Merge branch 'master' of https://github.com/dimovelev/metrics-sampler

.gitignore

@@ -5,4 +5,6 @@ bin/
 .classpath
 .idea/
 *.iml
+*.ipr
+*.iws
 

metrics-sampler-core/src/main/java/org/metricssampler/MetricsSampler.java

@@ -5,14 +5,7 @@
 import java.util.Map.Entry;
 import java.util.ResourceBundle;
 
-import org.metricssampler.cmd.CheckCommand;
-import org.metricssampler.cmd.HelpCommand;
-import org.metricssampler.cmd.MetadataCommand;
-import org.metricssampler.cmd.SamplerCommand;
-import org.metricssampler.cmd.StartCommand;
-import org.metricssampler.cmd.StatusCommand;
-import org.metricssampler.cmd.StopCommand;
-import org.metricssampler.cmd.TestCommand;
+import org.metricssampler.cmd.*;
 
 import com.beust.jcommander.JCommander;
 import com.beust.jcommander.ParameterException;
@@ -59,6 +52,7 @@ protected static HelpCommand addCommands(final ResourceBundle bundle, final JCom
 		commander.addCommand(new MetadataCommand());
 		commander.addCommand(new CheckCommand());
 		commander.addCommand(new TestCommand());
+		commander.addCommand(new MetricsCommand());
 
 		fixResourceBundleBug(commander, bundle);
 		return result;

metrics-sampler-core/src/main/java/org/metricssampler/cmd/MetricsCommand.java

@@ -0,0 +1,23 @@
+package org.metricssampler.cmd;
+
+import com.beust.jcommander.Parameters;
+import org.metricssampler.reader.MetricReadException;
+import org.metricssampler.sampler.Sampler;
+
+import java.util.Set;
+
+@Parameters(commandNames="metrics", commandDescriptionKey="help.metrics.command")
+public class MetricsCommand extends SamplersCommand {
+	@Override
+	protected void process(final Sampler sampler) {
+		logger.info("Listing metrics of {}", sampler);
+		try {
+			Set<String> metrics = sampler.metrics();
+            for (final String name : metrics) {
+                System.out.println(name);
+            }
+		} catch (final MetricReadException e) {
+			logger.warn("Sampler threw exception during check", e);
+		}
+	}
+}

metrics-sampler-core/src/main/java/org/metricssampler/sampler/Sampler.java

@@ -2,6 +2,8 @@
 
 import org.metricssampler.config.SamplerConfig;
 
+import java.util.Set;
+
 /**
  * An active component which fetches metrics from a configured input, selects and transforms them and sends them to a configured list of outputs.
  */
@@ -15,7 +17,9 @@ public interface Sampler {
 	 * @return fetch metrics and return {@code true} if all selectors match at least one metric
 	 */
 	boolean check();
-
+
+    Set<String> metrics();
+
 	SamplerConfig getConfig();
 
 	void reset();

metrics-sampler-core/src/main/resources/help.properties

@@ -19,4 +19,5 @@ help.param.logback=The logback configuration file to use
 help.param.sampler.action=What to do with the samplers. One of enable|disable|reset
 help.param.resource.names=A comma separated list of shared resource names (or regular expressions).
 help.param.resource.action=What to do with the matching shared resources. Either start or stop.
-help.missingCommand=Please specify a command
+help.missingCommand=Please specify a command
+help.metrics.command=List the metrics that are matched by the given sampler in an alphabetical order

metrics-sampler-extension-base/src/main/java/org/metricssampler/extensions/base/DefaultSampler.java

@@ -2,13 +2,8 @@
 
 import static org.metricssampler.util.Preconditions.checkArgumentNotNull;
 
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.Map.Entry;
-import java.util.Random;
 
 import org.metricssampler.reader.MetricReadException;
 import org.metricssampler.reader.MetricValue;
@@ -262,4 +257,25 @@ public void reset() {
 			selector.reset();
 		}
 	}
+
+    @Override
+    public Set<String> metrics() {
+        logger.debug("Listing the matched metrics");
+        try {
+            final Map<String, MetricValue> rawMetrics = readMetrics();
+            final Map<String, MetricValue> metrics = transformValues(rawMetrics);
+            final Set<String> result = new TreeSet<String>();
+            result.addAll(metrics.keySet());
+            return result;
+        } catch (final OpenMetricsReaderException e) {
+            final String msg = e.getCause() != null ? e.getCause().getMessage() : e.getMessage();
+            logger.warn("Failed to open reader: {}", msg);
+        } catch (final MetricReadException e) {
+            logger.warn("Failed to read metrics", e);
+        } catch (final MetricWriteException e) {
+            logger.warn("Failed to write metrics", e);
+        }
+        return Collections.emptySet();
+    }
+
 }