align valid metric names with spec (#877)

api/src/main/java/io/opentelemetry/internal/StringUtils.java

@@ -45,5 +45,19 @@ public final class StringUtils {
     return value == null || value.length() == 0;
   }
 
+  /**
+   * Determines whether the metric name contains a valid metric name.
+   *
+   * @param metricName the metric name to be validated.
+   * @return whether the metricName contains a valid name.
+   */
+  public static boolean isValidMetricName(String metricName) {
+    if (metricName.isEmpty()) {
+      return false;
+    }
+    String pattern = "[aA-zZ][aA-zZ0-9_\\-.]*";
+    return metricName.matches(pattern);
+  }
+
   private StringUtils() {}
 }

api/src/main/java/io/opentelemetry/metrics/DefaultMeter.java

@@ -51,7 +51,7 @@ public final class DefaultMeter implements Meter {
   public DoubleCounter.Builder doubleCounterBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopDoubleCounter.NoopBuilder();
   }
@@ -60,7 +60,7 @@ public final class DefaultMeter implements Meter {
   public LongCounter.Builder longCounterBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopLongCounter.NoopBuilder();
   }
@@ -69,7 +69,7 @@ public final class DefaultMeter implements Meter {
   public DoubleMeasure.Builder doubleMeasureBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopDoubleMeasure.NoopBuilder();
   }
@@ -78,7 +78,7 @@ public final class DefaultMeter implements Meter {
   public LongMeasure.Builder longMeasureBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopLongMeasure.NoopBuilder();
   }
@@ -87,7 +87,7 @@ public final class DefaultMeter implements Meter {
   public DoubleObserver.Builder doubleObserverBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopDoubleObserver.NoopBuilder();
   }
@@ -96,7 +96,7 @@ public final class DefaultMeter implements Meter {
   public LongObserver.Builder longObserverBuilder(String name) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     return new NoopLongObserver.NoopBuilder();
   }

api/src/test/java/io/opentelemetry/metrics/DefaultMeterTest.java

@@ -56,6 +56,48 @@ public final class DefaultMeterTest {
     defaultMeter.longMeasureBuilder(null);
   }
 
+  @Test
+  public void noopAddDoubleCumulative_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.doubleCounterBuilder("");
+  }
+
+  @Test
+  public void noopAddLongCumulative_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.longCounterBuilder("");
+  }
+
+  @Test
+  public void noopAddMeasureDouble_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.doubleMeasureBuilder("");
+  }
+
+  @Test
+  public void noopAddMeasureLong_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.longMeasureBuilder("");
+  }
+
+  @Test
+  public void noopAddObserverDouble_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.doubleObserverBuilder("");
+  }
+
+  @Test
+  public void noopAddObserverLong_EmptyName() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    defaultMeter.longObserverBuilder("");
+  }
+
   @Test
   public void testVarargsLabelSetValidation_UnmatchedKeysAndValues() throws Exception {
     thrown.expect(IllegalArgumentException.class);

sdk/src/main/java/io/opentelemetry/sdk/metrics/AbstractInstrumentBuilder.java

@@ -48,7 +48,7 @@ abstract class AbstractInstrumentBuilder<B extends Instrument.Builder<B, V>, V>
       InstrumentationLibraryInfo instrumentationLibraryInfo) {
     Utils.checkNotNull(name, "name");
     Utils.checkArgument(
-        StringUtils.isPrintableString(name) && name.length() <= NAME_MAX_LENGTH,
+        StringUtils.isValidMetricName(name) && name.length() <= NAME_MAX_LENGTH,
         ERROR_MESSAGE_INVALID_NAME);
     this.name = name;
     this.meterSharedState = meterSharedState;

sdk/src/test/java/io/opentelemetry/sdk/metrics/AbstractInstrumentBuilderTest.java

@@ -55,6 +55,25 @@ public class AbstractInstrumentBuilderTest {
     new TestInstrumentBuilder(null, METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
   }
 
+  @Test
+  public void preventEmpty_Name() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    new TestInstrumentBuilder("", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+  }
+
+  @Test
+  public void checkCorrect_Name() {
+    new TestInstrumentBuilder("a", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+    new TestInstrumentBuilder("METRIC_name", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+    new TestInstrumentBuilder("metric.name_01", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+    new TestInstrumentBuilder("metric_name.01", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name");
+    new TestInstrumentBuilder(
+        "01.metric_name_01", METER_SHARED_STATE, INSTRUMENTATION_LIBRARY_INFO);
+  }
+
   @Test
   public void preventNonPrintableName() {
     thrown.expect(IllegalArgumentException.class);