTime();
-		if (info.getSpan() != null) {
+		if (info != null) {
+			long overhead2 = System.nanoTime();
 			info.getSpan().finish();
+			trackOverhead(info.getOverhead1(), overhead2);
 		}
-
-		trackOverhead(info.getOverhead1(), overhead2);
 	}
 
 	public SpanContextInformation monitor(MonitoredRequest monitoredRequest) throws Exception {
@@ -100,25 +69,4 @@ private void trackOverhead(long overhead1, long overhead2) {
 		}
 	}
 
-	/*
-	 * In case the instance name is not set by configuration, try to read from monitored execution
-	 * (e.g. the domain name from a HTTP request)
-	 */
-	private synchronized void getInstanceNameFromExecution(MonitoredRequest monitoredRequest) {
-		final MeasurementSession measurementSession = Stagemonitor.getMeasurementSession();
-		if (measurementSession.getInstanceName() == null) {
-			MeasurementSession session = new MeasurementSession(measurementSession.getApplicationName(), measurementSession.getHostName(),
-					monitoredRequest.getInstanceName());
-			Stagemonitor.setMeasurementSession(session);
-		}
-	}
-
-	private synchronized void createMeasurementSession() {
-		if (Stagemonitor.getMeasurementSession().isNull()) {
-			MeasurementSession session = new MeasurementSession(corePlugin.getApplicationName(), corePlugin.getHostName(),
-					corePlugin.getInstanceName());
-			Stagemonitor.setMeasurementSession(session);
-		}
-	}
-
 }

stagemonitor-requestmonitor/src/main/java/org/stagemonitor/requestmonitor/RequestMonitorPlugin.java

@@ -313,7 +313,6 @@ public class RequestMonitorPlugin extends StagemonitorPlugin {
 	private static RequestMonitor requestMonitor;
 
 	private SpanWrappingTracer spanWrappingTracer;
-	private Tracer noopTracer = NoopTracer.INSTANCE;
 	private SamplePriorityDeterminingSpanEventListener samplePriorityDeterminingSpanInterceptor;
 	private ReportingSpanEventListener reportingSpanEventListener;
 	private CorePlugin corePlugin;
@@ -334,7 +333,7 @@ public Tracer getTracer() {
 		if (spanWrappingTracer != null && corePlugin.isStagemonitorActive()) {
 			return spanWrappingTracer;
 		} else {
-			return noopTracer;
+			return NoopTracer.INSTANCE;
 		}
 	}
 
@@ -376,7 +375,6 @@ public void initializePlugin(final StagemonitorPlugin.InitArguments initArgument
 		final ServiceLoader<SpanEventListenerFactory> factories = ServiceLoader.load(SpanEventListenerFactory.class, RequestMonitorPlugin.class.getClassLoader());
 		this.spanWrappingTracer = createSpanWrappingTracer(tracer, initArguments.getConfiguration(), metricRegistry,
 				factories, samplePriorityDeterminingSpanInterceptor, reportingSpanEventListener);
-		noopTracer = null;
 	}
 
 	public static SpanWrappingTracer createSpanWrappingTracer(final Tracer delegate, Configuration configuration, final Metric2Registry metricRegistry,

stagemonitor-requestmonitor/src/test/java/org/stagemonitor/requestmonitor/AbstractRequestMonitorTest.java

@@ -16,6 +16,7 @@
 import org.stagemonitor.core.metrics.metrics2.MetricName;
 import org.stagemonitor.requestmonitor.reporter.ReportingSpanEventListener;
 import org.stagemonitor.requestmonitor.sampling.SamplePriorityDeterminingSpanEventListener;
+import org.stagemonitor.requestmonitor.tracing.NoopTracer;
 import org.stagemonitor.requestmonitor.tracing.wrapper.SpanWrappingTracer;
 
 import java.util.Collections;
@@ -80,7 +81,13 @@ public void before() {
 		tracer = RequestMonitorPlugin.createSpanWrappingTracer(getTracer(), configuration, registry,
 				TagRecordingSpanEventListener.asList(tags),
 				samplePriorityDeterminingSpanInterceptor, reportingSpanEventListener);
-		when(requestMonitorPlugin.getTracer()).thenReturn(tracer);
+		when(requestMonitorPlugin.getTracer()).then((invocation) -> {
+			if (corePlugin.isStagemonitorActive()) {
+				return tracer;
+			} else {
+				return NoopTracer.INSTANCE;
+			}
+		});
 		assertTrue(TracingUtils.getTraceContext().isEmpty());
 	}
 

stagemonitor-requestmonitor/src/test/java/org/stagemonitor/requestmonitor/RequestMonitorTest.java

@@ -4,10 +4,8 @@
 import com.uber.jaeger.context.TracingUtils;
 import com.uber.jaeger.samplers.ConstSampler;
 
-import org.junit.Ignore;
 import org.junit.Test;
 import org.mockito.Mockito;
-import org.stagemonitor.core.Stagemonitor;
 import org.stagemonitor.requestmonitor.tracing.jaeger.LoggingSpanReporter;
 import org.stagemonitor.requestmonitor.tracing.wrapper.SpanWrapper;
 
@@ -82,15 +80,6 @@ private MonitoredRequest createMonitoredRequest() throws Exception {
 		}));
 	}
 
-	@Test
-	@Ignore
-	public void testGetInstanceNameFromExecution() throws Exception {
-		final MonitoredRequest monitoredRequest = createMonitoredRequest();
-		doReturn("testInstance").when(monitoredRequest).getInstanceName();
-		requestMonitor.monitor(monitoredRequest);
-		assertEquals("testInstance", Stagemonitor.getMeasurementSession().getInstanceName());
-	}
-
 	@Test
 	public void testExecutorServiceContextPropagation() throws Exception {
 		final ExecutorService executorService = TracingUtils.tracedExecutor(Executors.newSingleThreadExecutor());

stagemonitor-web/src/main/java/org/stagemonitor/web/monitor/MonitoredHttpRequest.java

@@ -70,11 +70,6 @@ public MonitoredHttpRequest(HttpServletRequest httpServletRequest,
 		clientIp = getClientIp(httpServletRequest);
 	}
 
-	@Override
-	public String getInstanceName() {
-		return httpServletRequest.getServerName();
-	}
-
 	@Override
 	public Span createSpan() {
 		boolean sample = true;

stagemonitor-web/src/main/java/org/stagemonitor/web/monitor/filter/HttpRequestMonitorFilter.java

@@ -21,6 +21,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.ServiceLoader;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
@@ -43,6 +44,7 @@ public class HttpRequestMonitorFilter extends AbstractExclusionFilter implements
 	private final List<HtmlInjector> htmlInjectors = new ArrayList<HtmlInjector>();
 	private boolean atLeastServletApi3 = false;
 	private final MonitoredHttpRequestFactory monitoredHttpRequestFactory;
+	private final AtomicBoolean firstRequest = new AtomicBoolean(true);
 
 	public HttpRequestMonitorFilter() {
 		this(Stagemonitor.getConfiguration());
@@ -68,7 +70,7 @@ public HttpRequestMonitorFilter(Configuration configuration) {
 	public void initInternal(FilterConfig filterConfig) throws ServletException {
 		final MeasurementSession measurementSession = new MeasurementSession(getApplicationName(filterConfig),
 				corePlugin.getHostName(), corePlugin.getInstanceName());
-		Stagemonitor.setMeasurementSession(measurementSession);
+		Stagemonitor.startMonitoring(measurementSession);
 		final ServletContext servletContext = filterConfig.getServletContext();
 		atLeastServletApi3 = servletContext.getMajorVersion() >= 3;
 
@@ -92,6 +94,9 @@ private String getApplicationName(FilterConfig filterConfig) {
 	@Override
 	public final void doFilterInternal(final HttpServletRequest request, final HttpServletResponse response, final FilterChain filterChain)
 			throws IOException, ServletException {
+		if (firstRequest.getAndSet(false) && Stagemonitor.getMeasurementSession().getInstanceName() == null) {
+			setInstanceAndStartMonitoring(request.getServerName());
+		}
 		if (corePlugin.isStagemonitorActive() && !isInternalRequest(request) &&
 				request.getDispatcherType() == REQUEST) {
 			doMonitor(request, response, filterChain);
@@ -100,6 +105,15 @@ public final void doFilterInternal(final HttpServletRequest request, final HttpS
 		}
 	}
 
+	private synchronized void setInstanceAndStartMonitoring(String instanceName) {
+		final MeasurementSession measurementSession = Stagemonitor.getMeasurementSession();
+		if (measurementSession.getInstanceName() == null) {
+			MeasurementSession session = new MeasurementSession(measurementSession.getApplicationName(),
+					measurementSession.getHostName(), instanceName);
+			Stagemonitor.startMonitoring(session);
+		}
+	}
+
 	private void doMonitor(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws IOException, ServletException {
 
 		final StatusExposingByteCountingServletResponse responseWrapper;

stagemonitor-web/src/test/java/org/stagemonitor/web/monitor/MonitoredHttpRequestTest.java

@@ -71,13 +71,6 @@ public void tearDown() throws Exception {
 	public void testGetRequestName() throws Exception {
 		final MonitoredHttpRequest monitoredHttpRequest = createMonitoredHttpRequest(new MockHttpServletRequest("GET", "/test.js"));
 		assertEquals("GET *.js", monitoredHttpRequest.getRequestName());
-		testGetInstanceName();
-	}
-
-	@Test
-	public void testGetInstanceName() throws Exception {
-		final MonitoredHttpRequest monitoredHttpRequest = createMonitoredHttpRequest(new MockHttpServletRequest("GET", "/test.js"));
-		assertEquals("localhost", monitoredHttpRequest.getInstanceName());
 	}
 
 	@Test