Adding NullStatsReporter and TestScope

core/src/main/java/com/uber/m3/tally/NullStatsReporter.java

@@ -0,0 +1,83 @@
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package com.uber.m3.tally;
+
+import com.uber.m3.util.Duration;
+
+import java.util.Map;
+
+/**
+ * NullStatsReporter is a noop implementation of StatsReporter.
+ */
+public class NullStatsReporter implements StatsReporter {
+ @Override
+ public void reportCounter(String name, Map<String, String> tags, long value) {
+ // noop
+ }
+
+ @Override
+ public void reportGauge(String name, Map<String, String> tags, double value) {
+ // noop
+ }
+
+ @Override
+ public void reportTimer(String name, Map<String, String> tags, Duration interval) {
+ // noop
+ }
+
+ @Override
+ public void reportHistogramValueSamples(
+ String name, Map<String,
+ String> tags,
+ Buckets buckets,
+ double bucketLowerBound,
+ double bucketUpperBound,
+ long samples
+ ) {
+ // noop
+ }
+
+ @Override
+ public void reportHistogramDurationSamples(
+ String name,
+ Map<String, String> tags,
+ Buckets buckets,
+ Duration bucketLowerBound,
+ Duration bucketUpperBound, long samples
+ ) {
+ // noop
+ }
+
+ @Override
+ public Capabilities capabilities() {
+ return CapableOf.NONE;
+ }
+
+ @Override
+ public void flush() {
+ // noop
+ }
+
+ @Override
+ public void close() {
+ // noop
+ }
+}

core/src/main/java/com/uber/m3/tally/ScopeBuilder.java

@@ -144,22 +144,29 @@ public Scope reportEvery(Duration interval) {
  }
 
  /**
- * Creates a root scope and starts reporting with the specified interval
+ * Creates a root scope and starts reporting with the specified interval.
+ * No reporting is done for the {@link NullStatsReporter}.
  * @param interval duration between each report
  * @param uncaughtExceptionHandler an {@link java.lang.Thread.UncaughtExceptionHandler} that's
  * called when there's an uncaught exception in the report loop
  * @return the root scope created
  */
- public Scope reportEvery(Duration interval,
- Thread.UncaughtExceptionHandler uncaughtExceptionHandler) {
- if (interval.compareTo(Duration.ZERO) <= 0) {
- throw new IllegalArgumentException("Reporting interval must be a positive Duration");
+ public Scope reportEvery(
+ Duration interval,
+ Thread.UncaughtExceptionHandler uncaughtExceptionHandler
+ ) {
+ if (reporter instanceof NullStatsReporter) {
+ interval = Duration.ZERO;
+ } else if (interval.compareTo(Duration.ZERO) <= 0) {
+ throw new IllegalArgumentException("Reporting interval must be a non-negative Duration");
  }
 
  ScopeImpl scope = build();
  registry.subscopes.put(ScopeImpl.keyForPrefixedStringMap(prefix, tags), scope);
 
- scheduler.scheduleWithFixedDelay(scope.new ReportLoop(uncaughtExceptionHandler), 0, interval.toMillis(), TimeUnit.MILLISECONDS);
+ if (interval.compareTo(Duration.ZERO) > 0) {
+ scheduler.scheduleWithFixedDelay(scope.new ReportLoop(uncaughtExceptionHandler), 0, interval.toMillis(), TimeUnit.MILLISECONDS);
+ }
 
  return scope;
  }

core/src/main/java/com/uber/m3/tally/ScopeImpl.java

@@ -32,7 +32,7 @@
 /**
  * Default {@link Scope} implementation.
  */
-class ScopeImpl implements Scope {
+class ScopeImpl implements Scope, TestScope {
  private StatsReporter reporter;
  private String prefix;
  private String separator;
@@ -244,6 +244,7 @@ String fullyQualifiedName(String name) {
  * Returns a {@link Snapshot} of this {@link Scope}.
  * @return a {@link Snapshot} of this {@link Scope}
  */
+ @Override
  public Snapshot snapshot() {
  Snapshot snap = new SnapshotImpl();
 

core/src/main/java/com/uber/m3/tally/TestScope.java

@@ -0,0 +1,60 @@
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package com.uber.m3.tally;
+
+import com.uber.m3.util.Duration;
+
+import java.util.Map;
+
+/**
+ * TestScope is a metrics collector that has no reporting, ensuring that
+ * all emitted values have a given prefix or set of tags.
+ */
+interface TestScope extends Scope {
+
+ /**
+ * Creates a new TestScope that adds the ability to take snapshots of
+ * metrics emitted to it.
+ */
+ static TestScope create() {
+ return (TestScope) new RootScopeBuilder()
+ .reporter(new NullStatsReporter())
+ .reportEvery(Duration.ZERO);
+ }
+
+ /**
+ * Creates a new TestScope with given prefix/tags that adds the ability to
+ * take snapshots of metrics emitted to it.
+ */
+ static TestScope create(String prefix, Map<String, String> tags) {
+ return (TestScope) new RootScopeBuilder()
+ .prefix(prefix)
+ .tags(tags)
+ .reporter(new NullStatsReporter())
+ .reportEvery(Duration.ZERO);
+ }
+
+ /**
+ * Snapshot returns a copy of all values since the last report execution
+ * This is an expensive operation and should only be used for testing purposes.
+ */
+ Snapshot snapshot();
+}

core/src/test/java/com/uber/m3/tally/NullStatsReporterTest.java

@@ -0,0 +1,37 @@
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package com.uber.m3.tally;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+
+public class NullStatsReporterTest {
+
+ @Test
+ public void capabilities() {
+ NullStatsReporter reporter = new NullStatsReporter();
+ assertNotNull(reporter.capabilities());
+ assertFalse(reporter.capabilities().reporting());
+ assertFalse(reporter.capabilities().tagging());
+ }
+}