Metrics updates (open-telemetry#1700)

* feat: renaming batcher to processor, fixing aggregators, adding missing metrics in api

* chore: fixing metrics in exporter collector, updated tests, fixing observer result

* chore: refactoring tests for rest of collectors

* chore: fixing monotonic sum observer, updated test to cover that scenario correctly

api/src/metrics/Meter.ts

@@ -23,6 +23,8 @@ import {
   BatchObserver,
   BatchMetricOptions,
   UpDownCounter,
+  SumObserver,
+  UpDownSumObserver,
 } from './Metric';
 import { ObserverResult } from './ObserverResult';
 
@@ -81,6 +83,30 @@ export interface Meter {
     callback?: (observerResult: ObserverResult) => void
   ): ValueObserver;
 
+  /**
+   * Creates a new `SumObserver` metric.
+   * @param name the name of the metric.
+   * @param [options] the metric options.
+   * @param [callback] the observer callback
+   */
+  createSumObserver(
+    name: string,
+    options?: MetricOptions,
+    callback?: (observerResult: ObserverResult) => void
+  ): SumObserver;
+
+  /**
+   * Creates a new `UpDownSumObserver` metric.
+   * @param name the name of the metric.
+   * @param [options] the metric options.
+   * @param [callback] the observer callback
+   */
+  createUpDownSumObserver(
+    name: string,
+    options?: MetricOptions,
+    callback?: (observerResult: ObserverResult) => void
+  ): UpDownSumObserver;
+
   /**
    * Creates a new `BatchObserver` metric, can be used to update many metrics
    * at the same time and when operations needs to be async

api/src/metrics/NoopMeter.ts

@@ -26,6 +26,7 @@ import {
   BatchObserver,
   UpDownCounter,
   BaseObserver,
+  UpDownSumObserver,
 } from './Metric';
 import {
   BoundValueRecorder,
@@ -84,6 +85,34 @@ export class NoopMeter implements Meter {
     return NOOP_VALUE_OBSERVER_METRIC;
   }
 
+  /**
+   * Returns constant noop sum observer.
+   * @param name the name of the metric.
+   * @param [options] the metric options.
+   * @param [callback] the sum observer callback
+   */
+  createSumObserver(
+    _name: string,
+    _options?: MetricOptions,
+    _callback?: (observerResult: ObserverResult) => void
+  ): ValueObserver {
+    return NOOP_SUM_OBSERVER_METRIC;
+  }
+
+  /**
+   * Returns constant noop up down sum observer.
+   * @param name the name of the metric.
+   * @param [options] the metric options.
+   * @param [callback] the up down sum observer callback
+   */
+  createUpDownSumObserver(
+    _name: string,
+    _options?: MetricOptions,
+    _callback?: (observerResult: ObserverResult) => void
+  ): UpDownSumObserver {
+    return NOOP_UP_DOWN_SUM_OBSERVER_METRIC;
+  }
+
   /**
    * Returns constant noop batch observer.
    * @param name the name of the metric.