otel: add LongUpDownCounterMetricInstrument

Author: AgraVator

core/src/main/java/io/grpc/internal/MetricRecorderImpl.java

@@ -26,6 +26,7 @@
 import io.grpc.LongCounterMetricInstrument;
 import io.grpc.LongGaugeMetricInstrument;
 import io.grpc.LongHistogramMetricInstrument;
+import io.grpc.LongUpDownCounterMetricInstrument;
 import io.grpc.MetricInstrument;
 import io.grpc.MetricInstrumentRegistry;
 import io.grpc.MetricRecorder;
@@ -82,7 +83,7 @@ public void addDoubleCounter(DoubleCounterMetricInstrument metricInstrument, dou
    * Records a long counter value.
    *
    * @param metricInstrument the {@link LongCounterMetricInstrument} to record.
-   * @param value the value to record.
+   * @param value the value to record. Must be non-negative.
    * @param requiredLabelValues the required label values for the metric.
    * @param optionalLabelValues the optional label values for the metric.
    */
@@ -103,6 +104,32 @@ public void addLongCounter(LongCounterMetricInstrument metricInstrument, long va
     }
   }
 
+  /**
+   * Adds a long up down counter value.
+   *
+   * @param metricInstrument    the {@link io.grpc.LongUpDownCounterMetricInstrument} to record.
+   * @param value               the value to record. May be positive, negative or zero.
+   * @param requiredLabelValues the required label values for the metric.
+   * @param optionalLabelValues the optional label values for the metric.
+   */
+  @Override
+  public void addLongUpDownCounter(LongUpDownCounterMetricInstrument metricInstrument, long value,
+                                   List<String> requiredLabelValues,
+                                   List<String> optionalLabelValues) {
+    MetricRecorder.super.addLongUpDownCounter(metricInstrument, value, requiredLabelValues,
+        optionalLabelValues);
+    for (MetricSink sink : metricSinks) {
+      int measuresSize = sink.getMeasuresSize();
+      if (measuresSize <= metricInstrument.getIndex()) {
+        // Measures may need updating in two cases:
+        // 1. When the sink is initially created with an empty list of measures.
+        // 2. When new metric instruments are registered, requiring the sink to accommodate them.
+        sink.updateMeasures(registry.getMetricInstruments());
+      }
+      sink.addLongUpDownCounter(metricInstrument, value, requiredLabelValues, optionalLabelValues);
+    }
+  }
+
   /**
    * Records a double histogram value.
    *