atomicreference+atomiclong

Author: fandreuz

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/aggregator/DoubleLastValueAggregator.java

@@ -22,7 +22,9 @@
 import io.opentelemetry.sdk.resources.Resource;
 import java.util.Collection;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Supplier;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
@@ -113,8 +115,8 @@ public MetricData toMetricData(
   }
 
   static final class Handle extends AggregatorHandle<DoublePointData, DoubleExemplarData> {
-    private final AtomicBoolean set = new AtomicBoolean(false);
-    private volatile double current = 0;
+    private final AtomicReference<AtomicLong> current = new AtomicReference<>(null);
+    private final AtomicLong valueBits = new AtomicLong();
 
     // Only used when memoryMode is REUSABLE_DATA
     @Nullable private final MutableDoublePointData reusablePoint;
@@ -135,27 +137,22 @@ protected DoublePointData doAggregateThenMaybeReset(
         Attributes attributes,
         List<DoubleExemplarData> exemplars,
         boolean reset) {
-      double currentLocal = current;
-      if ((reset && !set.compareAndSet(true, false)) || (!reset && !set.get())) {
-        throw new NullPointerException();
-      }
-
-      DoublePointData output;
+      AtomicLong valueBits =
+          Objects.requireNonNull(reset ? this.current.getAndSet(null) : this.current.get());
+      double value = Double.longBitsToDouble(valueBits.get());
       if (reusablePoint != null) {
-        reusablePoint.set(startEpochNanos, epochNanos, attributes, currentLocal, exemplars);
-        output = reusablePoint;
+        reusablePoint.set(startEpochNanos, epochNanos, attributes, value, exemplars);
+        return reusablePoint;
       } else {
-        output =
-            ImmutableDoublePointData.create(
-                startEpochNanos, epochNanos, attributes, currentLocal, exemplars);
+        return ImmutableDoublePointData.create(
+            startEpochNanos, epochNanos, attributes, value, exemplars);
       }
-      return output;
     }
 
     @Override
     protected void doRecordDouble(double value) {
-      current = value;
-      set.set(true);
+      valueBits.set(Double.doubleToLongBits(value));
+      current.compareAndSet(null, valueBits);
     }
   }
 }