Added MultiCollector example

Author: ganzuoni

examples/example-exporter-httpserver/src/main/java/io/prometheus/metrics/examples/httpserver/MainMultiTarget.java

@@ -14,6 +14,8 @@ public static void main(String[] args) throws IOException, InterruptedException
 
         SampleExtendedCollector xc = new SampleExtendedCollector();
         PrometheusRegistry.defaultRegistry.register(xc);
+        SampleExtendedMultiCollector xmc = new SampleExtendedMultiCollector();
+        PrometheusRegistry.defaultRegistry.register(xmc);
         HTTPServer server = HTTPServer.builder()
                 .port(9400)
                 .buildAndStart();

examples/example-exporter-httpserver/src/main/java/io/prometheus/metrics/examples/httpserver/SampleExtendedMultiCollector.java

@@ -0,0 +1,56 @@
+package io.prometheus.metrics.examples.httpserver;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import io.prometheus.metrics.core.metrics.Counter;
+import io.prometheus.metrics.core.metrics.Gauge;
+import io.prometheus.metrics.model.registry.ExtendedMultiCollector;
+import io.prometheus.metrics.model.registry.PrometheusScrapeRequest;
+import io.prometheus.metrics.model.snapshots.MetricSnapshot;
+import io.prometheus.metrics.model.snapshots.MetricSnapshots;
+
+public class SampleExtendedMultiCollector extends ExtendedMultiCollector {
+
+	public SampleExtendedMultiCollector() {
+		super();
+	}
+
+	@Override
+	protected MetricSnapshots collectMetricSnapshots(PrometheusScrapeRequest scrapeRequest) {
+		Counter sampleCounter;
+		Gauge sampleGauge;
+		sampleCounter = Counter.builder().name("x_calls_total").labelNames("target", "proc").build();
+		sampleGauge = Gauge.builder().name("x_load").labelNames("target", "proc").build();
+		String[] targetName = scrapeRequest.getParameterValues("target");
+		String[] procs = scrapeRequest.getParameterValues("proc");
+		if (targetName == null || targetName.length == 0) {
+			sampleCounter.labelValues("defaultTarget", "defaultProc").inc();
+			sampleGauge.labelValues("defaultTarget", "defaultProc").set(Math.random());
+		} else {
+			if (procs == null || procs.length == 0) {
+				sampleCounter.labelValues(targetName[0], "defaultProc").inc(Math.random());
+				sampleGauge.labelValues(targetName[0], "defaultProc").set(Math.random());
+			} else {
+				for (int i = 0; i < procs.length; i++) {
+					sampleCounter.labelValues(targetName[0], procs[i]).inc(Math.random());
+					sampleGauge.labelValues(targetName[0], procs[i]).set(Math.random());
+				}
+
+			}
+		}
+		Collection<MetricSnapshot> snaps = new ArrayList<MetricSnapshot>();
+		snaps.add(sampleCounter.collect());
+		snaps.add(sampleGauge.collect());
+		MetricSnapshots msnaps = new MetricSnapshots(snaps);
+		return msnaps;
+	}
+
+	public List<String> getPrometheusNames() {
+		List<String> names = new ArrayList<String>();
+		names.add("Multi");
+		return names ;
+	}
+
+}