Adopt asynchronous helpers in Cassandra target script (#21)

Author: rmfitzpatrick

contrib/jmx-metrics/README.md

@@ -28,7 +28,7 @@ otel.jmx.password = my-password
 def storageLoadMBean = otel.mbean("org.apache.cassandra.metrics:type=Storage,name=Load")
 otel.instrument(storageLoadMBean, "cassandra.storage.load",
         "Size, in bytes, of the on disk data size this node manages",
-        "By", "Count", otel.&longValueRecorder
+        "By", "Count", otel.&longValueObserver
 )
 ```
 

contrib/jmx-metrics/docs/target-systems/cassandra.md

@@ -10,118 +10,118 @@ These metrics are sourced from Cassandra's exposed Dropwizard Metrics for each n
 * Name: `cassandra.client.request.range_slice.latency.50p`
 * Description: Token range read request latency - 50th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.range_slice.latency.99p`
 * Description: Token range read request latency - 99th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.range_slice.latency.count`
 * Description: Total token range read request latency
 * Unit: `µs`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.range_slice.latency.max`
 * Description: Maximum token range read request latency
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.range_slice.timeout.count`
 * Description: Number of token range read request timeouts encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.range_slice.unavailable.count`
 * Description: Number of token range read request unavailable exceptions encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.read.latency.50p`
 * Description: Standard read request latency - 50th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.read.latency.99p`
 * Description: Standard read request latency - 99th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.read.latency.count`
 * Description: Total standard read request latency
 * Unit: `µs`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.read.latency.max`
 * Description: Maximum standard read request latency
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.read.timeout.count`
 * Description: Number of standard read request timeouts encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.read.unavailable.count`
 * Description: Number of standard read request unavailable exceptions encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.write.latency.50p`
 * Description: Regular write request latency - 50th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.write.latency.99p`
 * Description: Regular write request latency - 99th percentile
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.write.latency.count`
 * Description: Total regular write request latency
 * Unit: `µs`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.write.latency.max`
 * Description: Maximum regular write request latency
 * Unit: `µs`
-* Instrument Type: DoubleUpDownCounter
+* Instrument Type: DoubleValueObserver
 
 * Name: `cassandra.client.request.write.timeout.count`
 * Description: Number of regular write request timeouts encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.client.request.write.unavailable.count`
 * Description: Number of regular write request unavailable exceptions encountered
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 ### Compaction Metrics
 
 * Name: `cassandra.compaction.tasks.completed`
 * Description: Number of completed compactions since server [re]start
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.compaction.tasks.pending`
 * Description: Estimated number of compactions remaining to perform
 * Unit: `1`
-* Instrument Type: LongUpDownCounter
+* Instrument Type: LongValueObserver
 
 ### Storage Metrics
 
 * Name: `cassandra.storage.load.count`
 * Description: Size of the on disk data size this node manages
 * Unit: `by`
-* Instrument Type: LongUpDownCounter
+* Instrument Type: LongValueObserver
 
 * Name: `cassandra.storage.total_hints.count`
 * Description: Number of hint messages written to this node since [re]start
 * Unit: `1`
-* Instrument Type: LongCounter
+* Instrument Type: LongSumObserver
 
 * Name: `cassandra.storage.total_hints.in_progress.count`
 * Description: Number of hints attempting to be sent currently
 * Unit: `1`
-* Instrument Type: LongUpDownCounter
+* Instrument Type: LongValueObserver