lib: eliminate gauge applyDelta

Author: Qard

doc/api/metrics.md

@@ -115,7 +115,6 @@ import { memoryUsage } from 'node:process';
 const memory = gauge('memory.usage.bytes');
 
 memory.reset(memoryUsage().heapUsed);
-memory.applyDelta(1024);  // Add 1024 to current value
 ```
 
 ### `metrics.timer(name[, meta])`
@@ -450,26 +449,6 @@ memory.reset(memoryUsage().heapUsed); // Set to current memory usage
 memory.reset(1024, { source: 'system' }); // Set to 1024 with metadata
 ```
 
-#### `gauge.applyDelta(delta[, meta])`
-
-<!-- YAML
-added: REPLACEME
--->
-
-* `delta` {number} The amount to add to the current value.
-* `meta` {Object} Additional metadata for this report.
-
-Adds a delta to the current value and reports the new value.
-
-```mjs
-import { gauge } from 'node:metrics';
-
-const cpuUsage = gauge('cpu.usage.percent');
-
-cpuUsage.applyDelta(5); // Increase by 5
-cpuUsage.applyDelta(-2, { source: 'system' }); // Decrease by 2 with metadata
-```
-
 ### Class: `Timer`
 
 * Extends: {metrics.Gauge}

lib/metrics.js

@@ -218,25 +218,34 @@ class Metric {
  * reset() is called, or when applyDelta() is called with a non-zero value.
  */
 class Gauge {
+  #metric;
+  #value;
+
+  /**
+   * @param {Metric} metric The metric to report to.
+   */
+  constructor(metric) {
+    if (!(metric instanceof Metric)) {
+      throw new ERR_INVALID_ARG_TYPE('metric', ['Metric'], metric);
+    }
+    this.#metric = metric;
+    this.#value = 0;
+  }
+
   /**
    * The metric to report to.
    * @property {Metric} metric
    */
+  get metric() {
+    return this.#metric;
+  }
 
   /**
    * The value of the gauge.
    * @property {number} value
    */
-
-  /**
-   * @param {Metric} metric The metric to report to.
-   */
-  constructor(metric) {
-    if (!(metric instanceof Metric)) {
-      throw new ERR_INVALID_ARG_TYPE('metric', ['Metric'], metric);
-    }
-    this.metric = metric;
-    this.value = 0;
+  get value() {
+    return this.#value;
   }
 
   /**
@@ -245,18 +254,9 @@ class Gauge {
    * @param {object} [meta] Additional metadata to include with the report.
    */
   reset(value = 0, meta) {
-    this.value = value;
+    this.#value = value;
     this.metric.report(value, meta);
   }
-
-  /**
-   * Apply a delta to the gauge.
-   * @param {number} value The delta to apply to the gauge.
-   * @param {object} [meta] Additional metadata to include with the report.
-   */
-  applyDelta(value, meta) {
-    this.reset(this.value + value, meta);
-  }
 }
 
 /**
@@ -276,7 +276,7 @@ class Counter extends Gauge {
       n = 1;
     }
 
-    this.applyDelta(n, meta);
+    this.reset(this.value + n, meta);
   }
 
   /**
@@ -292,7 +292,7 @@ class Counter extends Gauge {
       n = 1;
     }
 
-    this.applyDelta(-n, meta);
+    this.reset(this.value + -n, meta);
   }
 }
 

test/parallel/test-metrics-gauge.js

@@ -19,7 +19,6 @@ assert.strictEqual(metric.channelName, 'metrics:gauge:test');
 
 const messages = [
   [123, { base: 'test', meta: 'first' }],
-  [357, { base: 'test', meta: 'second' }],
   [0, { base: 'test' }],
 ];
 
@@ -32,8 +31,7 @@ subscribe(metric.channelName, common.mustCall((report) => {
   const [value, meta] = messages.shift();
   assert.strictEqual(report.value, value);
   assert.deepStrictEqual(report.meta, meta);
-}, 3));
+}, 2));
 
 testGauge.reset(123, { meta: 'first' });
-testGauge.applyDelta(234, { meta: 'second' });
 testGauge.reset();