Fix NPE when using CGroup metrics with no cpu limit

Author: rob-bygrave

metrics/pom.xml

@@ -20,6 +20,12 @@
       <version>1.0</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.jspecify</groupId>
+      <artifactId>jspecify</artifactId>
+      <version>1.0.0</version>
+    </dependency>
+
     <dependency>
       <groupId>io.avaje</groupId>
       <artifactId>junit</artifactId>

metrics/src/main/java/io/avaje/metrics/Timer.java

@@ -1,5 +1,7 @@
 package io.avaje.metrics;
 
+import org.jspecify.annotations.Nullable;
+
 import java.util.function.Supplier;
 
 /**
@@ -122,7 +124,7 @@ public interface Timer extends Metric {
   /**
    * Return the bucket range or empty string if not a bucket.
    */
-  String bucketRange();
+  @Nullable String bucketRange();
 
   /**
    * Statistics collected by Timer.
@@ -132,7 +134,7 @@ interface Stats extends Meter.Stats {
     /**
      * Return the bucket range for these statistics.
      */
-    default String bucketRange() {
+    default @Nullable String bucketRange() {
       return null;
     }
   }

metrics/src/main/java/io/avaje/metrics/core/BaseReportName.java

@@ -1,11 +1,12 @@
 package io.avaje.metrics.core;
 
 import io.avaje.metrics.Metric;
+import org.jspecify.annotations.Nullable;
 
 abstract class BaseReportName {
 
   final String name;
-  String reportName;
+  @Nullable String reportName;
 
   BaseReportName(String name) {
     this.name = name;

metrics/src/main/java/io/avaje/metrics/core/DBucketTimer.java

@@ -1,6 +1,7 @@
 package io.avaje.metrics.core;
 
 import io.avaje.metrics.Timer;
+import org.jspecify.annotations.Nullable;
 
 import java.util.function.Supplier;
 
@@ -27,7 +28,7 @@ public String toString() {
   }
 
   @Override
-  public String bucketRange() {
+  public @Nullable String bucketRange() {
     return null;
   }
 

metrics/src/main/java/io/avaje/metrics/core/DCounter.java

@@ -20,7 +20,6 @@ final class DCounter extends BaseReportName implements Counter {
    * <p>
    * The rateUnit should be chosen to 'scale' the statistics in a reasonable
    * manor - typically events per hour, minute or second.
-   * </p>
    */
   DCounter(String name) {
     super(name);

metrics/src/main/java/io/avaje/metrics/core/DTimer.java

@@ -1,6 +1,7 @@
 package io.avaje.metrics.core;
 
 import io.avaje.metrics.Timer;
+import org.jspecify.annotations.Nullable;
 
 import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
@@ -14,7 +15,7 @@
 final class DTimer implements Timer {
 
   private final String name;
-  private final String bucketRange;
+  private final @Nullable String bucketRange;
   private final ValueCounter successCounter;
   private final ValueCounter errorCounter;
 
@@ -38,7 +39,7 @@ public String toString() {
   }
 
   @Override
-  public String bucketRange() {
+  public @Nullable String bucketRange() {
     return bucketRange;
   }
 

metrics/src/main/java/io/avaje/metrics/core/DTimerEvent.java

@@ -25,7 +25,7 @@ final class DTimerEvent implements Timer.Event {
 
   @Override
   public String toString() {
-    return metric.toString() + " durationMillis:" + duration();
+    return metric + " durationMillis:" + duration();
   }
 
   /**

metrics/src/main/java/io/avaje/metrics/core/DefaultMetricProvider.java

@@ -4,8 +4,6 @@
 import io.avaje.metrics.spi.SpiMetricBuilder;
 import io.avaje.metrics.spi.SpiMetricProvider;
 
-import java.io.IOException;
-import java.io.UncheckedIOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;

metrics/src/main/java/io/avaje/metrics/core/FileLines.java

@@ -1,5 +1,8 @@
 package io.avaje.metrics.core;
 
+import io.avaje.applog.AppLog;
+import org.jspecify.annotations.Nullable;
+
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
@@ -12,7 +15,7 @@
 
 final class FileLines {
 
-  private static final System.Logger log = System.getLogger("io.avaje.metrics");
+  private static final System.Logger log = AppLog.getLogger("io.avaje.metrics");
 
   private final File file;
 
@@ -65,7 +68,7 @@ List<String> readLines() {
     }
   }
 
-  private String readLine() {
+  private @Nullable String readLine() {
     try {
       try (LineNumberReader lineReader = new LineNumberReader(new FileReader(file))) {
         return lineReader.readLine();

metrics/src/main/java/io/avaje/metrics/core/JsonWriter.java

@@ -1,6 +1,7 @@
 package io.avaje.metrics.core;
 
 import io.avaje.metrics.*;
+
 import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.text.DecimalFormat;
@@ -114,7 +115,7 @@ public void visit(GaugeLong.Stats metric) {
 
   private void writeSummary(Meter.Stats valueStats) throws IOException {
     // valueStats == null when BucketTimedMetric and the bucket is empty
-    long count = (valueStats == null) ? 0 : valueStats.count();
+    long count = valueStats.count();
     writeKeyNumber("count", count);
     if (count != 0) {
       buffer.append(",");